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Geochronology and Geochemistry of Zengga Mesozoic Grantoids from East Gangdese Batholith, Implications for the Remelting Mechanism of Granite Formation
Author(s) -
ZHANG Lan,
YANG Jingsui,
ZHANG Jian
Publication year - 2015
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12308_68
Subject(s) - batholith , geochronology , geology , geochemistry , mesozoic , mechanism (biology) , earth science , paleontology , tectonics , philosophy , epistemology , structural basin
This paper reports geochemistry (major and trace elements), zircon U-Pb and Lu-Hf isotope studies of leucogranite, granodiorite and clinopyroxene-bearing diorite from the Zengga intrusive body, eastern Gangdese batholith, Tibet. Massive granodiorite is mainly composed of fineand medium-grained plagioclase (65 modal %), amphibole (17 modal %), quartz (13 modal %) and a lesser amount of clinopyroxene (3 modal % ) and magnetite (2 modal %). Clinopyroxene-bearing diorite is mainly composed of medium-coarse grained plagioclase (40 modal %), amphibole (38 modal %), clinopyroxene (12 modal %) and lesser sericite (2 modal %) and magnetite (2 modal % ). Biotite granite is mainly composed of medium-coarse grained plagioclase, amphibole, potassium feldspar, quartz and biotite. Leucogranite is mainly composed of fine-grained quartz, plagioclase and sericite. Leucogranite itself is crosscut by veinlets composed of medium-grained quartz, epodite, zoisite and calcite. Dong and Zhang (2013) discovered the early Jurassic (J1) magmatism in the Zengga region within the highly deformed and metamorphosed Gangdese rock group, which was thought to be the basement of the Lhasa Terrane. A large proportion of the Cretaceous and Paleocene granitoids also occur in the Zengga and nearby areas, which make our research area an ideal place for the study of Mesozoic and Cenozoic magmatic evolution of this part of the Gangdese batholith. The carefully selected and analyzed lithologies in this study are spatially related: granodiorite and clinopyroxenebearing diorite mainly occur in the southern part of our research area as early intrusive bodies. These are intruded by biotite granite covering most of the northern part of the region. Leucogranites occur as dykes within the biotite granite.