ABSTRACT: Sequence Stratigraphic Features of Nonmarine Tertiary Sediments in Rift Basins of East China
XU, HUAIDA, China University of Geosciences, Beijing, People's Republic of China
Many extensional half grabens filling with nonmarine clastic sediments are developed along the east portion of China from north to south, in which more than 200 oil and gas fields are developed and possess more than half of reserves and production of whole China per year. Most of Chinese geologists believe that the oil and gas are generated from the fine grain lacustrine sediments of Eocene and Oligocene, however, the author has found a variety of nanofossils, foraminiferas, dinoflagellates and glauconites from them besides nonmarine fossils. All of them indicate that the half grabens of East China have been invaded temporarily by the open sea several times in the Eocene and Oligocene. A base level changes curve is constructed by sequence stratigraphic study based on analysis of cores well logs and seismic data. Generally, the shape of this curve is similar with its counterpart constructed by Haq and Vail (1987) in long term changes but quite different in short terms (third order cycles). It shows that the curve of inland half grabens has been affected dramatically by local tectonic movement, local sediment supply and short term behavior of base level changes. Two nonmarine clastic rock sequence models are presented.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)