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Permian tectonic evolution and continental accretion in the eastern Central Asian Orogenic Belt:A perspective from the intrusive rocks

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Geoscience Frontiers 2024年第2期15卷 433-451页

作者： Anzong Fu Hongyan Geng Changzhou Deng Chenglu Li Jishuang Ding Bizheng Yang Wenpeng Yang Heilongjiang Institute of Natural Resources Survey Harbin 150036China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550002China Science Unit Lingnan UniversityHong KongChina College of Earth Sciences Jilin UniversityChangchun 130061China

The tectonic evolution and history of continental accretion of the eastern Central Asian Orogenic Belt(CAOB)are not yet fully understood.In this study,we investigate Permian intrusive rocks from the Jiamusi Block of the eastern CAOB to constrain the tectonic evolution and continental accretion of this region during the late-stage evolution of the Paleo-Asian Ocean.Our new data show that Early Permian gabbro-diorites were derived from the partial melting of depleted mantle metasomatized by oceanic-slab-released fluids.Middle Permian adakitic granites have low Na2O and MgO and high K2O contents,indicating a thickened-lower-crust source.Late Permian S-type granites were derived from the partial melting of continental crust.A compilation of the available geochronological data for Permian intrusive rocks(including adakitic and A-,S-,and I-type granites and mafic rocks)from the eastern CAOB reveals that the A-type granites formed mainly during the Early–Middle Permian,S-type and adakitic granites mostly during the Middle–Late Permian,and I-type granites and mantle-derived mafic rocks throughout the Permian.The A-type granites,which are proposed to have been sourced from thinned continental crust,indicate an extensional setting in the eastern CAOB during the Early Permian.The Middle–Late Permian adakitic granites imply a thickened continental crust,which indicates a compressional setting.Therefore,the eastern CAOB underwent a transition from extension to compression during the Middle Permian,which was probably triggered by the late-stage subduction of Paleo-Asian oceanic crust.Considering the petrogenesis of the intrusive rocks and inferred regional tectonic evolution of the eastern CAOB,we propose that vertical underplating of mantle-and oceanic-slabderived magmas contributed the materials for continental crust accretion.

关键词： Permian intrusive rocks Eastern Central Asian Orogenic Belt Paleo-Asian Ocean Tectonic evolution

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Isla San Pedro Nolasco as a Late Miocene intrusive record at the eastern margin of the Gulf of California:Insights from geological,geochemical and geochronological studies

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Geoscience Frontiers 2022年第3期13卷 100-114页

作者： L.A.Velderrain-Rojas J.R.Vidal-Solano L.M.Alva-Valdivia R.Vega-Granillo M.López-Martinez Departamento de Geología División de Ciencias Exactas y NaturalesUniversidad de SonoraC.P.83000 HermosilloSonoraMexico Laboratorio de Paleomagnetismo Instituto de GeofísicaUniversidad Nacional Autónoma de MéxicoCircuito de la Investigación CientíficaC.P.04510 MéxicoD.F.Mexico Departamento de Geología División de Ciencias de la TierraCentro de Investigación Científica y de Educación Superior de EnsenadaBaja CaliforniaMexico

Isla San Pedro Nolasco(ISPN)is a structural high bounded by inactive dextral oblique-slip faults in the east-central part of the Gulf of California rift zone and is composed of intrusive rocks not exposed on other Gulf of California islands.Here we present the reconnaissance results from geological mapping,as well as first geochemical and geochronological data for the ISPN intrusive complex.The intrusive rocks compose a sheet-like body of intermediate and felsic composition intruded by an intermediate and acidic dike swarm.All intrusive rocks(host and dikes)range in age from ca.9 Ma to 10 Ma(^(40)Ar/^(39)Ar)and show a hydrous ferromagnesian mineral association(amphibole and biotite)with a calc-alkalic and transitional affinity.This hydrated mineralogical association has not been recognized in the coeval rocks along the onshore western margin of the North American plate(coastal Sonora).However,such hydrous mineralogical association is found in the coeval rift transitional volcanic rocks from the Baja California Microplate at Santa Rosalía and Bahía de LosÁngeles–Bahía de LasÁnimas.The ISPN continental block,at least 40 km long,has been pulled apart by transtensional faulting of the late Miocene Gulf of California shear zone before the westward migration of the North America-Pacific plate boundary at ca.3–2 Ma.Eventually,ISPN became isolated as an island during the late Miocene flooding of the Gulf of California seaway.

