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Zircon SHRIMP Dating for the Weiya Pluton, Eastern Tianshan: Its Geological Implications
Author(s) -
Zunzhong ZHANG,
Lianxing GU,
Changzhi WU,
Weiqiang LI,
Aihua XI,
Shuo WANG
Publication year - 2005
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/j.1755-6724.2005.tb00914.x
Subject(s) - geology , pluton , zircon , underplating , geochemistry , diorite , subduction , gabbro , continental crust , crust , accretion (finance) , tectonics , continental margin , oceanic crust , petrology , igneous rock , paleontology , physics , astrophysics
The timing of the emplacement of the Weiya pluton remains controversial due to the absence of systematic and precise dating. This paper reports zircon SHRIMP U‐Pb dating of different lithologic phases in the Weiya pluton, and discusses the genesis and tectonic environment. The ages of gabbro, quartz syenite, diorite porphyrite and fine‐grained granite are 236±6 Ma, 246±6 Ma, 233±8 Ma and 237±8 Ma, respectively. All these phases were formed in early‐middle Indosinian (Triassic) in a post‐orogenic environment. In addition to underplating, intraplating of mantle‐derived magmas is also a substantial mechanism for magma generation and vertical accretion of the continental crust. Granitoid rocks are important products of vertical continental accretion as underplating evolves gradually to intraplating. The existence of post‐orogenic Indosinian granites shows that the middle Tianshan orogenic belt underwent an important tectonic conversion from the Paleo‐Asian ocean subduction‐collision system to the Paleo‐Tethys ocean regime.