青藏高原北部库赛湖自生碳酸盐稳定同位素记录的晚全新世气候组合特征  

LATE HOLOCENE CLIMATIC COMBINATION ON THE NORTHERN TIBETAN PLATEAU BASED ON STABLE ISOTOPE ANALYSIS OF AUTHIGENIC CARBONATE FROM KUSAI LAKE

作　　者：倪振宇 王永波 刘兴起[1] 

机构地区：[1]首都师范大学资源环境与地理信息系统北京市重点实验室,首都师范大学资源环境与旅游学院,北京100048

出　　处：《第四纪研究》2016年第4期961-969,共9页Quaternary Sciences

基　　金：中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室开放基金项目（批准号：2014SKL001）、国家自然科学基金面上项目（批准号：41572338）和国家自然科学基金青年项目（批准号：41502325）共同资助致谢王建军副研究员协助完成野外采样工作;张恩楼研究员、李凯博士在样品前处理方面给予指导;审稿专家和编辑部老师提出了建设性的修改意见,在此深表感谢.

摘　　要：青藏高原北部受亚洲季风和西风环流的共同影响，对区域乃至全球的气候变化响应敏感。但该区古气候记录相对较少，特别是缺少高分辨率的古气候记录，对该地区的气候组合特征（温度-湿度组合）的解释也存在着较大的争议。本研究选择位于青藏高原北部可可西里地区的库赛湖作为研究对象，通过湖泊自生碳酸盐稳定碳、氧同位素的分析，结合纹层定年，探讨了碳、氧同位素的气候指示意义，重建了1600年以来的气候演化模式。结果表明，当温度升高时，湖泊内源生物增加，水生生物选择性利用水体中溶解的12C，导致湖水中13C富集偏正，因此δ13C值能够指示流域气温的变化，即δ13C值偏正，温度偏高；与此同时，蒸发作用显著导致流域内有效湿度降低，造成湖水中18O富集，因此 δ18O值指示流域有效湿度的变化，即δ 18O值偏正，有效湿度偏低。在此基础上，重建了1600年以来青藏高原北部的气候演化序列：400~600A.D.（黑暗时代冷期DACP），气候冷湿；600~1400A.D.（中世纪暖期MWP），气候暖干；1400~1900A.D.（小冰期LIA），气候冷湿；20世纪后，进入近代暖期（CWP），暖干气候特点更加明显。过去1600年青藏高原北部地区温度和湿度的气候组合总体表现为冷湿、暖干的特点，其中冷期有效湿度的增加可能是由于中纬度环流活动频繁，具体表现为西风急流的增强，导致降水增加。The northern Tibetan Plateau（TP）is sensitive to climate change as a result of the joint influences of the Asian monsoon and the mid-latitude westerlies. Unfortunately, palaeoclimate data from this region are very rare, especially considering high resolution records of the Late Holocene. In addition, the temperature-moisture association in this region is still under debate. A 350cm sediment core KSS-V covering the past 1600 years was obtained from Kusai Lake（35°37＇~35°50＇N, 93°15＇~93°38＇E） in the Hoh Xil region of the northern TP. The high sedimentation rate allows us to investigate the climate variations at inter-annual to inter-decadal time scales. Mainly authigenic, fine-grained carbonates were used for stable carbon and oxygen isotope analyses. The palaeoclimatic significance of the isotope records was evaluated and the climate variations over the past 1600 years were reconstructed. Within the alpine lakes, the aquatic organisms increase when temperature rises, and prefer to utilize the 12C in total dissolved inorganic carbon （TDIC） of lake water, leading to the relative enrichment of 13C in the lake water, which was subsequently preserved in authigenic carbonates precipitated from the water column. Hence, the variation of δ13C value is mainly constrained by the aquatic productivity in response to the regional temperature change. On the other hand, the main factor influencing oxygen isotope composition in closed lakes is the regional effective moisture, i.e. the precipitation/evaporation ratio（P/E）. Positive δ18O values generally indicate reduced effective moisture, and vice versa. Stable carbon and oxygen isotopes of fine-grained, authigenic carbonates were investigated as proxies of aquatic productivity mostly driven by temperature, and the precipitation/evaporation ratio, respectively. The resulting inferences suggest that the climate was relatively cold and wet between 400A.D.and 600A.D.corresponding to the Dark Age Cold Period（DACP）. A warm and dry period occurred thereaf

关 键 词：青藏高原北部 晚全新世 自生碳酸盐 碳 氧同位素温度-湿度组合 

分 类 号：P941.74[天文地球—自然地理学] P941.78