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artikel, rapport, Reporting and intrepretation of results: Luminescence and radiocarbon dating of potsherds from Sino-Swedish expedition, Alashan Gobi desert, Inner Mongolia
1.3.0 2026-04-08 artikel, rapport, Reporting and intrepretation of results: Luminescence and radiocarbon dating of potsherds from Sino-Swedish expedition, Alashan Gobi desert, Inner Mongolia Rådata 615418 arkivdokument Statens museer för världskultur - Östasiatiska museet SMVK-OM Dokument http://kulturarvsdata.se/SMVK-OM/arkivdokument/615418 2012-Janz, K-13203-011, K-13207-006, K-13207-010, K-13203-006, K-13203-008, K-13207-002, K-13248-003, K-13298-001, K-13212-006, K-13248-006, K-13203-002, K-13207-003, K-13207-009, K-13248-005, K-13203-003, K-13207-007, K-13212-123, K-13248-008, K-13203-004, K-13207-004, K-13212-001, K-13298-015, K-13203-007, K-13203-010, K-13207-001, K-13207-005, K-13207-008, K-13212-128, K-13298-025, K-13203-001, K-13203-009 Artikel/rapport av Lisa Janz om resultatet av analyser av keramikskärvor från Inre Mongoliet som samlades in av Folke Bergman under fjärde Hedinexpeditionen. Ten ceramic sherds1 were selected from Folke Bergman’s archaeological collections held at the Museum of Far Eastern Antiquities. These samples were all drawn from collections made in the Alashan Gobi during Sven Hedin’s scientific expedition in the north-western provinces of China between 1927 and 1935. Eight were dated using luminescence dating techniques and one was dated using radiocarbon. The remaining sherd was significant because had remnants of molten metal on one surface. I originally intended to take a thin section of this sherd and have a colleague undertake microscopic analysis to determine the chemical composition of the metal. However, my colleague became disinterested in doing so when he discovered that the artefact was found in the context of a surface scatter. He did visually examine the sherd under a microscope and told me that the metal was certainly copper, rather than bronze. No further information was available and the whole specimen is being returned with this report. Prior to this study, Chikhen Agui, a cave site in the Gobi-Altai mountains (Derevianko et al., 2003), was the only dated post-glacial archaeological site in the Gobi Desert. The purpose of this analysis was to acquire chronometric dates for some of the numerous archaeological assemblages collected in the Gobi Desert. Large collections of Stone Age material from Mongolia and China were collected and removed to Western museums in the 1920s and 1930s by Sven Hedin’s and Roy Chapman Andrews’ scientific expeditions. A brief surge of publication and descriptive analysis ensued during the early part of the 20th century. However, the political climate increasingly disallowed any further research by Western scholars and the collections were largely ignored until the collapse of the Soviet Union. (för fortsättning, se rapporten), REPORTING AND INTREPRETATION OF RESULTS: LUMINESCENCE AND RADIOCARBON DATING OF POTSHERDS FROM SINO-SWEDISH EXPEDITION, ALASHAN GOBI DESERT, INNER MONGOLIA Lisa Janz, PhD Research Associate School of Anthropology University of Arizona Tucson, United States LJANZ@email.arizona.edu +1 510 223 5866/+1 520 271 5242 October 5, 2012 Introduction Ten ceramic sherds 1 were selected from Folke Bergman’s archaeological collections held at the Museum of Far Eastern Antiquities. These samples were all drawn from collections made in the Alashan Gobi during Sven Hedin’s scientific expedition in the north-western provinces of China between 1927 and 1935. Eight were dated using luminescence dating techniques and one was dated using radiocarbon. The remaining sherd was significant because had remnants of molten metal on one surface. I originally intended to take a thin section of this sherd and have a colleague undertake microscopic analysis to determine the chemical composition of the metal. However, my colleague became disinterested in doing so when he discovered that the artefact was found in the context of a surface scatter. He did visually examine the sherd under a microscope and told me that the metal was certainly copper, rather than bronze. No further information was available and the whole specimen is being returned with this report. Prior to this study, Chikhen Agui, a cave site in the Gobi-Altai mountains (Derevianko et al., 2003), was the only dated post-glacial archaeological site in the Gobi Desert. The purpose of this analysis was to acquire chronometric dates for some of the numerous archaeological assemblages collected in the Gobi Desert. Large collections of Stone Age material from Mongolia and China were collected and removed to Western museums in the 1920s and 1930s by Sven Hedin’s and Roy Chapman Andrews’ scientific expeditions. A brief surge of publication and descriptive analysis ensued during the early part of the 20 th century. However, the political climate increasingly disallowed any further research by Western scholars and the collections were largely ignored until the collapse of the Soviet Union. Despite a renewed interest in the archaeology of the Gobi Desert, a disciplinary preference for fieldwork has contributed to continued disinterest. The collections were easily dismissed as “biased” and “undateable” due to the fact that they were collected from surface contexts; however, fieldwork has so far proven inadequate in reconstructing a chronology for Gobi Desert prehistory. Until now our knowledge of the Gobi Desert has consisted primarily of the understanding that post- glacial habitation was centered in dune-fields and around former wetlands, with sites post-dating the Last Glacial Maximum (ca. 18,000 year ago) and pre-dating the Bronze Age (ca. 1500 BC or 3500 years ago in Mongolia). 1 Ostrich eggshell fragments and broken eggshell beads were also selected for dating, but were generally much older than the archaeological sites with which they were associated. A separate report on these results was filed with the Museum of Far Eastern Antiquities in February 2010. The dating of these specimens, which are part of the collections made by Folke Bergman and described by Maringer (1950), was part of a larger project aimed at building a foundational chronology of technology and land-use for the prehistory of the Gobi Desert. Additional samples were selected from those housed at the American Museum of Natural History (AMNH), which were collected during Andrews’ Central Asiatic Expeditions. A complete description of this project is available in my doctoral dissertation, entitled The Chronology of Post-Glacial Settlement in the Gobi Desert and the Neolithization of Arid Mongolia and China. A copy of this work has been included, Dottore-namak, K. 13248: 1-14 The estimated age of site is ca. 500 BC, contemporary with the early Iron Age in China. Nomadic pastoralism was established across Northeast Asia at this time. Debitage from microblade manufacture and other stone tool manufacture detritus was found in this group, suggesting the continuation of stone tool working amongst Gobi Desert peoples, in combination with copper or bronze casting. High-fired red-ware was still being used, but appears to have been more coarsely manufactured by this time. K13248: 5 UW2356 2.15 + 0.31 ka 140 + 310 BC (470 BC – AD 170) K13248: 6 (not pictured, but similar appearance to K13248: 5) UW2355 2.74 + 0.23 ka 730 + 230 BC (960-500 BC) K. 13248: 3 Undated, diagnostic potsherd. K13248: 8 Visual microscopic examination by Dr. David Killick, School of Anthropology, University of Arizona (Tucson, United States). Droplets of copper melted copper onto over-fired potsherd, probably on exterior surface. This potsherd was an unusual specimen and destructive analysis was not used to obtain dates. It has been returned to the Museum of Far Eastern Antiquities along with this destructive analysis report and a copy of my dissertation thesis on the Gobi Desert materials (Janz, 2012). Mantissar 12, K. 13298: 1-61 According to the luminescence dates (see below), this site assemblage comprises artefacts from different time periods, including components contemporary with both the Neolithic and the early Bronze Age of China. This site assemblage, like many of the site assemblages from the Gurnai Depression, contains red, thin-walled and high-fired potsherds painted with black geometric and curvilinear designs. These are comparable to Majiayao designs and probably also date to the Late Neolithic. Palaeontologist B. Bohlin made archaeological collections in the Gurnai Depression at the end of 1932. The site was collected on October 22. Bohlin reported a series of nearly uninterrupted prehistoric sites along the whole approximately 100 km stretch of dune belt, mostly “from the terrain between the saxual belt and reed territory” (see Maringer, 1950: 151- 163). Fragmentary remains from the manufacture of ostrich eggshell beads were also unusually common amongst these sites (K. 13277-13319). K13298: 15 Textile impressed pottery with deep cord markings. UW2362 6.48 + 0.71 ka 4470 + 710 BC (5180-3760 BC) K13298: 25 Burnished pottery. UW2359 3.85 + 0.34 ka 1840 + 340 BC (2180-1500 BC) APPENDIX B. LUMINESCENCE ANALYSIS OF CERAMICS FROM MONGOLIA AND NORTHWEST CHINA Prepared by: James Feathers Luminescence Dating Laboratory University of Washington Box 353412 Seattle, WA 98195-3412 jimf@u.washington.edu Thirteen ceramic sherds from several sites in the desert areas of Mongolia and northwestern China, were submitted for luminescence analysis by Lisa Janz, University of Arizona. The sherds were collected in the 1920s and 1930s from sand dune blow-outs and were stored in museums since then. No associated sediment samples were available to assess the external dose rates, nor are the original burial depths known. This will be discussed later. Table 1 lists the sample and site numbers. Laboratory procedures are given under subheading “Methods.” Table 1. Provenience UW lab # Archaeological designation Site UW2355 K13248:6 Olon-toroi UW2356 K13248:5 Olon-toroi UW2357 K13212:123 Yingen-khuduk UW2358 K13212:6 Yingen-khuduk UW2359 K13298:25 Mantissar UW2360 K13212:128 Yingen-khuduk UW2361 K13203:5 Jabochin-khure UW2362 K13298:15 Mantissar UW2450 73/2237B Baron Shabaka Well UW2451 73/1190A Shabarakh-usu UW2452 73/1791K Orok Nor UW2453 73/890A Shabarakh-usu UW2454 73/1608D Arts Bogd-Ulan Nor Plain Dose rate -- Dose rate measurements were made on each ceramic,, -value** UW2355 260-380 1.0 Quadratic 14.5±4.2 UW2356 320-430 1.50±0.18 Linear 9.4±2.5 UW2357 250-420 0.52±0.16 Linear No test UW2358 250-420 1.0 Quadratic 10.4±2.9 UW2359 250-400 1.0 Linear No test UW2360 250-370 1.0 Linear 9.2±4.2 UW2361 250-310 13.7±7.2 Linear 11.8±9.0 UW2362 300-370 1.54±0.09 Linear 0.5±1.5 UW2450 250-430 1.29±0.14 Linear 5.7±1.0 UW2451 250-400 0.41±0.07 Linear 13.5±2.2 UW2452 250-420 0.54±0.07 Linear 9.0±3.3 UW2453 310-380 1.0 Quadratic 2.6±2.1 UW2454 280-330 0.65±0.05 Linear 8.5±1.4 *Refers to slope ratio between the first and second glow growth curves. A glow refers to luminescence as a function of temperature; a second glow comes after heating to 450°C. **g-value is the fading rate expressed as % per decade, where a decade is a power of 10. OSL/IRSL was measured on from 3 to 6 aliquots per sample (Table 4). Scatter among aliquots was generally low with derived over-dispersion in OSL of less than 6% for all but two samples. Dose recovery was within 1-sigma of the given dose for all but two samples. The OSL signal was from 3 to 100 times larger than the IRSL signal. This is normal for ceramics, and in cases where the OSL signal is much larger (say more than 10 times), feldspars (which are sensitive to IR stimulation and which are often subject to anomalous fading) probably do not contribute much to the OSL signal. The latter is therefore likely dominated by quartz, which suggests the OSL signal does not fade appreciably. Fading of the OSL signal is more likely when the OSL signal is only 3 or 4 times as large as the IRSL signal. Equivalent dose values are given in Table 5. They differ in value, even if they yield the same age, because of variation in b- value (also given in Table 5), which is a measure of alpha efficiency in producing luminescence. The b-value for quartz is around 0.4-0.6, while the b-value for feldspar is much higher. Low b- values for OSL means the signal is dominated by quartz and thus not likely to fade. (Fading tests were not run on IRSL or OSL because of exorbitant machine time.) Table 4. OSL/IRSL data Sample # aliquots* Over-dispersion (%) Dose Recovery (OSL) Approx. OSL/IRSL signal ratio OSL IRSL OSL IRSL Given Dose (sß) Recovered Dose (sß) UW2355 6 5 0 0 60 53.3±4.0 8 UW2356 6 4 31.9±11.4 0 80 70.0±13.2 4 UW2357 3 4 2.8±3.8 14.1±6.2 60 59.0±3.7 4 UW2358 6 6 0 0 200 174.9±7.2 13 UW2359 4 3 9.1±4.4 0 60 61.5±2.4 10 UW2360 5 5 5.6±2.4 8.2±4.1 60 58.2±2.2 12 UW2361 6 2.5±1.9 20 20.8±0.8 No IRSL UW2362 5 5 0 4.1±7.6 150 150.6±10.7 4 UW2450 4 4 0 0 40 39.1±6.8 20 UW2451 6 6 0 6.1±5.0 100 105.3±5.6 7 UW2452 6 6 3.3±2.2 0 200 188.7±7.5 40 UW2453 5 6 0 18.7±7.0 200 194.2±6.6 100 UW2454 6 5 0 0 40 38.8±5.0 3 * Denotes number of aliquots with measurable signals. Table 4. Equivalent dose Sample Equivalent dose (Gy) b-value (Gy µm 2 ) TL IRSL OSL TL IRSL OSL UW2355 6.83±0.54 10.86±0.89 11.46±0.27 0.90±0.12 1.90±0.30 0.61±0.04 UW2356 9.31±1.21 4.22±0.38 9.39±1.36 1.35±0.17 1.55±0.09 1.06±0.08 UW2357 19.72±2.70 17.03±1.35 19.66±0.59 1.23±0.16 0.95±0.05 1.30±0.04 