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Imaging the western boundary of the sichuan Craton from multiple geophysical observations

Journal of Earth science 2024年

作者： Qihang Yin Xi Xu Xiaodong Yang Xuhua shi Lei Wu Andrew V.Zuza Liu Yang Hefeng Tian Yuanhai shu.s.ufeng Yang Nevada Bureau of Mines and Geology university of Nevada China Aero Geophysical survey and Remote sensing Center for Natural Resources China geological survey school of Earth sciences Zhejiang university Research Center for structures in Oil and Gas Bearing Basins Ministry of Education Key Laboratory of Ocean and Marginal sea Geology south China sea Institute of Oceanology Innovation Academy of south China sea Ecology and Environmental Engineering Chinese Academy of sciences school of Mechanical and Electrical Engineering Hubei Open university

The boundary between the cratonic and orogenic lithospheres is one of the most significant seismogenic zones characterized by strong lithospheric deformation. As the essential tectonic block bounding the eastern Tibetan Plateau， the sichuan Craton (sCC) resists the eastward escape of Plateau.s.crustal materials， resulting in the uplift of the songpan-Ganzi Block (sGB) and the crustal deformation of the Longmenshan tectonic belt (LMTB). To uncover the compressional structures and deformational mode of the LMTB and sCC， it is crucial to determine the precise location and geometry of the western boundary of the sCC. To address this issue， the lithospheric properties of the obduction sGB， the underthrusting sCC， and the LMTB were analyzed using a series of geophysical data， including seismic reflection profiles， magnetotellurics， aeromagnetics， gravity， and seismic tomography. The crust of the sGB is characterized by low magnetism， low seismic velocity， low resistivity and low Bouguer gravity， while that of the sCC features non-uniform high magnetism， high seismic velocity， high resistivity and high Bouguer gravity. The LMTB， as the boundary between the sGB and sCC， shows the geophysical characteristics similar to the sCC along the southern and central segments. The integration of all these geophysical observations suggests that the sCC’s western boundary follows the Yingxiu-Beichuan fault along the northern segment， without obvious underthrust. However， this boundary is located west of the Wenchuan-Maoxian fault zone along the southern and central segments， with distinct westward wedging/underthrusting. The irregular geometry of the sCC’s western boundary can further explain the variation in structural deformation along the LMTB. By comparing the differences in crustal thickness and lithospheric strength between the sGB and sCC， this study suggests that the varying crustal strength between tectonic blocks may be the controlling factor for the irregular geometry of the

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Geochronology and Petrogenesis of Late Carboniferous to Early Permian Basalts in the Central Lhasa subterrane, southern Tibet: Implications for the Evolution of the sumdo Paleo-Tethys Ocean

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Acta Geologica sinica(English Edition) 2024年第4期98卷 955-968页

作者： MA Wang LIu Yingchao YANG Zhusen Jan-Marten HuIZENGA LI Zhenqing YuE Longlong ZHAO sibo school of Earth sciences and Resources China University of GeosciencesBeijing 100083China Institute of Geology Sinoprobe LaboratoryChinese Academy of Geological SciencesBeijing 100037China MLR Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China Faculty of Environmental sciences and Natural Resource Management Norwegian University of Life SciencesNO-1432ÅsNorway Economic Geology Research Centre(EGRu) College of Science and EngineeringJames Cook UniversityTownsvilleQueensland 4811Australia Department of Geology University of JohannesburgAuckland Park 2006South Africa

