Structural Evolution Of Nanxiong Basin,North Guangdong And The Impact To Development Of Red Bed Landform

The Nanxiong basin is located in border areas of the northern part of Guangdong province and in the southern part of Jiangxi province.Nanxiong basin formed in Late Cretaceous,which is a half garben dusptan fault basin like a irregular strip,basin strike NE-SW.It's a typical extensional down-faulted red bed basin in northern part of Guangdong.Nanxiong fault is a basin controlling fault of Nanxiong basin.This paper focus on regional geological background,geologic origin,basin structural-depositional evolution and red bed landform development of Nanxiong basin and Nanxiong fault,based on geochemical characteristics,stratigraphy,geochronology,geomorphology and other related subjects.The main understanding made by this paper is as follows:1.Nanxiong fault may be in the early days of the early cretaceous(about 140 Ma)started the tension,Nanxiong basin as Nanxiong fault tension began to form and accept the deposit,then because of the regional stress field from tension to compression,Nanxiong basin exist the stratigraphic gap of early cretaceous.2.Nanxiong fault formation is the result of many factors,formed by indosinian to yanshanian orogenic belt tension caused by the gravitational instability,as well as regional extensional stress field or fracture,the main reasons and yanshanian magmatic thermal long on a smaller scale,insufficient fracture of activities to provide enough power for a long time,therefore can only is the secondary factor for the formation of fracture.3.Nanxiong fault's petrology characteristics indicates a fault movement is ductile-brittle transition,fault zone in the rock has more obvious zoning characteristics,the supremacy of faulting footwall plate according to the lithology physicochemical take roughly divided into tectonic slices,silicide transition zone and tectonic fracture zone.4.Nanxiong basin basement composition is relatively complex,different parts of the basement rock density and bouguer gravity anomaly characteristics showed different characteristics,in basin of the west half basin basement rock density is small,composed of early Paleozoic metamorphic rocks,the east half basin basement density is larger,as the crystallization of strong,the density of large granite.5.The formation and development of Nanxiong basin and Nanxiong fault activity stage,the relation between fault in different periods of Nanxiong movement are reflected in the basin formation.When Nanxiong fault rapid extension,inside the basin corresponding a rapid deposition of coarse clastic sedimentary formation,poor sorting all round,and accompanied by small bedding basalt invaded.When Nanxiong fault extensional movement is relatively stable,corresponding to the basin within a set of particle size is fine sandstone and siltstone,etc.When Nanxiong fault in Eocene by the tension into compression,stopped Nanxiong basin sedimentary process and gradually closed up,suffered from erosion.6.Nanxiong basin of the red bed landform development and is closely related to tectonic movement,during the late Cretaceous to Eocene for red bed deposition provided the necessary space,the late tectonic movement and regional stress under the action of formation of the conjugate shear joints,profile control,the mountain basin,the morphology and distribution of the danxia landform,the intermittent uplift since the neotectonic movement in the basin causing 4 red bed of the formation of terrace,under the influence of surface water and gravity collapse late formed the rugged hilly red layer,but the interior of the basin in the desert of man-made causes poor type red bed.