Quaternary Geochronology 10 (2012) 394e398 Contents lists available at SciVerse ScienceDirect Quaternary Geochronology journal homepage: www.elsevier.com/locate/quageo Research paper Luminescence and radiocarbon chronologies for the Xindian Culture site of Lamafeng in the Guanting Basin on the NE edge of the Tibetan Plateau GuangLiang Hou a,b, ZhongPing Lai b,c,*, YongJuan Sun c,d, MaoLin Ye e a Key Laboratory of Qinghai-Tibetan Plateau Environment and Resource (MOE), School of Life and Geographic Science, Qinghai Normal University, XiNing 810008, China b State Key Laboratory of Cryosphere Sciences, Cold and Arid Regions Environment and Engineering Research Institute, Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou 730000, China c Luminescence Dating Group, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, 18 XinNing Road, XiNing 810008, China d Graduate University of Chinese Academy of Sciences, Beijing 100049, China e Institute of Archaeology, Chinese Academy of Social Sciences, Beijing 100077, China article info abstract Article history: The archaeological Lajia and Lamafeng sites were situated in the Guanting Basin in the northeastern edge Received 15 October 2011 of the Tibetan Plateau, and were in the second terrace of the Yellow River. The Lamafeng site is only Received in revised form 1500 m away from Lajia site. The Lajia site belongs to typical Qijia culture (4100e3600 cal a BP). Many 23 February 2012 human skeletons were found in the Lajia site. These remains presented a state of unnatural deaths. They Accepted 25 February 2012 were all buried in-situ. The Lajia site recorded a prehistoric natural disaster, and the cause of which was Available online 7 March 2012 probably a combination of earthquake and flooding due to the outburst of a lake that had been dammed by a landslide on the Yellow River. The Lajia site was abandoned by the prehistoric people after the Keywords: OSL dating disaster, but follow-up cultural relics were not found. Lamafeng site is a representative of Xindian Culture e Radiocarbon dating (3400 2600 cal a BP). The investigation of the Xindian Culture is intensive. However, the chronological Lajia and Lamafeng archaeological sites data is still very limited, and no luminescence data has been reported so far. In the current study, both Qijia and Xindian Cultures optically stimulated luminescence (OSL) (three samples) and accelerator mass spectrometry (AMS) (five NE Tibetan Plateau charcoal samples) dating are applied to samples from Lamafeng archaeological site. The results showed that: (1) For the sample from the cultural layer, within error margins OSL and 14C ages are in good agreement. The 14C ages show that the cultural layer has an age range of w2400e2300 cal a BP. (2) The Lamafeng site was inhabited by the people of Xindian Culture, which indicated that the natural disaster occurred in the Qijia culture period did not completely destroy the prehistoric culture in the basin. (3) There was an enhanced extreme flood activity during Qijia and Xindian Culture periods, and the extreme flood period was ended at 2.6 Æ 0.2 ka. http://ir.isl.ac.cnÓ 2012 Elsevier B.V. All rights reserved. 1. Introduction (35510N, 102480E) is located within the fluvial sediments of the second river terrace above the Yellow River. The excavation of the There are many prehistoric sites distributed in the Guangting Lajia site started in 1999, and revealed a number of surprising Basin in Qinghai Province covering the time period from 6000 cal discoveries (Institute of Archaeology, Chinese Academy of Social a BP to 2600 cal a BP, including Yangshao culture (6000e5000 cal Sciences & Qinghai Provincial Institute of Cultural Relics and a BP), Majiayao culture (5000e4000 cal a BP), Qijia culture (ca Archaeology, 2002). More than twenty human skeletons were 4100e3600 cal a BP), and Xindian Culture (3400e2600 cal a BP) found within an area of about 100 square metres. In a house of about (State Cultural Relics Bureau, 1996). There are two archaeological 15 square metres there were fourteen skeletons, which presented sites close to each other in the Guanting Basin (Fig. 1). One is Lajia a state of unnatural deaths. They were all buried in-situ. The Lajia occupied during the Qijia period, and the other is Lamafeng, occu- site recorded a prehistoric natural disaster, whose reason was pied during the Xindian Culture period. The Lajia archaeological site thought to be a combination of earthquake, debris flow, and Yellow River floodings resulted from climate changes (Xia and Yang, 2003), or the outburst of a lake that had been dammed by a landslide on * Corresponding author. State Key Laboratory of Cryosphere Sciences, Cold and the Yellow River triggered by