Petrogenesis and Rb-Sr Isotopic Characteristics of Paleo-Mesoproterozoic Mirgarani Granite Sonbhadra Uttar Pradesh India:Geodynamics Implication for Supercontinent Cycle  

作　　者：A.P.Dhurandhar Suresh Khirwal D.V.L.N.Sastry 

机构地区：[1]Orion Geohytech India,G-10 Bramhaputra Apartment,Aakar Nagar,Katol Road,Nagpur,440013,India [2]Atomic Minerals Directorate for Exploration&Research,Jamshedpur,831014,India [3]Atomic Minerals Directorate for Exploration&Research,Hyderabad,009140,India

出　　处：《Advances in Geological and Geotechnical Engineering Research》2023年第1期57-85,共29页地质与岩土工程研究进展（英文）

摘　　要：The Rb-Sr whole-rock isochron,age 1636±66 Ma of Mirgarani granite,is the one of the oldest granite dated in the northwestern part of the Chhotanagpur Granite Gneiss Complex(CGGC).The initial Sr ratio is 0.715±0.012(MSWD=0.11),showing an S-type affinity.The Mirgarani granite has intruded the migmatite complex of the Dudhi Group and forms the Mirgarani formation comparable to the granites of the Bihar Mica Belt around Hazaribagh(1590±30 Ma).The present studies have established the chronostratigraphy of the Dudhi Group and adjoining areas in CGGC.Petro-graphic and geochemical studies revealed that the granite is enriched in Rb(271 ppm),Pb(77 ppm),Th(25 ppm),and U(33 ppm)and depleted in Sr(95 ppm),Nb(16 ppm),Ba(399 ppm)and Zr(143 ppm)contents as compared to the normal granite.The Mirgarani granite is a peraluminous(A/CNK=1.23),high potassic(K_(2)O 6.42%),Calc-Alkalic to Alkali-Calcic{(Na_(2)O+K_(2)O)-CaO=6.29}S-Type granite,a feature supported by the presence of modal garnet and normative corundum(2.68%).The Mirgarani granite is considered to have been formed by the anatexis of a crustal sedimentary protolith at a depth of approximately 30 km with temperatures ranging from 685-700℃ during the Co-lumbian-Nuna Supercontinent.

关 键 词：Miragrani granite PETROGENESIS Isochron dating Radiogenic heat Dudhi group CGGC Palaeo-Mesoproterozoic SUPERCONTINENTS 

分 类 号：P58[天文地球—岩石学]