Zircon U-Pb age of the Triassic granitoids at Nui Phao, northern Viet Nam.

舜三, 石原; 裕二, 折橋

doi:10.9795/bullgsj.65.17

Cited by 9 publications

(1 citation statement)

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“…Three metamorphic rocks were dated with the 40 Ar/ 39 Ar method in this study. Two samples yielded Ishihara and Orihashi (2014), Hieu et al (2015) and Halpin et al (2016). Similar magmatic activity is reported from SE China by Shao et al (1995), Yu et al (2010), Deng et al (2012, and Mao et al (2013), and from Hainan Island by Li et al (2006) and Jiang et al (2015).…”

Section: Triassic Metamorphismsupporting

confidence: 83%

A Triassic to Cretaceous Sundaland–Pacific subduction margin in West Sarawak, Borneo

et al. 2017

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Metamorphic rocks in West Sarawak are poorly exposed and studied. They were previously assumed to be pre-Carboniferous basement but had never been dated. New 40 Ar/ 39 Ar ages from white mica in quartz-mica schists reveal metamorphism between c. 216 to 220 Ma. The metamorphic rocks are associated with Triassic acid and basic igneous rocks, which indicate widespread magmatism. New U-Pb dating of zircons from the Jagoi Granodiorite indicate Triassic magmatism at c. 208 Ma and c. 240 Ma. U-Pb dating of zircons from volcaniclastic sediments of the Sadong and Kuching Formations confirm contemporaneous volcanism. The magmatic activity is interpreted to represent a Triassic subduction margin in westernmost West Sarawak with sediments deposited in a forearc basin derived from the magmatic arc at the Sundaland-Pacific margin. West Sarawak and NW Kalimantan are underlain by continental crust that was already part of Sundaland or accreted to Sundaland in the Triassic. One metabasite sample, also previously assumed to be pre-Carboniferous basement, yielded Early Cretaceous 40 Ar/ 39 Ar ages. They are interpreted to indicate resumption of subduction which led to deposition of volcaniclastic sediments and widespread magmatism. U-Pb ages from detrital zircons in the Cretaceous Pedawan Formation are similar to those from the Schwaner granites of NW Kalimantan, and the Pedawan Formation is interpreted as part of a Cretaceous forearc basin containing material eroded from a magmatic arc that extended from Vietnam to west Borneo. The youngest U-Pb ages from zircons in a tuff layer from the uppermost part of the Pedawan Formation indicate volcanic activity continued until c. 86 to 88 Ma when subduction terminated.

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