藏南聂拉木地区上三叠统与侏罗系中伸展不整合以及各组地层的厘定

晚三叠世及侏罗纪是特提斯大洋形成和扩张的时期。藏南聂拉木地区的相应地层中普遍存在裂陷盆地沉积及众多的伸展不整合。根据这些不整合面之上的“超越下伏地层不正常的化石混积事件”,判断早侏罗世赫唐早期和中侏罗世巴通期裂陷幅度分别为大于 1 60 0 m和大于80 0 m。作者根据这些不整合面以及遵循地层命名的“优先法则”,对各个组的地层划分与名称进行了厘定。

Extension-unconformities within the Upper Triasso-Jurassic sequence in the Nyalam area,southern Tibet and stipulation of various formations concerned

The meso Tethys was formed and extended during the Late Triasso Jurassic,when in the Nyalam area of southern Tibet there were extensive and corresponding sediments accummulated in the rift basin,as well as numerous extension unconformities.Judged by the abnormal event,i,e.the presence of mixed fossils derived from different horizons at various depths,which overlaid the unconformities,it is concluded that the Early Hettangian and Bathonian stages had reached the rift amplitude of over 1 600 m and 800 m respectively.On the basis of these unconformities and in accordance with the law of priority for stratigraphic nomenclature,the present paper stipulates the stratigraphic subdivision and nomenclature of the various formations concernd.