【作者】 万晓樵；

【Author】 Wan Xiaoqiao (Beijing Graduate School of Wuhan college of Geology)

【机构】 武汉地质学院北京研究生部；

【摘要】 <正>岗巴地区海相白垩系发育良好,化石丰富,为西藏南部研究较早、划分比较详细的地层之一。早在1903—1904年间,海登(Hayden,H．H．)就对本区做过地质调查;近年来,中国科学院西藏科学考察队等单位又做了比较详细的地层工作。1980—1981年,作者随地质部青藏高原地质调查第十一分队对本区白垩系实测了岗巴东山和岗巴宗山两条剖面,更多还原

【Abstract】 Marine Cretaceous strata with abundant fossil forams are well developed in Gangba region.Detailed investigations of stratigraphic sections and collec- tion of foraminifera-bearing rock samples had been made by the the writer in 1980-1981.69 species of 24 genera of foraminifera have been identified, of which 5 species are new.Above all,the planktonic foraminifera are well preserved and show great importance in stratigraphic division and correla- tion. Cretaceous strata may be divided into 7 formations,in which 6 forami- nieral assemblages are distinguished.The details of these formations are given in ascending order as follows: The Dongshan Formation is mainly composed of black shales with side- rite nodules in the lower part.Foraminifera are rather rare and badly pres- erved.The age may be from Berriasian to Aptian. The Chaqiela Formation is chiefly consist of grey-black shale and greyish siltstone.Foraminifera are more abundant and belong to the Ticinella roberli- Hedbergella trochoidea assemblage,which indicates the Albian age. The Lengqingre Formation is chiefly composed of black shale intercalated with knotty limestone.Foraminifera are abundant with great diversity in both genera and species.The assemblage is characterized by Rotalipora and Praeglobotruncana of Cenomanian. The Xiawuchubo Formation is consists of yellow-green shale intercalated with thin-bedded limestone,containing the foraminiferal assemblage represen- ted mainly by Praeglobotruncana helvetica and Hedbergella murphi which are index forms of the Turonian Stage. The Jiubao Formation is a series of grey limestone interbedded with greenish mudstone,yielding fairly good fossil assemblage of foraminifera, predominated by Globotruncana schneegansi and G.renzi.This assemblage indicates the age from Coniacian to Santonian. The Zongshan Formation:Its Lower member consists of limestone and marl and yields a very rich assemblage of foraminifera,comprising mainly Globotruncana elevata,G.stuaritiformis and Orbitoides tissoti.The age is Campanian.its Upper Member is mainly composed of dark-grey foraminiferal limestone.Plenty of large benthic foraminifera are fairly well preserved. The assemblage is mainly represented by Orbitoides and Omphalocyclus and indicates the age of Maastrichtian. The Jidula Formation is mainly represented by white-grey quartzose sandstone,in which seldom fossils have been found and may be Late Maas- trichtian in age. 19 spaeies are described in this paper.更多还原