UW2358 12.06±1.19 11.83±1.39 15.51±0.27 0.66±0.05 1.04±0.06 0.51±0.02 UW2359 18.4±9.5* 17.17±1.66 22.08±1.17 1.60±1.05 1.64±0.16 0.53±0.02 UW2360 23.20±2.22 14.37±0.66 13.72±0.40 3.74±0.86 1.33±0.05 1.08±0.03 UW2361 4.14±1.70* 20.93±0.35 1.88±0.73 1.10±0.30 0.54±0.04 UW2362 25.16±1.36 13.07±0.58 16.55±0.46 1.07±0.06 1.08±0.06 1.44±0.07 UW2450 4.79±0.40 2.53±0.24 3.63±0.32 2.06±0.20 1.62±0.20 0.81±0.10 UW2451 58.2±10.8 14.49±0.61 21.64±0.50 1.00±0.21 1.41±0.06 1.28±0.12 UW2452 14.40±1.22 7.44±0.45 7.46±0.15 2.74±0.43 0.95±0.04 0.75±0.02 UW2453 43.92±1.59 30.57±2.66 27.61±0.44 1.19±0.12 0.94±0.07 0.52±0.01 UW2454 5.04±0.35 4, Material is drilled from the center of the cross- section, more than 2 mm from either surface, using a tungsten carbide drill tip. The material retrieved is ground gently by a corundum mortar and pestle, treated with HCl, and then settled in acetone for 2 and 20 minutes to separate the 1-8 µm fraction. This is settled onto a maximum of 72 stainless steel discs. Glow-outs Thermoluminescence is measured by a Daybreak reader using a 9635Q photomultiplier with a Corning 7-59 blue filter, in N2 atmosphere at 1°C/s to 450°C. A preheat of 240°C with no hold time precedes each measurement. Artificial irradiation is given with a 241 Am alpha source and a 90 Sr beta source, the latter calibrated against a 137 Cs gamma source. Discs are stored at room temperature for at least one week after irradiation before glow out. Data are processed by Daybreak TLApplic software. Fading test Several discs are used to test for anomalous fading. The natural luminescence is first measured by heating to 450°C. The discs are then given an equal alpha irradiation and stored at room temperature for varied times: 10 min, 2 hours, 1 day, 1 week and 8 weeks. The irradiations are staggered in time so that all of the second glows are performed on the same day. The second glows are normalized by the natural signal and then compared to determine any loss of signal with time (on a log scale). If the sample shows fading and the signal versus time values can be reasonably fit to a logarithmic function, an attempt is made to correct the age following procedures recommended by Huntley and Lamothe (2001). The fading rate is calculated as the g-value, which is given in percent per decade, where decade represents a power of 10. Equivalent dose The equivalent dose is determined by a combination additive dose and regeneration (Aitken 1985). Additive dose involves administering incremental doses to natural material. A growth curve plotting dose against luminescence can be extrapolated to the dose axis to estimate an equivalent dose, but for pottery this estimate is usually inaccurate because of errors in extrapolation due to nonlinearity. Regeneration involves zeroing natural material by heating to 450°C and then rebuilding a growth curve with incremental doses. The problem here is sensitivity change caused by the heating. By constructing both curves, the regeneration curve can be used to define the extrapolated area and can be corrected for sensitivity change by comparing it with the additive dose curve. This works where the shapes of the curves differ only in scale (i.e., the sensitivity change is independent of dose). The curves are combined using the “Australian slide” method in a program developed by David Huntley of Simon Fraser University (Prescott et al. 1993). The equivalent dose is taken as the horizontal distance between the two curves after a scale adjustment for sensitivity change. Where the growth curves are not linear, they are fit to quadratic functions. Dose increments (usually five) are determined so that the maximum additive dose results in a signal about three times that of the natural and the maximum regeneration dose about five times the natural. If the regeneration curve has a significant negative intercept, which is not expected given current understanding, the additive dose intercept is taken as the best, if not fully reliable approximation. A plateau region is determined by calculating the equivalent dose at temperature increments between 240° and 450°C and determining over which temperature range the values do not differ significantly. This plateau region is compared with a similar one constructed for the b-value (alpha efficiency), and the overlap defines the integrated range for final analysis. Alpha effectiveness Alpha efficiency is determined by comparing additive dose curves using alpha and, 19 b BS 19 c BS 19 d BS 19 e CH 35 SC 16 Figure 1. Results of dates (cal yr BP or ka at the 2σ range of error) for the entire Gobi Desert sample. Luminescence dates are represented by much larger margins of error. Dates are shown in calibrated years before present rather than BC. Alashan Gobi Gobi-Altai East Gobi The earliest habitation sites in the Alashan Gobi date to about 6000 years ago, or about 4000 BC. Archaeological assemblages are characterized primarily by the use of pottery and small stone tools made from blade-like flakes. This type of stone technology became prevalent across Northeast Asia between 20,000 and 15,000 years ago. As sedentary agriculture emerged across the Central Plains of China, the use of “microblade” technology declined rapidly. Pottery has been used in Northeast Asia since at least 16,500 years ago (Keally et al., 2003) and the earliest pottery from the Gobi Desert (housed at the AMNH) has been dated to 9500 years ago (from Shara Khata Well in the East Gobi). Microblade tools and pottery continued to be used by mobile hunter-gatherers and some agriculturalists north of the Central Plains, but polished stone and bone tools were added to toolkits. Large grinding slabs, handstones and pestles were also found in some Gobi Desert assemblages, but larger such equipment is relatively rare outside of the East Gobi. Therefore, the general character of Gobi Desert technological suites is one of Northeast Asian hunter-gatherers influenced by the technological advances of more sedentary neighbours. Likewise, the presence of painted black-on-red pottery in several of the Alashan Gobi sites is notable and suggests the influence of neighbouring sedentary agriculturalists. Considering the geographical location of Gobi Desert hunter-gatherers – separating and straddling the territories of western nomadic pastoralists and eastern sedentary agriculturalists – it would be highly desirable to more closely investigate the role these groups played in the emergence of early trade networks and agro-pastoralism in China. Understanding the role of Gobi Desert hunter-gatherers in the larger Northeast Asian interaction sphere is also important in understanding the shift from a hunter-gatherer economy to a full-fledged nomadic pastoralist economy. By 1000 BC, burial and other ritual monuments testify to the dominance of nomadic pastoralism across Mongolia and northern China. At the same time, archaeological remains indicate continuity with earlier post-glacial hunter-gatherer cultures. This suggests that dune-field/wetland dwelling hunter-gatherers were either contemporaries of early nomadic pastoralist settlers, or were themselves being incorporated into a new wave of economic specialization focused on domesticated herd animals. Certain remains collected in the Alashan Gobi by Folke Bergman and others suggest that although Gobi Desert groups may have practiced a mixed economy dependant on hunting and gathering, they may also have had access to products more often associated with pastoralists – spindle whorls, slag, and geometric-incised pottery (similar to recent findings from the Dzhungar Basin in Kazhakstan- see Frachetti 2008: 166). Cowry shells from East Gobi sites further suggest that these groups were not isolated from a greater regional economy that included food producing neighbours. The seemingly ritualized production of stone beads in an inaccessible cave site (K. 13230) and the concentrated production of ostrich eggshell beads at sites from the Gurnai Depression add to a picture of internal culture change during Oasis 3. These collections represent one the most important resources for broad-scale identification of regional shifts in technology, land-use, and subsistence. The dates derived from these samples have offered invaluable information about the timing and, horse harnessing and milking. Science 323, 1332- 1335. Sampson, C. G., Bailiff, I., Barnett, S., 1997. Thermoluminescence dates from Later Stone Age Pottery on Surface Sites in the Upper Karoo. The South African Archaeological Bulletin, 52(165), 38-42. Wright, J., Honeychurch, W., Amartuvshin, C., 2007. Initial findings of the Baga Gazaryn Chuluu archaeological survey (2003-2006). Antiquity 81 (313). Online content. http://www.antiquity.ac.uk/projgall/wright313/ Appendix A. Details of Dated Artefacts and Site Assemblages Jabochin-khure, K. 13203: 1-11 It is not clear if this potsherd is contemporaneous with the rest of the artefacts in the K. 13203 site assemblage (Maringer, 1950: 138-139). However, the diagnostic quality of the decorative finish makes the luminescence date an important one for local chronology. This type of decoration can be described as “geometric-incised,” and is found on pottery from other sites in the Alashan Gobi and Gobi-Altai region of southern Mongolia, including Yingen-khuduk and Shabarakh-usu. Judging by the direct luminscence date on this artefact and dates on potsherds from other sites of a similar age, this type of decorative treatment was characteristic of the Late Neolithic to Early Bronze Age transition (ca. 3000 to 1000 BC according to Janz, 2012). K13203: 5 UW2361 3.51 + 0.30 ka 1500 + 300 BC (1800-1200 BC) Gashun Well, K. 13207: 1-34 The radiocarbon date for this potsherd also indicates that the site assemblage belongs to the Late Neolithic/ Early Bronze Age period and is contemporary with the majority of other Stone Age Gobi Desert sites, including, Jabochin-khure (above), components of Yingen-khuduk (below), and components of the famous Mongolian Shabarakh-usu locality (see Fairservis, 1993; Janz, 2012). The collection of artefacts is consistent with similarly aged sites (see Janz, 2012), but notable in that it contains many large stone tools made on brown jasper. These are probably unfinished adzes or axes. Similar stone specimens were recovered from Abderungtei (K. 13209: 128) and Mongol (K. 13210: 132). K13207: 1 AA91693 3385 + 40 BP 3634 + 48 cal yr BP/ 1684 + 48 BC (1732-1636 BC) Yingen-khuduk, K. 13212: 1-186 The three luminescence dates from this site correspond with a period spanning the end of the Yangshao to the Qijia periods in the Upper Yellow River Valley of China (Northwest China). More correctly, they date to two specific periods – the latter half of the Yangshao and the early part of the Qijia. Based on a study of Gobi Desert chronology, the habitation of the locality can be said to have occurred during both the early and late phases of intensive dune-field/wetland habitation – Oasis 2 and Oasis 3 (after Janz, 2012). The artefact assemblage, as compared to other Gobi Desert sites, is consistent with these dates (see Janz, 2012). Until more dates are available, it is impossible to say whether occupation of the dune-field/wetland habitat around Yingen-khuduk was relatively continuous, or whether individual occupation episodes were separated by millennia. High-fired, homogeneous red-ware appears to date more closely to the Machang or Qijia periods, than to the earlier Majiayao period (for comparison, see description of Mantissar sites, below). The “net-impressed” pottery (K. 13212: 123) is diagnostic of the early period of dune-field/wetland habitation in the Gobi Desert and has been collected from sites across the Gobi Desert (see Janz, 2012: Chapter 3). String-paddled pottery is roughly contemporaneous with that from Gashun Well (K. 13207). K13212: 6 UW2358 3.93 + 0.30 ka 1920 + 300 BC (2220-1620 BC) K13212: 123 UW2357 5.72 + 0.35 ka 3710 + 350 BC (4060-3360 BC) K13212: 128 UW2360 3.93 + 0.23 ka 1920 + 230 BC (2150-1690 BC), described herein and if the date had been affected by contamination from the exterior portion, it would be older rather than younger. For this particular specimen, the source of carbon was residue from burning on the vessel surface. Results The majority of artefacts date to the Neolithic-to-Bronze Age transition between 2000 and 1000 BC. Despite the large range of error, these dates are extremely significant because they indicate that the many of the site assemblages are much younger than previously thought (Maringer, 1963; Fairservis, 1992; Bettinger et al., 1994). Periods of earlier occupation are evident at Yingen-khuduk (K. 13212: 1-186) and Mantissar 12 (K. 13298: 14). Figure 1 illustrates how the range of dates from Alashan fits into the entire Gobi Desert-wide sample, including those from the AMNH collections. Based on these dates and changes in artefact-types, as outlined in Janz (2012), four key phases of Gobi Desert habitation can be synthesized for the prehistoric periods following the Last Glacial Maximum: Epipalaeolithic/Mesolithic dating from 11,500 to 6000 BC; the Neolithic, dating to between 6000 and 4000 BC; the Eneolithic/Late Neolithic/Neolithic-to- Bronze Age transition, dating from 4000 to 1000 BC; and the Metal Ages, post-dating 1000 BC. My dissertation establishes a regional nomenclature, by which the first three of these periods can be referred to as Oasis 1 (incipient), Oasis 2 (intensive), and Oasis 3 (transitional), respectively. Results from the entire sample are illustrated below in Figure 1. Dates from the Alashan Gobi are highly consistent with those derived from the Gobi-Altai region, which is the region directly north of the Alashan, in Mongolia. Collections from these two regions span the latter half of Oasis 2, but are mostly associated with Oasis 3 occupations. Although this may be a vagary of sampling, it might also suggest more intensive occupation during the terminal phase of dune-field/wetland habitation. So far, the earliest habitation sites have been found in the East Gobi region. This difference in the timing of dune-field/wetland habitation may be related to the establishment of high elevation and riparian forests (Janz, 2012: 343-351). Occurrence of Bronze Age and early Iron Age ceramics in assemblages collected in dune-field/wetland settings indicates that habitation of such environments continued into the Metal Ages, although it was not necessarily as intensive as during earlier periods. Survey data from the northern reaches of the Gobi Desert indicates that during the Metal Ages, the focus of human habitation shifted away from the low elevation wetlands towards the foothills (Wright et al., 2007). 