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Early Cretaceous mantle upwelling and melting of juvenile lower crust in the Middle-Lower Yangtze River Metallogenic Belt: Example from Tongshankou Cu-(Mo-W) ore deposit

journal contribution
posted on 2023-05-20, 13:26 authored by Chu, G, Chen, H, Trevor FalloonTrevor Falloon, Han, J, Zhang, S, Cheng, J, Zhang, X
The linkage between intracontinental extension and the Early Cretaceous Cu-Mo-W polymetallic metallogenesis in the Middle-Lower Yangtze River Belt (MLYRB) has long been a subject of controversy due to the lack of convincing petrogenetic evidence to identify the nature of magmatic sources and their geological histories during extensional mantle upwelling. Here we present new zircon U-Pb ages, isotopic and geochemical data for granodiorites, quartz diorites and mafic microgranular enclaves (MMEs) in the Tongshankou area. Comparing the MMEs with their host porphyries, the different ratios of incompatible elements and the similar formation ages, coupled with quenched margins and the xenocrysts in the MMEs, indicate that the MMEs was most likely formed by mixing between mafic magma and their host felsic magma. The MMEs share similar geochemical and isotopic characteristics with the Cretaceous mafic rocks from MLYRB, indicating that MMEs were mostly derived from an enriched lithospheric mantle source without adakitic characteristics. Mixing of a crustal melt derived by melting of an amphibolite bearing juvenile lower crust with a mantle melt derived from melting of enriched lithospheric mantle can account for the generation of the Tongshankou prophyries. The melting of juvenile mafic lower crust and enriched lithospheric mantle is suggested to be caused by upwelling of asthenospheric mantle and the reactivity of trans-lithospheric faults in the intracontinental extensional environment. Our results therefore highlight that juvenile mafic lower crust beneath the Yangtze plate is one of the likely source for ore-forming magmatic rocks in the Early Cretaceous.

History

Publication title

Gondwana Research

Volume

83

Pagination

183-200

ISSN

1342-937X

Department/School

School of Natural Sciences

Publisher

Int Assoc Gondwana Research

Place of publication

Kochi Univ, Faculty Science Akebono-Cho 2-5-1, Kochi, Japan, 780-8520

Rights statement

Copyright 2020 International Association for Gondwana Research

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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