The Tianshan range,a Paleozoic orogenic belt in Central Asia,has undergone multiple phases of tectonic activities characterized by the N-S compression after the early Mesozoic,including the far-field effects of the Ce...The Tianshan range,a Paleozoic orogenic belt in Central Asia,has undergone multiple phases of tectonic activities characterized by the N-S compression after the early Mesozoic,including the far-field effects of the Cenozoic Indian-Asian collision.However,there are limited reports on the tectonic deformation and initiation of Triassic intracontinental deformation in the Tianshan range.Understanding this structural context is crucial for interpreting the early intracontinental deformation history of the Eurasian continent during the early Mesozoic.Growth strata and syn-tectonic sediments provide a rich source of information on tectonic activities and have been extensively used in the studies of orogenic belts.Based on detail fieldwork conducted in this study,the middle-late Triassic Kelamayi Formation of the northern Kuqa Depression in the southern Tianshan fold-thrust belt has been identified as the typical syn-tectonic growth strata.The youngest detrital zircon component in two lithic sandstone samples from the bottom and top of the Kelamayi growth strata yielded U-Pb ages of 223.4±3.1 and 215.5±2.9 Ma,respectively,indicating that the maximum depositional age of the bottom and top of the Kelamayi growth strata is 226-220 and 218-212 Ma.The geochronological distribution of detrital samples from the Early-Middle Triassic and Late Triassic revealed abrupt changes,suggesting a new source supply resulting from tectonic activation in the Tianshan range.The coupling relationship between the syn-tectonic sedimentation of the Kelamayi Formation and the South Tianshan fold-thrust system provides robust evidence that the Triassic intracontinental deformation of the South Tianshan range began at approximately 226-220 Ma(during the Late Triassic)and ended at approximately 218-212 Ma.These findings provide crucial constraints for understanding the intraplate deformation in the Tianshan range during the Triassic.展开更多
The Langshan Group is an important constituent of the Precambrian metamorphic rocks in the Langshan area.The accurate determination of its metamorphic age is of great scientific significance for the further study of t...The Langshan Group is an important constituent of the Precambrian metamorphic rocks in the Langshan area.The accurate determination of its metamorphic age is of great scientific significance for the further study of the Precambrian geological evolution in the region.Disputes remain regarding the metamorphism and deformation overprinting of the Langshan Group.This paper presents a detailed study comprising a field geological investigation,petrological observations,and zircon U-Pb aging of garnet-bearing mica quartz schists in the BangBang District.The result of detrital zircon U-Pb dating from the metamorphosed volcanic sedimentary rock series and geological investigation of the garnet-bearing mica quartz schists suggest the strata formed in the Neoproterozoic.The results from cathodoluminescence(CL)image analysis and U-Pb dating of zircons indicate a large number of metamorphic zircons exist in the garnet-bearing mica quartz schists.The metamorphic overgrowth rims of zircon from two samples were analyzed by LA-ICP-MS.The ^(206)Pb/^(238)U weighted average age of ca.244 Ma of the zircon metamorphism rims represents the timing of Indosinian greenschist-amphibolite facies metamorphism in the Langshan area,which may be in response to the collision-type orogeny of the North China and Siberian plates in the Late Paleozoic.Acid-intermediate magmatic intrusive activities occurred in the Langshan area,and metamorphic events developed at the same time or at a later stage during the closure of the Paleo-Asian Ocean.展开更多
基金supported by the National Key Research and Development Project(Grant No.2018YFC0603700)research grants from the China Geological Survey(Grant Nos.DD20230408,DD20190011,DD20191011 and DD20221824)+1 种基金the Fundamental Research Funds from the Chinese Academy of Geological Sciences(Grant No.JKY202011)the Key Laboratory of Airborne Geophysics and Remote Sensing Geology Ministry of Natural Resources(Grant No.2023YFL23)。
文摘The Tianshan range,a Paleozoic orogenic belt in Central Asia,has undergone multiple phases of tectonic activities characterized by the N-S compression after the early Mesozoic,including the far-field effects of the Cenozoic Indian-Asian collision.However,there are limited reports on the tectonic deformation and initiation of Triassic intracontinental deformation in the Tianshan range.Understanding this structural context is crucial for interpreting the early intracontinental deformation history of the Eurasian continent during the early Mesozoic.Growth strata and syn-tectonic sediments provide a rich source of information on tectonic activities and have been extensively used in the studies of orogenic belts.Based on detail fieldwork conducted in this study,the middle-late Triassic Kelamayi Formation of the northern Kuqa Depression in the southern Tianshan fold-thrust belt has been identified as the typical syn-tectonic growth strata.The youngest detrital zircon component in two lithic sandstone samples from the bottom and top of the Kelamayi growth strata yielded U-Pb ages of 223.4±3.1 and 215.5±2.9 Ma,respectively,indicating that the maximum depositional age of the bottom and top of the Kelamayi growth strata is 226-220 and 218-212 Ma.The geochronological distribution of detrital samples from the Early-Middle Triassic and Late Triassic revealed abrupt changes,suggesting a new source supply resulting from tectonic activation in the Tianshan range.The coupling relationship between the syn-tectonic sedimentation of the Kelamayi Formation and the South Tianshan fold-thrust system provides robust evidence that the Triassic intracontinental deformation of the South Tianshan range began at approximately 226-220 Ma(during the Late Triassic)and ended at approximately 218-212 Ma.These findings provide crucial constraints for understanding the intraplate deformation in the Tianshan range during the Triassic.
基金funded by the work program of the National Key Research Program of China(No.2016YFC0600502)。
文摘The Langshan Group is an important constituent of the Precambrian metamorphic rocks in the Langshan area.The accurate determination of its metamorphic age is of great scientific significance for the further study of the Precambrian geological evolution in the region.Disputes remain regarding the metamorphism and deformation overprinting of the Langshan Group.This paper presents a detailed study comprising a field geological investigation,petrological observations,and zircon U-Pb aging of garnet-bearing mica quartz schists in the BangBang District.The result of detrital zircon U-Pb dating from the metamorphosed volcanic sedimentary rock series and geological investigation of the garnet-bearing mica quartz schists suggest the strata formed in the Neoproterozoic.The results from cathodoluminescence(CL)image analysis and U-Pb dating of zircons indicate a large number of metamorphic zircons exist in the garnet-bearing mica quartz schists.The metamorphic overgrowth rims of zircon from two samples were analyzed by LA-ICP-MS.The ^(206)Pb/^(238)U weighted average age of ca.244 Ma of the zircon metamorphism rims represents the timing of Indosinian greenschist-amphibolite facies metamorphism in the Langshan area,which may be in response to the collision-type orogeny of the North China and Siberian plates in the Late Paleozoic.Acid-intermediate magmatic intrusive activities occurred in the Langshan area,and metamorphic events developed at the same time or at a later stage during the closure of the Paleo-Asian Ocean.
