Abstract: The Jiangxigou Locality 2 (JXG 2) is located in the northeastern edge of Tibetan Plateau in Qinghai Province, Northwest China. The site lies on the southern slope of Qinghai Nanshan Mountains, a transition zone between the plain of the Qinghai Lake and the piedmont hills of the mountains, approximately 3312 meters to the lakeshore. JXG 2 was first discovered in 2004 and excavated in 2012. A total of 659 stone artifacts and some pottery fragments were found from the site. According to tech-typological study of artifacts and the existence of pottery sherds, the section can be divided into two cultural layers. The upper layer mainly contains the microblades related products and the pottery sherds; the lower layers contains the microblades related products and the bipolar products on quartz, while no pottery sherds. The results of optically stimulated luminescence (OSL) dating method and AMS14C dating method suggested that the age of the two cultural layers were younger than 8.0ka BP and 9.5ka~8.0ka BP respectively. In the lower cultural layer, 316 pieces of stone artifacts were the only remains unearthed. Around 50% of the lithic artifacts are microblade-related products made on chert, and the others are bipolar products on quartz. The archaeological remains of the upper cultural layer include 343 pieces of stone artifacts and some pottery fragments. Different from the lower layer, the lithic artifacts in the upper layer are mainly made on chert and no bipolar related ones were found. The change of the lithic raw materials and the knapping technology, coupled with the use of pottery revealed the cultural transition. Based on the paleoenvironmental study results of the current study and the previous studies, the upper layer also corresponded to the Holocene Megathermal, and the pollen analysis may indicate the appearance of early agriculture. The JXG 2 site is an important site at the marginal area of Tibetan Plateau. It provides successive archaeological deposits during the Holocene, and clearly suggested the society transition around 8ka BP. The preliminary study on the site cannot reveal all the details of the transition, while more detailed research work in the area will give us the whole process of the transition from hunter-gatherers to a mixture mode including hunting, herding and agriculture.

Key words: Jiangxigou Locality 2; Lithic artifacts; Techno-typology; Society transition