2 This pretreatment is also known as an acid-base-acid (ABA) pretreatment. Lab. No. Cat. No. (K.13 or 73/) Site Method δ13C 14C age BP +- 1δ/ KA +- 1 δ KYA (cal. to 68% range) Range BC UW2361 203: 5 Jabochin- khure L 3510 +- 300 4.11-2.91 1800-1200 AA91693 207: 1 Gashun Well AMS -32.4 3385 +- 40 3.59-3.68 1732-1636 UW2358 212: 6 Yingen- khuduk L 3930 +- 300 4.53-3.33 2220-1620 UW2357 212: 123 Yingen- khuduk L 5720 +- 350 6.42-5.02 4060-3360 UW2360 212: 128 Yingen- khuduk L 3930 +- 230 4.39-3.47 2150-1690 UW2856 248: 5 Dottore- namak L 2150 +- 310 2.77-1.53 470 – AD 170 UW2355 248: 6 Dottore- namak L 2740 +- 230 3.20-2.28 960-500 UW2362 298: 15 Mantissar 12 L 6480 +- 710 7.90-5.06 5180-3760 UW2359 298: 25 Mantissar 12 L 3850 +-340 4.53-3.17 2180-1500 Table 1. Results of chronometric dating for Alashan Gobi samples. 0 2000 4000 6000 8000 10000 12000 J-k G Y-k a Y-k b Y-k c D- n a D- n b M 12 a M 12 b S-u 1 S-u 4 a S-u 4 b S-u 10 a S-u 10 b S-u 10 c UN P a UN P b UN P c ON BD SK W BS 19 a BS, with my report to be archived in the library of the Museum of Far Eastern Antiquities. The manuscript has been accepted for publication by Archaeopress. It is currently being revised and should be available in 2013 as a BAR Monograph. In this report I will briefly summarize the results of chronometric dating and contextualize their significance in relation to the AMNH sample and to the greater regional archaeology of northern China and Inner Asia. Tabulated results of chronometric dating for these ten samples are summarized Table 1. Appendix A gives a more detailed account of each sample in the context of its respective site assemblage. Methods Accelerator Mass Spectrometry (AMS) radiocarbon and luminescence dating are complementary techniques. AMS provides dates with a low margin of error, while luminescence dates on pottery can be used in the absence of organic temper or surfical carbonization. Ceramics from the Alashan Gobi Desert rarely contain organics, the clay having been tempered entirely with sand rather than fibres. As such, the majority of these specimens were dated using luminescence at the University of Washington Luminescence Dating Laboratory in Seattle, Washington (United States). The full laboratory report is included in Appendix B. Luminescence dating is more destructive than radiocarbon (a fragment of pottery must be at least 5 mm thick and 30 mm in diameter), but provides a direct age range for the firing or use of the pot (Aiken, 1985; Feathers, 2003) rather than for the organics contained within it. Although there is a larger degree of uncertainty in luminescence dating, it is effective in building a relative chronology for pottery types (Godfrey-Smith et al., 1997; Herbert et al., 2002). The utility of dating surface ceramics by luminescence has been demonstrated in several cases (Dunnell and Feathers, 1994; Sampson et al., 1997); the technique is especially useful in circumstances where multiple occupation episodes may have been intermixed (Feathers, 2003). The main problem with using luminescence to date these samples is uncertainty in determining the external dose rate, which includes both gamma and cosmic contributions. For ceramics, an associated sediment sample is often collected for this purpose where in situ measurements cannot be made. Since the dated specimens were collected decades ago no such sediments are available. The problem was diminished by employing fine-grained dating (see Appendix C), which is less reliant on the external dose rate. The fact that the museum-curated samples come from the surface is advantageous, because the atmosphere contains little radioactivity, thus reducing the gamma contribution. Unfortunately, due to uncertainty in the external dose rate, the range of error for samples dated using luminescence was much higher than those dated using AMS. Dating pottery using AMS is becoming more common and has been successfully employed successfully at other Northeast Asian archaeological sites (O’Malley et al., 1998; Keally et al., 2003; Kuzmin and Shewkomud, 2003). All dated ceramic samples underwent a standard acid-alkali-acid (AAA) 2 pretreatment and were combusted on a vacuum line with CuO at approximately 400 o C. Previous studies suggest that low temperature combustion is most reliable for AMS dating on pottery as it releases carbon from the temper, but is not hot enough to release old carbon from the clay (O’Malley et al., 1998). In these earlier studies, interior portions of the pottery were sampled in order to avoid contamination from the exterior surface. Bulk samples were not combusted at low temperatures, but exterior and interior portions were dated separately using low temperature combustion. Interior subsamples generally provide older ages than the exterior counterparts (O’Malley et al., 1998). Bulk samples were used for the one sample, nature of Gobi Desert habitation from about 4000-1000 BC. Chronometric dating has provided a basis for creating a preliminary chronology for a region that was otherwise uncontextualized within the greater milieu of cultural and technological change across Northeast Asia during the Neolithic. Valuable information remains to be derived from these collections, both in the form of additional lithic analysis (as exemplified in Janz, 2012) and in the form of additional chronometric dating. Residue analysis of pottery sherds would also be a valuable analytical tool, as it might indicate more about local subsistence, including the possible use of milk products (Evershed et al., 2008; Outram et al., 2009). Conscientious and conservative sample selection is required in order to ensure that the value of these collections is preserved for future scholars. References Aiken, M. J., 1985. Thermoluminescence Dating. Academic Press, New York. Bettinger, R. L., Madsen, D. B., Elston, R. G., 1994. Prehistoric settlement categories and settlement systems in the Alashan Desert of Inner Mongolia, PRC. Journal of Anthropological Archaeology 13, 74-101. Derevianko, A. P., Gladyshev, S. A., Nohrina, T. I., Olsen, J. W., 2003. The Mongolian Early Holocene excavations at Chikhen Agui Rockshelter in the Gobi Altai. The Review of Archaeology 24(2), 50-56. Dunnell, R. C., Feathers, J. K., 1994. Thermoluminescence dating of surficial archaeological material in: Beck, C. (Ed.), Dating in Exposed and Surface Contexts. University of New Mexico Press, Albuquerque, pp. 115-137. Evershed, R. P., Payne, S., Sherratt, et al., 2008. Earliest date for milk use in the Near East and southeastern Europe linked to cattle herding. Nature 455, 528-531. Fairservis, W. A., 1993. The Archaeology of the Southern Gobi, Mongolia. Carolina Academic Press, Durham. Feathers, J. K., 2003. Use of luminescence dating in archaeology. Measurement Science and Technology 14, 1493-1509. Frachetti, M. D., 2008. Pastoralist Landscapes and Social Interaction in Bronze Age Eurasia. University of California Press, Berkeley and Los Angeles. Godfrey-Smith, D. I., Deal, M., Kunelius, I., 1997. Thermoluminscence dating of St. Croix ceramics: chronology building in southwestern Nova Scotia. Geoarchaeology 12(3), 251-273. Herbert, J. M., Feathers, J. K., Cordell, A. S., 2002. Building ceramic chronologies with thermoluminescence dating: a case study from the Carolina Sandhills. Southeastern Archaeology 21(1), 92-109. Janz, L., 2012. Chronology of Post-Glacial Settlement in the Gobi Desert and the Neolithization of Arid Mongolia and China. Unpublished Ph.D. thesis. University of Arizona, Tucson. Keally, C. T., Taniguchi, Y., Kuzmin, Y. V., 2003. Understanding the beginnings of pottery technology in Japan and neighbouring East Asia. The Review of Archaeology 24(2), 3- 14. Kuzmin, Y. V., Shewkomud, I. Y., 2003. The Palaeolithic-Neolithic transition in the Russian Far East. The Review of Archaeology 24(2), 37-45. Maringer, J., 1950. Contribution to the Prehistory of Mongolia. Reports from the Scientific Expedition to the North-western Provinces of China under the Leadership of Sven Hedin, Sino-Swedish Expedition Publication, Publication 34. Statens Etnografiska Museum, Stockholm. Maringer, J., 1963. Mongolia before the Mongols. Arctic Anthropology 1(2), 75-85. O’Malley, J. M., Kuzmin, Y. V., Burr, G. S., Donahue, D. J., Jull, A. J. T., 1998. Direct radiocarbon accelerator mass spectrometric dating of the earliest pottery from the Russian Far East and Transbaikal in: Groupe des Méthodes Pluridisciplinaires Contribuant à l'Archéologie (Eds.), Actes du colloque “14C et Archéologie”. Revue d'Archéométrie, Paris, pp.19-24. Outram, A. K., Stear, N. A., Bendry, R., Olsen, S., Kasparov, A., Zaibert, V., Thorpe, N., Evershed, R. P., 2009. The earliest, but no associated sediment sample was available. Dose rates were mainly determined using alpha counting and flame photometry. The beta dose rate calculated from these measurements was compared with the beta dose rate measured directly by beta counting. These were in agreement for all samples but UW2361. The reason for the discrepancy in the latter is uncertain. It could relate to disequilibrium in the uranium decay chain, not uncommon for clays, but it is unlikely this effect would be very significant given the very high K content for this sample. An error in K measurement from flame photometry is possible, so the age for this sample was calculated using the beta dose rate from beta counting, which is a more direct measure. For the external dose rate, an average quantity of measured radioactive nuclides from several sand samples from Mongolia processed earlier in the lab for another project were used. Generous error terms reflecting the variation used to compute this average were assigned. The sherds were assumed to come from the surface, probably not accurate for their entire history, but the error from this is probably small given the low radioactivity of sand dunes, and at any rate not significant given the error in the external dose rate. Moisture content was estimated as 3 ± 3 % of saturated value for the sherds, and 6 ± 3 percent for the sediments, both reflecting the arid environment. Table 2 gives relevant data, including the total dose rate for each sample. Table 2. Dose rate Sample 238 U (ppm) 233 Th (ppm) K (%) Beta dose rate (Gy/ka) Total dose rate* (Gy/ka) ß- counting α-counting/ flame photometry UW2355 3.72±0.27 12.73±1.42 2.46±0.28 2.45±0.21 2.87±0.23 4.52±0.35 UW2356 3.54±0.27 13.51±1.56 2.44±0.15 2.58±0.22 2.84±0.14 4.99±0.35 UW2357 2.40±0.16 3.95±0.81 1.98±0.15 1.83±0.15 2.05±0.12 3.31±0.25 UW2358 2.59±0.20 10.29±1.23 2.84±0.23 2.58±0.22 2.94±0.19 4.11±0.28 UW2359 3.57±0.28 16.35±1.64 4.18±0.32 3.86±0.32 4.32±0.27 7.05±1.54 UW2360 2.28±0.15 2.65±0.67 2.63±0.22 2.51±0.24 2.51±0.18 4.88±0.54 UW2361 3.75±0.25 9.33±1.31 6.67±0.42 4.78±0.40 6.15±0.34 7.34±0.94 UW2362 2.35±0.17 6.61±0.96 2.62±0.16 2.45±0.21 2.62±0.13 3.97±0.23 UW2450 4.13±0.27 9.41±1.23 2.23±0.14 2.67±0.22 2.65±0.12 5.59±0.35 UW2451 3.47±0.28 8.04±1.96 2.21±0.10 2.35±0.20 2.50±0.11 4.05±0.31 UW2452 3.99±0.24 6.53±1.01 1.10±0.06 1.70±0.14 1.65±0.06 4.85±0.51 UW2453 4.92±0.34 14.39±1.68 2.90±0.10 3.34±0.29 3.44±0.10 5.80±0.33 UW2454 2.30±0.17 6.21±1.00 2.90±0.13 2.41±0.20 2.42±0.11 3.84±0.22 sediment 1.7±0.9 5.1±3.6 1.3±0.07 *Dose rate calculated for TL. It will be slightly lower for OSL because of lower alpha efficiency. Equivalent Dose -- Equivalent dose was determined by TL, IRSL and OSL, as described in the appendix. The TL measurements were characterized by relatively broad plateaus, four of them with a span of 50-70°C, and the others all over 100°C (Table 3). All but five had a sensitivity change with second glows. It was an unusually strong change for UW2361. The equivalent dose for this sample was determined by the intercept of an additive dose curve because the slide method was not reliable due to a large negative intercept from the regeneration curve. The additive dose intercept was also used for UW2359 for the same reason. TL anomalous fading was apparent in all sherds where it was measured (although not significant for UW2362), and ages were corrected for it following Huntley and Lamothe (2002). On some the correction was not significant, partly because of poor precision in the fading measurements. Fading rates were generally high, so high on UW2451 that the correction produced an infinite age (Table 3). Table 3. TL