Basalts from the Late Carboniferous to Early Permian are extensively developed in the central Lhasa subterrane, southern Tibet. studying the petrogenesis of these rocks may have implications for the late Paleozoic arc magmatism along the central Lhasa subterrane uncovering more of the evolution of the sumdo Paleo-Tethys Ocean and its dynamic mechanism. Basalt samples from the Luobadui Formation in the Leqingla area, NW of Linzhou City in the central Lhasa subterrane, southern Tibet exhibit arc-like geochemical signatures in a subduction-zone tectonic setting characterized by high Al_(2)O_(3) and low TiO_(2) contents, fractionated REE patterns with low Nb/La ratios and high LREE concentrations, and negative HFsE anomalies. Based on their higher Th/Ce, Nb/Zr, and lower Ba/Th, Pb/Nd ratios, slightly negative to positive ε_(Nd)(t) valu.s. and the relatively high sr-Pb isotopic compositions, these samples were probably derived from partial melting of a depleted mantle source of garnet + spinel lherzolite, metasomatized by subducted sediments around 297 Ma. Modeling of the trace elements indicates that these basalts experienced fractional crystallization of olivine, clinopyroxene and minor plagioclase during magma ascent and eruption. It is proposed that these Late Carboniferous–Early Permian basalts are associated with the northward subduction of the sumdo Paleo-Tethys Ocean seafloor along the southern margin of the central Lhasa subterrane.

关键词： geochemistry northward subduction sumdo Paleo-Tethys Ocean Lhasa terrane Tibet

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Late Mesoproterozoic to Early Neoproterozoic Tectonic Evolution of the sW Yangtze Block, south China: Evidence from u-Pb Geochronology and Lu-Hf Isotopes of Detrital Zircons from sedimentary Rocks

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Journal of Earth science 2024年第3期35卷 812-827页

作者： Peiwen Liu Xiaozhong Ding Yanxue Liu Jibiao Zhang Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China school of Civil and Hydraulic Engineering Xichang UniversityXichang 615000China

In situ zircon u-Pb geochronological and Lu-Hf isotope studies of detrital zircons from Late Mesoproterozoic to Early Neoproterozoic sedimentary units on the southwestern margin of the Yangtze Block have important implications for the tectonic evolution of the Yangtze *** Huili Group contains zircons whose ages are mainly Late Archean to Mesoproterozoic(2650-2450,2100-1800,and 1350-1150 Ma).The Dengxiangying Group has one major age population of 1900-1600 Ma,and two subordinate age populations of 1350-1100 and 2300-2000 *** Group sedimentary rocks have a zircon age population mainly in the range of 970-850 Ma,contemporaneous with the ages of widespread arc-related magmatism in the western Yangtze *** these results with previous work,the Huili and Dengxiangying grou.s.were most likely deposited during ca.1160 to 1000 Ma in an intra-continental rift basin setting,while the Yanbian Group accumulated during>920 to 782 Ma in a back-arc basin setting at the southwestern margin of the Yangtze *** addition,all these results further suggest a tectonic transition from a continental rift basin to a convergent environment at the southwestern margin of the Yangtze Block at 1000-970 Ma.

关键词： Late Mesoproterozoic Early Neoproterozoic zircon u-Pb age Lu-Hf isotope southwestern Yangtze Block geochronology

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Provenance of the Lower Jurassic pyroclastic sediments in the Zigui Basin:Implication for crustal thickening in the eastern Qinling orogenic belt

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science China Earth sciences 2024年第1期67卷 196-207页

作者： Rong CHAI Jianghai YANG Yuansheng Du Chengshan WANG school of Earth sciences and Resources China University of Geosciences(Beijing)Beijing 100023China school of Earth sciences China University of Geosciences(Wuhan)Wuhan 430074China Chinese Academy of geological sciences Beijing 100037China

The Late Triassic witnessed significant collisional orogenic events in the Qinling orogenic belt,accompanied by magma underplating and tectonic *** processes potentially resulted in su.s.antial crustal thickening and uplift of the Qinling ***,due to the absence of igneous rock records from this period in the eastern section of the Qinling orogen,the changes in crustal thickness during this orogenic process have not been thoroughly investigated.A series of foreland basins emerged during the Early Mesozoic to the south of the East Qinling orogenic *** basins have preserved clastic sedimentary rocks derived from the uplift and erosion of the orogenic *** sedimentary records serve as crucial records to reconstruct the evolutionary history of the Qinling *** further clarify the collisional orogenic process of the Qinling orogenic belt,this study conducted in situ volcanic lithic fragment geochemistry,detrital zircon u-Pb chronology and trace element composition analysis on the sandstones of the Lower Jurassic Tongzhuyuan Formation in the Zigui *** results suggest that the sandstones,which exhibit a significant abundance of volcanic lithic fragments,has a characteristic detrital zircon age group of 250–200 Ma,indicating a major provenance from the Triassic volcanic *** with regional correlation and paleocurrent analysis,the detrital zircon u-Pb age data show that the source area of volcanic rocks should be in the Qinling orogenic belt to the north of the *** interpretation is further supported by the Triassic granitic rocks exposed in the western part of the orogenic belt,representing the magmatism during the Triassic collisional orogenesis in the Qinling *** on the co-varying relationships between present-day crust thickness with the chemical compositions of granite rocks and zircons,the La/Yb ratio of volcanic lithic fragments in the Tongzhuyuan Formation and the Eu/Eu*ratio of detrital zircon

