多元地球化学指标指示的32-9kaB．P.罗布泊地区环境及其对全球变化的响应

Paleoclimate of Lop Nur and the response to global change by geochemical elements multi-analysis

对位于新疆罗布泊地区罗北洼地的CK-2钻孔柱样,自距顶0.94m到10.35m部分,以5cm间距采样,6个样的质谱-铀系法年龄为32～9kaB.P.,用仪器-化学分析法得到了样品中Na、K、Ca、Mg、Fe、Cu、Hg、Zn、Mn、Sr、As、Pb、P、Cl和TOC共15种元素的含量。通过对元素含量变化和主成分序列分析,探讨了罗布泊地区在32～9kaB.P.期间,经历的从末次盛冰期(阶段Ⅰ)、暖干期(阶段Ⅱ)、末次冰期晚期(阶段Ⅲ),到全新世早期(阶段Ⅳ)的不同程度冷湿与暖干的变化阶段。与格陵兰冰芯(GISP2)和深海沉积物氧同位素序列对比结果表明,罗布泊地区经历了MIS3晚期、MIS2和早MIS1早期。在罗布泊环境演化序列中也出现了发生在北大西洋冰漂碎屑的Heinrich事件(H3、H2和H1)和新仙女木(YD)事件,以及快速回暖的D/O事件(IS4、IS3、IS2和IS1)。这表明高纬度的大气环流影响到中纬度西风带的强度、相位和位移,制约了我国西北干旱化地区气候环境变化的格局。为此,罗布泊地区的湖相沉积环境不仅记录了受到西风带、青藏高原隆升以及远离东亚和南亚季风影响所具有区域性的冷湿与暖干的水热配置特点,并且还具有全球变化的印迹。

A record of climatic and enviromnental changes core （CK-2） from the Luobei billabong, Lop Nut, Xinjiang, is presented inferred from the geochemistry of sediment NW China. The samples that were sampled at intervals of 5 cm of the core were analyzed for 15 elements, including Na, K, Ca, Mg, Fe, Cu, Hg, Zn, Mn, Sr, As, Pb, P, Cl and TOC, by atomic absorption spectrophotometer, atomic fluorescence spectrometer and some chemical methods. The chronology is provided by 6 uranium/thorium disequilibrium ages. The results suggest four paleoclimatic stages during 32-9 ka B.P., the characteristics of which were cold-humid and warm-arid environment, corresponding to Late Glacial Maximum （LGM）, Interglacial, Late Glacial and early Holocene.According to the comparison with Greenland ice core （GISP2） and marine isotope stage （MIS）, the climate evolution of Lop Nur district experienced late MIS3, MIS2 and early MIS1. Some climate events, such as Heinrich Events and Younger Dryas in North Atlantic and Dansgaard/Oeschger Oscillations （D/O）, were also investigated in Core CK-2. It is concluded that the climate variability of this district was restricted by the global change. High latitude atmosphere circumfluence influenced the climate evolution of the arid NW China by influencing the strength and cycle of middle latitude westerlies. The lacustrine sediments in Lop Nur have recorded the characteristics of regional precipitation and temperature, which were influenced by westerlies and the uplift of Qinghai-Xizang Plateau, and beyond the impact of east and south Asian Monsoon.