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Journal of Earth Science 1999年第4期18卷 295-298页

作者： Zhao Zhidan Zhou Wenge Xie Hongsen Guo Jie Xu Zuming(Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002)Zhang Zeming(Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037) Institute of Geochemistry Chinese Academy of SciencesGuiyang 550002 Institute of Geology Chinese Academy of Geological SciencesBeijing 100037

P-wave velocities in the rocks of Dabieshan, central China were measured at pressures up to 5.0 GPa and temperatures up to 1 300℃. The ultrahigh pressure eclogites have the highest density and P-wave velocity (Vp) and lower anisotropy. Pressure derivatives of the eclogites range from 0. 22 to 0. 33 km. s-1 GPa-1. Average temperature derivative of the eclogites is - 3. 41×10-4 km. s-1. °C -1. The density and VP of the eclogites imply that there will be two united possibilities related to crust-mantle recycling after the eclogite formed in the deep lithosphere. One is that some eclogites in the deep lithosphere were detached and sunk into deeper mantle due to their denser density. Another is that some eclogites returned to the crust and exposed to the surface.Small amounts (crust beneath Dabieshan based on our calculation.

关键词： eclogite P-wave velocity density high pressure high temperature lower crust

lower crustal xenoliths from Junan,Shandong province and their bearing on the nature of the lower crust beneath the North China Craton

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Lower crustal xenoliths from Junan,Shandong province and the...

Petrogenesis and tectonic implications of the Early Cretaceous Dagushan adakitic porphyries in the Anshan area,North China Craton

中国科学院地质与地球物理研究所第十届(2010年度)学...

作者： Ji-Feng Ying~*,Hong-Fu Zhang,Yan-Jie Tang State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,P.O.Box 9825,Beijing 100029,China

Geochronological,petrological and geochemical studies were performed on the granulite xenoliths from a Late Cretaceous basaltic breccia dike in Junan,Shandong province,eastern China.These xenoliths show close similarities to the Nushan granulite xenoliths from the southern margin of the North China Craton(NCC)and the Archean granulite terrains in terms of mineralogy and bulk rock compositions,but are quite different from the Hanuoba mafic granulite xenoliths from the northern NCC.In-situ zircon U-Pb age and Hf isotopic analyses,together with geochemical data reveal that the protolith of these xenoliths was formed around 2.3 Ga ago,through assimilation-fractional crystallization of a mafic magma.P-T conditions of these xenoliths suggest that the lower crust beneath the Junan region reaches to a depth of 35 km,which agree well with the result deduced from various geophysical methods.The consistent petrological and seismic Moho depths,the observed velocity structure and calculated velocity of these xenoliths imply the absence of underplating induced crust-mantle transition zone,which was well formed in the northern NCC.Compared to 40-50 km depth of the lower crust in Early Jurassic,the lower crust beneath Junan extended to a depth of 30 km in Late Cretaceous,suggesting that the lower crust of NCC was significantly thinned during Late Mesozoic.

关键词： Granulite xenoliths lower crust Petrology Geochemistry North China Craton

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Acta Geochimica 2022年第1期41卷 24-38页

作者： Xiaohui Sun Haoshu Tang Yan Luan Key Laboratory of Western China’s Mineral Resources and Geological Engineering MOESchool of Earth Science and ResourcesChang’an UniversityXi'an 710054China State Key Laboratory of Ore Deposit Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The eastern part of the North China Craton suffered significant lithospheric thinning since the Mesozoic,and petrogenesis of the Dagushan adakitic diorite porphyries provides an excellent opportunity to investigate the lithospheric thinning mechanism and geodynamic setting.The zircon LA-ICP-MS U–Pb geochronology reveals that the representative Dagushan adakitic porphyry was formed at 120.5±0.5 Ma.The Dagushan diorite porphyries are characterized by the relatively high contents of SiO_(2)(64.25–65.70 wt%),Al_(2) O_(3)(15.00–15.38 wt%),Sr(333–491 ppm),low contents of Y(6.50–10.3 ppm),and Yb(0.57–0.85 ppm),and resultant high Sr/Y(47–57)and La/Yb(37–55)ratios,exhibiting geochemical characteristics of typical adakites.Moreover,the relatively high Mg O contents(MgO=2.23–2.29 wt%)and Mg numbers(Mg^(#)-=54–56)of the Dagushan adakitic rocks imply that the pristine adakitic magma interacted with mantle peridotite.However,the zircon Hf isotopic signatures(εHf(t)=-19.0 to-28.0;TDM2=2378–2944 Ma)suggest an ancient lower crustal source.Therefore,it is proposed that the Dagushan adakitic rock was probably generated by partial melting of delaminated lower crust which was triggered by the Tan-Lu Fault Zone,and the interaction of pristine adakitic magma with mantle peridotite during the ascent finally generated the Dagushan high Mg^(#)adakitic rocks.It is suggested that delamination was an important mechanism for lithospheric thinning of the NCC.

