Major-and Trace-Element Chemistry of Clinopyroxene and Amphibole from High-Mg Diorite in Chelyabinsk Massif(Urals):Insights into Petrogenesis and Magma Source Constraints  

作　　者：Tatiana Osipova Gennadiy Kallistov Maria Chervyakovskaya Vasiliy Chervyakovskiy 

机构地区：[1]Zavaritsky Institute of Geology and Geochemistry,Ural Branch of RAS,Ekaterinburg 620110,Russia

出　　处：《Journal of Earth Science》2025年第2期508-523,共16页地球科学学刊(英文版)

摘　　要：Field-and petrographic investigations,together with microanalytical major-and traceelement studies,were carried out on clinopyroxene and amphibole from high-Mg diorite in the subduction-related Chelyabinsk granitic massif to understand its petrogenesis and source.The clinopyroxene composition(high Mg#,Cr-content,sum of REE and Ti/Eu ratio;depletion in HREE;negative Eu-anomaly)indicates that it formed from a reduced melt derived from a mantle source metasomatized by fluids/melts having crustal affinity.Melt compositions in equilibrium with clinopyroxene and amphibole were calculated using solid/liquid partition coefficients.The high Nb/Y and Zr/Y ratio values of a liquid simulated from clinopyroxene,which appears to have very similar characteristics to sanukitoid melts,indicate a low degree of melting of the mantle source.Melt simulated from amphibole is more evolved and more felsic(dacitic).It displays a geochemical“amphibole fractionation”signature,indicating the peritectic transformation of clinopyroxene to amphibole in the lower crust.Rock textures and major element mineral compositions suggest that further amphibole was precipitated directly from the melt in the middle crust.The results show that the Chelyabinsk highMg diorite was probably formed as a cumulate from sanukitoid-like melt during its ascent and cooling below dacitic liquidus inside the amphibole stability field.

关 键 词：high-Mg diorite CLINOPYROXENE amphibole trace elements cumulus mineral SANUKITOID URALS geochemistry 

分 类 号：P588.3[天文地球—岩石学]