Research Of Lithofacies And Paleogeography Of Early Permian In Northeast Area

In this paper, the study area is located in the northeast of China, includingcenter and south of Heilongjiang Province, most of Jilin Province, Eastern ofthe Inner Mongolia Autonomous Region, mostly located at longitude111°30’-132°,43°-50°40′range.This article is from the subject: Late Paleozoicmarine strata sedimentary environment and hydrocarbon source rockresearch.For the study of the early Permian lithofacies paleogeography in previousstudies mainly tectonic palaeogeography (Wang Hongzhen et al.,1987), veryrough lithofacies paleogeography (Li Li et al.,1984; Huang Benhong et al.,1982; Guo Shengzhe,1995) or local area lithofacies paleogeography (GuoShengzhe,1992; Wen Qiongying et al.,1996; Yu Zhonghe et al.,2001)and soon.These job involve the whole aera is too sketchy; much of them attached toa tectonics theory.Depositional system types and characteristics of spatial andtemporal distribution are important geological basis of hydrocarbon sourcerock study, northeast of Late Paleozoic strata sedimentary environmentresearch is still weak until now.These rough lithofacies paleogeography is hardto meet the need of the study of hydrocarbon source rocks.In this paper, the sequence stratigraphy, sedimentology, geochemistry,ore deposit geology, biostratigraphy and other multidisciplinary researchmethods are adopt to achieve study goal.The outcrop and basin geology,microscopic analysis and geological observations confirming each other,microscopic or micro study and test analysis combination are overall technicalroute.By the field backbone profile measured as the basis, to sedimentologyand sequence stratigraphy theory as guidance, carry out the study oflithofacies paleogeography.Specific for, from the primary profile measured andobserved profile on the start, a partition section of sedimentary facies of thestudy area, combining the research results having, we workout the lithofaciespalaeogeography map.In this paper, in the northeast area in the early Permian lithofaciespalaeogeography map mapping unit is in strict accordance with the isochronous contrast principle, with field measured section as the main body,madding of sedimentary microfacies research, in the northeastern region ofoutcrop section we identify terrestrial margin sedimentary system, neritic shelfsedimentary system, deep basin sedimentary system, platform margin andplatform depositional system, lacustrine sedimentary system, deltadepositional system.Based on the geochemical laboratory data and mappingand the sedimentary environment discrimination table aided determination ofthe sedimentary environment, shale geochemical data confirm Jia-Mongolianregion of the Northeast of early Permian strata is marine sediments,sedimentary environment of the study area is reduced; Research area ofPingyang town of shallow marine-bathyal facies mudstone develop, hugesedimentary thickness, widespread distribution, is a very good potential oil andgas source rocks.In outcrops on the basis of a measure, point to line to line,belt surface, we analyse sedimentary environment.In the field section ofsedimentary microfacies based on fine division, combining with regionalgeological data, we workout of sandstone thickness map, mudstone thicknessmap, the ratio of sandstone in the formation map、the ratio of mudstone in theformation map、percentage of rock map etc., on the basis of quantitativeanalysis, combining the advantages of the principle of phase, we workout ofnortheast area in Early Permian lithofacies palaeogeography map.NortheastJia-Mongolian region in early Permian is of between Eergu’Na.Jia MusiPangea and the paleo Asian Ocean residual sea sediment.This area in EarlyPermian develop marine, transitional facies, marine facies including shallowsea clastic facies, shallow marine platform facies, Littoral facies;marine-continental transitional facies-delta facies including delta front facies(underwater distributary channel, mouth bar facies), front delta facies.