parameters Sample Plateau (°C) 1 st /2 nd ratio* fit g, .47±0.21 5.45±0.18 1.17±0.08 1.43±0.06 1.25±0.05 * Equivalent dose taken from additive dose intercept. Ages -- Table 5 gives the best estimated ages for each sample. They will be discussed in terms of their reliability. Three samples showed statistical agreement in age among TL, OSL, and IRSL. No fading test on the TL signal was performed on UW2357, but agreement among the three signals would not be expected if there was any significant fading because they are not expected to fade at the same rate. For UW2360 and UW2452 the agreement of OSL and IRSL is with the uncorrected TL signal. In the case of UW2360, the TL fading was not significant. TL fading was significant for UW2452, but the measured rate was based on only three points (and one outlier was removed), so it is not highly reliable. Agreement between OSL and IRSL is not expected if any fading is significant. Plus the OSL b-value was reasonably low and the OSL signal 40 times larger than the IRSL signal, meaning the OSL signal probably reflects mainly quartz. All three of these ages are thus considered reliable. The OSL and IRSL ages agreed for UW2453 as well, but the uncorrected TL age was significantly older. The b-value for OSL was in the range of quartz, and OSL signal was 100 times larger than the IRSL signal. The OSL signal thus appears to be dominated by quartz . The TL fading rate was low and the correction not significant, so there is not much evidence of fading in this sample. There was high scatter in the TL growth curves, so the best conclusion is that the TL age is not reliable, but the OSL/IRSL one is. For UW2356 and UW2450, the OSL age agrees with the corrected TL age, so these should be reliable ages. The IRSL signal on both surely fades. The OSL and uncorrected TL ages agree on UW2359. No fading test was conducted. The OSL b-value is in the range of quartz, so the OSL signal does not likely fade, making this age reliable. On UW2355, UW2361 and UW2451, the age is based only on OSL. For UW2355, both the TL and IRSL probably fade (but the correction for TL was very imprecise), so the OSL age is probably reliable. The OSL b- value indicates a signal dominated by quartz. For UW2451, the TL age is unreasonably old (Pleistocene) and the IRSL age probably fades. This leaves the OSL age, which also might fade, as suggested by a high b-value. The OSL age should be considered a minimum. For UW2361, the TL data were of poor quality (high sensitivity change with second glow and large negative intercept on the regeneration curve), and no IRSL signal was recorded. Again this leaves the OSL signal, but a b-value in the range of quartz, suggests this age should be reliable. The corrected TL age was selected as the best estimate for UW2362 and UW2454. In both cases, both the OSL and IRSL ages were younger, but high OSL b-values suggest OSL fading along with IRSL. The corrected TL ages remain the best age. Table 5. Ages Sample Age (ka) % error Date (years BC/AD) Basis for age UW2355 2.74±0.23 8.4 BC 730 ± 230 OSL UW2356 2.15±0.31 14.5 BC 140 ± 310 OSL/corrected TL UW2357 5.72±0.35 6.1 BC 3710 ± 350 OSL/IRSL/TL UW2358 3.93±0.30 7.7 BC 1920 ± 300 OSL/corrected TL UW2359 3.85±0.34 8.7 BC 1840 ± 340 OSL/uncorrected TL UW2360 3.93±0.23 5.8 BC 1920 ± 230 OSL/IRSL/uncorrected TL UW2361 3.51±0.30 8.6 BC 1500 ± 300 OSL UW2362 6.48±0.71 11.0 BC 4470 ± 720 Corrected TL UW2450 0.94±0.08 8.3 AD 1070 ± 80 OSL/corrected TL UW2451 5.03±0.36 7.9 BC 3020 ± 360 OSL UW2452 2.48±0.13 5.3 BC 470 ± 130 OSL/IRSL/uncorrected TL UW2453 5.69±0.30 5.3 BC 3670 ± 300 OSL/IRSL UW2454 2.17±0.33 15.4 BC 160 ± 330 Corrected TL * Corrected for anomalous fading. Methods - Procedures for Thermoluminescence Analysis of Pottery Sample preparation -- fine grain The sherd is broken to expose a fresh profile., 100s at 125°C of OSL (470nm diodes). Detection is through 7.5mm of Hoya U340 (ultra-violet) filters. The two stimulations are used to construct IRSL and OSL growth curves, so that two estimations of equivalent dose are available. Anomalous fading usually involves feldspars and only feldspars are sensitive to IRSL stimulation. The rationale for the IRSL stimulation is to remove most of the feldspar signal, so that the subsequent OSL (post IR blue) signal is free from anomalous fading. However, feldspar is also sensitive to blue light (470nm), and it is possible that IRSL does not remove all the feldspar signal. Some preliminary tests in our laboratory have suggested that the OSL signal does not suffer from fading, but this may be sample specific. The procedure is still undergoing study. A dose recovery test is performed by first zeroing the sample by exposure to light and then administering a known dose. The SAR protocol is then applied to see if the known dose can be obtained. Alpha efficiency will surely differ among IRSL, OSL and TL on fine-grained materials. It does differ between coarse-grained feldspar and quartz (Aitken 1985). Research is currently underway in the laboratory to determine how much b-value varies according to stimulation method. Results from several samples from different geographic locations show that OSL b- value is less variable and centers around 0.5. IRSL b-value is more variable and is higher than that for OSL. TL b-value tends to fall between the OSL and IRSL values. We currently are measuring the b-value for IRSL and OSL by giving an alpha dose to aliquots whose luminescence have been drained by exposure to light. An equivalent dose is determined by SAR using beta irradiation, and the beta/alpha equivalent dose ratio is taken as the b-value. Age and error terms The age and error for both OSL and TL are calculated by a laboratory constructed spreadsheet, based on Aitken (1985). All error terms are reported at 1-sigma. References Adamiec, G., and Aitken, M. J., 1998, Dose rate conversion factors: update. Ancient TL 16:37- 50. Aitken, M. J., 1985, Thermoluminescence Dating, Academic Press, London. Banerjee, D., Murray, A. S., Bøtter-Jensen, L., and Lang, A., 2001, Equivalent dose estimation using a single aliquot of polymineral fine grains. Radiation Measurements 33:73-93. Bøtter-Jensen, L, and Mejdahl, V., 1988, Assessment of beta dose-rate using a GM multi-counter system. Nuclear Tracks and Radiation Measurements 14:187-191. Brady, N. C., 1974, The Nature and Properties of Soils, Macmillan, New York. Huntley, D. J., and Lamothe, M., 2001, Ubiq uity of anomalous fading in K-feldspars, and measurement and correction for it in optical dating. Canadian Journal of Earth Sciences 38:1093-1106. Mejdahl, V., 1983, Feldspar inclusion dating of ceramics and burnt stones. PACT 9:351-364. Murray, A. S., and Wintle, A. G., 2000, Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. Radiation Measurements 32:57-73. Prescott, J. R., Huntley, D. J., and Hutton, J. T., 1993, Estimation of equivalent dose in thermoluminescence dating – the Australian slide method. Ancient TL 11:1-5. Prescott, J. R., and Hutton, J. T., 1988, Cosmic ray and gamma ray dose dosimetry for TL and ESR. Nuclear Tracks and Radiation Measurements 14:223-235. Roberts, H. M., and Wintle, A. G., 2001, Equivalent dose determinations for polymineralic fine- grains using the SAR protocol: application to a Holocene sequence of the Chinese Loess Plateau. Quaternary Science Reviews 20:859-863., beta irradiations. The slide program is also used in this regard, taking the scale factor (which is the ratio of the two slopes) as the b-value (Aitken 1985). Radioactivity Radioactivity is measured by alpha counting in conjunction with atomic emission for 40 K. Samples for alpha counting are crushed in a mill to flour consistency, packed into plexiglass containers with ZnS:Ag screens, and sealed for one month before counting. The pairs technique is used to separate the U and Th decay series. For atomic emission measurements, samples are dissolved in HF and other acids and analyzed by a Jenway flame photometer. K concentrations for each sample are determined by bracketing between standards of known concentration. Conversion to 40 K is by natural atomic abundance. Radioactivity is also measured, as a check, by beta counting, using a Risø low level beta GM multicounter system. About 0.5 g of crushed sample is placed on each of four plastic sample holders. All are counted for 24 hours. The average is converted to dose rate following Bøtter-Jensen and Mejdahl (1988) and compared with the beta dose rate calculated from the alpha counting and flame photometer results. Both the sherd and an associated soil sample are measured for radioactivity. Additional soil samples are analyzed where the environment is complex, and gamma contributions determined by gradients (after Aitken 1985: appendix H). Cosmic radiation is determined after Prescott and Hutton (1988). Radioactivity concentrations are translated into dose rates following Adamiec and Aitken (1998). Moisture Contents Water absorption values for the sherds are determined by comparing the saturated and dried weights. For temperate climates, moisture in the pottery is taken to be 80 ± 20 percent of total absorption, unless otherwise indicated by the archaeologist. Again for temperate climates, soil moisture contents are taken from typical moisture retention quantities for different textured soils (Brady 1974: 196), unless otherwise measured. For drier climates, moisture values are determined in consultation with the archaeologist. Methods - Procedures for Optically Stimulated or Infrared Stimulated Luminescence of Fine-grained pottery. Optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) on fine-grain (1-8µm) pottery samples are carried out on single aliquots following procedures adapted from Banerjee et al. (2001) and Roberts and Wintle (2001. Equivalent dose is determined by the single-aliquot regenerative dose (SAR) method (Murray and Wintle 2000). The SAR method measures the natural signal and the signal from a series of regeneration doses on a single aliquot. The method uses a small test dose to monitor and correct for sensitivity changes brought about by preheating, irradiation or light stimulation. SAR consists of the following steps: 1) preheat, 2) measurement of natural signal (OSL or IRSL), L(1), 3) test dose, 4) cut heat, 5) measurement of test dose signal, T(1), 6) regeneration dose, 7) preheat, 8) measurement of signal from regeneration, L(2), 9) test dose, 10) cut heat, 11) measurement of test dose signal, T(2), 12) repeat of steps 6 through 11 for various regeneration doses. A growth curve is constructed from the L(i)/T(i) ratios and the equivalent dose is found by interpolation of L(1)/T(1). Usually a zero regeneration dose and a repeated regeneration dose are employed to insure the procedure is working properly. For fine-grained ceramics, a preheat of 240°C for 10s, a test dose of 3.1 Gy, and a cut heat of 200°C are currently being used, although these parameters may be modified from sample to sample. The luminescence, L(i) and T(i), is measured on a Risø TL-DA-15 automated reader by a succession of two stimulations: first 100 s at 60°C of IRSL (880nm diodes), and then Tillverkad Janz, Lisa 2012-01, 2012-12 image/jpeg https://collections.smvk.se/carlotta-om/web/image/blob/700218/MFEACeramicsReport.jpg https://collections.smvk.se/carlotta-om/web/image/zoom/700219/MFEACeramicsReport.jpg https://collections.smvk.se/carlotta-om/web/image/blob/700216/MFEACeramicsReport.pdf http://kulturarvsdata.se/resurser/License#by-nc-nd Janz, Lisa Statens museer för världskultur http://kulturarvsdata.se/SMVK-OM/arkiv/203611 http://kulturarvsdata.se/SMVK-OM/objekt/597007 http://kulturarvsdata.se/SMVK-OM/objekt/581753 http://kulturarvsdata.se/SMVK-OM/objekt/584528 http://kulturarvsdata.se/SMVK-OM/objekt/583575 http://kulturarvsdata.se/SMVK-OM/objekt/581755 http://kulturarvsdata.se/SMVK-OM/objekt/582202 http://kulturarvsdata.se/SMVK-OM/objekt/597501 http://kulturarvsdata.se/SMVK-OM/objekt/597503 http://kulturarvsdata.se/SMVK-OM/objekt/581748 http://kulturarvsdata.se/SMVK-OM/objekt/582207 http://kulturarvsdata.se/SMVK-OM/objekt/581759 http://kulturarvsdata.se/SMVK-OM/objekt/581761 http://kulturarvsdata.se/SMVK-OM/objekt/597008 http://kulturarvsdata.se/SMVK-OM/objekt/597009 http://kulturarvsdata.se/SMVK-OM/objekt/597010 http://kulturarvsdata.se/SMVK-OM/objekt/581752 http://kulturarvsdata.se/SMVK-OM/objekt/581757 http://kulturarvsdata.se/SMVK-OM/objekt/581760 http://kulturarvsdata.se/SMVK-OM/objekt/582080 http://kulturarvsdata.se/SMVK-OM/objekt/583576 http://kulturarvsdata.se/SMVK-OM/objekt/597500 http://kulturarvsdata.se/SMVK-OM/objekt/597502 http://kulturarvsdata.se/SMVK-OM/objekt/584538 http://kulturarvsdata.se/SMVK-OM/objekt/583578 http://kulturarvsdata.se/SMVK-OM/objekt/581754 http://kulturarvsdata.se/SMVK-OM/objekt/583573 http://kulturarvsdata.se/SMVK-OM/objekt/597428 http://kulturarvsdata.se/SMVK-OM/objekt/581756 http://kulturarvsdata.se/SMVK-OM/objekt/581758 http://kulturarvsdata.se/SMVK-OM/objekt/582085 http://kulturarvsdata.se/SMVK-OM/objekt/584514 http://kulturnav.org/85f22960-b1b1-47e4-811b-2e47000b0669 http://kulturarvsdata.se/SMVK-EM/name/3212965 http://kulturarvsdata.se/SMVK-OM/arkivdokument/html/615418 http://kulturarvsdata.se/SMVK-OM/arkivdokument/xml/615418 http://kulturarvsdata.se/SMVK-OM/arkivdokument/rdf/615418
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Artikel/rapport av Lisa Janz om resultatet av analyser av keramikskärvor från Inre Mongoliet som samlades in av Folke Bergman under fjärde Hedinexpeditionen.
