Zircon U-Pb ages and Hf isotopic compositions of alkaline silicic magmatic rocks in the Phan Si Pan-Tu Le region, northern Vietnam: Identification of a displaced western extension of the Emeishan Large Igneous Province

Tadashi Usuki, Ching Ying Lan, Trong Hoa Tran, Thi Dung Pham, Kuo Lung Wang, Gregory J. Shellnutt, Sun Lin Chung

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31 Citations (Scopus)

Abstract

In-situ zircon U-Pb and Hf isotope analyses were carried out for alkaline silicic magmatic rocks from the Phan Si Pan-Tu Le region in northern Vietnam to constrain their possible sources and to determine their petrogenetic relationship with the Emeishan Large Igneous Province (ELIP), SW China. Nine granites and nine rhyolites yield zircon 206Pb/238U ages from 262Ma to 249Ma, coinciding with the timing of silicic magmatism in the Panxi area of the ELIP. The zircon εHf(t) values (+14 to +3) of these granites and rhyolites suggest a moderately depleted mantle source and overlap with those of peralkaline and metaluminous granites in the Panxi area [i.e. εHf(t)=+14 to +4]. The zircon Hf isotope ratios show that the zircons probably record the original source characteristics whereas whole-rock Nd isotope data indicate an evidence for crustal contamination that may have occurred at lower temperatures during magma emplacement. The synchroneity, coupled with petrological and geochemical similarities, indicate that silicic rocks from the Phan Si Pan-Tu Le region are cogenetic with the Panxi silicic plutonic rocks and that they are likely derived by similar petrogenetic processes (i.e. fractionation of mafic magmas or partial melting of mafic rocks). Therefore, we propose that the Phan Si Pan-Tu Le region represents a displaced portion of the ELIP inner zone.

Original languageEnglish
Pages (from-to)1-89
Number of pages89
JournalJournal of Asian Earth Sciences
Volume97
Issue numberPA
DOIs
Publication statusPublished - 2015 Jan 1

Keywords

  • Alkaline silicic magmatism
  • Emeishan Large Igneous Province
  • Hf isotope
  • Northern Vietnam
  • Zircon U-Pb age

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes

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