Geochemical studies of hybrid granite from Madugulapalli area, Eastern Dharwar Craton, Southern India: Implications for crustal mixing

作     者：Nagamma J Ratnakar J Ajay kumar A Ashok Ch Nagamma J;Ratnakar J;Ajay kumar A;Ashok Ch

作者机构：State Mines and Geology Department508001 NalgondaIndia Department of GeologyOsmania University500007 HyderabadIndia CSIR-National Geophysical Research Institute500007 UppalHyderabadIndia 

出 版 物：《Acta Geochimica》 (地球化学学报（英文）)

年 卷 期：2023年第42卷第1期

页      面：9-23页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 070901[理学-矿物学、岩石学、矿床学] 0708[理学-地球物理学] 

基　　金：the UGC (New Delhi) for awarding RGNF-Research Fellowships UGC-Emeritus Fellowship (#201718-Eme ritus-10196-1)。 

主　　题：Madugulapalli granite Hybrid granite Crustal mixing Subduction 

摘      要：Magma produced by melting of continental crust and mantle at the Archean-Proterozoic boundary are compositionally variable and chemical compositions provide evidence for the mixing of two sources. Understanding the composition of hybrid magma is essential for determining the comparative infl uence of crust and mantle sources during orogenesis. The hybrid granites are less documented in Indian cratons, especially less in Dharwar Craton. Here we present petrographic and whole-rock geochemical data of Madgulapalli granitic rocks situated in the NE part of the Eastern Dharwar Craton(EDC), to elucidate their petrogenesis and role in crust formation. The Madugulapalli granites(MPG) are composed chiefl y of plagioclase, quartz, and alkali feldspar with associated biotite showing alteration and inter-granular textures. Geochemically, they are metaluminous to peraluminous in nature with calc-alkaline hybrid granite. The hybrid granites exhibit both negative and positive europium anomalies;the lower Rb/Sr, Rb, Sr, and higher Sr/Y,(Dy/Yb)N ratios suggest that the interaction of older rocks with residual garnet source melted at high pressures. We hypothesize that hybrid granites are formed by interaction(e.g., metasomatism, mingling, or mixing) between parental magmas and pre-existing rocks with the infl uence of sanukitoid melts(heat source) in a subduction environment. The genesis of the hybrid granites demonstrates the mixing coupled with diff erentiation in the petrogeny’s residue system in a syn-collision setting followed by continental crust stability in EDC during the Neoarchean period.