Peraluminous A-type granites formed through synchronous fractionation,magma mixing,mingling,and undercooling:evidence from microgranular enclaves and host Mesoproterozoic Kanigiri granite pluton,Nellore Schist Belt,southeast India

作     者：Ch.Narshimha Santosh Kumar Ch.Narshimha;Santosh Kumar

作者机构：Department of GeologyCentre of Advanced StudyKumaun UniversityNainital 263001India 

出 版 物：《Acta Geochimica》 (地球化学学报（英文）)

年 卷 期：2023年第42卷第4期

页      面：603-636页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：UGC-Dr.D.S.Kothari Postdoctoral Fellowship No.F.4-2/2006(BSR)/ES/20-21/0005 supported under a research grant[Mo ES/P.O.(Geo)/101(v)/2017]to SK 

主　　题：Enclave Kanigiri granite Magma mixing-fractionation Nellore schist belt SE India 

摘      要：The field and microstructural features coupled with mineral chemical data from microgranular enclave(ME)and host Mesoproterozoic Kanigiri granite(KG)pluton of Nellore Schist Belt(NSB),Southeastern India,have been documented in order to infer the likely processes responsible for the origin and evolution of ME and host KG *** ME and host KG bear the same mineral assemblages barring the KG which does not contain amphibole;however,they are modally *** ME in KG is originated due to multiple intrusions of ME magmas into the crystallizing host KG magma *** and textural features indicate the dynamic magma flow,mingling,and undercooling of the ME against a relatively cooler surface of host KG *** presence of NSB country rock xenoliths and its diffuse boundaries suggest the intrusive relation and marginal assimilation by the intruding KG *** occasional cumulate texture in the ME appears to have formed by the accumulation of early-formed minerals that crystallized rapidly in the ME magma *** ME shows the magmatically deform features developed due to the flowage and erosion by the subsequent intrusions of ME magma pulses into the crystallizing host KG magma *** ME amphiboles show unusual composition as ferro-edenitic hornblende to potassian-hastingsitic hornblende,that crystallized in the subalkaline-alkaline transition,low fO_(2)(reducing to mildly oxidizing)*** unusual extremely low Mg/Mg+Fe^(t)=0.015(avg.)of ME amphiboles may be related to the changing physico-chemical(P,T,fO_(2),and H_(2)O)condition of the ME magma or they might have crystallized in equilibrium with more evolved KG *** KG(FeOt/MgO=37.04,avg.)and ME(FeO~t/MgO=77.72,avg.)biotites are siderophyllite,and buffered between QFM and NNO syn-crystallizing in the water undersaturated(H_(2O)≈3.58 wt.%in KG;≈3.53wt.%in ME),alkaline anorogenic(A-type)host magmas that were emplaced at mid-crustal(4–5 kbar;17 km)***,microtextural and mineral