摘要
青藏高原甜水海湖钻孔岩心是一套连续和完整的第四纪沉积层序，通过对沉积地球化学信息的综合分析，初步建立了２３万年来的气候曲线。揭示了几次较大的降温信息，约１５万年以前，年平均气温为－１．６３℃，气候温干，沉积以氧化环境为主导；在６阶段后期，呈现气候波动频繁，沉积环境不稳定；进入５阶段，即进入末次间冰期，气温下降，年平均气温较６阶段降低２．８３℃；约７．４万年以来，即进入末次冰期，４阶段气温较５ａ亚段降低０．７３℃；约２．５万年以来，即进入末次冰期最盛期，２ｂ亚段气温较３ａ亚段降低２．２１℃。２３万年以来甜水海湖岩心的沉积记录研究所划分的７个沉积阶段基本上可与深海氧同位素标准曲线对比。初步认为甜水海古湖大约形成于１５万年以来，即青藏高原第三成湖期，同时与青藏高原１５万年构造运动的再次隆升有关。
The drilling core mentioned in the paper consists of a suite of continuous Quaternary sediments,and may be considered as a representative section for the study of sedimentary geochemistry of Late Quaternary.The drilling core is situated at 35°21′N,79°30′E.The drilling well stands at 4 840m above sea level,with a depth of 56 32m.Synthetic analysis of geochemical information has preliminarily established climatic curves since 230 kaB.P..Temperature drop was recorded in the core.Before 150kaB.P.,the mean annual air temperature was-1 63℃,climate was warm and dry,and the sediments were mainly in an oxidation environment.Then climatic fluctuation occurred,and the sedimentary environment became unsteady at the late stage6.The mean annual air temperature of stage 5(last interglacial stage)was 2 83 ℃ lower than stage 6.The mean annual air temperature of substage 5d was -8 52℃,3 15℃ lower than substage 5e.The mean annual temperature of stage 4(last glacial)was 0 73℃ lower than substage 5a.The mean annual air temperature of substage 2b(last glacial maximum) was 2 21℃ lower than substage 3a.The sediments can be divided into seven stages of environment evolution based on geochemical features of iron oxides since 230kaB.P.,which can basically compare with the oxygen isotope stages in the deep sea sediments.This study preliminarily suggests that the ancient Tianshuihai Lake was formed at 150kaB.P.,i.e.during the third lake forming period when Qinghai Xizang Plateau was uplifted again.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
1998年第3期63-70,共8页
Marine Geology & Quaternary Geology
基金
"八五"国家攀登计划
关键词
铁元素
气候记录
湖岩心
青藏高原
甜水海
iron oxides climatic records since 230 kaB.P. Qinghai Xizang Plateau
