Sedimentary Structural Evolution Of Mesozoic-Cenozoic Basin On Southeastern Margin Of Dabie Orogenic Belt

This dissertation regards Mesozoic-Cenozoic strata on Southeastern margin of Dabie Orogenic Belt as main study object,adopts theory and methods of the Sedimentology,based on the sedimentary filling character,systematically studies the rock combination of basin strata and its distribution characteristics,basin types and sequence filling analyzes regional tectonic setting,basic framework,basement structure and igneous rock character of basin;amply studies each period strata development characteristics of basin and the law of crossbar variation,sedimentary system and phase order and temporal allocation of sedimentary system,the character of sequence interface and structural superimposed sequence,the evolution of ancient geography,though the synthetical analysis of study region's basin fillings and filling law,geochemical characteristics of volcanic rocks,discusses structure and properties of the basin and its evolution process;RSTablishes time series of basin filling and corresponding relationship between basins,and discusses cause,type and tectonic evolution of basin,coupling relationship between basin and range.This article obtains following results and understanding.(1)Systematically reorganized the Late Mesozoic-Cenozoic continental stages of research area , determined the relationship between lithostratigraphy and chronostratigraphy,further studied the correlation of the whole research area.(2)On the comprehensive analysis of Field-RSTing profile,drilling and other date,the author considered there are five kinds of depositional system in the continental sedimentary basin of the study area,which are alluvial,fan delta,fluvial,lake delta and lacustrine. At the same time,the characters of all kinds of depositional system are disscused.(3)Using Sequence stratigraphy in the theory as the guiding ideology,structure Sequence and sedimentary sequence study objective and based on the studying the characters of sequence boundary, sedimentary cycles and so on,9 tectonic sequence and 22 sedimentary sequence were recognized,then regarded the tectonic sequence as untis of chronostratigraphic correlation. (4)Regarded the sequence boundary and maximum-flooding surface of tectonic sequence as the boundary,taken the lake basin expansion systems tract and lake basin contraction systems tract as the map-making untis to RSTablish lithofacies and paleogeogphy maps of the tectonic-sequence , represent the lithofacies and paleogeogphy features of lake basin expansion and contration.Emphasis on studied the development status of sedimentary basin,evolution characteristics and exhibition of space-time of lithofacies and paleogeogphy. On this basis,combinating characteristics of the tectonic evolution of study area,the thesis analysed the sequence structure and the sedimentary basin development of lake basin systolic expansion and Contraction,the evolution of lithofacies palaeogeography and the characteristics of the spatial and temporal distribution of the law.(5)Based on studying the regional setting,basin types and regional sedimentary patterns,from the material composition, phase sequence, structure and sequence evolution, the author considerd the Mesozoic-Cenozoic basin of the studying area as superimposed basin,and the evolution of the basin could be divided five stages: Middle to Later Triassic-foreland basin ; Early to Middle Jurassic-continental depressional basin; Later Jurassic to Early stage of Early Cretaceous-volcano;Middle stage of Early Cretaceous to Later Cretaceous-strike-slip pull-apart basin;Paleogene to Neogene- depressional basin.(6)Combined with the understanding of Dabie orogenic belt's geological structure,and starting from the consentaneous views about the relationship between basin and range,the article emphasizes particularly on formation,evolution,property,characteristic of sedimentary basin and its signification ; discusses coupling relationship between Dabie orogenic belt and basin and hill basin of YANJIANG sedimentary basin in Mesozoic-Cenozoic era;and achieves academic explanation on the cause of collision.