关键词： Diorite porphyry Adakite lower crust Delamination NCC

Composition and evolution of the continental crust:Retrospect and prospect

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Geoscience Frontiers 2022年第5期13卷 1-15页

作者： J.L.R.Touret M.Santosh J.M.Huizenga Institut de Minéralogie Physique des MatériauxCosmochimieSorbonne Universités4 Place JussieuF-75005 ParisFrance 121 Rue de la Réunion 75020 ParisFrance School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Department of Earth Science University of AdelaideAdelaideSA 5005Australia Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life SciencesP.O.Box 5003NO-1432ÅsNorway EGRU(Economic Geology Research Centre) James Cook UniversityTownsvilleQueensland 4811Australia Department of Geology University of JohannesburgPO Box 524Auckland Park 2006South Africa

Until the middle of the 20th century,the continental crust was considered to be dominantly granitic.This hypothesis was revised after the Second World War when several new studies led to the realization that the continental crust is dominantly made of metamorphic rocks.Magmatic rocks were emplaced at peak metamorphic conditions in domains,which can be defined by geophysical discontinuities.Low to medium-grade metamorphic rocks constitute the upper crust,granitic migmatites and intrusive granites occur in the middle crust,and the lower crust,situated between the Conrad and Moho discontinuities,comprises charnockites and granulites.The continental crust acquired its final structure during metamorphic episodes associated with mantle upwelling,which mostly occurred in supercontinents prior to their disruption,during which the base of the crust experienced ultrahigh temperatures(>1000℃,ultrahigh temperature granulite-facies metamorphism).Heat is provided by underplating of mantle-derived mafic magmas,as well as by a massive influx of low H_(2)O activity mantle fluids,i.***.high-density CO_(2) and highsalinity brines.These fluids are initially stored in ultrahigh temperature domains,and subsequently infiltrate the lower crust,where they generate anhydrous granulite mineral assemblages.The brines can reach upper crustal levels,possibly even the surface,along major shear zones,where granitoids are generated through brine streaming in addition to those formed by dehydration melting in upper crustal levels.

关键词： Brines CO_(2) Continental crust Granulite lower crust

Geochemistry and crystal shape,size and spatial distribution in arc-related gabbro,Urmia,NW Iran

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Acta Geochimica 2022年第6期41卷 1000-1018页

作者： Monir Modjarrad Faculty of Science Department of GeologyUrmia UniversityUrmiaIran