a strong earthquake (Wu et al., 2009). Arid Regions Environment and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China. The world oldest millet noodle was found at this site, which was E-mail addresses: [email protected], [email protected] (Z. Lai). covered by a bowl when the disaster occurred, whose age 1871-1014/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.quageo.2012.02.024 G. Hou et al. / Quaternary Geochronology 10 (2012) 394e398 395 represents the time of the disaster. It was dated by 14C accelerator 360 mm with w70% of precipitation during summer. The basin mass spectrometry (AMS) at 4000 cal a BP (Lu et al., 2005). elevation is 1754e1906 m. The Lamafeng section (355103900N, The Lajia site was abandoned by the prehistoric people after the 1024805700,elevation1791m,Fig.1b) is exposed in a naturally eroded disaster. It was re-inhabitated ca. 600 years later by the people of gully slope, and has a thickness of 400 cm (Fig. 2a). From the top to the Xindian Culture at the Lamafeng site (Xie, 2002), which is situated bottom, it consists of soil (0e310 cm), cultural layer (310e335 cm), 1500 m to the east of Lajia. Because the distance between the two and fluvial deposit (>335 cm). The cultural layer is rich in black sites is very close, we can regard them as a whole. Lamafeng site is organic matter, charcoals, animal bones, and some pottery pieces. The a representative of Xindian Culture and is located in the center of pottery shards indicate that they belong to the Xindian Culture. the Guanting Basin. Xindian Culture is the successor of Qijia culture, The soil layer is in dark colour, with some organic matter and and radiocarbon ages (only six in total by far) on charcoal associ- apparent mycelia and worm hole. Fluvial deposit belongs to the ated with slags range from about 3400 cal a BP to about 2600 cal sedimentary characteristic of slackwater deposits (Yang et al., aBP(Xie, 2002). However, the chronological data is still very limited and no luminescence ages have been reported so far. In this study, both optically stimulated luminescence (OSL) dating and radiocarbon dating will be used to provide more absolute age control for the Lamafeng site. The implications for archaeology and environment will be discussed. 2. Study area, section and samples The Guanting Basin is in the northeastern edge of the Tibetan Plateau (Fig. 1a). It is surrounded by the Laji Mountains to the north- west, and the Jishi-Mountains to the south. The Yellow River runs in the southern part of the basin from west to east. The basin has an annual average temperature of 8.6 C, and an annual precipitation of http://ir.isl.ac.cn Fig. 1. (a) DEM (Digital Elevation Model) image of the Qinghai-Tibetan Plateau (QTP), with the Guanting Basin (black dot) in the northeastern edge, in between the cities of Lanzhou and Xining. (b) Locations of the archaeological sites of Lajia and Lamafeng in the Guanting Basin. The numbers show the sites of different cultures. Yangshao culture: 3, 5, 20; Majiayao culture: 2, 4, 6, 8, 9, 12; Qijia culture: 1, 3, 5, 7, 8, 9, 10, 11, 12, 13, 14, 18; Xindian Culture: 4, 6, 9, 15, 16, 17, 19 (State Cultural Relics Bureau, 1996; Yang Fig. 2. Pictures showing the sections (a), and the locations of samples and their et al., 2004). ages (b). 396 G. Hou et al. / Quaternary Geochronology 10 (2012) 394e398 2500 size of 0.5 Â 0.5 Â 0.5 cm in volume. It is in a block with some a angles, suggesting that the charcoal is buried in-situ. N 2000 3. Sample preparation and measurements 14.5 Gy 0 Gy In the luminescence laboratory, the 38e63 mm quartz grains 1500 were extracted following the procedures described by Lai (2010). Laboratory preparation included treatment with HCl (10%) and H2O2 (30%) to remove carbonates and organics, respectively. The m 1000 grain size of 38e63 m fraction was isolated by sieving, and then was treated with H2SiF6 for about two weeks. Quartz purity was monitored by IR stimulation. Any samples with measurable IRSL signals were retreated with H2SiF6 to avoid De underestimation OSL intensity (c/0.16s) intensity OSL 500 (Aitken, 1998; Roberts, 2007; Lai and Brückner, 2008). Pure quartz samples were then fixed onto an area of about 0.6 cm diameter in 1.0 cm diameter stainless steel discs using silicone oil. The grains 0 are sparsely distributed and 4000e6000 grains could be mounted 012345in a disc with a diameter of 1 cm according to Duller (2008). stimulated time (s) OSL measurements were performed on an automated Risoe TL/ 2 OSL-DA-20 reader. Stimulation was by blue LEDs (with emission b band of 470 Æ 20 nm) for 40 s at 130 C, and detection was through a 7.5 mm Hoya U-340 filter. Preheat was using 260 C for 10 s, and cut-heat at 220 C for 10 s.