关键词： Qinling orogenic belt Zigui Basin Late Triassic Detrital zircons Crustal thickening

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Mantle Driven Early Eocene Magmatic Flare-up of the Gangdese Arc, Tibet: A Case study on the Nymo Intrusive Complex

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Acta Geologica sinica(English Edition) 2024年第4期98卷 878-903页

作者： MA Xuxuan Joseph GMEERT CAO Wenrong TIAN Zuolin LIu Dongliang XIONG Fahui LI Haibing Key Laboratory of Continental Tectonics and Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Borehole Crustal Activity National Observation and Research station DonghaiJiangsu 222300China Department of geological sciences Neil Opdyke Paleomagnetic LaboratoryUniversity of Florida241 Williamson HallGainesvilleFL 32611USA Department of geological sciences and Engineering University of NevadaRenoMS-1721664 N.Virginia St.RenoNV 89557USA

Magmatic periodicity is recognized in continental arcs worldwide, but the mechanism responsible for punctuated arc magmatism is controversial. Continental arcs in the Trans-Himalayan orogenic system display episodic magmatism and the most voluminous flare-up in this system was in early Eocene during the transition from subduction to collision. The close association of the flare-up with collision is intriguing. Our study employs zircon Lu-Hf and bulk rock sr-Nd isotopes, along with mineral geochemistry, to track the melt sources of the Nymo intrusive complex and the role of mantle magma during the early Eocene flare-up of the Gangdese arc, Tibet. The Nymo intrusive complex is composed of gabbronorite, diorite, quartz diorite, and granodiorite which define an arc-related calc-alkaline suite. Zircon u-Pb ages reveal that the complex was emplaced between ~50–47 Ma. Zircon Hf isotopes yield εHf(t) valu.s.of 8.2–13.1, while whole-rock sr and Nd isotopes yield εNd(t) valu.s.of 2.7–6.5 indicative of magmatism dominated by melting of a juvenile mantle source with only minor crustal assimilation(~15%–25%) as indicated by assimilation and fractional crystallization modeling. Together with published data, the early Eocene magmatic flare-up was likely triggered by slab breakoff of subducted oceanic lithosphere at depths shallower than the overriding plate. The early Eocene magmatic flare-up may have contributed to crustal thickening of the Gangdese arc. This study provides important insights into the magmatic flare-up and its significant role in the generation of large batholiths during the transition from subduction to collision.

关键词： mantle magmatic flare-up subduction–collision transition Nymo intrusive complex Gangdese Tibet

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structural,^(40)Ar/^(39)Ar Geochronological and Rheological Feature Analysis of the Guoxuepu.s.ear Zone:Indications for the Jitang Metamorphic Complex in the Northern Lancangjiang Zone

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Acta Geologica sinica(English Edition) 2024年第1期98卷 32-49页

作者： FENG Yipeng WANG Genhou WANG shulai LI Dian WANG Huan Lu Yang LIu Han ZHANG Peilie Beijing Institute of Geology for Mineral Resources Co. Ltd.Beijing 100012China school of Earth sciences and Resources China University of Geosciences(Beijing)Beijing 100083China College of Earth sciences Chengdu University of TechnologyChengdu 610059China Rock Analysis Laboratory Regional Geology Survey Institute of Hebei ProvinceLangfangHebei 065099China Chengdu Center China Geology SurveyChengdu 610081China