The mafic intrusive Moskin and Parvaneh regions in the northwest and south of Urmia were investigated for their geochemistry and petro-physical properties such as size,shape,and spatial distribution of their crystals.This type of study can be a powerful tool for analyzing the history of magma crystallization,along with geochemistry examinations.The gabbroic calc-alkaline rocks,with the Early Cenozoic is the relative age,consist of coarse plagioclase and amphibole with rare clinopyroxene and olivine in the Sanandaj-Sirjan zone at sedimentary-structural subdivisions of Iran.The depletion of HFSEs and enrichment of LILEs as arc-related rocks,as well as lower crust contamination(Nb/Th and K/Ce)symptoms,show that these gabbros formed at the continental arc setting from an enriched source.Considering the geographical position and relative age of the gabbros,they possibly outcropped during the Neo-Tethys subduction processes after the enrichment by considerably lower crust effects.The amphibole and plagioclase crystals with considerable abundance show linear crystal size distribution(CSD)patterns with a slope of(-1/Gt)-3 to-4 for amphiboles and plagioclase except for Parvaneh plagioclase which shows-16.The annealing(Ostwald ripening)caused the convex CSD on the small grains part at Parvaneh gabbro.Therefore,the ratio of nucleation to growth rates(J/G)for these minerals is 5-6 times,only for Parvaneh plagioclase is ten times which numerous nuclei were made by a significant degree of overstepping in the rocks.There is no magma mixing evidence because of the linear(one population of crystals)CSD patterns.The shape of amphibole crystals in gabbros is bladed(with S/I=0.4-0.5 and I/L=0.1-0.3)and bladed to tabular for plagioclase(S/I=0.4 and I/L=0.6-0.7).The spatial distribution patterns(SDPs)are calculated from a big R-value based on the nearest neighbor’s theory for amphibole and plagioclase crystals,confirming clustered SDP for all of them.Also,the dihedral angle measurements(between amphibole and plagioclase grains)display

关键词： Gabbro lower crust CSD SDP DA Urmia-Iran

lower crustal attenuation in northeastern Tibetan Plateau from ML amplitude

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Earthquake Science 2021年第4期34卷 378-386页

作者： Yanbing Liu Shunping Pei Beijing Earthquake Agency Beijing 100080China State Key Laboratory of Tibetan Plateau Earth System Resources and Environment(TPESRE)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

This study investigated the crustal attenuation structures of Sg and Lg waves of the northeastern Tibetan Plateau.We collected ML amplitude data recorded at 168 permanent stations between 1985 and 2016 and 11 temporary broadband stations between 2014 and 2016.Detailed Q0 variation maps of Sg and Lg waves were obtained by applying ML amplitude tomography.The average Q0 values of the Sg and Lg wave were 440 and 220,respectively.Relatively high attenuation anomalies of both waves appeared in the central and eastern regions of the Bayan Har Block and the east edge of the Qiangtang Block,which may be related to partial melting,high geotemperature,and strong tectonic processes.High attenuation anomalies were also found in the Qilian Orogenic Belt and Hetao Graben,which may be related to their active tectonic behavior and densely distributed faults.The relatively low attenuation anomalies of both waves were revealed in the Alax and Ordos blocks,Qaidam,Tarim,Qinghai Lake,and Gonghe basins,which can be explained by the tectonically stable properties and ancient composition of geological elements.These results indicate that the path between the highly attenuated lower crust of the Bayan Har Block and the Qilian Orogenic Belt is obstructed by three adjacent low attenuated areas(i.e.,the Qilian,Qinghai Lake,and Gonghe basins);thus,it appears unlikely that a crustal flow channel from the interior of the Tibetan Plateau to the Qilian Orogenic Belt will form.

关键词： lower crust attenuation northeastern Tibetan Plateau Q value

Underplating in the middle-lower Yangtze Valley and model of geodynamic evolution:Constraints from geophysical data

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Science China Earth Sciences 2005年第7期48卷 985-999页

作者： Lü Qingtian, HOU Zengqian, YANG Zhusen & SHI Danian Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China Institute of Mineral Resources Chinese Academy of Geoloqical Sciences Beijina 100037 China

The lower crust and Moho are the most active boundary layers in the process of continental evolution, in which marks left by tectonic and magmatic activities during the process are preserved. The evolutionary process of the continental lithosphere may be reconstructed by exploring the structures of the lower crust and Moho. According to a study of the deep seismic reflection data obtained from the middle-lower Yangtze Valley, the authors find bright layered reflections ubiquitous in the lower crust and think that the bright reflections are caused by un-derplating of basic or ultrabasic magmas, which might be related to delamination of the lithosphere. On the basis of an integrated analysis of the geophysical and geological data of the region, the authors propose a model for geodynamic evolution of the middle-lower Yangtze Valley. This model suggests that the middle-lower Yangtze Valley had undergone such geodynamic processes as collision-compression, delamination-extension and underplating-melting since the end of the Permian, finally forming the gigantic middle-lower Yangtze Valley metallogenic belt.

