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Tytuł:
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Geochemistry and geochronology of OIB-type, Early Jurassic magmatism in the Zhangguangcai range, NE China, as a result of continental back-arc extension.
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Autorzy:
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Feng, Guangying (AUTHOR)
Dilek, Yildirim (AUTHOR)
Niu, Xiaolu (AUTHOR)
Liu, Fei (AUTHOR)
Yang, Jingsui (AUTHOR)
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Temat:
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GEOCHEMISTRY
GEOLOGICAL time scales
MAFIC rocks
MAGMATISM
DIABASE
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Źródło:
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Geological Magazine. Jan2021, Vol. 158 Issue 1, p143-157. 15p.
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Terminy geograficzne:
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CHINA
EAST Asia
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The Zhangguangcai Range in the Xing'an Mongolian Orogenic Belt, NE China, contains Early Jurassic (c. 188 Ma) Dabaizigou (DBZG) porphyritic dolerite. Compared with other island-arc mafic rocks, the DBZG dolerite is characterized by high trace-element contents, relatively weak Nb and Ta enrichments, and no Zr, Hf or Ti depletions, similar to OIB-type rocks. Analysed rocks have (87Sr/86Sr)i ratios of 0.7033–0.7044, relatively uniform positive ɛNd(t) values of 2.3–3.2 and positive ɛHf(t) values of 8.5–17.1. Trace-element and isotopic modelling indicates that the DBZG mafic rocks were generated by partial melting of asthenospheric mantle under garnet- to spinel-facies conditions. The occurrence of OIB-like mafic intrusion suggests significant upwelling of the asthenosphere in response to lithospheric attenuation caused by continental rifting. These processes occurred in an incipient continental back-arc environment in the upper plate of a palaeo-Pacific slab subducting W–NW beneath East Asia. [ABSTRACT FROM AUTHOR]
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