Age and petrogenesis of late Paleozoic granites from the northernmost Alxa region, northwest China, and implications for the tectonic evolution of the region
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- 作者：Wen Zhang ; Victoria Pease ; Qingpeng Meng…
- 关键词：Granite ; Alxa ; Central Asia Orogenic Belt ; Paleozoic ; Tectonics
- 刊名：International Journal of Earth Sciences
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：106
- 期：1
- 页码：79-96
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Geology; Geophysics/Geodesy; Sedimentology; Structural Geology; Mineral Resources; Geochemistry;
- 出版者：Springer Berlin Heidelberg
- ISSN：1437-3262
- 卷排序：106
文摘
The Wudenghan, Huhetaoergai and Zhuxiaobuguhe plutons, northern Alxa region, in the southern Central Asia Orogenic Belt are dated by U–Pb zircon to 383 ± 3, 356 ± 3 and 286 ± 2 Ma, respectively. The late Devonian Wudenghan monzogranite, a highly fractionated I-type granite with εNd(t) (−0.2 to −0.1) and very low (87Sr/86Sr)t (0.704719–0.706113), is from mantle-derived magmas and shows volcanic arc characteristics. The early Carboniferous Huhetaoergai granodiorite with medium-K calc-alkaline peraluminous characteristics represents a volcanic arc granite generated from partial melting of lower continental crust combined with mantle-derived input. The early Permian Zhuxiaobuguhe pluton, an unfractionated calc-alkaline granodiorite with moderately low εNd(t) (−2.0 to −1.1) and low (87Sr/86Sr)t (0.708370–0.708462), was likely derived from partial melting of the mafic lower crust of a paleo-volcanic arc and represents a post-collisional granite. Our revised tectonic evolution of the region includes (1) northward subduction of the oceanic crust represented by the Engger Us Ophiolitic Belt and formation of the late Devonian Wudenghan monzogranite, (2) northward subduction of the ocean between the Huhetaoergai and Zhusileng tectonic zones and the formation of the Huhetaoergai volcanic arc granite during the early Carboniferous and (3) the emplacement of the Zhuxiaobuguhe pluton in the early Permian during post-collisional extension.