关键词： lower crust deep seismic reflection underplating tectonic evolution.

Velocity　structure　of　the　crust　and　upper　mantle　in　Xingtai　earthquake　region　and　its　adjacent　area

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Acta Seismologica Sinica(English Edition) 1995年第3期8卷 405-412页

作者：祝治平张称康盖玉杰张建狮聂文英石金虎张成科阮红 Geophysical Prospecting Brigade State Seismological Bureau Zhengzhou China

Two seismic refraction profiles which are perpendicular to each other, running through Xingtai earthquake region,reveal the anomalous variations of crust-mantle velocity structure and deep tectonics. Pg wave attenuatesrapidly with distance in the earthquake region. A group of strong reflections from a depth of 21. 0 km can be identified along the section from Longyao to the piedmont of Taihang Mountain, but P. waves characterized generally by strong amplitude are not obvious. Under the earthquake region and its western neighboring region, thecrustal velocity structure features high and low velocities changed alternatively. From North China plain toShanxi plateau, the velocity at the top of the upper mantle decreases progressively, while crustal thickness increases by 11 km. Moho uplifts locally in the earthquake region. The crustal fault stretching deeply to Moho andthe discontinuous sections of Moho in the earthquake region are supposed to be the channels and zones for magmatic intrusion. The uplifting of upper mantle and magmatic intrusion are responsible for the formation ofanomalous crust-mantle structures and extending basins, and for the occurrence of Xingtai earthquake as well.

关键词： velocity structure lower crust upper crust upper mantle refraction

Nanorocks, volatiles and plate tectonics

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Geoscience Frontiers 2021年第5期12卷 202-214页

作者： Gautier Nicoli Silvio Ferrero Institut für Geowissenschaften Universität Potsdam14476 Potsdam-GolmGermany Museum für Naturkunde(MfN) Leibniz-Institut für Evolutions-und Biodiversitätsforschung10115 BerlinGermany

The global geological volatile cycle(H,C,N)plays an important role in the long term self-regulation of the Earth system.However,the complex interaction between its deep,solid Earth components(i.***.crust and mantle),Earth’s fluid envelopes(i.***.atmosphere and hydrosphere)and plate tectonic processes is a subject of ongoing debate.In this study we want to draw attention to how the presence of primary melt(MI)and fluid(FI)inclusions in high-grade metamorphic minerals could help constrain the crustal component of the volatile cycle.To that end,we review the distribution of MI and FI throughout Earth’s history,from ca.3.0 Ga ago up to the present day.We argue that the lower crust might constitute an important,longterm,volatile storage unit,capable to influence the composition of the surface envelopes through the mean of weathering,crustal thickening,partial melting and crustal assimilation during volcanic activity.Combined with thermodynamic modelling,our compilation indicates that periods of well-established plate tectonic regimes atcrustal lithologies and the storage of volatiles in the lower crust.Such hypothesis has implication beyond the scope of metamorphic petrology as it potentially links geodynamic mechanisms to habitable surface conditions.MI and FI in metamorphic crustal rocks then represent an invaluable archive to assess and quantify the co-joint evolution of plate tectonics and Earth’s external processes.

关键词： Nanorocks Plate tectonics Volatiles lower crust

Lithospheric structure and geodynamic properties of the Tibetan plateau and its adjacent regions

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Earthquake Science 2012年第5期25卷 353-362页

作者： Junmeng Zhao Institute of Tibetan Plateau Research Chinese Academy of Sciences

The Tibetan plateau has an elevation of 4-5 km above sea level and a crustal thickness of -80 km （Zhao et al., 2010d）, and its ongoing tectonic evolution is one of the most important Meso-Cenozoic events affect- ing... 详细信息

关键词： Tibetan Plateau lower crust Tarim Basin Qaidam Basin Lithospheric Structure