Materials Evolution Analysis In Upper Jurassic Of Mohe Basin

Tectonically,the Mohe basin is generally considered to be the northern part of the Erguna block,located collision suture between the Siberian plate and the Heilongjiang micro-continental blocks.As an important tectonic unit of the Great Hinggan,the Mohe basin,situated in northwestern Heilongjiang Province in China,is characterized by east-west distribution with an outcrop area of about 21500 km2.In the past,a great deal of research has been done in the Mohe basin,this study focuses on the analysis and research on the materials evolution of the Mohe basin.Based on the previous literatures and the research results of the Province Institute,this paper will propose three component units for the Mohe basin:pre-Cambrian metamorphic basements,Paleozoic marine stratum,Upper Jurassic sedimentary strata,and Lower Cretaceous volcanic strata.The sedimentary strata in this basin include the Xiufeng,Kaikukang,Ershierzhan and Mohe formations are dominated by conglomerates,sandstones,siltstones,mudstones and transitional rocks.The overlying Lower Cretaceous Yiliekede,Shangkuli and Tamulangou formations are dominated by volcanic rocks and volcanic clastic rocks.In this study,we present the results of our integrated research on the Upper Jurassic sedimentary rocks in the Mohe basin by field investigations and studies in doors,including the characteristic of conglomerates and sandstones detrital composition,heavy mineral association,detrital zircon and geochemical study.These data provide insights into the present rocks and tectonic discrimination of provenances.Though this research,mainly achieved the following results:? the detrital component characteristics of Mohe basin indicate that their present rocks is dominated by granites,minor metamorphic,sedimentary and intermediate acid volcanics,and rare intermediate-basic igneous rocks;? the dating of their detrital zircons indicated that the Lower Cretaceous(348±3.2 Ma)strata is one of the provenances for these study samples;? on the basis of the characteristics of clastic rock composition and REE distribution patterns show that the provenance of Mohe basin is mainly from the upper crust;? the provenance of Upper Jurassic sandstones from the Mohe basin is the active continental margin setting in the K2O/Na2O vs.SiO2,Al2O3/SiO2 vs.K2O/Na2O,QFR provenance analysis,and TFe2O+MgO vs.Al2O3/SiO2 tectonic discrimination diagrams?...