Cambrian magmatic flare-up, central Tibet: Magma mixing in proto-Tethyan arc along north Gondwanan margin

Pei Yuan Hu, Qing Guo Zhai, Peter A. Cawood, Guo Chun Zhao, Jun Wang, Yue Tang, Zhi Cai Zhu, Wei Wang, Hao Wu

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7 Citations (Scopus)


Accompanying Gondwana assembly, widespread but diachronous Ediacaran–early Paleozoic magmatism of uncertain origin occurred along the supercontinent’s proto-Tethyan margin. We report new geochemical, isotopic, and geochronological data for Cambrian magmatic rocks (ca. 500 Ma) from the Gondwana-derived North Lhasa terrane, located in the present-day central Tibetan Plateau. The magmatic rocks are composed of basalts, gabbros, quartz monzonites, granitoids (with mafic microgranular enclaves), and rhyolites. Nd-Hf isotopic and whole-rock geochemical data indicate that these rocks were probably generated by mixing of mantlederived mafic and crust-derived felsic melts. The mantle end-member volumes of mafic, intermediate, and felsic rocks are ˜75%–100%, 50%–60%, and 0–30%, respectively. Integration of our new data with previous studies suggests that the North Lhasa terrane experienced long-term magmatism through the Ediacaran to Ordovician (ca. 572–483 Ma), with a magmatic flare-up at ca. 500 Ma. This magmatism, in combination with other Ediacaran–early Paleozoic magmatism along the proto-Tethyan margin, was related to an Andean-type arc, with the magmatic flare-up event related to detachment of the oceanic slab following collisional accretion of Asian microcontinental fragments to northern Gondwana. Diachroneity of the proto-Tethyan arc system along the northern Gondwanan margin (ca. 581–531 Ma along the Arabian margin and ca. 512–429 Ma along the Indian-Australian margin) may have been linked to orogenesis within Gondwana. The North Lhasa terrane was probably involved in both Arabian and Indian-Australian proto-Tethyan Andeantype orogens, based on its paleogeographic location at the northern end of the East African orogen.

Original languageEnglish
Pages (from-to)2171-2188
Number of pages18
JournalGeological Society of America Bulletin
Issue number9-10
Publication statusPublished - 1 Sep 2021

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