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Ten ceramic sherds1 were selected from Folke Bergman’s archaeological collections held at the Museum of Far Eastern Antiquities. These samples were all drawn from collections made in the Alashan Gobi during Sven Hedin’s scientific expedition in the north-western provinces of China between 1927 and 1935. Eight were dated using luminescence dating techniques and one was dated using radiocarbon. The remaining sherd was significant because had remnants of molten metal on one surface. I originally intended to take a thin section of this sherd and have a colleague undertake microscopic analysis to determine the chemical composition of the metal. However, my colleague became disinterested in doing so when he discovered that the artefact was found in the context of a surface scatter. He did visually examine the sherd under a microscope and told me that the metal was certainly copper, rather than bronze. No further information was available and the whole specimen is being returned with this report. Prior to this study, Chikhen Agui, a cave site in the Gobi-Altai mountains (Derevianko et al., 2003), was the only dated post-glacial archaeological site in the Gobi Desert. The purpose of this analysis was to acquire chronometric dates for some of the numerous archaeological assemblages collected in the Gobi Desert. Large collections of Stone Age material from Mongolia and China were collected and removed to Western museums in the 1920s and 1930s by Sven Hedin’s and Roy Chapman Andrews’ scientific expeditions. A brief surge of publication and descriptive analysis ensued during the early part of the 20th century. However, the political climate increasingly disallowed any further research by Western scholars and the collections were largely ignored until the collapse of the Soviet Union. (för fortsättning, se rapporten)
REPORTING AND INTREPRETATION OF RESULTS: LUMINESCENCE AND RADIOCARBON DATING OF POTSHERDS FROM SINO-SWEDISH EXPEDITION, ALASHAN GOBI DESERT, INNER MONGOLIA Lisa Janz, PhD Research Associate School of Anthropology University of Arizona Tucson, United States LJANZ@email.arizona.edu +1 510 223 5866/+1 520 271 5242 October 5, 2012 Introduction Ten ceramic sherds 1 were selected from Folke Bergman’s archaeological collections held at the Museum of Far Eastern Antiquities. These samples were all drawn from collections made in the Alashan Gobi during Sven Hedin’s scientific expedition in the north-western provinces of China between 1927 and 1935. Eight were dated using luminescence dating techniques and one was dated using radiocarbon. The remaining sherd was significant because had remnants of molten metal on one surface. I originally intended to take a thin section of this sherd and have a colleague undertake microscopic analysis to determine the chemical composition of the metal. However, my colleague became disinterested in doing so when he discovered that the artefact was found in the context of a surface scatter. He did visually examine the sherd under a microscope and told me that the metal was certainly copper, rather than bronze. No further information was available and the whole specimen is being returned with this report. Prior to this study, Chikhen Agui, a cave site in the Gobi-Altai mountains (Derevianko et al., 2003), was the only dated post-glacial archaeological site in the Gobi Desert. The purpose of this analysis was to acquire chronometric dates for some of the numerous archaeological assemblages collected in the Gobi Desert. Large collections of Stone Age material from Mongolia and China were collected and removed to Western museums in the 1920s and 1930s by Sven Hedin’s and Roy Chapman Andrews’ scientific expeditions. A brief surge of publication and descriptive analysis ensued during the early part of the 20 th century. However, the political climate increasingly disallowed any further research by Western scholars and the collections were largely ignored until the collapse of the Soviet Union. Despite a renewed interest in the archaeology of the Gobi Desert, a disciplinary preference for fieldwork has contributed to continued disinterest. The collections were easily dismissed as “biased” and “undateable” due to the fact that they were collected from surface contexts; however, fieldwork has so far proven inadequate in reconstructing a chronology for Gobi Desert prehistory. Until now our knowledge of the Gobi Desert has consisted primarily of the understanding that post- glacial habitation was centered in dune-fields and around former wetlands, with sites post-dating the Last Glacial Maximum (ca. 18,000 year ago) and pre-dating the Bronze Age (ca. 1500 BC or 3500 years ago in Mongolia). 1 Ostrich eggshell fragments and broken eggshell beads were also selected for dating, but were generally much older than the archaeological sites with which they were associated. A separate report on these results was filed with the Museum of Far Eastern Antiquities in February 2010. The dating of these specimens, which are part of the collections made by Folke Bergman and described by Maringer (1950), was part of a larger project aimed at building a foundational chronology of technology and land-use for the prehistory of the Gobi Desert. Additional samples were selected from those housed at the American Museum of Natural History (AMNH), which were collected during Andrews’ Central Asiatic Expeditions. A complete description of this project is available in my doctoral dissertation, entitled The Chronology of Post-Glacial Settlement in the Gobi Desert and the Neolithization of Arid Mongolia and China. A copy of this work has been included
Dottore-namak, K. 13248: 1-14 The estimated age of site is ca. 500 BC, contemporary with the early Iron Age in China. Nomadic pastoralism was established across Northeast Asia at this time. Debitage from microblade manufacture and other stone tool manufacture detritus was found in this group, suggesting the continuation of stone tool working amongst Gobi Desert peoples, in combination with copper or bronze casting. High-fired red-ware was still being used, but appears to have been more coarsely manufactured by this time. K13248: 5 UW2356 2.15 + 0.31 ka 140 + 310 BC (470 BC – AD 170) K13248: 6 (not pictured, but similar appearance to K13248: 5) UW2355 2.74 + 0.23 ka 730 + 230 BC (960-500 BC) K. 13248: 3 Undated, diagnostic potsherd. K13248: 8 Visual microscopic examination by Dr. David Killick, School of Anthropology, University of Arizona (Tucson, United States). Droplets of copper melted copper onto over-fired potsherd, probably on exterior surface. This potsherd was an unusual specimen and destructive analysis was not used to obtain dates. It has been returned to the Museum of Far Eastern Antiquities along with this destructive analysis report and a copy of my dissertation thesis on the Gobi Desert materials (Janz, 2012). Mantissar 12, K. 13298: 1-61 According to the luminescence dates (see below), this site assemblage comprises artefacts from different time periods, including components contemporary with both the Neolithic and the early Bronze Age of China. This site assemblage, like many of the site assemblages from the Gurnai Depression, contains red, thin-walled and high-fired potsherds painted with black geometric and curvilinear designs. These are comparable to Majiayao designs and probably also date to the Late Neolithic. Palaeontologist B. Bohlin made archaeological collections in the Gurnai Depression at the end of 1932. The site was collected on October 22. Bohlin reported a series of nearly uninterrupted prehistoric sites along the whole approximately 100 km stretch of dune belt, mostly “from the terrain between the saxual belt and reed territory” (see Maringer, 1950: 151- 163). Fragmentary remains from the manufacture of ostrich eggshell beads were also unusually common amongst these sites (K. 13277-13319). K13298: 15 Textile impressed pottery with deep cord markings. UW2362 6.48 + 0.71 ka 4470 + 710 BC (5180-3760 BC) K13298: 25 Burnished pottery. UW2359 3.85 + 0.34 ka 1840 + 340 BC (2180-1500 BC) APPENDIX B. LUMINESCENCE ANALYSIS OF CERAMICS FROM MONGOLIA AND NORTHWEST CHINA Prepared by: James Feathers Luminescence Dating Laboratory University of Washington Box 353412 Seattle, WA 98195-3412 jimf@u.washington.edu Thirteen ceramic sherds from several sites in the desert areas of Mongolia and northwestern China, were submitted for luminescence analysis by Lisa Janz, University of Arizona. The sherds were collected in the 1920s and 1930s from sand dune blow-outs and were stored in museums since then. No associated sediment samples were available to assess the external dose rates, nor are the original burial depths known. This will be discussed later. Table 1 lists the sample and site numbers. Laboratory procedures are given under subheading “Methods.” Table 1. Provenience UW lab # Archaeological designation Site UW2355 K13248:6 Olon-toroi UW2356 K13248:5 Olon-toroi UW2357 K13212:123 Yingen-khuduk UW2358 K13212:6 Yingen-khuduk UW2359 K13298:25 Mantissar UW2360 K13212:128 Yingen-khuduk UW2361 K13203:5 Jabochin-khure UW2362 K13298:15 Mantissar UW2450 73/2237B Baron Shabaka Well UW2451 73/1190A Shabarakh-usu UW2452 73/1791K Orok Nor UW2453 73/890A Shabarakh-usu UW2454 73/1608D Arts Bogd-Ulan Nor Plain Dose rate -- Dose rate measurements were made on each ceramic,
-value** UW2355 260-380 1.0 Quadratic 14.5±4.2 UW2356 320-430 1.50±0.18 Linear 9.4±2.5 UW2357 250-420 0.52±0.16 Linear No test UW2358 250-420 1.0 Quadratic 10.4±2.9 UW2359 250-400 1.0 Linear No test UW2360 250-370 1.0 Linear 9.2±4.2 UW2361 250-310 13.7±7.2 Linear 11.8±9.0 UW2362 300-370 1.54±0.09 Linear 0.5±1.5 UW2450 250-430 1.29±0.14 Linear 5.7±1.0 UW2451 250-400 0.41±0.07 Linear 13.5±2.2 UW2452 250-420 0.54±0.07 Linear 9.0±3.3 UW2453 310-380 1.0 Quadratic 2.6±2.1 UW2454 280-330 0.65±0.05 Linear 8.5±1.4 *Refers to slope ratio between the first and second glow growth curves. A glow refers to luminescence as a function of temperature; a second glow comes after heating to 450°C. **g-value is the fading rate expressed as % per decade, where a decade is a power of 10. OSL/IRSL was measured on from 3 to 6 aliquots per sample (Table 4). Scatter among aliquots was generally low with derived over-dispersion in OSL of less than 6% for all but two samples. Dose recovery was within 1-sigma of the given dose for all but two samples. The OSL signal was from 3 to 100 times larger than the IRSL signal. This is normal for ceramics, and in cases where the OSL signal is much larger (say more than 10 times), feldspars (which are sensitive to IR stimulation and which are often subject to anomalous fading) probably do not contribute much to the OSL signal. The latter is therefore likely dominated by quartz, which suggests the OSL signal does not fade appreciably. Fading of the OSL signal is more likely when the OSL signal is only 3 or 4 times as large as the IRSL signal. Equivalent dose values are given in Table 5. They differ in value, even if they yield the same age, because of variation in b- value (also given in Table 5), which is a measure of alpha efficiency in producing luminescence. The b-value for quartz is around 0.4-0.6, while the b-value for feldspar is much higher. Low b- values for OSL means the signal is dominated by quartz and thus not likely to fade. (Fading tests were not run on IRSL or OSL because of exorbitant machine time.) Table 4. OSL/IRSL data Sample # aliquots* Over-dispersion (%) Dose Recovery (OSL) Approx. OSL/IRSL signal ratio OSL IRSL OSL IRSL Given Dose (sß) Recovered Dose (sß) UW2355 6 5 0 0 60 53.3±4.0 8 UW2356 6 4 31.9±11.4 0 80 70.0±13.2 4 UW2357 3 4 2.8±3.8 14.1±6.2 60 59.0±3.7 4 UW2358 6 6 0 0 200 174.9±7.2 13 UW2359 4 3 9.1±4.4 0 60 61.5±2.4 10 UW2360 5 5 5.6±2.4 8.2±4.1 60 58.2±2.2 12 UW2361 6 2.5±1.9 20 20.8±0.8 No IRSL UW2362 5 5 0 4.1±7.6 150 150.6±10.7 4 UW2450 4 4 0 0 40 39.1±6.8 20 UW2451 6 6 0 6.1±5.0 100 105.3±5.6 7 UW2452 6 6 3.3±2.2 0 200 188.7±7.5 40 UW2453 5 6 0 18.7±7.0 200 194.2±6.6 100 UW2454 6 5 0 0 40 38.8±5.0 3 * Denotes number of aliquots with measurable signals. Table 4. Equivalent dose Sample Equivalent dose (Gy) b-value (Gy µm 2 ) TL IRSL OSL TL IRSL OSL UW2355 6.83±0.54 10.86±0.89 11.46±0.27 0.90±0.12 1.90±0.30 0.61±0.04 UW2356 9.31±1.21 4.22±0.38 9.39±1.36 1.35±0.17 1.55±0.09 1.06±0.08 UW2357 19.72±2.70 17.03±1.35 19.66±0.59 1.23±0.16 0.95±0.05 1.30±0.04 UW2358 12.06±1.19 11.83±1.39 15.51±0.27 0.66±0.05 1.04±0.06 0.51±0.02 UW2359 18.4±9.5* 17.17±1.66 22.08±1.17 1.60±1.05 1.64±0.16 0.53±0.02 UW2360 23.20±2.22 14.37±0.66 13.72±0.40 3.74±0.86 1.33±0.05 1.08±0.03 UW2361 4.14±1.70* 20.93±0.35 1.88±0.73 1.10±0.30 0.54±0.04 UW2362 25.16±1.36 13.07±0.58 16.55±0.46 1.07±0.06 1.08±0.06 1.44±0.07 UW2450 4.79±0.40 2.53±0.24 3.63±0.32 2.06±0.20 1.62±0.20 0.81±0.10 UW2451 58.2±10.8 14.49±0.61 21.64±0.50 1.00±0.21 1.41±0.06 1.28±0.12 UW2452 14.40±1.22 7.44±0.45 7.46±0.15 2.74±0.43 0.95±0.04 0.75±0.02 UW2453 43.92±1.59 30.57±2.66 27.61±0.44 1.19±0.12 0.94±0.07 0.52±0.01 UW2454 5.04±0.35 4
