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SHRIMP U‐Pb Zircon Age of the Ka'erjiao Intrusion in the Sawur Region in West Junggar, Xinjiang
Author(s) -
Taofa ZHOU,
Lugui TAN,
Yu FAN,
Feng YUAN,
Wenping YANG,
Lixin HE,
Shucang YUE
Publication year - 2007
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.1755-6724.2007.tb00955.x
Subject(s) - geology , permian , zircon , geochemistry , carboniferous , crust , paleozoic , petrology , paleontology , structural basin
Acid intrusions are widespread in the Sawur region, Xinjiang. The Ka'erjiao intrusion is mainly composed of albite granite porphyry, K‐feldspar granite porphyry, ivernite and granite porphyry. Being a transitional product between magma intrusion and eruption in the Sawur region, the Ka'erjiao intrusion was formed at the telophase of the late Carboniferous to the begining of early Permian as determined by the SHRIMP U‐Pb zircon dating, with an age of 302.6±7.6 Ma (1 γ). The intrusion consists of alkali‐enriched rock, whose REE distribution patterns are of the LREE enrichment type, the δEu value is low and Nd, Sr, Pb isotopes reflect its mantle source characteristics. The δ 18 O value of intrusion is low as a result of isotope exchange with meteoric water. The geochemical characteristics show that it was formed in a post‐collisional tectonic setting. Taking combined considerations of current studies of A‐type granites and Permian volcanic rocks, we think that in the telophase of the late Carboniferous to the beginning of the early Permian, the Sawur region was within the extension or compressional to extensional period of a post‐collisional stage. The Ka'erjiao intrusion from mantle sources can confirm the vertical continental crust growth in the late Paleozoic. The Sawur region in west Junggar is consistent with east Junggar in post‐collisional tectonic evolution process.