藏南江孜甲不热剖面阿普特期有孔虫动物群的发现

DISCOVERY OF THE APTIAN FORAMINIFERS FROM THE GYABULA FORMATION AT THE GYABURE SECTION,GYANGTSE,SOUTHERN TIBET,CHINA

通过对江孜甲不热剖面甲不拉组下部地层的研究,在两块样品中发现了大量的有孔虫。研究层段顶部的灰岩透镜体中(样品JBL 35)含有丰富的浮游有孔虫个体,可识别出浮游有孔虫2属4种,包括:Globigerinelloides ferreolensis,Hedbergella aptiana,H.gorbachikae和H.praetrocoidea,底栖有孔虫则有Gavelinellaspp.和Lenticulina spp.等。根据浮游有孔虫各属、种的地质延限,可以确定产有孔虫灰岩透镜体的形成时代应为阿普特期。该有孔虫动物群可与岗巴察且拉剖面的Globigerinelloidesferreolensis化石延限带中的主要分子对比,为在甲不热剖面寻找阿普特早期的大洋缺氧事件(OAE 1a)提供重要线索。

A rich foraminiferal fauna was recovered from the Gyabula Formation at the Gyabure section,eastern Gyangtse,southern Tibet,China.This fauna consists of the following planktic foraminiferal taxa,Globigerinelloides ferreolensis,Hedbergella aptiana,H.gorbachikae,H.praetrocoideaand Hedbegellaspp.,and the benthic foraminifers Lenticulinaspp.and Gavelinellaspp.According to the global stratigraphic distribution of the planktic species mentioned above,the foraminiferal fauna indicates an Aptian age of the Early Cretaceous.This foraminiferal fauna can be correlated with the Globigerinelloides ferreolensis Taxon-Range Zone at the Chaqiela section of Gamba.Based on the published data of high total organic carbon(TOC)value in the Gyabure section,the age constraint from the foraminiferal fauna may provide a key clue to search for the Oceanic Anoxic Event 1a(OAE 1a).