Material is drilled from the center of the cross- section, more than 2 mm from either surface, using a tungsten carbide drill tip. The material retrieved is ground gently by a corundum mortar and pestle, treated with HCl, and then settled in acetone for 2 and 20 minutes to separate the 1-8 µm fraction. This is settled onto a maximum of 72 stainless steel discs. Glow-outs Thermoluminescence is measured by a Daybreak reader using a 9635Q photomultiplier with a Corning 7-59 blue filter, in N2 atmosphere at 1°C/s to 450°C. A preheat of 240°C with no hold time precedes each measurement. Artificial irradiation is given with a 241 Am alpha source and a 90 Sr beta source, the latter calibrated against a 137 Cs gamma source. Discs are stored at room temperature for at least one week after irradiation before glow out. Data are processed by Daybreak TLApplic software. Fading test Several discs are used to test for anomalous fading. The natural luminescence is first measured by heating to 450°C. The discs are then given an equal alpha irradiation and stored at room temperature for varied times: 10 min, 2 hours, 1 day, 1 week and 8 weeks. The irradiations are staggered in time so that all of the second glows are performed on the same day. The second glows are normalized by the natural signal and then compared to determine any loss of signal with time (on a log scale). If the sample shows fading and the signal versus time values can be reasonably fit to a logarithmic function, an attempt is made to correct the age following procedures recommended by Huntley and Lamothe (2001). The fading rate is calculated as the g-value, which is given in percent per decade, where decade represents a power of 10. Equivalent dose The equivalent dose is determined by a combination additive dose and regeneration (Aitken 1985). Additive dose involves administering incremental doses to natural material. A growth curve plotting dose against luminescence can be extrapolated to the dose axis to estimate an equivalent dose, but for pottery this estimate is usually inaccurate because of errors in extrapolation due to nonlinearity. Regeneration involves zeroing natural material by heating to 450°C and then rebuilding a growth curve with incremental doses. The problem here is sensitivity change caused by the heating. By constructing both curves, the regeneration curve can be used to define the extrapolated area and can be corrected for sensitivity change by comparing it with the additive dose curve. This works where the shapes of the curves differ only in scale (i.e., the sensitivity change is independent of dose). The curves are combined using the “Australian slide” method in a program developed by David Huntley of Simon Fraser University (Prescott et al. 1993). The equivalent dose is taken as the horizontal distance between the two curves after a scale adjustment for sensitivity change. Where the growth curves are not linear, they are fit to quadratic functions. Dose increments (usually five) are determined so that the maximum additive dose results in a signal about three times that of the natural and the maximum regeneration dose about five times the natural. If the regeneration curve has a significant negative intercept, which is not expected given current understanding, the additive dose intercept is taken as the best, if not fully reliable approximation. A plateau region is determined by calculating the equivalent dose at temperature increments between 240° and 450°C and determining over which temperature range the values do not differ significantly. This plateau region is compared with a similar one constructed for the b-value (alpha efficiency), and the overlap defines the integrated range for final analysis. Alpha effectiveness Alpha efficiency is determined by comparing additive dose curves using alpha and
19 b BS 19 c BS 19 d BS 19 e CH 35 SC 16 Figure 1. Results of dates (cal yr BP or ka at the 2σ range of error) for the entire Gobi Desert sample. Luminescence dates are represented by much larger margins of error. Dates are shown in calibrated years before present rather than BC. Alashan Gobi Gobi-Altai East Gobi The earliest habitation sites in the Alashan Gobi date to about 6000 years ago, or about 4000 BC. Archaeological assemblages are characterized primarily by the use of pottery and small stone tools made from blade-like flakes. This type of stone technology became prevalent across Northeast Asia between 20,000 and 15,000 years ago. As sedentary agriculture emerged across the Central Plains of China, the use of “microblade” technology declined rapidly. Pottery has been used in Northeast Asia since at least 16,500 years ago (Keally et al., 2003) and the earliest pottery from the Gobi Desert (housed at the AMNH) has been dated to 9500 years ago (from Shara Khata Well in the East Gobi). Microblade tools and pottery continued to be used by mobile hunter-gatherers and some agriculturalists north of the Central Plains, but polished stone and bone tools were added to toolkits. Large grinding slabs, handstones and pestles were also found in some Gobi Desert assemblages, but larger such equipment is relatively rare outside of the East Gobi. Therefore, the general character of Gobi Desert technological suites is one of Northeast Asian hunter-gatherers influenced by the technological advances of more sedentary neighbours. Likewise, the presence of painted black-on-red pottery in several of the Alashan Gobi sites is notable and suggests the influence of neighbouring sedentary agriculturalists. Considering the geographical location of Gobi Desert hunter-gatherers – separating and straddling the territories of western nomadic pastoralists and eastern sedentary agriculturalists – it would be highly desirable to more closely investigate the role these groups played in the emergence of early trade networks and agro-pastoralism in China. Understanding the role of Gobi Desert hunter-gatherers in the larger Northeast Asian interaction sphere is also important in understanding the shift from a hunter-gatherer economy to a full-fledged nomadic pastoralist economy. By 1000 BC, burial and other ritual monuments testify to the dominance of nomadic pastoralism across Mongolia and northern China. At the same time, archaeological remains indicate continuity with earlier post-glacial hunter-gatherer cultures. This suggests that dune-field/wetland dwelling hunter-gatherers were either contemporaries of early nomadic pastoralist settlers, or were themselves being incorporated into a new wave of economic specialization focused on domesticated herd animals. Certain remains collected in the Alashan Gobi by Folke Bergman and others suggest that although Gobi Desert groups may have practiced a mixed economy dependant on hunting and gathering, they may also have had access to products more often associated with pastoralists – spindle whorls, slag, and geometric-incised pottery (similar to recent findings from the Dzhungar Basin in Kazhakstan- see Frachetti 2008: 166). Cowry shells from East Gobi sites further suggest that these groups were not isolated from a greater regional economy that included food producing neighbours. The seemingly ritualized production of stone beads in an inaccessible cave site (K. 13230) and the concentrated production of ostrich eggshell beads at sites from the Gurnai Depression add to a picture of internal culture change during Oasis 3. These collections represent one the most important resources for broad-scale identification of regional shifts in technology, land-use, and subsistence. The dates derived from these samples have offered invaluable information about the timing and
horse harnessing and milking. Science 323, 1332- 1335. Sampson, C. G., Bailiff, I., Barnett, S., 1997. Thermoluminescence dates from Later Stone Age Pottery on Surface Sites in the Upper Karoo. The South African Archaeological Bulletin, 52(165), 38-42. Wright, J., Honeychurch, W., Amartuvshin, C., 2007. Initial findings of the Baga Gazaryn Chuluu archaeological survey (2003-2006). Antiquity 81 (313). Online content. http://www.antiquity.ac.uk/projgall/wright313/ Appendix A. Details of Dated Artefacts and Site Assemblages Jabochin-khure, K. 13203: 1-11 It is not clear if this potsherd is contemporaneous with the rest of the artefacts in the K. 13203 site assemblage (Maringer, 1950: 138-139). However, the diagnostic quality of the decorative finish makes the luminescence date an important one for local chronology. This type of decoration can be described as “geometric-incised,” and is found on pottery from other sites in the Alashan Gobi and Gobi-Altai region of southern Mongolia, including Yingen-khuduk and Shabarakh-usu. Judging by the direct luminscence date on this artefact and dates on potsherds from other sites of a similar age, this type of decorative treatment was characteristic of the Late Neolithic to Early Bronze Age transition (ca. 3000 to 1000 BC according to Janz, 2012). K13203: 5 UW2361 3.51 + 0.30 ka 1500 + 300 BC (1800-1200 BC) Gashun Well, K. 13207: 1-34 The radiocarbon date for this potsherd also indicates that the site assemblage belongs to the Late Neolithic/ Early Bronze Age period and is contemporary with the majority of other Stone Age Gobi Desert sites, including, Jabochin-khure (above), components of Yingen-khuduk (below), and components of the famous Mongolian Shabarakh-usu locality (see Fairservis, 1993; Janz, 2012). The collection of artefacts is consistent with similarly aged sites (see Janz, 2012), but notable in that it contains many large stone tools made on brown jasper. These are probably unfinished adzes or axes. Similar stone specimens were recovered from Abderungtei (K. 13209: 128) and Mongol (K. 13210: 132). K13207: 1 AA91693 3385 + 40 BP 3634 + 48 cal yr BP/ 1684 + 48 BC (1732-1636 BC) Yingen-khuduk, K. 13212: 1-186 The three luminescence dates from this site correspond with a period spanning the end of the Yangshao to the Qijia periods in the Upper Yellow River Valley of China (Northwest China). More correctly, they date to two specific periods – the latter half of the Yangshao and the early part of the Qijia. Based on a study of Gobi Desert chronology, the habitation of the locality can be said to have occurred during both the early and late phases of intensive dune-field/wetland habitation – Oasis 2 and Oasis 3 (after Janz, 2012). The artefact assemblage, as compared to other Gobi Desert sites, is consistent with these dates (see Janz, 2012). Until more dates are available, it is impossible to say whether occupation of the dune-field/wetland habitat around Yingen-khuduk was relatively continuous, or whether individual occupation episodes were separated by millennia. High-fired, homogeneous red-ware appears to date more closely to the Machang or Qijia periods, than to the earlier Majiayao period (for comparison, see description of Mantissar sites, below). The “net-impressed” pottery (K. 13212: 123) is diagnostic of the early period of dune-field/wetland habitation in the Gobi Desert and has been collected from sites across the Gobi Desert (see Janz, 2012: Chapter 3). String-paddled pottery is roughly contemporaneous with that from Gashun Well (K. 13207). K13212: 6 UW2358 3.93 + 0.30 ka 1920 + 300 BC (2220-1620 BC) K13212: 123 UW2357 5.72 + 0.35 ka 3710 + 350 BC (4060-3360 BC) K13212: 128 UW2360 3.93 + 0.23 ka 1920 + 230 BC (2150-1690 BC)
