Petrogenesis of silicic rocks from the Phan Si Pan–Tu Le region of the Emeishan large igneous province, northwestern Vietnam

Thuy Thanh Pham*, J. Gregory Shellnutt, Tuan Anh Tran, Steven W. Denyszyn, Yoshiyuki Iizuka

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

3 Citations (Scopus)

Abstract

The Permian silicic rocks in the Phan Si Pan (PSP) Uplift area and Tu Le (TL) basin of NW Vietnam (collectively the PSP–TL region) are associated with the Emeishan large igneous province (ELIP). The Permian Muong Hum, Phu Sa Phin and Nam Xe–Tam Duong granites and Tu Le rhyolites are alkali ferroan A1-type granitic rocks, which probably formed by fractional crystallization of high-Ti basaltic magma that was contaminated by melts derived from the Neoproterozoic host rocks. Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) geochronology yielded weighted-mean206Pb/238U ages of 246 + 3 to 259 + 3 Ma for granites, and 249 + 3 and 254 + 2 Ma for rhyolites. This is contrasted with previously published high precision U–Pb ages, obtained using chemical abrasion–isotope dilution–thermal ionization mass spectrometry method applied on the same zircon grains, which suggests that the calculated LA–ICP–MS U– Pb ages are variably inaccurate by up to 10 Ma, although at the single-grain level dates generally agree within uncertainty. The similarity of rock texture, whole-rock geochemistry, emplacement ages and fractionation phases between the PSP–TL region and silicic rocks in the Inner Zone ELIP (i.e. Panzhihua, Binchuan) suggests they were spatially proximal before being sinistrally displaced along the Ailao Shan–Red River shear zone.

Original languageEnglish
Title of host publicationGeological Society Special Publication
PublisherGeological Society of London
Pages227-254
Number of pages28
Edition1
DOIs
Publication statusPublished - 2022

Publication series

NameGeological Society Special Publication
Number1
Volume518
ISSN (Print)0305-8719

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Geology

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