Provenance Analysis Of Dainan Formation In Gaoyou Depression,subei Basin

The focus of this research is to make an in-depth study on the provenance of the Dainan Formation in Gaoyou Depression,Subei Basin and its influence on the characteristics of sand bodies.Based on the theory of sedimentary petrology and geochemistry,the provenance system of Dainan Formation in Gaoyou Depression is studied in detail by using the related technologies of sedimentology,elemental geochemistry and chronogeology,and according to the idea of "determining the source area of elemental quartz and drawing the provenance under the mirror".By means of major elements,trace elements,rare-earth elements and quartz cathodoluminescence of sedimentary rocks,the geotectonic setting and parent rock attribution(including age and lithology)of provenance area are determined,and the provenance direction is preliminarily discussed.Through heavy mineral analysis and thin-section microscopic identification of sedimentary rocks,the provenance system of the sedimentary area can be described in detail as far as possible,so as to identify the direction of primary and secondary provenance,delineate the influence scope and spatial distribution of provenance,and establish the distribution pattern of provenance system in different sedimentary periods of the Dainan Formation.The knowledge gained is as follows:1.Under the guidance of the idea of "determining the source area of elemental quartz and drawing the provenance under the mirror".the geotectonic setting of the source area is the active continental margin by means of major elements,trace elements,rare-earth elements and quartz cathodoluminescence.The parent rocks of the source area are mainly metamorphic or igneous rocks,and the local sedimentary rocks are abundant,and the whole area is re-cyclic deposits.2.According to heavy mineral analysis and thin-section microscopic identification,the sediments on the northern slope mainly come from the source area of Zhedou low uplift direction,while the sediments on the southern steep slope are mainly affected by the direction of Tongyang uplift and Wubao low uplift direction.Huangjue,Shaobo and Xiaoliuzhuang are relatively close to the source area,but their distances and proximities vary in different sedimentary periods.3.During the LSC1 sedimentary period,the southern Huazhuang area was greatly influenced by the direction source area of Wubao low uplift.The provenance of Majiazui area near the Hanliu fault and Lianmengzhuang area was relatively complex,but the former was greatly affected by the direction source area of Lingtangqiao low uplift,while the latter was mainly affected by the direction source area of Zhedou low uplift.4.According to the supply mode of provenance,source distance,source rock properties and other conditions,the characteristics of sand body in Lake Basin have been recognized.The distribution direction of the sand body is basically the same as that of the provenance.The sand body distributes from south to northeast and northwest.The distribution pattern is banded and the connectivity· of the sand body is good.