关键词： PAC-NAM plate boundary Gulf of California intrusive rocks Isla San Pedro Nolasco

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Geochronology of Intermediate-Acid intrusive rocks from Tongling,Anhui

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Continental Dynamics 2000年第1期 15-23页

作者： WU Cailai, WANG Fusheng, HAO Meiying and SHI Rendeng Institute of Geology, CAGS, Beijing 100037, China WANG Zhihong Xi’an Engineering College, Xi’an 710054, China QIAO Dewu Geological mechanics institute, CAGS, Beijing 100081, China

Ar/39Ar isotopic chronologic studies of intrusive rocks from Tongling area, Anhui province have shown that the ages of these rocks are all younger than 140 Ma and belong to Late Yanshanian period, with granodiorite, quartz monzodiorite, pyroxene monzodiorite and gabbro-diabase being 139.8-137 Ma, 137-135.8 Ma, 138.2-136.6 Ma and 133.7 Ma, respectively. Compared with 40Ar/39Ar isotopic chronologic studies of these intrusive rocks, the authors have also dealt with their K-Ar and Rb-Sr isotopic ages, and pointed out that the age error is caused by the late hydrothermal alteration and the mixture of mantle magma and crustal magma. In addition, the mineralization ages are found to be close to the smaller ages of 40Ar/39Ar age spectra, which is in accordance with the regional metallogenic character that mineralization took place later than magmatic activity.

关键词： Ar/ 39Ar isotopic ages intrusive rocks Tongling

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3-D shear wave velocity structure in the shallow crust of the Tan-Lu fault zone in Lujiang,Anhui,and adjacent areas,and its tectonic implications

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Earth and Planetary Physics 2020年第3期4卷 317-328页

作者： Cheng Li HuaJian Yao Yuan Yang Song Luo KangDong Wang KeSong Wan Jian Wen Bin Liu School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

The Tan-Lu fault zone is a large NNE-trending fault zone in eastern China.Investigations of the structures of the fault zone and its surrounding areas have attracted much attention.In this study,we used dense-array ambient noise tomography to construct a threedimensional shear wave velocity model of shallow crust in an area about 80km×70km in Lujiang,Anhui Province,eastern China.For approximately one month we collected continuous ambient noise signals recorded by 90 short-period seismographs in the region,and obtained the short-period Rayleigh wave empirical Green's functions between stations by the cross-correlation method;we also extracted 0.5–8 s fundamental mode Rayleigh wave group velocity and phase velocity dispersion curves.Based on the direct surface wave tomography method,we jointly inverted the group velocity and phase velocity dispersion data of all paths and obtained the 3-D shear wave velocity structure in the depth range of 0–5 km.The results revealed important geological structural features of the study area.In the north region,the sedimentary center of the Hefei Basin—the southwestern part of the Chaohu Lake—shows a significant low-velocity anomaly to a depth of at least 5 km.The southwestern and southeastern regions of the array are the eastern margin of the Dabie orogenic belt and the intrusion area of Luzong volcanic rocks,respectively,and both show obvious high-speed anomalies;the sedimentary area within the Tan-Lu fault zone(about 10 km wide)shows low-velocity anomalies.However,the volcanic rock intrusion area in the fault zone is shown as high velocity.Our shallow crustal imaging results reflect the characteristics of different structures in the study area,especially the high-speed intrusive rocks in the Tan-Lu fault zone,which were probably partially derived from the magmatic activity of Luzong volcanic basin.From the Late Cretaceous to Early Tertiary,the Tan-Lu fault zone was in a period of extensional activity;the special stress environment and the fractured fault zone morphology provided

关键词： Tan-Lu fault zone Lujiang of Anhui ambient noise tomography shallow crust structure intrusive rocks

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