鄂尔多斯盆地西南部古构造指示的构造-沉积过程及砂岩型铀成矿意义OACSTPCD

Ordos Basin has been a focal point of multiple plate convergence since the Late Mesozoic era and experienced the intra structural deformation and layer superposition from the various tectonic forces over times.Therefore,investigating the paleotectonic features of the Lower Cretaceous in the southwestern part of the Ordos Basin during different geological periods is crucial to comprehende the tectonic-sedimentary processes and uranium mineralization in the region.This study trys to reconstruct the paleotectonic features of the late Early Cretaceous in the Ordos Basin by utilizing borehole layering data,seismic profile interpretation results,and gradual back-stripping algorithm for stratigraphic de-compaction correction.Reference data from previous studies on stripping volume were also considered.The paleotectonic map of the late Early Cretaceous revealed that the Tianhuan depression structure,as observed in the present-day was not formed during that period.Furthermore,significant changes were noted in the paleotectonic features of the top surface of the Huachi-Huanhe Formation compared to the underlying strata.These observations suggested the presence of a distinct secondary stratigraphic interface between the Huachi-Huanhe Formation and the Luohandong Formation.The dynamics of this transformation may have originated from the initial rifting of the Liupanshan Rift Basin and associated magmatic intrusion.The Tianhuan depression structure in the Pre-Cretaceous initially formed by the end of the Late Jurassic and experienced further superposition in the Late Miocene,while the Tianhuan depression during the Lower Cretaceous formed exclusively in the Late Miocene.The paleotectonic conditions of the study area and their evolutionary process indicate the possibility of"oxudation"uranium mineralization in the region.