High Mg# of the continental crust explained by calc-alkaline differentiation  

作　　者：Ming Tang Xuanyu Liu Kang Chen 

机构地区：[1]Key Laboratory of Orogenic Belt and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing 100871,China [2]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China

出　　处：《National Science Review》2023年第3期86-93,共8页国家科学评论（英文版）

基　　金：financially supported by National Natural Science Foundation of China (42125302, 42073026, 41888101 and42073024);the support from the Xplorer Prize。

摘　　要：We used compiled geochemical data to investigate the mechanisms that control Mg#(molar ratio of Mg/(Mg+Fe_T)) in andesitic arc lavas.We find that andesites from mature continental arcs with crustal thickness of>45 km have systematically higher Mg# than those from oceanic arcs with crustal thickness of<30 km.The elevated Mg# in continental arc lavas results from strong Fe depletion during high-pressure differentiation favored in thick crusts.This proposal is reinforced by our compiled melting/crystallization experiment data.We show that the Mg# characteristics of continental arc lavas match that of the continental crust.These findings suggest that the formation of many high-Mg#andesites and the continental crust may not require slab-melt/peridotite interactions.Instead,the high Mg# of the continental crust can be explained by intracrustal calc-alkaline differentiation processes in magmatic orogens.

关 键 词：high-Mg#andesite calc-alkaline differentiation Fe depletion slab melting continental crust 

分 类 号：P542[天文地球—构造地质学] P59[天文地球—地质学]