青藏高原晚始新世干旱化事件:改则盆地康托组碳酸盐岩碳氧同位素的记录

发布时间：2018-01-21 15:24

本文关键词： 改则盆地康托组碳氧同位素晚始新世干旱青藏高原隆升　出处：《地质学报》2016年08期 　论文类型：期刊论文

【摘要】：改则盆地位于青藏高原腹地,盆地内沉积物记录了高原古环境变化的重要信息。本文对改则盆地康托组碳酸盐岩碳氧同位素进行研究,结果显示改则盆地中-晚始新世的演化分为两个阶段:1中始新世湿润气候下开放湖盆阶段:虽然碳酸盐岩δ~(18)O值在43层处向正值偏移,但整体~(18)O和~(13)C强烈亏损,并且该时期碳酸盐岩δ~(18)O值和δ~(13)C变化相关系数为R~2=0.082。表明该阶段的研究区虽然经历过短期蒸发作用增强或补给水减少,但整体是气候湿润条件下补给水丰富的开放型湖盆。2晚始新世干旱气候下封闭湖盆阶段:经过中新世晚期(63层)气候和湖泊水文状态的过渡,晚始新世~(18)O和~(13)C同位素富集,δ~(18)O值和δ~(13)C值变化相关系数为R~2=0.7762。表明该阶段气候干旱,蒸发作用强烈,湖盆萎缩成为封闭湖盆。综合前人研究,认为青藏高原腹地及北缘、东北缘在晚始新世存在明显的区域性干旱化事件。对比分析青藏高原隆升、全球气候记录、全球海水Sr和大气CO_2记录,认为青藏高原腹地和北部的干旱化事件主要受青藏高原隆升的影响。
[Abstract]:The basin is located in the hinterland of the Qinghai-Tibet Plateau and the sediments in the basin record the important information of paleoenvironmental changes in the plateau. The results show that the evolution of the modified basin can be divided into two stages: the open lacustrine basin stage under the humid climate of Miocene: although the 未 ~ (18) O value of carbonate rocks shifts positively at the 43rd layer. Overall, however, there were significant losses. And the 未 ~ (18) O value and 未 ~ (13)) of carbonate rocks in this period. The correlation coefficient of the change of C is Ru _ 2N _ (0.082), which indicates that the study area in this stage has experienced a short period of evaporation enhancement or a decrease in recharge water. But the whole is the transition of the open lake basin with abundant recharge water under humid climate. 2. The closed lake basin stage under the late Eocene arid climate: through the late Miocene (63 layers) climate and the lake hydrological state. The late Eocene ~ (18) O and ~ (13) ~ (13) C isotopes were enriched, and the correlation coefficients of 未 ~ (18) ~ (18) O and 未 ~ (13) ~ (13) ~ C values were R ~ (2 +) ~ 0. 776 ~ (2), indicating that the climate was dry in this stage. The evaporation is strong and the lake basin shrinks into a closed lake basin. Based on previous studies, it is considered that there are obvious regional drought events in the hinterland, northern margin and northeast margin of the Qinghai-Tibet Plateau in the late Eocene. The uplift of the Qinghai-Xizang Plateau is comparatively analyzed. Global climate records, sea water Sr and atmospheric CO_2 records indicate that drought events in the hinterland and north of the Qinghai-Xizang Plateau are mainly affected by the uplift of the Qinghai-Xizang Plateau.
【作者单位】：中国地质科学院水文地质环境地质研究所;中国地质大学地球科学学院;中国地质大学生物地质与环境地质国家重点实验室;中国地质大学地质调查研究院;中国地质调查局成都地质调查中心;
【基金】：中国地质调查局青藏专项项目(编号:1212011121261)资助的成果
【分类号】：P532;P597
【正文快照】： 新生代以来,地球由全球无冰的“温室”状态,逐渐转变为现今两级发育大冰盖的“冰室”状态(Zoach et al.,2001)。期间,青藏高原的隆升不仅影响着亚洲季风-干旱气候的格局(An Zhishenget al.,2001;Guo Zhengtang et al.,2002;Liu Xiaodong et al.,2013;Zhang Chunxia et al.,201

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