Extensive lacustrine deposits in the eastern Tarim Basin provide records of climate change influenced by the westerly winds and the Asian monsoon. To characterize the evolution of climate change in this region, we analyze elemental concentrations of barium(Ba) from the Ls2 drill core of Lop Nor, a paleo-lakebed located in the eastern Tarim Basin. Biogenic Ba concentrations from this drill core display a large-amplitude oscillation that generally follows a pattern similar to that of Artemisia content and ostracod assemblages, suggesting that is may serve as an index for climate change experienced in the basin. Our results indicate that biogenic Ba is especially sensitive to precipitation. All climatic proxies served in this study vary significantly over late Miocene to early Pleistocene time period. Strong aridification of eastern Tarim in the late Miocene to the early Pliocene may be attributed to a latitudinal shift in the westerly winds, which would have resulted in more moisture transported to southern and eastern Tibet. The growth of the Himalaya and Tibetan Plateau may have acted as an orographic barrier that blocked moisture sourced in the south from the northern margins of the plateau. We link weaker aridification in the late Pliocene to an increased intensity of the Indian Monsoon.
Hong ChangZhisheng AnWeiguo LiuFeng WuXiaoke QiangYougui Song
The Qinghai Lake in North China is the largest interior plateau lake in Central Asia, and is sensitive to climate change and the environmental effects of Tibetan Plateau uplift. An almost continuous 626 m long sediment core was drilled in an in-filled part of the southern lake basin in the Scientific Drilling at Qinghai Lake.
FU ChaofengJan BLOEMENDALQIANG XiaokeMimi J.HILLAN Zhisheng
In this paper,we report 3780-m-thick Neogene deposits accumulated in the Kuqa foreland basin of southern Tians...
Zhenqing Zhang,Jimin Sun~* Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,P.O.Box 9825,Beijing 100029,China
Otoliths are biogenic carbonate minerals in the inner ear of teleost fish, whose compositions can record the physical and chem- ical conditions of the ambient water environment inhabited by individual fish. In this research, the fishbones and otoliths of naked carp sampled near the Bird Island, offshore Lake Qinghai, were dated and analyzed for mineralogy and microchemical compositions. Comparing the microchemical compositions of ancient otoliths with those of modem otoliths, we conclude that the ancient naked carps inhabited a relict lake formed when the lake shrank from a high lake level, by combining with the AMS-lnC ages of fishbones and otoliths, the stratigraphy and surrounding topography of the sample site. AMS-14C dating resuits of ancient fishbones and otoliths show that these naked carps lived from 680 to 300 years ago, i.e. during the Ming Dynasty of China. The X-ray diffraction （XRD） patterns demonstrate that the ancient lapillus is composed of pure aragonite, iden- tical to modem one, indicating that the mineral of lapillus didn＇t change after a long time burial and that the ancient lapillus is suitable for comparative analysis thereafter. Microchemical results show that both ratios of Mg/Ca （（70.12±18.50）× 10-2） and δ18O （（1.76±1.03）‰） of ancient lapilli are significantly higher than those of modem lapilli （average Mg/Ca=（3.1 1±0.41）× 10-5 and δ18O =（-4.82±0.96）‰）. This reflects that the relict water body in which the ancient naked carp lived during the Ming Dynasty was characterized by higher Mg/Ca and δ18O ratios than modem Lake Qinghai, resulting from strong evaporation after being isolated from the main lake, similar to today＇s Lake Gahai. Based upon the stratigraphy and altitude of naked carp re- mains, it can be inferred that the altitude of lake level of Lake Qinghai reached at least 3202 m with a lake area of 4480 km2 during the Ming Dynasty, approximately ~5% larger than it is today.
WANG YuJiaoJIN ZhangDongZHOU LingLI FuChunZHANG FeiCHEN LiuMeiQIU XinNingQI RuGui
