Provenance Analysis Of Sandstone, Character Of Paleocurrent Direction And Geotectonic Significance Of Triassic In South Of Gonghe Basin In East Kunlun

Author and work teams collected samples at Triassic sandstone region In South of Gonghe basin,And Selected the rock samples on both sides of A’ayemaqen area, polished thin slices and microscopy analysised. Analysised Provenance orientation and Paleocurrent Feature on both sides of A’ayemaqen area with sandstone debris provenance analysis and Paleocurrent analysis.Collected126rock samples on both sides of A’ayemaqenor ogenic area,grounded related thin slices of34,age of the strata of rock samples is mainly Early and Middle-Triassic.All thin slices were used to do sandstone debris analysis under the microscope,observed and calculated the content of which quartz、feldspar and detritus under the analytic process.After finishing the data, the software investment and geting Dickinson graphic and analyzed the results.Observations indicate that the sandstone types are mainly arkose, a small amount of feldspathic lithic sandstone,selecting situation is poor-medium, rounded subangular-sub-rounded, mainly grain-supported. Composition of sandstone maturity is not high, indicating that the provenance area is closed.Dickinson graphic shows that the sandstone composition fall into the recycling orogen mainly, a small amount to fall into the mixing zone. Combining with more pyroclastic content in the thin slices,author considers that the tectonic environment is the early fold orogenesis accompanied by a volcanic eruption.A small amount of sandstone composition are in the junction of Cutting island arc and re-cycle orogenic belt, indicating that the mother rock district experienced a process from Subduction suture to Orogenic.All of composition of sandstone away from the area of craton, linked to the regional tectonic environment, and consider that the mother rock area is not Stable continental block.Collected a large number of cross-bedding and other paleocurrent data in six locations on both sides of A’ayemaqenor ogenic area.Stratum of rock samples is mainly in Longwuhe group, and the Gulangdi formation in the Middle Triassic and Triassic Bayanhar group.The results show that paleocurrent on both sides of A’ayemaqenor ogenic area is almost opposite and all point to A’ayemaqen orogenidirection.Speculate that early in the the Triassic A’ayemaqen orogenic belt has been elevated, and cut off the Gonghe basin and Bayanhar basin.By two analysis methods combined with regional geological background, I believe that in Early-Middle Triassic A’ayemaqen orogen has already uplift, cuted off Gonghe basin and Bayanhar basin, then there is no communication in debris, and have evolution of the relative independence.