Identifying Crystal Accumulation in Granitoids through Amphibole Composition and <i>In Situ</i> Zircon O Isotopes in North Qilian Orogen

Abstract Granitoids are the main constituents of continental crust, and an understanding their petrogenesis is key to origin evolution continents. Whether crystal fractionation dominant way generate evolved magmas has long been debated, mostly because such processes would produce large volumes complementary cumulates, which remains elusive. Mafic magmatic enclaves (MMEs) ubiquitous in granitoids presence was initially recognized as cumulates. However, many MMEs lack obvious evidence accumulation, classic cumulate textures modal layering, abandoned model magma mixing between mafic felsic become popular. In this study, we conduct a combined study amphibole composition situ O isotopes zircons on three suites orogenic with from North Qilian Orogenic Belt (NQOB). We find that host granodiorites show overlapping zircon ?18O values, affirming they share same parental magmas. The compositions indicate amphiboles not equilibrium melt whose bulk-rock. These new data, together published bulk-rock suggest our have clear signatures thus origin. Our provides for accumulation NQOB. This calls re-examination some intermediate rocks (granitoid/andesite) discussing models crustal growth.