Evolution of an Ancient Large Lake in the Southeast of the Northern Tibetan Plateau

Nam Co is the largest (1920 km2 in area) and highest (4718 m above sea level) lake in Tibet. According to the discovery of lake terraces and highstand lacustrine deposits at several places in Nam Co and its adjacent areas, the authors confirm the existence of an ancient large lake in the southeastern part of the northern Tibetan Plateau. On the basis of the U-series, 14C and ESR dating, coupled with the levelling survey of lake deposits and geomorphology, the evolutionary process of the ancient large lake in the southeastern part of the northern Tibetan Plateau may fall into three stages: (1) the ancient large lake stage at 115-40 ka BP, when the ancient lake level was 140-26 m above the level of present Nam Co; (2) the outflow lake stage at 40-30 ka BP, when the ancient level was 26-19 m above the present lake level; and (3) the Nam Co stage since 30 ka BP, when the ancient lake level was < 19 m above the present lake level. During the ancient large lake stage, a large number of modern large, medium-sized and small lakes, including Nam Co, Siling Co and Zhari Namco, in the southeastern part of the northern Tibetan Plateau, were connected into a single large ancient lake, rather than several separate lakes connected by river channels. Its areal extent may have gone beyond the watersheds of the modern endorheic and exorheic drainage systems; so it may be called the 'ancient east lake', 'ancient south lake' and 'ancient west lake'. It might also be connected with other ancient lakes in the southern and western parts of the northern Tibetan Plateau to form a unified 'ancient large lake' on the northern Tibetan Plateau.

Uranium Series Chronology of the Late Pleistocene Basalt from the Longgang Volcanoes, Jilin Province

The Longgang volcanic cluster located in Jilin Province belongs to one of the active volcanic regions in northeast China, and has been active in modern times. In view of the multiple eruptions in history, it is very important to determine the age of each eruption for evaluating the volcanic hazards. Two alkaline basalt samples taken from Dayizishan and Diaoshuihu were analyzed with the U-series component dating after magnetic separation. The ages of the two samples are (71±9) ka and (106±13) ka B.P., respectively. These data indicate that there existed intensive eruption activities during the late Pleistocene.

120-150 ka human tooth and ivory engravings from Xinglongdong Cave, Three Gorges Region, South China

Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and a Stegodon tusk exhibiting intentional engravings.Based on biostratigraphic data and uranium series dating,the cave was utilized as a human shelter about 120000-150000 years ago. It is the first time that an archaic Homo sapiens fossil has been unearthed from the Three Gorges Region. Engravings on the Stegodon tusk appear in groups,making up simple and abstract images. It is the earliest known engravings created by human beings; it exhibits great potential for the study of the origin of art and the development of ancient cultures in south China and bears important implications for the origin of modern humans in East Asia.