described herein and if the date had been affected by contamination from the exterior portion, it would be older rather than younger. For this particular specimen, the source of carbon was residue from burning on the vessel surface. Results The majority of artefacts date to the Neolithic-to-Bronze Age transition between 2000 and 1000 BC. Despite the large range of error, these dates are extremely significant because they indicate that the many of the site assemblages are much younger than previously thought (Maringer, 1963; Fairservis, 1992; Bettinger et al., 1994). Periods of earlier occupation are evident at Yingen-khuduk (K. 13212: 1-186) and Mantissar 12 (K. 13298: 14). Figure 1 illustrates how the range of dates from Alashan fits into the entire Gobi Desert-wide sample, including those from the AMNH collections. Based on these dates and changes in artefact-types, as outlined in Janz (2012), four key phases of Gobi Desert habitation can be synthesized for the prehistoric periods following the Last Glacial Maximum: Epipalaeolithic/Mesolithic dating from 11,500 to 6000 BC; the Neolithic, dating to between 6000 and 4000 BC; the Eneolithic/Late Neolithic/Neolithic-to- Bronze Age transition, dating from 4000 to 1000 BC; and the Metal Ages, post-dating 1000 BC. My dissertation establishes a regional nomenclature, by which the first three of these periods can be referred to as Oasis 1 (incipient), Oasis 2 (intensive), and Oasis 3 (transitional), respectively. Results from the entire sample are illustrated below in Figure 1. Dates from the Alashan Gobi are highly consistent with those derived from the Gobi-Altai region, which is the region directly north of the Alashan, in Mongolia. Collections from these two regions span the latter half of Oasis 2, but are mostly associated with Oasis 3 occupations. Although this may be a vagary of sampling, it might also suggest more intensive occupation during the terminal phase of dune-field/wetland habitation. So far, the earliest habitation sites have been found in the East Gobi region. This difference in the timing of dune-field/wetland habitation may be related to the establishment of high elevation and riparian forests (Janz, 2012: 343-351). Occurrence of Bronze Age and early Iron Age ceramics in assemblages collected in dune-field/wetland settings indicates that habitation of such environments continued into the Metal Ages, although it was not necessarily as intensive as during earlier periods. Survey data from the northern reaches of the Gobi Desert indicates that during the Metal Ages, the focus of human habitation shifted away from the low elevation wetlands towards the foothills (Wright et al., 2007). 2 This pretreatment is also known as an acid-base-acid (ABA) pretreatment. Lab. No. Cat. No. (K.13 or 73/) Site Method δ13C 14C age BP +- 1δ/ KA +- 1 δ KYA (cal. to 68% range) Range BC UW2361 203: 5 Jabochin- khure L 3510 +- 300 4.11-2.91 1800-1200 AA91693 207: 1 Gashun Well AMS -32.4 3385 +- 40 3.59-3.68 1732-1636 UW2358 212: 6 Yingen- khuduk L 3930 +- 300 4.53-3.33 2220-1620 UW2357 212: 123 Yingen- khuduk L 5720 +- 350 6.42-5.02 4060-3360 UW2360 212: 128 Yingen- khuduk L 3930 +- 230 4.39-3.47 2150-1690 UW2856 248: 5 Dottore- namak L 2150 +- 310 2.77-1.53 470 – AD 170 UW2355 248: 6 Dottore- namak L 2740 +- 230 3.20-2.28 960-500 UW2362 298: 15 Mantissar 12 L 6480 +- 710 7.90-5.06 5180-3760 UW2359 298: 25 Mantissar 12 L 3850 +-340 4.53-3.17 2180-1500 Table 1. Results of chronometric dating for Alashan Gobi samples. 0 2000 4000 6000 8000 10000 12000 J-k G Y-k a Y-k b Y-k c D- n a D- n b M 12 a M 12 b S-u 1 S-u 4 a S-u 4 b S-u 10 a S-u 10 b S-u 10 c UN P a UN P b UN P c ON BD SK W BS 19 a BS
with my report to be archived in the library of the Museum of Far Eastern Antiquities. The manuscript has been accepted for publication by Archaeopress. It is currently being revised and should be available in 2013 as a BAR Monograph. In this report I will briefly summarize the results of chronometric dating and contextualize their significance in relation to the AMNH sample and to the greater regional archaeology of northern China and Inner Asia. Tabulated results of chronometric dating for these ten samples are summarized Table 1. Appendix A gives a more detailed account of each sample in the context of its respective site assemblage. Methods Accelerator Mass Spectrometry (AMS) radiocarbon and luminescence dating are complementary techniques. AMS provides dates with a low margin of error, while luminescence dates on pottery can be used in the absence of organic temper or surfical carbonization. Ceramics from the Alashan Gobi Desert rarely contain organics, the clay having been tempered entirely with sand rather than fibres. As such, the majority of these specimens were dated using luminescence at the University of Washington Luminescence Dating Laboratory in Seattle, Washington (United States). The full laboratory report is included in Appendix B. Luminescence dating is more destructive than radiocarbon (a fragment of pottery must be at least 5 mm thick and 30 mm in diameter), but provides a direct age range for the firing or use of the pot (Aiken, 1985; Feathers, 2003) rather than for the organics contained within it. Although there is a larger degree of uncertainty in luminescence dating, it is effective in building a relative chronology for pottery types (Godfrey-Smith et al., 1997; Herbert et al., 2002). The utility of dating surface ceramics by luminescence has been demonstrated in several cases (Dunnell and Feathers, 1994; Sampson et al., 1997); the technique is especially useful in circumstances where multiple occupation episodes may have been intermixed (Feathers, 2003). The main problem with using luminescence to date these samples is uncertainty in determining the external dose rate, which includes both gamma and cosmic contributions. For ceramics, an associated sediment sample is often collected for this purpose where in situ measurements cannot be made. Since the dated specimens were collected decades ago no such sediments are available. The problem was diminished by employing fine-grained dating (see Appendix C), which is less reliant on the external dose rate. The fact that the museum-curated samples come from the surface is advantageous, because the atmosphere contains little radioactivity, thus reducing the gamma contribution. Unfortunately, due to uncertainty in the external dose rate, the range of error for samples dated using luminescence was much higher than those dated using AMS. Dating pottery using AMS is becoming more common and has been successfully employed successfully at other Northeast Asian archaeological sites (O’Malley et al., 1998; Keally et al., 2003; Kuzmin and Shewkomud, 2003). All dated ceramic samples underwent a standard acid-alkali-acid (AAA) 2 pretreatment and were combusted on a vacuum line with CuO at approximately 400 o C. Previous studies suggest that low temperature combustion is most reliable for AMS dating on pottery as it releases carbon from the temper, but is not hot enough to release old carbon from the clay (O’Malley et al., 1998). In these earlier studies, interior portions of the pottery were sampled in order to avoid contamination from the exterior surface. Bulk samples were not combusted at low temperatures, but exterior and interior portions were dated separately using low temperature combustion. Interior subsamples generally provide older ages than the exterior counterparts (O’Malley et al., 1998). Bulk samples were used for the one sample
nature of Gobi Desert habitation from about 4000-1000 BC. Chronometric dating has provided a basis for creating a preliminary chronology for a region that was otherwise uncontextualized within the greater milieu of cultural and technological change across Northeast Asia during the Neolithic. Valuable information remains to be derived from these collections, both in the form of additional lithic analysis (as exemplified in Janz, 2012) and in the form of additional chronometric dating. Residue analysis of pottery sherds would also be a valuable analytical tool, as it might indicate more about local subsistence, including the possible use of milk products (Evershed et al., 2008; Outram et al., 2009). Conscientious and conservative sample selection is required in order to ensure that the value of these collections is preserved for future scholars. References Aiken, M. J., 1985. Thermoluminescence Dating. Academic Press, New York. Bettinger, R. L., Madsen, D. B., Elston, R. G., 1994. Prehistoric settlement categories and settlement systems in the Alashan Desert of Inner Mongolia, PRC. Journal of Anthropological Archaeology 13, 74-101. Derevianko, A. P., Gladyshev, S. A., Nohrina, T. I., Olsen, J. W., 2003. The Mongolian Early Holocene excavations at Chikhen Agui Rockshelter in the Gobi Altai. The Review of Archaeology 24(2), 50-56. Dunnell, R. C., Feathers, J. K., 1994. Thermoluminescence dating of surficial archaeological material in: Beck, C. (Ed.), Dating in Exposed and Surface Contexts. University of New Mexico Press, Albuquerque, pp. 115-137. Evershed, R. P., Payne, S., Sherratt, et al., 2008. Earliest date for milk use in the Near East and southeastern Europe linked to cattle herding. Nature 455, 528-531. Fairservis, W. A., 1993. The Archaeology of the Southern Gobi, Mongolia. Carolina Academic Press, Durham. Feathers, J. K., 2003. Use of luminescence dating in archaeology. Measurement Science and Technology 14, 1493-1509. Frachetti, M. D., 2008. Pastoralist Landscapes and Social Interaction in Bronze Age Eurasia. University of California Press, Berkeley and Los Angeles. Godfrey-Smith, D. I., Deal, M., Kunelius, I., 1997. Thermoluminscence dating of St. Croix ceramics: chronology building in southwestern Nova Scotia. Geoarchaeology 12(3), 251-273. Herbert, J. M., Feathers, J. K., Cordell, A. S., 2002. Building ceramic chronologies with thermoluminescence dating: a case study from the Carolina Sandhills. Southeastern Archaeology 21(1), 92-109. Janz, L., 2012. Chronology of Post-Glacial Settlement in the Gobi Desert and the Neolithization of Arid Mongolia and China. Unpublished Ph.D. thesis. University of Arizona, Tucson. Keally, C. T., Taniguchi, Y., Kuzmin, Y. V., 2003. Understanding the beginnings of pottery technology in Japan and neighbouring East Asia. The Review of Archaeology 24(2), 3- 14. Kuzmin, Y. V., Shewkomud, I. Y., 2003. The Palaeolithic-Neolithic transition in the Russian Far East. The Review of Archaeology 24(2), 37-45. Maringer, J., 1950. Contribution to the Prehistory of Mongolia. Reports from the Scientific Expedition to the North-western Provinces of China under the Leadership of Sven Hedin, Sino-Swedish Expedition Publication, Publication 34. Statens Etnografiska Museum, Stockholm. Maringer, J., 1963. Mongolia before the Mongols. Arctic Anthropology 1(2), 75-85. O’Malley, J. M., Kuzmin, Y. V., Burr, G. S., Donahue, D. J., Jull, A. J. T., 1998. Direct radiocarbon accelerator mass spectrometric dating of the earliest pottery from the Russian Far East and Transbaikal in: Groupe des Méthodes Pluridisciplinaires Contribuant à l'Archéologie (Eds.), Actes du colloque “14C et Archéologie”. Revue d'Archéométrie, Paris, pp.19-24. Outram, A. K., Stear, N. A., Bendry, R., Olsen, S., Kasparov, A., Zaibert, V., Thorpe, N., Evershed, R. P., 2009. The earliest
but no associated sediment sample was available. Dose rates were mainly determined using alpha counting and flame photometry. The beta dose rate calculated from these measurements was compared with the beta dose rate measured directly by beta counting. These were in agreement for all samples but UW2361. The reason for the discrepancy in the latter is uncertain. It could relate to disequilibrium in the uranium decay chain, not uncommon for clays, but it is unlikely this effect would be very significant given the very high K content for this sample. An error in K measurement from flame photometry is possible, so the age for this sample was calculated using the beta dose rate from beta counting, which is a more direct measure. For the external dose rate, an average quantity of measured radioactive nuclides from several sand samples from Mongolia processed earlier in the lab for another project were used. Generous error terms reflecting the variation used to compute this average were assigned. The sherds were assumed to come from the surface, probably not accurate for their entire history, but the error from this is probably small given the low radioactivity of sand dunes, and at any rate not significant given the error in the external dose rate. Moisture content was estimated as 3 ± 3 % of saturated value for the sherds, and 6 ± 3 percent for the sediments, both reflecting the arid environment. Table 2 gives relevant data, including the total dose rate for each sample. Table 2. Dose rate Sample 238 U (ppm) 233 Th (ppm) K (%) Beta dose rate (Gy/ka) Total dose rate* (Gy/ka) ß- counting α-counting/ flame photometry UW2355 3.72±0.27 12.73±1.42 2.46±0.28 2.45±0.21 2.87±0.23 4.52±0.35 UW2356 3.54±0.27 13.51±1.56 2.44±0.15 2.58±0.22 2.84±0.14 4.99±0.35 UW2357 2.40±0.16 3.95±0.81 1.98±0.15 1.83±0.15 2.05±0.12 3.31±0.25 UW2358 2.59±0.20 10.29±1.23 2.84±0.23 2.58±0.22 2.94±0.19 4.11±0.28 UW2359 3.57±0.28 16.35±1.64 4.18±0.32 3.86±0.32 4.32±0.27 7.05±1.54 UW2360 2.28±0.15 2.65±0.67 2.63±0.22 2.51±0.24 2.51±0.18 4.88±0.54 UW2361 3.75±0.25 9.33±1.31 6.67±0.42 4.78±0.40 6.15±0.34 7.34±0.94 UW2362 2.35±0.17 6.61±0.96 2.62±0.16 2.45±0.21 2.62±0.13 3.97±0.23 UW2450 4.13±0.27 9.41±1.23 2.23±0.14 2.67±0.22 2.65±0.12 5.59±0.35 UW2451 3.47±0.28 8.04±1.96 2.21±0.10 2.35±0.20 2.50±0.11 4.05±0.31 UW2452 3.99±0.24 6.53±1.01 1.10±0.06 1.70±0.14 1.65±0.06 4.85±0.51 UW2453 4.92±0.34 14.39±1.68 2.90±0.10 3.34±0.29 3.44±0.10 5.80±0.33 UW2454 2.30±0.17 6.21±1.00 2.90±0.13 2.41±0.20 2.42±0.11 3.84±0.22 sediment 1.7±0.9 5.1±3.6 1.3±0.07 *Dose rate calculated for TL. It will be slightly lower for OSL because of lower alpha efficiency. Equivalent Dose -- Equivalent dose was determined by TL, IRSL and OSL, as described in the appendix. The TL measurements were characterized by relatively broad plateaus, four of them with a span of 50-70°C, and the others all over 100°C (Table 3). All but five had a sensitivity change with second glows. It was an unusually strong change for UW2361. The equivalent dose for this sample was determined by the intercept of an additive dose curve because the slide method was not reliable due to a large negative intercept from the regeneration curve. The additive dose intercept was also used for UW2359 for the same reason. TL anomalous fading was apparent in all sherds where it was measured (although not significant for UW2362), and ages were corrected for it following Huntley and Lamothe (2002). On some the correction was not significant, partly because of poor precision in the fading measurements. Fading rates were generally high, so high on UW2451 that the correction produced an infinite age (Table 3). Table 3. TL parameters Sample Plateau (°C) 1 st /2 nd ratio* fit g
