西藏措勤地区地层古生物研究新进展——兼论古生物学在新一轮地质大调查中的作用

Advances in stratigraphy and paleontology in Coqen, Xizang with discussions on the role of paleontology in the geological surveying

关键词:  措勤  地质调查  古生物学  进展  重要作用

Key words:  Coqen  geological survey  paleontology  advance  impo rtant role

摘要:

在西藏措勤地区进行的1∶25万区调中,地层古生物的研究取得一些新进展,在原来被认为属上新世陆相沉积的“乌郁群”上部发现丰富的有孔虫化石,根据有孔虫化石组合,这套地层应属阿普特期至赛诺曼期的滨浅海沉积;在早白垩世至晚白垩世早期的角砾凝灰岩中首次发现大量硅化木化石,表明在此期间西藏气候温暖湿润,并有大量森林被毁于频繁的火山喷发;在拉果错-川巴断层南、北两侧的下二叠统中存在不同的化石群落,其南侧为代表浅海环境的珊瑚-群落,北侧为深浅海的菊石群落。由此可以看出古生物化石研究在区调中的重要作用。

Abstract:

Some advances in stratig raphy and paleontology have been made in the 1:250000 regional geological survey in the Coqen district, Xizang. Abundant foraminiferal fossils were discovered in the upper part of the "Wuyu Group" originally assigned to the continental deposits during the Pliocene. Acco rding to the foraminifera assemblages, the Group should be ascribed to the Aptian-Cenom anian littoral-neritic deposits. The discovery of plenty of silicified wood for the first time in the brecciated tuffs of Early Cretaceous and early Late Cretaceous age has disclosed that the climates were tem perate and humid, and a vast area of forests were destroyed by frequent volcanic eruption in Xizang during these periods. T here occur different fossil com munities in the Lower Permian strata on both sides of the Lagkor lake-Chuanba fault:the coral-fusulinid comm unity in the shallower neritic environments on the southern side and the ammonoid community indicating the deeper neritic environments on the northern side.