Geochronology and geochemistry of Early Permian mafic-ultramafic complexes in the Beishan area, Xinjiang, NW China: Implications for late Paleozoic tectonic evolution of the southern Altaids

被引：163

作者：

Ao, S. J. ^{[1
,2
]}

Xiao, W. J. ^{[1
]}

Han, C. M. ^{[1
]}

Mao, Q. G. ^{[1
]}

Zhang, J. E. ^{[1
]}

机构：

[1] Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China

[2] Chinese Acad Sci, Grad Univ, Beijing 100864, Peoples R China

来源：

GONDWANA RESEARCH | 2010年 / 18卷 / 2-3期

基金：

中国国家自然科学基金;

关键词：

Hongshishan complex; U-Pb zircon age; Hf isotopes; Beishan; Geochemistry; Tectonics; Altaids; NI SULFIDE DEPOSITS; ASIAN OROGENIC BELT; ZIRCON U-PB; NORTHERN XINJIANG; TIEN-SHAN; ACCRETIONARY OROGENESIS; COLLISIONAL TECTONICS; GEODYNAMIC EVOLUTION; CONTINENTAL GROWTH; CRUSTAL EVOLUTION;

D O I：

10.1016/j.gr.2010.01.004

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

The Hongshishan and Pobei mafic-ultramafic complexes outcrop in the Beishan area in the southernmost Altaids. They consist of olivine gabbros, dunites, and pyroxenites. Zircons from olivine gabbros from the Hongshishan complex yield a U-Pb age for emplacement of 281.8 +/- 2.6 Ma. The olivine gabbros have low SiO2 (47.08-48.66%), TiO2 (0.14-0.29%), MnO (0.07-0.09%), and K2O (0.06-0.09%), but high Mg-# values (81 <Mg-# <81.4) together with high MgO (8.95-12.54%) and TFe2O3 (4.93-6.29%). The Hongshishan and Pobei mafic-ultramafic complexes are characterized by negative anomalies in high field strength elements (Zr, Hf, Nb, Ta), which we interpret as arc-related signatures. They also have spikes in large ion lithophile fluid mobile elements (Ba, U, Pb, Sr) and high mobile/immobile element ratios (i.e. primitive mantle-normalized Sr/Nd, Ba/La >> 1), which are attributed to an aqueous fluid component in the source. Zircon Hf isotopes indicate that the source magma was derived either from a depleted mantle with some crustal contamination or from an enriched mantle. These data are interpreted to indicate that the Hongshishan and Pobei mafic-ultramafic complexes were emplaced in the Early Permian subduction-related environment, which suggests that the Paleo-Asian Ocean in the southernmost part of Altaids did not close until after Early Permian. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

引用

页码：466 / 478

页数：13

共 104 条

[51]

Kusky TM, 2007, GEOL SOC AM SPEC PAP, V431, P207, DOI 10.1130/2007.2431(09)

[52] Emplacement of the Resurrection Peninsula ophiolite in the southern Alaska forearc during a ridge-trench encounter [J].