西藏聂拉木三叠系土隆群-曲龙共巴组稳定碳同位素组成及对比

古生代-中生代之交生物灭绝后，三叠纪海洋长期、复杂的生物和环境变化过程受到高度关注.基于牙形石、菊石生物时代及土隆地区三叠系全岩稳定碳同位素曲线，识别出6次负偏和5次正偏.其中早三叠世碳同位素的N1-N4四次负偏和P1-P4四次正向偏移过程，能与我国华南、日本等多个剖面进行对应，反映我国藏南所在的高纬度地区经历了与低纬度地区相同的全球碳循环异常.首次报道了土隆剖面识别出的晚三叠世卡尼期碳同位素负偏，其幅度达到3.3‰，可对应意大利、日本以及我国川西北地区和华南南盘江盆地所记录的卡尼期极端气候事件.中卡尼期温度升高，降雨量急剧增多，风化作用显著加强，陆源硅质碎屑输入增强，可能是土隆剖面岩性剧烈变化的环境驱动因素. 

Stable Carbon Isotope Perturbations Recorded in Triassic Tulong Group-Qulonggongba Formation of South Tibet

In the aftermath of the Permian-Triassic mass extinction during the Paleozoic-Mesozoic transition,Triassic oceans were characterized by the long-term and complex biological and environmental changes. Here it reports a stratigraphic study of the Tulong section using ammonites,conodonts and stable carbon isotope in South Tibet. The carbon isotope curves show six negative shifts and five positive peaks from earliest Triassic to middle Late Triassic. Within these carbon isotopic perturbations,the four negative and four positive shifts of the Early Triassic are well correlative with the profiles of South China and Japan,suggesting that the studied area records global signals for multi-phase environmental and biotic changes. Meanwhile,a distinct negative carbon isotope shift,with a decrease of 3.3‰,occurred in the Late Triassic of the Tulong section,is indicative to the Carnian climatic event,which has been extensively found in Italy,Japan and South China. This study presents a successive carbon isotope curve with few biostratigraphic records throughout the Triassic,firstly reporting the Carnian climatic event in Tibet. The rapid temperature rise in the humid climate,intensive weathering and strong terrestrial input might contribute to the distinct lithological changes of the Middle Carnian in the study area.