Study On The Late Cretaceous Sedimentary Environment Of The Kangsuhe Section Of Southwest Tarim Basin

Southwest Tarim Basin is located at the junction of Central Asia orogenic belt and Tethys tectonic domain,which has always been concerned by geologists.Although there has been a preliminary consensus on the tectonic setting of Southwest Tarim Basin in recent ten years,the mesozoic and cenozoic tectonic setting of Southwest Tarim Basin is complex,and the Cretaceous sedimentary environment is diverse.Therefore,based on the kangsuhe section in the Southwest Tarim Basin,the characteristics of typical stratigraphic sections and geochemical elements are studied to reveal the sedimentary environment of the kangsuhe section in the late Cretaceous.Kangsuhe section is located in the transitional zone between Kezilesu group and kukebai formation.The sedimentary environment of kangsuhe section can be divided into two sections.The lower section is located in Kezilesu group,with alluvial fan facies in the West and braided river facies in the East.The upper section is the delta front subfacies of kukebai formation.The major element characteristics of mudstone and sandstone show that the whole section belongs to the shallow to semi deep water sedimentary environment under the same provenance condition,and the seawater intrusion was slow and continuous in the late Cretaceous.The upper formation is an oxidation environment with higher oxygen content than the lower formation.The paleosalinity decreased with the depositional sequence,indicating the humid paleoclimate.The characteristics of trace elements show that the strata are freshwater continental deposits in general,and there are marine continental transitional deposits in the lower part of the strata.The content trend of LREE in the lower part of the formation is relatively gentle,and the LREE in the upper part of the formation is generally characterized by "right dip" type,enrichment of LREE and depletion of hree.The light rare earth elements are more likely to migrate from the water than the heavy rare earth elements.Figure 32;Table 15;Reference 68...