During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subducti...During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subduction.However,controversy exists about the Paleo-Pacific subduction's initiation time.This study uses detrital zircon U-Pb ages to discuss the Late Triassic source-tosink system in the SESCB.It provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons'trace elements.The paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic:1.the Yangchun-Kaiping-Gaoming area,comprising major age ranges of 260-220,460-400,and 1200-800 Ma,which might be sourced from the Yunkai terrane;2.the Jiexi-Kanshi-Nanjing area,characterized by the significant age component of 2000-1800 Ma,which corresponded to the Wuyi terrane;3.the Xinan area,consisting of significant age groups of 290-250 and 380-320 Ma,which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction.Note that 290-250 Ma zircons were widely distributed in the Upper Triassic strata,and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290-250 Ma.Thus,we propose that the Paleo-Pacific subduction might have begun in the Early Permian.展开更多
The depositional and metamorphic ages and provenances of the Ailaoshan(ALS) Group in the Ailaoshan-Red River(ALS-RR) shear zone, southwestern South China Block(SCB), were investigated to constrain the tectonic history...The depositional and metamorphic ages and provenances of the Ailaoshan(ALS) Group in the Ailaoshan-Red River(ALS-RR) shear zone, southwestern South China Block(SCB), were investigated to constrain the tectonic history of the southwestern SCB. In this study, we use petrology, geochemical analysis, zircon cathodoluminescence imaging and UPb geochronology to analyse samples of quartzite, garnet-bearing two-mica schist and metapelite. The age spectra of detrital zircon grains from these metasediments show two dominant age peaks at 550–424 Ma and 876–730 Ma and two subordinate peaks at 970–955 Ma and ~2450 Ma. The youngest peak, corresponding to the early Palaeozoic, accounts for more than 20% of the total dates and constrains the deposition of the ALS Group to the Palaeozoic rather than the Palaeoproterozoic as traditionally thought. Moreover, two peaks of metamorphic ages corresponding to the Permo-Triassic and Cenozoic were also identified, and these ages document the tectonothermal events associated with the Indosinian collision between the Indochina Block and the SCB and the Himalayan collision between the Indian and Asian plates. Geochemical data suggest that the provenances of the ALS Group were dominated by continental arc and recycled metasedimentary rocks. The comparison of probability density distribution plots of the detrital zircon U-Pb age data indicates that the Neoproterozoic detritus in the ALS Group was probably derived from the arc-related Neoproterozoic intrusive bodies in the northwestern and southwestern SCB. Furthermore, the early Palaeozoic detritus might have been sourced from eroded early Palaeozoic strata and magmatic plutons in Cathaysia and volcanic rocks in the western Indochina Block.展开更多
基金supported by the National Natural Science Foundation of China(No.41872101)the Graduate Innovation Fund of Jilin University(No.2022046)。
文摘During the Late Paleozoic-Early Mesozoic Era,the sediment transport system and tectonic regime in the southeastern margin of the South China Block(SESCB)all changed,significantly affected by the Paleo-Pacific subduction.However,controversy exists about the Paleo-Pacific subduction's initiation time.This study uses detrital zircon U-Pb ages to discuss the Late Triassic source-tosink system in the SESCB.It provides some references for the Paleo-Pacific subduction process based on crucial age information and zircons'trace elements.The paleogeography and similarity of detrital zircon age distribution indicate that three sinks were found in the SESCB during the Late Triassic:1.the Yangchun-Kaiping-Gaoming area,comprising major age ranges of 260-220,460-400,and 1200-800 Ma,which might be sourced from the Yunkai terrane;2.the Jiexi-Kanshi-Nanjing area,characterized by the significant age component of 2000-1800 Ma,which corresponded to the Wuyi terrane;3.the Xinan area,consisting of significant age groups of 290-250 and 380-320 Ma,which might be sourced from the magmatic rocks formed by the Huinan Movement and Paleo-Pacific subduction.Note that 290-250 Ma zircons were widely distributed in the Upper Triassic strata,and their trace elements suggested the existence of a magmatic arc near the SESCB during the 290-250 Ma.Thus,we propose that the Paleo-Pacific subduction might have begun in the Early Permian.
基金supported by the National Natural Science Foundation of China (Project No. 91855206, 41802072 and 41372069)the national key research and development plan (Project No. 2016YFC0600310)China Postdoctoral Science Foundation (Project No. 2017M620853)
文摘The depositional and metamorphic ages and provenances of the Ailaoshan(ALS) Group in the Ailaoshan-Red River(ALS-RR) shear zone, southwestern South China Block(SCB), were investigated to constrain the tectonic history of the southwestern SCB. In this study, we use petrology, geochemical analysis, zircon cathodoluminescence imaging and UPb geochronology to analyse samples of quartzite, garnet-bearing two-mica schist and metapelite. The age spectra of detrital zircon grains from these metasediments show two dominant age peaks at 550–424 Ma and 876–730 Ma and two subordinate peaks at 970–955 Ma and ~2450 Ma. The youngest peak, corresponding to the early Palaeozoic, accounts for more than 20% of the total dates and constrains the deposition of the ALS Group to the Palaeozoic rather than the Palaeoproterozoic as traditionally thought. Moreover, two peaks of metamorphic ages corresponding to the Permo-Triassic and Cenozoic were also identified, and these ages document the tectonothermal events associated with the Indosinian collision between the Indochina Block and the SCB and the Himalayan collision between the Indian and Asian plates. Geochemical data suggest that the provenances of the ALS Group were dominated by continental arc and recycled metasedimentary rocks. The comparison of probability density distribution plots of the detrital zircon U-Pb age data indicates that the Neoproterozoic detritus in the ALS Group was probably derived from the arc-related Neoproterozoic intrusive bodies in the northwestern and southwestern SCB. Furthermore, the early Palaeozoic detritus might have been sourced from eroded early Palaeozoic strata and magmatic plutons in Cathaysia and volcanic rocks in the western Indochina Block.
