Strongly peraluminous fractionated S-type granites in the Baoshan Block, SW China: Implications for two-stage melting of fertile continental materials following the closure of Bangong-Nujiang Tethys

Strongly peraluminous fractionated S-type granites are important indicators of compositional maturity of the continental crust. Here we report the finding of strongly peraluminous fractionated S-type granites from the western Baoshan Block in the southeastern Tibetan–Himalayan orogenic belt. We pres...

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Bibliographic Details
Published in:Lithos 2018-09, Vol.316-317, p.178-198
Main Authors: Zhu, Ren-Zhi, Lai, Shao-Cong, Qin, Jiang-Feng, Zhao, Shao-Wei, Santosh, M.
Format: Article
Language:English
Subjects:
Crustal melting
Fractionated S-type granite
Geochemistry
Tethys ocean closure
Zircon geochronology
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Summary:Strongly peraluminous fractionated S-type granites are important indicators of compositional maturity of the continental crust. Here we report the finding of strongly peraluminous fractionated S-type granites from the western Baoshan Block in the southeastern Tibetan–Himalayan orogenic belt. We present LA ICP-MS zircon U–Pb ages from biotite- and two-mica- granites which reveal two distinct periods of magmatism at 121.8 ± 1.1 Ma and 81.9–79.7 Ma. These Cretaceous granites are strongly peraluminous (A/CNK = 1.18–1.31), high-K calc-alkaline, enriched in Rb, Th, K, and Pb, and depleted in Ba, Sr and Ti. They also show high normative- corundum contents of 2.84–4.42 wt%, moderately high P2O5 content (0.22–0.28 wt%) and high differentiation index (DI) of 93.1–96.8, similar to the features of fractionated S-type granites. The low total Fe2O3T + MgO + TiO2 contents (
ISSN:0024-4937
1872-6143
DOI:10.1016/j.lithos.2018.07.016