巴丹吉林盆地路井凹陷下白垩统巴音戈壁组沉积体系及铀成矿远景预测OA

Lujing sag is located at the western margin of Juyanhai depression in the northern part of Badain Jaran Basin.Currently,the overall level of uranium exploration in Badain Jaran Basin remains extremely low,and specialized scientific research and basic geological studies on uranium deposits in the basin are still in a relatively blank state.The basic geological characteristics of the basin have not been systematically ascertained,and the understanding of key geological factors such as the tectonic-sedimentary evolution and sedimentary systems of the target strata in Lujing sag remains unclear,making it difficult to accurately determine the direction of uranium exploration,which severely constrain the substantial breakthroughs in uranium exploration and the in-depth advancement of exploration efforts in the basin.This paper takes Bayingebi Formation as the target stratigraphic unit and aims to predict uranium metallogenic prospects through multi-dimensional analysis of its sedimentary system characteristics,so as to provide guidance for further exploration in this area.The study systematically investigated the tectonic-sedimentary evolution of Lujing sag in Badain Jaran Basin,as well as the lithofacies,sedimentary facies,well-log facies,and sedimentary structural characteristics of Lower Cretaceous Bayingebi Formation,and conducted a segmented sedimentary system analysis of the formation.The results indicated that the middle member of Bayingebi Formation was predominantly characterized by alluvial fan-fan delta-lacustrine sedimentary systems,while the upper member was dominated by fluvial delta and alluvial fan-fan delta-lacustrine systems.Through standard sequence stratigraphic correlation,an isochronous stratigraphic framework was established,which divided the Bayingebi Formation into lowstand systems tract,transgressive systems tract,and highstand systems tract.Based on the theoretical understandings that"rifting basins control sedimentary systems,faults control sandbody trends,and slopes control sandbody scales,"combined with drilling data and the fact that sandbodies in Bayingebi Formation within Lujing sag were primarily controlled by fan delta and delta facies,it was finally predicted that sandbodies of the highstand and lowstand systems tracts developed along the long-axis direction of the sag were the favorable targets for future uranium exploration.