Breakup of the Neoarchean supercontinent Kenorland:Evidence from zircon and baddeleyite U-Pb ages of LIP-related mafic dykes in the Coorg Block,southern India  

作　　者：Cheng-Xue Yang M.Santosh Jarred Lloyd Stijn Glorie Y.Anilkumar K.S.Anoop Pin Gao Sung-Won Kim 

机构地区：[1]School of Earth Sciences and Resources,China University of Geosciences Beijing,Beijing 100083,PR China [2]Institute of Earth Sciences,China University of Geosciences Beijing,Beijing 100083,PR China [3]Department of Earth Sciences,University of Adelaide,Adelaide SA,Australia [4]Department of Geology,University of Kerala,Kariavattom,Trivandrum,India [5]Geology Division,Korea Institute of Geoscience and Mineral Resources,Daejeon 34132,Republic of Korea

出　　处：《Geoscience Frontiers》2024年第4期97-114,共18页地学前缘（英文版）

基　　金：supported by Foreign Expert grant from China University of Geosciences Beijing,China and Professorial Fellow Research Grant from University of Adelaide,Australia to M.Santosh;It was also partially supported by the Basic Research Project(GP2020-003,Geological survey in the Korean Peninsula and publication of the geological maps)of Korea Institute of Geoscience and Mineral Resources(KIGAM);funded by the Ministry of Science,ICT(Information,Communication,and Technology);Future Planning,Korea.SG was supported by an Australian Research Council Future Fellowship(FT210100906)。

摘　　要：The Coorg Block in southern Peninsular India is one of the oldest crustal blocks on Earth that preserves the evidence for continental crust formation during the Paleo-Mesoarchean through subductionrelated arc magmatism,followed by granulite facies metamorphism in the Mesoarchean.In this study,we report for the first time,the'bar codes'of a major Paleoproterozoic Large Igneous Province in the Coorg Block through the finding of mafic dyke swarms.The gabbroic dykes from the Coorg Block,dom-inantly composed of plagioclase-pyroxene assemblage,show a restricted range in SiO_(2)values of 50.04-51.27 wt.%,and exhibit a sub-alkaline tholeiitic nature.These rocks show relatively flat LREE and constant HREE patterns and lack obvious Eu anomalies.Trace element modeling suggests that the dyke swarm was fed from a melt that originated at a shallow mantle level in the spinel stability field.Zircon grains are rare in the gabbro samples and those separated from two samples yielded 207Pb/206Pb weighted mean dates of 2214±12 Ma and 2221±7 Ma.The grains show magmatic features with depleted LREE and enriched HREE and positive Ce and negative Eu anomalies.Baddeleyite grains were dated from five gabbro samples which yielded 207Pb/206Pb weighted mean ages ranging between 2217±7 Ma and 2228±10 Ma.The combined data show a clear age peak at ca.2.2 Ga.The mafic dykes in the Coorg Block show geochemical similarities with ca.2.2 Ga mafic dyke swarms in different regions of the Dharwar and other cratons in Peninsular India and elsewhere on the globe.The data also support the inference that the global mafic magmatism at ca.2.2 Ga was linked with intracontinental rifting of the Archean cratons through mantle upwelling or plume activity.We correlate the mafic dyke swarms in the Coorg Block with attempted rifting of the Neoarchean supercontinent Kenorland.

关 键 词：Mafic dyke swarm Paleoproterozoic Large Igneous Province Geochronology Continental rifting Neoarchean supercontinent 

分 类 号：P534.3[天文地球—古生物学与地层学] P588.3[天文地球—地质学] P597.3