Provenance analysis and tectonic implications for the Cretaceous sandstones in the Jixi and Boli Basins,Heilongjiang

The modal analysis of the Cretaceous sandstones from the Jixi and Boli Basins,Heilongjiang suggests that the provenance of the Lower Cretaceous Chengzihe Formation and Muleng Formation sandstones is a dissected island arc.The palaeocurrents and geochemical signatures of the sandstones have revealed that the major source areas are the Xiao Hingganling and Zhangguangcailing Mountains while the source areas of the Upper Cretaceous Houshigou Formation sandstones are the basement uplift and dissected island arc.According to the palaeocurrents and gravel compositional statistics,the source areas of the Jixi and Boli Basins consist of Huanan uplift,Mishan uplift,Xiao Hingganling and Zhangguangcailing Mountains.It is inferred from the provenance analysis of the Cretaceous sandstones,Late Cretaceous gravel compositional statistics and regional geological data that the Jixi,Boli and other basins in eastern Heilongjiang originally were once a unified protopyte basin during the Early Cretaceous(deposition of the Chengzihe and Muleng Formations).This protopyte basin was subsequently subjected to the collapse with the uplifting of the Huanan and Mishan uplifts during the latest Early Cretaceous.Till the Late Cretaceous(deposition of the Houshigou Formation),the Huanan and Mishan uplifts were constantly uplifted,and delivered the sediments for the surrounding basins.The present-day basin-range framework came into being in northeastern Heilongjiang at that time.