Sequence Stratigrapphy And Basin Filling Sequence Of Upper Jurassic To Neogene In Mid-Yangtze Area

The structure of the mid-Yangtze block, central China in the Mesozoic and Cenozoic has reconstructed the reservoirs in the middle assemblage of southern China, which is the main exploration target in southern China. The success on petroleum exploration in Jianghan basin indicates that the basin of late Jurassic to Neocene in mid-Yangtze area has a great potential to create oil and gas. However, the mid-Yangtze block has been only focused on limited regional geologic studies, especially only in Jianghan basin. It is necessary, therefore, to study the sequence stratigraphy and basin filling sequence in the basin of late Jurassic to Neocene in mid-Yangtze area coupling basins and orogens to correctly identify sedimentary basin development and structural history of mid-Yangtze block and its surrounding orogenic belts.Based on the theories and methods of sedimentology, sequence stratigraphy and basin analysis, this paper establishes the sequence stratigraphic framework from Late Jurassic through Neocene and its temporal and spatial configuration on the basis of stratigraphic division and correlation and the research on depositional system. This paper also focuses on the palocurrents, composition of sandstone, rare earth elements and trace elements analysis of the study area. By integrating of all the data, the basin filling sequences are identified through mid-Yangtze basin in the late Jurassic to Neocene. In addition, tectonic movements and its control on basin filling patterns have been discussed.After the outcrop-based sedimentologic, well logging and seismic stratigraphic analyses of the study area, 31 sequence boundaries were identified on the basis of erosion surfaces, unconformities, transition surface of rock character and facie, seismic reflection character and termination. The sequence boundaries divide the Upper Jurassic to Neogene into 30 sequences through Zigui basin and Jianghan basin. Considering the tectonic movement, the 30 sequences are divided into 9 supersequences and 5 tectono-sequences.The integration of palocurrents, composition of sandstone and heavy minerals, rare earth elements and trace elements analysis of the studied strata allowed for several conclusions regarding basin filling evolution and characterization of late Jurassic to Neocene in mid-Yangtze area to be proposed. Considering all the elements and impacted by Qinling–Dabieshan orogenic belt, Jiangnan fold-thrust belt and Huangling anticline, the most likely basin-fill processes in mid-Yangtze basin of late Jurassic to Neocene consist of (1) the depositional setting of the upper Jurassic in Zigui basin is foreland basin and the provenance is recycling orogenic belt mainly. The provenance originating of Suining Fm is Shenrongjia paleouplift in the north and Penglaizhen Fm is Huangling anticline in the east. (2) The provenance originating of the Lower Cretaceous in Yichang area is Huangling anticline. The alluvial fan and fluvial depositional systems are identified due to the fast uplift of Huangling anticline. (3) The depositional setting of the upper Cretaceous in the northern Yangtze block is fault basin and the provenances originating of the Upper Cretaceous in Yuanan basin, Jiengmen basin and Hanshui basin come from the steep slopes mainly. The depositional setting of the upper cretaceous in the southern Yangtze block is the analogous foreland Basin. Jiangnan fold-thrust belt provides most of the provenance. (4) The depositional filled pattern in the Paleocene is dominated by two groups fault systems. The first strike (K2y-Ex) is NE or NEE and the second one (Ej-Ejh) is nearly EW. The provenance originating is the steep slopes. (5) Because of the uplift of all Yangtze block in Himalayan tectonic period, the Neogene only exist in Jianghan basin.