.47±0.21 5.45±0.18 1.17±0.08 1.43±0.06 1.25±0.05 * Equivalent dose taken from additive dose intercept. Ages -- Table 5 gives the best estimated ages for each sample. They will be discussed in terms of their reliability. Three samples showed statistical agreement in age among TL, OSL, and IRSL. No fading test on the TL signal was performed on UW2357, but agreement among the three signals would not be expected if there was any significant fading because they are not expected to fade at the same rate. For UW2360 and UW2452 the agreement of OSL and IRSL is with the uncorrected TL signal. In the case of UW2360, the TL fading was not significant. TL fading was significant for UW2452, but the measured rate was based on only three points (and one outlier was removed), so it is not highly reliable. Agreement between OSL and IRSL is not expected if any fading is significant. Plus the OSL b-value was reasonably low and the OSL signal 40 times larger than the IRSL signal, meaning the OSL signal probably reflects mainly quartz. All three of these ages are thus considered reliable. The OSL and IRSL ages agreed for UW2453 as well, but the uncorrected TL age was significantly older. The b-value for OSL was in the range of quartz, and OSL signal was 100 times larger than the IRSL signal. The OSL signal thus appears to be dominated by quartz . The TL fading rate was low and the correction not significant, so there is not much evidence of fading in this sample. There was high scatter in the TL growth curves, so the best conclusion is that the TL age is not reliable, but the OSL/IRSL one is. For UW2356 and UW2450, the OSL age agrees with the corrected TL age, so these should be reliable ages. The IRSL signal on both surely fades. The OSL and uncorrected TL ages agree on UW2359. No fading test was conducted. The OSL b-value is in the range of quartz, so the OSL signal does not likely fade, making this age reliable. On UW2355, UW2361 and UW2451, the age is based only on OSL. For UW2355, both the TL and IRSL probably fade (but the correction for TL was very imprecise), so the OSL age is probably reliable. The OSL b- value indicates a signal dominated by quartz. For UW2451, the TL age is unreasonably old (Pleistocene) and the IRSL age probably fades. This leaves the OSL age, which also might fade, as suggested by a high b-value. The OSL age should be considered a minimum. For UW2361, the TL data were of poor quality (high sensitivity change with second glow and large negative intercept on the regeneration curve), and no IRSL signal was recorded. Again this leaves the OSL signal, but a b-value in the range of quartz, suggests this age should be reliable. The corrected TL age was selected as the best estimate for UW2362 and UW2454. In both cases, both the OSL and IRSL ages were younger, but high OSL b-values suggest OSL fading along with IRSL. The corrected TL ages remain the best age. Table 5. Ages Sample Age (ka) % error Date (years BC/AD) Basis for age UW2355 2.74±0.23 8.4 BC 730 ± 230 OSL UW2356 2.15±0.31 14.5 BC 140 ± 310 OSL/corrected TL UW2357 5.72±0.35 6.1 BC 3710 ± 350 OSL/IRSL/TL UW2358 3.93±0.30 7.7 BC 1920 ± 300 OSL/corrected TL UW2359 3.85±0.34 8.7 BC 1840 ± 340 OSL/uncorrected TL UW2360 3.93±0.23 5.8 BC 1920 ± 230 OSL/IRSL/uncorrected TL UW2361 3.51±0.30 8.6 BC 1500 ± 300 OSL UW2362 6.48±0.71 11.0 BC 4470 ± 720 Corrected TL UW2450 0.94±0.08 8.3 AD 1070 ± 80 OSL/corrected TL UW2451 5.03±0.36 7.9 BC 3020 ± 360 OSL UW2452 2.48±0.13 5.3 BC 470 ± 130 OSL/IRSL/uncorrected TL UW2453 5.69±0.30 5.3 BC 3670 ± 300 OSL/IRSL UW2454 2.17±0.33 15.4 BC 160 ± 330 Corrected TL * Corrected for anomalous fading. Methods - Procedures for Thermoluminescence Analysis of Pottery Sample preparation -- fine grain The sherd is broken to expose a fresh profile.
100s at 125°C of OSL (470nm diodes). Detection is through 7.5mm of Hoya U340 (ultra-violet) filters. The two stimulations are used to construct IRSL and OSL growth curves, so that two estimations of equivalent dose are available. Anomalous fading usually involves feldspars and only feldspars are sensitive to IRSL stimulation. The rationale for the IRSL stimulation is to remove most of the feldspar signal, so that the subsequent OSL (post IR blue) signal is free from anomalous fading. However, feldspar is also sensitive to blue light (470nm), and it is possible that IRSL does not remove all the feldspar signal. Some preliminary tests in our laboratory have suggested that the OSL signal does not suffer from fading, but this may be sample specific. The procedure is still undergoing study. A dose recovery test is performed by first zeroing the sample by exposure to light and then administering a known dose. The SAR protocol is then applied to see if the known dose can be obtained. Alpha efficiency will surely differ among IRSL, OSL and TL on fine-grained materials. It does differ between coarse-grained feldspar and quartz (Aitken 1985). Research is currently underway in the laboratory to determine how much b-value varies according to stimulation method. Results from several samples from different geographic locations show that OSL b- value is less variable and centers around 0.5. IRSL b-value is more variable and is higher than that for OSL. TL b-value tends to fall between the OSL and IRSL values. We currently are measuring the b-value for IRSL and OSL by giving an alpha dose to aliquots whose luminescence have been drained by exposure to light. An equivalent dose is determined by SAR using beta irradiation, and the beta/alpha equivalent dose ratio is taken as the b-value. Age and error terms The age and error for both OSL and TL are calculated by a laboratory constructed spreadsheet, based on Aitken (1985). All error terms are reported at 1-sigma. References Adamiec, G., and Aitken, M. J., 1998, Dose rate conversion factors: update. Ancient TL 16:37- 50. Aitken, M. J., 1985, Thermoluminescence Dating, Academic Press, London. Banerjee, D., Murray, A. S., Bøtter-Jensen, L., and Lang, A., 2001, Equivalent dose estimation using a single aliquot of polymineral fine grains. Radiation Measurements 33:73-93. Bøtter-Jensen, L, and Mejdahl, V., 1988, Assessment of beta dose-rate using a GM multi-counter system. Nuclear Tracks and Radiation Measurements 14:187-191. Brady, N. C., 1974, The Nature and Properties of Soils, Macmillan, New York. Huntley, D. J., and Lamothe, M., 2001, Ubiq uity of anomalous fading in K-feldspars, and measurement and correction for it in optical dating. Canadian Journal of Earth Sciences 38:1093-1106. Mejdahl, V., 1983, Feldspar inclusion dating of ceramics and burnt stones. PACT 9:351-364. Murray, A. S., and Wintle, A. G., 2000, Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. Radiation Measurements 32:57-73. Prescott, J. R., Huntley, D. J., and Hutton, J. T., 1993, Estimation of equivalent dose in thermoluminescence dating – the Australian slide method. Ancient TL 11:1-5. Prescott, J. R., and Hutton, J. T., 1988, Cosmic ray and gamma ray dose dosimetry for TL and ESR. Nuclear Tracks and Radiation Measurements 14:223-235. Roberts, H. M., and Wintle, A. G., 2001, Equivalent dose determinations for polymineralic fine- grains using the SAR protocol: application to a Holocene sequence of the Chinese Loess Plateau. Quaternary Science Reviews 20:859-863.
beta irradiations. The slide program is also used in this regard, taking the scale factor (which is the ratio of the two slopes) as the b-value (Aitken 1985). Radioactivity Radioactivity is measured by alpha counting in conjunction with atomic emission for 40 K. Samples for alpha counting are crushed in a mill to flour consistency, packed into plexiglass containers with ZnS:Ag screens, and sealed for one month before counting. The pairs technique is used to separate the U and Th decay series. For atomic emission measurements, samples are dissolved in HF and other acids and analyzed by a Jenway flame photometer. K concentrations for each sample are determined by bracketing between standards of known concentration. Conversion to 40 K is by natural atomic abundance. Radioactivity is also measured, as a check, by beta counting, using a Risø low level beta GM multicounter system. About 0.5 g of crushed sample is placed on each of four plastic sample holders. All are counted for 24 hours. The average is converted to dose rate following Bøtter-Jensen and Mejdahl (1988) and compared with the beta dose rate calculated from the alpha counting and flame photometer results. Both the sherd and an associated soil sample are measured for radioactivity. Additional soil samples are analyzed where the environment is complex, and gamma contributions determined by gradients (after Aitken 1985: appendix H). Cosmic radiation is determined after Prescott and Hutton (1988). Radioactivity concentrations are translated into dose rates following Adamiec and Aitken (1998). Moisture Contents Water absorption values for the sherds are determined by comparing the saturated and dried weights. For temperate climates, moisture in the pottery is taken to be 80 ± 20 percent of total absorption, unless otherwise indicated by the archaeologist. Again for temperate climates, soil moisture contents are taken from typical moisture retention quantities for different textured soils (Brady 1974: 196), unless otherwise measured. For drier climates, moisture values are determined in consultation with the archaeologist. Methods - Procedures for Optically Stimulated or Infrared Stimulated Luminescence of Fine-grained pottery. Optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) on fine-grain (1-8µm) pottery samples are carried out on single aliquots following procedures adapted from Banerjee et al. (2001) and Roberts and Wintle (2001. Equivalent dose is determined by the single-aliquot regenerative dose (SAR) method (Murray and Wintle 2000). The SAR method measures the natural signal and the signal from a series of regeneration doses on a single aliquot. The method uses a small test dose to monitor and correct for sensitivity changes brought about by preheating, irradiation or light stimulation. SAR consists of the following steps: 1) preheat, 2) measurement of natural signal (OSL or IRSL), L(1), 3) test dose, 4) cut heat, 5) measurement of test dose signal, T(1), 6) regeneration dose, 7) preheat, 8) measurement of signal from regeneration, L(2), 9) test dose, 10) cut heat, 11) measurement of test dose signal, T(2), 12) repeat of steps 6 through 11 for various regeneration doses. A growth curve is constructed from the L(i)/T(i) ratios and the equivalent dose is found by interpolation of L(1)/T(1). Usually a zero regeneration dose and a repeated regeneration dose are employed to insure the procedure is working properly. For fine-grained ceramics, a preheat of 240°C for 10s, a test dose of 3.1 Gy, and a cut heat of 200°C are currently being used, although these parameters may be modified from sample to sample. The luminescence, L(i) and T(i), is measured on a Risø TL-DA-15 automated reader by a succession of two stimulations: first 100 s at 60°C of IRSL (880nm diodes), and then
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Reporting and intrepretation of results: Luminescence and radiocarbon dating of potsherds from Sino-Swedish expedition, Alashan Gobi desert, Inner Mongolia
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Janz, Lisa
Statens museer för världskultur