Multi-isotope and geochemical approach to the magma source and tectonic setting of Proterozoic anorthosite massifs and Anorthosite-Mangerite-Charnockite-Granite(AMCG)suites

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外文摘要：The occurrence of massif-type anorthosite intrusions is a widespread Proterozoic phenomenon.They are usually associated with gabbroic,charnockitic,and granitic rocks,comprising the so-called anorthosite-mangerite-charnockite-granite(AMCG)suite.Although these rocks have been extensively studied world-wide,several aspects concerning their formation remain unsettled.Among them,the magma source and the tectonic setting are the most important.To evaluate these issues,we first compiled geochemical and isotopic data of Proterozoic anorthosite massifs and AMCG suites worldwide and stored it in a database named datAMCG.This plethora of data allows us to make some important interpretations.We argue that the wide-ranging multi-isotopic composition of this group of rocks reflects varying proportions of juve-nile mantle-derived melts and crustal components.We interpret that the precursor magmas of most massive anorthosite bodies and associated mafic rocks have a mantle-dominated origin.However,we highlight that a crustal component is indispensable to generate these lithologies.Adding variable amounts of this material during succeeding multi-stage assimilation-fractional crystallization(AFC)pro-cesses gives these intrusions their typical mantle-crustal hybrid isotopic traits.In contrast,a crustal-dominant origin with a complementary mantle component is interpreted for most MCG rocks.In sum-mary,the isotopic information in datAMCG indicates that both sources are necessary to generate AMCG rocks.Therefore,we suggest that hybridized magmas with different mantle-crust proportions originate these rocks.This interpretation might offer a more nuanced and accurate depiction of this phe-nomenon in future work instead of choosing a single-sourced model as in the past decades.Finally,tectonomagmatic diagrams suggest that the rocks under study were likely generated in a tectonic envi-ronment that transitioned between collision and post-collisional extension,sometimes involving subduction-modified mantle sources.This interpretation is supported by geological and geochronological information from most complexes,thus challenging the Andean-type margins as an ideal tectonic setting.

外文关键词：

Massif-type anorthositeAnorthosite-granite suiteMagmatic sourcesHybridized magmasTectonic settingPost-orogenic extension

作者：

L.A.Elizondo-Pacheco、L.A.Solari、R.González-Guzmán、H.L.He、E.Becerra-Torres、J.A.Ramírez-Fernández、R.Maldonado

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作者单位：

Posgrado en Ciencias de la Tierra,Instituto de Geociencias,Universidad Nacional Autónoma de México,Santiago de Querétaro 76230,Mexico

Instituto de Geociencias,Universidad Nacional Autónoma de México,Santiago de Querétaro 76230,Mexico

Departamento de Geología,División de Ciencias de la Tierra,CICESE,Ensenada 22860,Mexico

School of Earth Sciences,Yunnan University,Kunming 650500,PR China

Yunnan International Joint Laboratory of Critical Mineral Resource,Kunming 650500,PR China

Escuela Nacional de Estudios Superiores Unidad Juriquilla,Universidad Nacional Autónoma de México,Santiago de Querétaro 76230,México

Facultad de Ciencias de la Tierra,Universidad Autónoma de Nuevo León,Linares 67700,Mexico

Instituto de Geología,Universidad Nacional Autónoma de México,Ciudad de México 04510,Mexico

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出版年：

2024

DOI：

10.1016/j.gsf.2024.101880

地学前缘(英文版)

中国地质大学（北京）北京大学

地学前缘(英文版)

CSTPCD

影响因子：0.576

ISSN：1674-9871

年,卷(期)：2024.15(6)