The Jitang metamorphic complex is key to studying the tectonic evolution of the Northern Lancangjiang *** structural-lithological mapping,structural analysis and laboratory testing,the composition of the Jitang metamorphic complex was *** macro-and microstructural analyses of the ductile detachment shear zone(Guoxuepu ductile shear zone,2–4 km wide)between the metamorphic complex and the overlying sedimentary cap show that the shear sense of the ductile shear zones is *** presence of various deformation features and quartz C-axis electron backscatter diffraction(EBsD)fabric analysis suggests multiple deformation events occurring at different *** average stress is 25.68 MPa,with the strain rates(έ)ranging from 9.77×10^(−14)s^(−1)to 6.52×10^(−16)s^(−1).The finite strain of the Guoxuepu ductile shear zone indicates an elongated strain *** average kinematic vorticity of the Guoxuepu ductile shear zone is 0.88,implying that the shear zone is dominated by simple *** muscovite selected from the protomylonite samples in the Guoxuepu ductile shear zone yields a 40Ar-39Ar age of 60.09±0.38 *** is suggested that,coeval with the initial Indo–Eurasian collision,the development of strike-slip faults led to a weak and u.s.able crust,upwelling of lower crust magma,then induced the detachment of the Jitang metamorphic complex in the Eocene.

关键词： ^(40)Ar/^(39)Ar dating strain pattern vorticity EBsD Guoxuepu.s.ear zone Jitang metamorphic complex

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A survey of LLM Datasets:From Autoregressive Model to AI Chatbot

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Journal of Computer science & Technology 2024年第3期39卷 542-566页

作者：杜非马新建杨婧如柳熠罗超然王学斌姜海鸥景翔 National Key Laboratory of Data space Technology and system Beijing 100195China Advanced Institute of Big Data Beijing 100195China Fu Foundation school of Engineering and Applied science Columbia UniversityNY 10027U.S.A. school of software and Microelectronics Peking UniversityBeijing 100091China

since OpenAI opened access to ChatGPT,large language models(LLMs)become an increasingly popular topic attracting researchers’attention from abundant ***,public researchers meet some problems when developing LLMs given that most of the LLMs are produced by industries and the training details are typically *** datasets are an important setup of LLMs,this paper does a holistic survey on the training datasets used in both the pre-train and fine-tune *** paper first summarizes 16 pre-train datasets and 16 fine-tune datasets used in the state-of-the-art ***,based on the properties of the pre-train and fine-tune processes,it comments on pre-train datasets from quality,quantity,and relation with models,and comments on fine-tune datasets from quality,quantity,and *** study then critically figures out the problems and research trends that exist in current LLM *** study helps public researchers train and investigate LLMs by visual cases and provides useful comments to the research community regarding data *** the best of our knowledge,this paper is the first to summarize and discu.s.datasets used in both autoregressive and chat *** survey offers insights and suggestions to researchers and LLM developers as they build their models,and contributes to the LLM study by pointing out the existing problems of LLM studies from the perspective of data.

关键词： large language model(LLM) autoregressive model AI chatbot natural language processing(NLP)corpora OpenAI

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Genesis of the Maoling gold deposit in the Liaodong Peninsula:Constraints from a combined fluid inclusion,C-H-O-s-Pb-He-Ar isotopic and geochronological studies

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Geoscience Frontiers 2022年第4期13卷 11-33页

作者： Peng Zhang Linlin Kou Yan Zhao Deming sha shenyang geological survey Center China Geological SurveyShenyang 110034China

