Destruction of the lower crust beneath the North China Craton recorded by granulite and pyroxenite xenoliths

The lower crust beneath the North China Craton (NCC) was transformed during the craton destruction in the Mesozoic, however, the transformation processes are yet to be fully understood. Compositional and geochronological variations of granulite and pyroxenite xenoliths provided insights into the nat...

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Bibliographic Details
Published in:Science China. Earth sciences 2023-02, Vol.66 (2), p.190-204
Main Authors: Zou, Dongya, Zhang, Hongfu
Format: Article
Language:English
Subjects:
Cenozoic
Composition
Cratons
Depletion
Destruction
Earth and Environmental Science
Earth mantle
Earth Sciences
Geochemistry
Geochronology
Geochronometry
Hafnium
Igneous rocks
Isotope composition
Isotopes
Lava
Magma
Melting
Mesozoic
Minerals
Phanerozoic
Precambrian
Rare earth elements
Review
Strontium
Trace elements
Transition zone
Zircon
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Summary:The lower crust beneath the North China Craton (NCC) was transformed during the craton destruction in the Mesozoic, however, the transformation processes are yet to be fully understood. Compositional and geochronological variations of granulite and pyroxenite xenoliths provided insights into the nature of the lower crust before and after the craton destruction. In this study, we summarized the latest results of geochemistry and zircon geochronology coupled with Hf-O isotopes from granulite and pyroxenite xenoliths hosted by Phanerozoic igneous rocks in NCC. Comparing previous studies on the granulite terranes and adakitic rocks of NCC, we aim to discuss the destruction processes of lower crust beneath the NCC. The granulite and pyroxenite xenoliths of NCC were divided into two and three groups, respectively, based on the differences of geochemical features. Group I granulite xenoliths from the NCC have silicic-basic compositions, with metamorphic ferrosilite. The Group I granulite xenoliths show relatively lower Mg# values of pyroxenes and whole-rock than that of the Group II granulite xenoliths, and enrichments of light rare earth elements and Sr-Nd isotopic compositions. Their zircons display Archean-Phanerozoic ages with three peaks of Neoarchean, Paleoproterozoic, and Mesozoic. Generally, Group I granulite xenoliths show close affinities to the granulite terranes of the NCC in terms of the major and trace elements and Sr-Nd isotopic compositions, with a consistent Archean-Proterozoic evolutionary history. However, Group I granulite xenoliths have abundant Phanerozoic zircons with variable Hf isotopic compositions from depleted to enriched, which could be formed by modifications of magma underplating. Therefore, Group I granulite xenoliths represent the modified ancient lower crust beneath the NCC. The Group II granulite and Group III pyroxenite xenoliths from the NCC have similar geochemical features and are basic in compositions, with metamorphic to magmatic orthopyroxenes. The Group II granulite and Group III pyroxenite xenoliths usually show higher MgO and lower incompatible elements compositions in minerals and bulk rocks than that in the granulite terranes and Group I granulite xenoliths, but their Sr-Nd isotopic compositions fall into the fields of granulite terranes and group I granulite xenoliths. Zircons from the Group II granulite and Group III pyroxenite xenoliths are predominantly Phanerozoic with subordinate Archean-Proterozoic ages, and t
ISSN:1674-7313
1869-1897
DOI:10.1007/s11430-022-1007-5