Geochemical characteristics,zircon U-Pb dating and geological implication of sandstone in Suweiyi formation in Kalabulake area,Tarim basin
The Oligocene Suweiyi formation is an important uranium-bearing stratum in the northern margin of Tarim basin,but few studies was reported on the provenance of the sandstone in formation.In this study,elemental geochemistry and detrital zircon U-Pb dating were used to explore the source of detrital materials and the nature of the provenance of the Suweiyi formation sandstone in the Kalabulak area,northern Tarim basin by comparing the age data of the adjacent area to further limit the provenance.The results of element geochemical analysis showed that the source area of the Suweiyi formation sandstone was neutral or acidic provenance,and the type of parent rock was igneous rock or granite.Detrital zircon U-Pb dating results showed that the age of the sandstone samples of the Suweiyi formation was divided into two sectors:Early Permian(～282 Ma)and Late Triassic(～226 Ma).Compared with the zircon U-Pb age of the rock in the Tianshan orogenic belt in the northern part of the basin,it was found that the Early Permian and Late Triassic zircons were mainly from the Tianshan orogenic belt.Therefore,it can be considered that the provenance area of the Oligocene Suweiyi formation was mainly granite and volcanic rocks distributed in the Tianshan orogenic belt.Combined with the structural movement of Tianshan orogenic belt and Kuche depression,it was found that the zircon age just recorded the magmatic intrusion events during the Carboniferous-Permian period in Tianshan orogenic belt.The Tianshan orogenic belt has been squeezed and uplifted since the Tertiary period,resulting in the Late Paleozoic and Early Mesozoic rock exposed to the surface and subjected to weathering and denudation,which provided a detrital source for the sedimentation in the northern part of the basin,and also the uranium source for the Suweiyi formation.The oil and gas migrated along the fault to the sand body reduced the primary red sand body to gray and active uranium in the oxygen-containing uranium-bearing water,which precipitated and enriched near the redox interface.
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