TY - CHAP
T1 - Petrogenesis of silicic rocks from the Phan Si Pan–Tu Le region of the Emeishan large igneous province, northwestern Vietnam
AU - Pham, Thuy Thanh
AU - Shellnutt, J. Gregory
AU - Tran, Tuan Anh
AU - Denyszyn, Steven W.
AU - Iizuka, Yoshiyuki
PY - 2022
Y1 - 2022
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85113620247&partnerID=8YFLogxK
UR - https://sp.lyellcollection.org/content/specpubgsl/518/1/local/front-matter.pdf
UR - https://sp.lyellcollection.org/content/518/1/227
U2 - 10.1144/SP518-2020-253
DO - 10.1144/SP518-2020-253
M3 - Other chapter contribution
AN - SCOPUS:85113620247
VL - 518
T3 - Geological Society Special Publication
SP - 227
EP - 254
BT - Large Igneous Provinces and their Plumbing Systems
PB - Geological Society of London
ER -