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double-sided subduction with contrasting polarities beneath the Pamir-Hindu Kush:Evidence from focal mechanism solutions and stress field inversion

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Geoscience Frontiers 2022年第4期13卷 98-113页

作者： Yu Yang Zuoxun Zeng Scott D.King Xiao Shuang School of Earth Sciences China University of Geosciences(Wuhan)Wuhan 430074China Huazhong Tectonomechanical Research Center China University of Geosciences(Wuhan)Wuhan 430074China Department of Geosciences Virginia TechBlacksburgVA 24061USA Fuyang Branch of Hangzhou Bureau of Planning and Natural Resources Hangzhou 311499China

The Pamir-Hindu Kush region at the western end of the Himalayan-Tibet orogen is one of the most active regions on the globe with strong seismicity and deformation and provides a window to evaluate continental collision linked to two intra-continental subduction zones with different polarities.The seismicity and seismic tomography data show a steep northward subducting slab beneath the Hindu Kush and southward subducting slab under the Pamir.Here,we collect seismic catalogue with 3988 earthquake events to compute seismicity images and waveform data from 926 earthquake events to invert focal mechanism solutions and stress field with a view to characterize the subducting slabs under the Pamir-Hindu Kush region.Our results define two distinct seismic zones:a steep one beneath the Hindu Kush and a broad one beneath the Pamir.Deep and intermediate-depth earthquakes are mainly distributed in the Hindu Kush region which is controlled by thrust faulting,whereas the Pamir is dominated by strike-slip stress regime with shallow and intermediate-depth earthquakes.The area where the maximum principal stress axis is vertical in the southern Pamir corresponds to the location of a highconductivity low-velocity region that contributes to the seismogenic processes in this region.We interpret the two distinct seismic zones to represent a double-sided subduction system where the Hindu Kush zone represents the northward subduction of the Indian plate,and the Pamir zone shows southward subduction of the Eurasian plate.A transition fault is inferred in the region between the Hindu Kush and the Pamir which regulates the opposing directions of motion of the Indian and Eurasian plates.

关键词： Pamir-Hindu Kush Seismicity Stress field double-sided subduction Low-velocity body

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Lithospheric dripping in a soft collision zone:Insights from late Paleozoic magmatism suites of the eastern Central Asian Orogenic Belt

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Geoscience Frontiers 2023年第1期14卷 101-117页

作者： Zheng Ji Wen-Chun Ge M.Santosh Chuan-Biao Wan Yan-Long Zhang Jun-Hui Bi Hao Yang Yu Dong Yan Jing College of Geo-exploration Science and Technology Jilin UniversityChangchun 130026China College of Earth Sciences Jilin UniversityChangchun 130061China School of Earth Science and Resources China University of GeosciencesBeijingBeijing 100083China Department of Earth Sciences University of AdelaideAdelaideSouth Australia 5005Australia Exploration and Development Research Institute Daqing Oilfield Limited CompanyDaqing 163712China Tianjin Center China Geological SurveyTianjin 300170China

The closure of Paleo-Asian Ocean is considered to have occurred along the Solonker Suture in the southernmost segment of the Central Asian Orogenic Belt(CAOB),the largest Phanerozoic accretionary orogen on the globe.The suture branches to the east to form the northern Hegenshan-Heihe Suture and the southern Solonker-Changchun Suture.The Hegenshan-Heihe Suture is an ideal natural laboratory for studying the post-collisional geodynamic processes operating in a soft collision zone driven by divergent double-sided subduction.Here we report results from an integrated study of the petrology,geochronology,geochemistry,and Sr-Nd-Hf isotopic compositions of the Early Carboniferous-Early Permian mag-matic suite in the Hailar Basin of the Xing'an-Erguna Block.The Early Carboniferous igneous rocks are represented by 356-349 Ma andesitic tuffs,exhibiting typical subduction-related features,such as enrichment in large-ion lithophile elements and depletion in high-field-strength elements.These features,together with the relatively depleted Sr-Nd-Hf isotopic compositions,constant Nb/Y values,but highly variable Rb/Y and Ba values indicate that these rocks were generated by partial melting of a depleted mantle wedge metasomatized by slab-derived fluids.The Late Carboniferous-Early Permian magmatic suite(317-295 Ma)is characterized by high Sr contents(313-1080 ppm)and low Y contents(5-13 ppm),and these can be subdivided into calc-alkaline adakitic rocks and high-K calc-alkaline adakitic rocks.The calc-alkaline adakitic rocks have higher values of Sr/Y,(Sm/Yb)_(source normalized),and Mg#,and lower values of Y,_(Ybsource normalized),and K_(2)O/Na_(2)O than the high-K calc-alkaline adakitic rocks,which suggests that the former was generated by partial melting of foundered lower continental crust and the latter by partial melting of normal lower continental crust.Based on our new data,in conjunction with those in previous studies,we conclude that the tectonic evolution of the Hegenshan-Heihe Suture involved Early Carboniferous double-

关键词： Soft collision Lithospheric dripping double-sided subduction Central Asian Orogenic Belt Late Paleozoic

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Geochemistry and Geochronology of the High-Mg Gabbro Dykes from Quanji Massif: Implications for the Amalgamation of Tarim Block in NW China and Assembly of the Rodinia Supercontinent

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Acta Geologica Sinica(English Edition) 2016年第S1期90卷 104-105页

作者： LIAO Fanxi CHEN Nengsong M.Santosh SUN Min WANG Qinyan XU Yixian International Research Centre for Geology and Resources along the Silk Roads China University of Geosciences Faculty of Earth Science China University of Geosciences Journal Center China University of Geosciences Beijing Department of Earth Sciences The University of Hong Kong Institute of Geophysics and Geomatics China University of Geosciences

The Tarim Craton is one of the major continental blocks in China.Mafic dykes,ultra-mafic–mafic–carbonatite complex and ultra-mafic–mafic pluton of 0.82–0.75 Ga widely occur in Kuluktage,Aksu and Tieklik area along

关键词： High-Mg gabbro dykes Geochemistry and geochronology double-sided subduction Northwest China Supercontinent Rodinia

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