TY - JOUR
T1 - Zircon U-Pb ages and Hf isotopic compositions of alkaline silicic magmatic rocks in the Phan Si Pan-Tu Le region, northern Vietnam
T2 - identification of a displaced western extension of the Emeishan Large Igneous Province
AU - Usuki, Tadashi
AU - Lan, Ching Ying
AU - Tran, Trong Hoa
AU - Pham, Thi Dung
AU - Wang, Kuo Lung
AU - Shellnutt, Gregory J.
AU - Chung, Sun Lin
PY - 2015/1/1
Y1 - 2015/1/1
N2 - 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.
AB - 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.
KW - Alkaline silicic magmatism
KW - Emeishan Large Igneous Province
KW - Hf isotope
KW - Northern Vietnam
KW - Zircon U-Pb age
UR - http://www.scopus.com/inward/record.url?scp=84921856720&partnerID=8YFLogxK
U2 - 10.1016/j.jseaes.2014.10.016
DO - 10.1016/j.jseaes.2014.10.016
M3 - Article
AN - SCOPUS:84921856720
VL - 97
SP - 102
EP - 124
JO - Journal of Asian Earth Sciences
JF - Journal of Asian Earth Sciences
SN - 1367-9120
IS - PA
ER -