Geochemical s...rustal mixing_Nagamma J.pdf

ORIGINAL ARTICLE Acta Geochim(2023)42(1):923 https:/doi.org/10.1007/s11631-022-00568-5 in the petrogenys residue system in a syn-collision setting followed by continental crust stability in EDC during the Neoarchean period.Keywords Madugulapalli granite Hybrid granite Crustal mixing Subduction 1 Introduction The origin and secular history of the Archean continental crust in time and space impose signifi cant constraints on the thermal and chemical evolution of the mantle and its involvement in the development of various geodynamic mechanisms via the cooling mantle and its diff erentiation(Laurent et al.2014;Jayananda et al.2018;Singh et al.2019).The mantle formation occurred due to the sluggish lid-to-plate tectonic process;some are retained in granite-greenstone Meso-Neoarchean terranes found in various cratons worldwide(Hawkesworth et al.2010;Cawood et al.2013).Granitic magmatism results from hydrous man-tle melting and serves as a primary proof for subduction zone magmatism unique to the Earth(Martin et al.2005;Lpez et al.2006;Moyen 2011).The formation of conti-nental crust throughout the 3.4,3.0,2.7,1.7,and 1.0 Ga periods are present in cratons worldwide as described by Hawkesworth and Kemp(2006)and Roberts et al.(2015).Nevertheless,the majority of experts believe that 2.72.5 Ga represents a worldwide peak development in the con-tinental crust as shown by the Dharwar Craton(Jayananda et al.2019).The corridor made of Archean crust was domi-nated by four lithotypes:(i)tonalitetrondhjemitegrano-diorite(TTG),developed mainly during the early stages;(ii)volcano-sedimentary greenstone belt sequences;and(iii)late-stage high-K biotite granitic intrusions,and(iv)sanukitoids(Laurent et al.2014).The occurrence of hybrid Abstract Magma produced by melting of continental crust and mantle at the Archean-Proterozoic boundary are compo-sitionally variable and chemical compositions provide evi-dence 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 dur-ing 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 petrogen-esis and role in crust formation.The Madugulapalli gran-ites(MPG)are composed chiefl y of plagioclase,quartz,and alkali feldspar with associated biotite showing altera-tion 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 inter-action 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 gran-ites demonstrates the mixing coupled with diff erentiation Ashok Ch 1 State Mines and Geology Department ,508001 Nalgonda ,India 2 Department of Geology ,Osmania University ,500007 Hyderabad ,India 3 CSIR-National Geophysical Research Institute ,500007 Uppal,Hyderabad ,India Received:15 February 2022/Revised:16 July 2022/Accepted:19 July 2022 /Published online:28 October 2022 The Author(s),under exclusive licence to Science Press and Institute of Geochemistry,CAS and Springer-Verlag GmbH Germany,part of Springer Nature 2022 Geochemical studies of hybrid granite from Madugulapalli area,Eastern Dharwar Craton,Southern India:Implications for crustal mixing Nagamma J 1 Ratnakar J 2 Ajay kumar A 2 Ashok Ch 3 Acta Geochim(2023)42(1):923granitoids has not been documented in every Late-Archean craton,and when they do exist,they may constitute either a negligible volume or a substantial portion of the crust.These hybrid granites formed due to the interaction(e.g.,metasomatism,mingling,and mixing)between magmas or sources of any of the previously described TTGs,biotite granites,and sanukitoids.They constitute a highly diverse family that cannot be classifi ed only on geochemical criteria since their origins and petrogenetic processes vary consider-ably across locations.They are most frequently formed by interactions between sanukitoids and biotite-or two-mica granites,as seen in the Superior Province(Stevenson et al.1999;Whalen et al.2004)and the southern Indian Dharwar craton(Moyen et al.2001;Jayananda et al.2006).The term sanukitoid refers to a group of granitic rocks discovered in Canadas Late Archaean Superior Province recommended by Shirey and Hanson(1984).These authors classifi ed sanu-kitoids as diorites to granodiorites with a high Mg#(70)and high Ni and Cr contents.Late magmatism of granites in Archean time was widespre