摘要
利用沉积响应来识别印度—亚洲大陆碰撞启动时间是最直接和有效的方法之一。西藏仲巴错江顶群被甄别为碰撞型三角洲沉积,由下组可能代表了碰撞启动时期的建造。藏南定日的海相白垩-古近系沉积演化、锶和碳同位素变化也支持两大陆碰撞启动时间大约在K/T界线时期。对比喜马拉雅西段碰撞启动时间并考虑大印度北缘失掉的宽度,提出两大陆最可能的碰撞启动时间是65Ma左右。
Many methods have been used to diagnose the initial India/Asia collision and its age, of which the recovering of sediment records during the collision is one of the most direct and valid ways. The latest marine Cretaceous and Paleogene sediments in southern Tibet are one of the records of sedimentary response to the process of the collision between the Greater India and Asia. It is proposed that the positive bias of the 87Sr/86Sr ratio and negative changes of δ13C in marine sediments indicate increased erosion during the latest Cretaceous to early Paleogene, which, together with the development of the Cuojiangding Group collision-type fan delta and the litho-facies change from hemi-pelagic limestone to shore sandstone of the Zhepure Shanpo Formation and the Jidula Formation, support the initial collision of the Indian and Asian continental plates as occurring near the Cretaceous-Paleogene boundary, i. e. ca. 65 Ma. The thought of diachronic collision results from different evidences and regardless of the Grater India. We do not think the end of the marine Eocene deposition in Tibet can be used as the representative of the initial collision of India with Asia.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2003年第1期16-24,共9页
Acta Geologica Sinica
基金
国家重点基础研究计划(编号G1998040861)和国家杰出青年自然科学基金(编号49625203)联合资助的成果
关键词
印度-亚洲大陆碰撞
碳同位素
锶同位素
地球化学
沉积记录
collision-type delta
Sr/C stable isotope
sedimentary evolution
initial collision age
Greater India
Tibet
