西藏南部岗巴地区白垩纪化石碳酸盐岩微相与沉积环境研究

西藏南部岗巴地区发育着我国最完整的海相白垩纪地层,对该时期海相沉积演化特征的研究,能够较好地反映该地区在印度板块和欧亚板块碰撞前的演化信息。对白垩纪岗巴地区的化石碳酸盐岩微相进行了较为详细和系统的分析与研究。初步识别出12种微相和7种生物相类型,在此基础上对西藏特提斯白垩纪沉积环境的演变进行了初步的探讨。西藏特提斯在白垩纪的海水进退规程总体上表现为:Berriasian—Aptian期发生海侵,Albian早期发生海退,Albian晚期—Cenomanian期水体有进一步加深的趋势,Turonian期再次发生大规模海侵,Santonian—Coniacian期海侵持续进行,Maastrichtian期海水急剧变浅。

Microfacies and Sedimentary Environments of Cretaceous Fossil Carbonate in Gamba, Southern Tibet

Cretaceous marine strata are well exposed in Gamba,southern Tibet,and the study of which may provide abundant information about the evolution of Tibet-Tethyan ocean before the collision between Indian and Asian plates.This research carried out a detailed study on the Cretaceous fossil carbonate microfacies of Gamba.Twelve types of microfacies(MF1-MF12) and seven types of biofacies had been recognized.On the basis of these,the research made a preliminary discussion on the environmental evolution of TibetanTethys during Cretaceous,which could be concluded as follows: a transgression took place during the Barremian-Aptian;in the early of Albian,Gamba area was generally in a regressive environment;from the Late Albian to Cenomanian the seawater had a deepening trend;there was a big transgression which took place during the Turonian and lasted to Santonian-Coniacian;the seawater became shallow rapidly during the Maastrichtian.