The large tonnage Maoling gold deposit(25 t@3.2 g/t)is located in the southwest Liaodong Peninsula,North China *** deposit is hosted in the Paleoproterozoic metamorphic *** stages of mineralization were identified in the deposit:(stageⅠ)quartz-arsenopyrite±pyrite,(stageⅡ)quartz-goldarsenopyrite-pyrrhotite,(stageⅢ)quartz-gold-polymetallic sulfide,and(stageⅣ)*** this paper,we present fluid inclusion,C-H-O-s-Pb-He-Ar isotope data,zircon u-Pb,and gold-bearing sulfide(*** and pyrrhotite)Rb-sr age of the Maoling gold deposit to constrain its genesis and ore-forming *** types of fluid inclusions were distingu.s.ed in quartzbearing veins,including liquid-rich two-phase(WL type),gas-rich two-phase(GL type),and daughter mineral-bearing fluid inclusions(s type).Fluid inclusions data show that the homogenization at temperatures 197 to 372°C for stageⅠ,126 to 319°C for stageⅡ,119 to 189°C for stageⅢ,and 115 to 183°C for stageⅣ,with corresponding salinities of 3.7 to 22.6 wt.%,4.7 to 23.2 wt.%,5.3 to 23.2 wt.%,and 1.7 to14.9 wt.%Na Cl equiv.,*** boiling was the critical factor controlling the gold and associated sulfide precipitation at *** and oxygen stable isotopic analyses for quartz yielded δ^(18)O=-5.0‰ to 9.8‰ and δD=-133.5‰ to-77.0‰.Carbon stable isotopic analyses for calcite and ankerite yielded δ^(13)C=-2.3‰to-1.2‰ and O=7.9‰ to 14.1‰.The C-H-O isotope data show that the oreforming fluids were originated from magmatic water with meteoric water input during *** inclusions in arsenopyrite have ^(3)He/^(4)He ratios of 0.002 Ra to 0.054 Ra,and ^(40)Ar/^(36)Ar rations of 1225 to 3930,indicating that the ore-forming fluids were dominantly derived from crustal sources almost no mantle *** isotopic valu.s.of Maoling fine-grained granite range from6.‰1 to 9.8‰,with a mean of 7.7‰,δ^(34)s valu.s.of arsenopyrite from the mineralized phyllite(host rock)range fr

关键词： Geochronology Fluid inclusions Isotope geochemistry Maoling gold deposit Liaodong Peninsula

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Working and playing with Don:Memories of Donald ***

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Earthquake science 2022年第1期35卷 24-25页

作者： David J.Wald u.s.geological survey GoldenColorado 80401USA

You might find it hard to believe,but I went to Caltech’s seismological Lab for my *** a football ***,perhaps I should explain.I received my *** Geophysics(Earthquake seismology)at university of Arizona in 1986,under the tutelage of Terry Wallace(Caltech Ph.D.,1983).Terry worked with Don prior to joining the faculty at the university of *** there the Helmberger stories began.

关键词： Earthquake Wallace explain

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Cassiterite u-Pb dating of the Yelonggou pegmatite-type lithium deposit in western sichuan and its metallogenic age constraints

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China Geology 2024年第1期7卷 153-156页

作者： Xiang-yuan Yue Qian Zhang Jun-jun Zhang Wei Zhang Jing Zhang Zhi-quan Jia Li-ping Luo Institute of Multipurpose utilization of Mineral Resources Chinese Academy of Geological SciencesChengdu610041China shandong Lunan Geology and Exploration Institute(No.2 Brigade of shandong BGMR) Jining272100China sichuan shudao Advanced Material science Group Co.Ltd. Chengdu610041China No.3 geological Brigade of sichuan Province Chongzhou611230China

*** Pegmatite hosts important resource of rare metals,e.g.,lithium(Li)and beryllium(Be).In recent years,increasingly more studies were dedicated to characterize and unravel the formation of pegmatite-type deposits,for which accurate dating of pegmatite formation and mineralization is *** songpan-Ganzi orogenic belt is a major rare metal metallogenic belt in China,hosting many important pegmatite-type Li deposits,including the Lijiagou,Dangba,Jiajika,Yelonggou,Cuola,and *** age data(mica Ar-Ar and zircon/cassiterite u-Pb)from these Li deposits are sparse,ranging from 210 to 152 ***,obtaining reliable zircon u-Pb dates can be a challenge due to the strong decidualization in *** a result,the formation and mineralization ages of these rare metal pegmatites remain controversial,which hampers the development of pegmatite-type metallogenic model for the songpan-Ganzi orogenic belt.

关键词： dating metallogenic zircon

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