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Geochemistry and petrogenesis of Mesoproterozoic mafic granulite and amphibolite dykes from Saltora, Bankura district, Chhotanagpur Gneissic Complex, eastern India: Implications for their emplacement in within-plate setting

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China Geology 2025年第1期8卷 159-186页

作者： Poulami Roy Bapi Goswami Ankita Basak Anwesa Sen Chittaranjan Bhattacharyya Department of Geology University of Calcutta35 Ballygunge Circular RoadKolkata 700019India

Distinguishing high-grade mafic-ultramafic rocks originally crystallized from within-plate basaltic magmatism is challenging and crucial because the chemical composition of the igneous rocks has been modified during high-grade metamorphism,causing misidentification of the characters of the parental *** metamorphosed mafic dykes occur throughout the Chhotanagpur Gneissic Complex(CGC)of eastern Indian *** E-W trending mafic dykes from the Saltora area in the southeastern CGC underwent metamorphism in two episodes:M1(650 MPa;770℃)and M2(300 MPa;744℃).The metamafics are enriched in LILE,depleted in HFSE,and display strong fractionation of LREE,nearly flat HREE patterns in a chondrite-normalized REE diagram,and show tholeiitic differentiation *** geochemical affinity is towards rift-related,continental within-plate *** 7%–10%melting of the carbonated spinel-peridotite sub-continental lithospheric mantle(SCLM)produced the parental mafic *** pre-existing SCLM was metasomatized by slab-derived fluid during the previous *** upwelling of the asthenosphere in a post-collisional tectonic setting caused E-W trending fractures,lithospheric thinning,and gravitational *** dykes were emplaced during crustal extension around 1070 *** remarkable geochemical similarity between the mafic dykes of Saltora and Dhanbad,the ca.1096 Ma Mahoba(Bundelkhand craton),and the ca.1070 Ma Alcurra mafic dykes in Australia supports a genetic link.

关键词： Metamorphosed mafic dykes Within-plate basaltic magmatism Carbonated spinel-peridotite Chhotanapgpur Gneissic Complex Mesoproterozoic continental rift Crustal extension SCLM Petrogenesis India

Geochronological and geochemical constraints on the petrogenesis of late Mesoproterozoic mafic and granitic rocks in the southwestern Yangtze Block

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Geoscience Frontiers 2021年第1期12卷 39-52页

作者： Guichun Liu Jing Li Xin Qian Qinglai Feng Wei Wang Guangyan Chen Shaobin Hu Guargdong Provincial Key lab of Geodynamics and Geohazards School of Eorth Scliences and Engheerng Sun Yat-sen UnbversityGuangzhou510275China Yurnan Ins diute of Geolbgical Survey Kuruming 650216China Southem Marine Sciance and Engineerirg Guangiong Laboratory(Zhuhai) Zhuhai519082China State Key Laboratonry of Geological Processes and Mineral Resources China University of GeosdencesWuhan430074China

Late Mesoproterozoic igneous rocks in the SW Yangtze Block are important for understanding the role of it in reconstruction of the Rodinia *** the present study,we report new geochronological,geochemical,and Nd-Hf isotopic data for the Cuoke plagioclase amphibolites and granites in the SW Yangtze *** results show that the plagioclase amphibolites and granites have similar late Mesoproterozoic zircon U-Pb ages of 1168-1162 Ma,constituting a bimodal igneous *** plagioclase amphibolites have high and variable TiO2 contents(1.15-4.30 wt.%)and Mg#(34-66)values,similar to the tholeiitic *** are characterized by enrichment in LREEs and LILEs,and have OIB-like affinities with positive Nb and Ta *** plagioclase amphibolites have positive whole-rockεNd(t)(+3.2 to+4.3)and zirconεHf(t)(+4.3 to+10.7)values,indicating that they were derived from an OIB-like asthenospheric mantle *** granites belong to the reduced peralkaline A-type series and have negativeεNd(t)value of-6.0 andεHf(t)values of-5.8 to-13.8,indicating a derivation from the partial melting of ancient mafic lower *** combination with the~1.05-1.02 Ga bimodal igneous assemblage in the SW Yangtze Block,we propose that the Cuoke 1168-1162 Ma igneous rocks were likely formed in a continental rift basin and argue against the existance of Grenvillian Orogen in the SW Yangtze Block during the late Mesoproterozoic.

关键词： Late Mesoproterozoic Zircon U-Pb geochronology Elemental and isotopic data Within-plate igneous rocks continental rift Yangtze Block

Mid—Late Neoproterozoic rift-related volcanic rocks in China:Geological records of rifting and break-up of Rodinia

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Geoscience Frontiers 2012年第4期3卷 375-399页

作者： Linqi Xia Zuchun Xia Xueyi Xu Xiangmin Li Zhongping Ma Xi＇an Institute of Geology and Mineral Resources China Geological Survey Xi＇an Shaanxi 710054 China

Early Cambrian and Mid--Late Neoproterozoic volcanic rocks in China are widespread on several Precambrian continental blocks, which had aggregated to form part of the Rodinia supercon- tinent by ca. 900 Ma. On the basis of petrogeochemical data, the basic lavas can be classified into two major magma types： HT （Ti/Y 〉 500） and LT （Ti/Y 〈 500） that can be further divided into HT1 （Nb/La 〉 0.85） and HT2 （Nb/La ≤ 0.85）, and LT1 （Nb/La 〉 0.85） and LT2 （Nb/La ≤ 0.85） subtypes, respectively. The geochemical variation of the HT2 and LT2 lavas can be accounted for by lithospheric contamination of asthenosphere- （or plume-） derived magmas, whereas the parental magmas of the HT1 and LT1 lavas did not undergo, during their ascent, pronounced lithospheric contamination. These volcanics exhibit at least three characteristics：（1） most have a compositional bimodality; （2） they were formed in an intracontinental rift setting; and （3） they are genetically linked with mantle plumes or a mantle surperplume. This rift-related volcanism at end of the Mid-- Neoproterozoic and Early Cambrian coincided temporally with the separation between Australia-- East Antarctica, South China and Laurentia and between Australia and Tarim, respectively.

关键词： Neoproterozoic Bimodal volcanism continental rift Mantle plume Rodinia supercontinent China

U-Pb zircon chronology,geochemistry and isotopes of the Changyi banded iron formation in the eastern Shandong Province:Constraints on BIF genesis and implications for Paleoproterozoic tectonic evolution of the North China Craton

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U-Pb zircon chronology,geochemistry and isotopes of the Chan...

Depositional environment and tectonic implications of the Paleoproterozoic BIF in Changyi area,eastern North China Craton:Evidence from geochronology and geochemistry of the metamorphic wallrocks

中国科学院地质与地球物理研究所2014年度（第14届）学术年会

作者： Ting-Guang Lan Hong-Rui Fan M.Santosh Fang-Fang Hu Kui-Feng Yang Yongsheng Liu Key Laboratory of Mineral Resources Institute of Geology and GeophysicsChinese Academy of Sciences School of Earth Sciences and Resources China University of Geosciences Beijing State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

The Changyi banded iron formation(BIF) in the eastern North China Craton(NCC) occurs within the Paleoproterozoic Fenzishan *** BIF shows alternating quartz-rich light and magnetite-rich dark bands with magnetite(15-65 vol.%),quartz(25-65 vol.%) and amphibole(15-30 vol.%) constituting the major *** garnet,epidote,chlorite,calcite,biotite and pyrite occur *** BIF bands are interlayered with amphibolite,hornblende gneiss,biotite quartz schist,garnet biotite schist,biotite gneiss and leptynite,and are intruded by ***-ICP-MS U-Pb dating on zircons separated from the BIF bands and the wallrocks constrains the depositional age as 2240-2193 Ma and metamorphic age as-1864 *** dominant composition of SiO + FeO(average value of 92.3 wt.%) of the BIF bands suggests their formation mainly through chemical ***,the widely varying contents of major elements such as A1O(0.58-6.99 wt.%),MgO(1.00-3.86 wt.%),CaO(0.22-4.19 wt.%) and trace elements such as Rb(2.06-40.4 ppm),Sr(9.36-42.5 ppm),Zr(0.91-23.6 ppm),Hf(0.04-0.75 ppm),Cr(89.1-341 ppm),Co(2.94-30.4 ppm),and Ni(1.43-52.0 ppm) clearly indicate the incorporation of elastics,especially continental felsic elastics,as also confirmed by the presence of ancient detrital zircons in the BIF *** normalized against Post Archean Average Shale(PAAS),the seawater-like signatures of REE distribution patterns,such as LREE depletion,positive La and Y anomalies,and superchondritic Y/Ho ratios(average value of 36.3),support the deposition in *** positive Eu anomalies(Eu/Eu*PAAS = 1.14-2.86) also suggest the participation of hydrothermal *** addition,the sympathetic correlation between Cr,Co and Ni as well as the Co + Ni + Cu vs.Σ REE and the A1O *** relations further indicates that the iron and silica mainly originated from hydrothermal *** with regional geological investigation and protolith restoration of the wallrocks,a continental rift environment is su

关键词： Banded iron formation Geochemistry Paleoproterozoic continental rift North China Craton

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Depositional environment and tectonic implications of the Pa...