气候变化领域集成服务门户(CCPortal): Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains; northern West Junggar; NW China: implications for accretionary orogeny

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DOI	10.1007/s00531-020-01822-y
	Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains; northern West Junggar; NW China: implications for accretionary orogeny
	Weng K.; Dong Y.; Xu X.; Ma Z.; Chen B.; Cao K.
发表日期	2020
ISSN	14373254
起始页码	605
结束页码	630
卷号	109 期号:2
英文摘要	The accretionary orogeny of the Central Asian Orogenic Belt (CAOB) has been a popular topic over the past decades due to its complex tectonic process. The Carboniferous magmatism in the Sawur Mountains of the northern West Junggar plays an important role in understanding the accretionary process of West Junggar. Detailed geological mapping has revealed that the Carboniferous Heishantou Formation in the Sawur Mountains consists mainly of pillow lavas, basaltic andesites, dacites, tuffs and sedimentary rocks, which were intruded by the Lasite intrusion. The pillow lavas display low SiO2 and TiO2 as well as high MgO and FeOt contents and enrichment in light rare earth elements (LREEs) and Nb–Ta, suggesting derivation from an enriched lithospheric mantle in an oceanic island setting. With the oceanic crust subduction, they were scraped off and accreted in a fore-arc setting. Basaltic andesites exhibit high SiO2 and Al2O3 contents, low Mg#, Zr, and Nb contents as well as Nb/La ratios, and a clear depletion of Nb–Ta, indicating derivation from a mantle wedge affected by the inputs of slab-derived fluids in an island arc setting. Dacites possess calc-alkaline and adakitic geochemical features with high Sr and Ba contents, high Th/Yb ratios, enrichment in LREEs, low Nb/La ratios, a depletion of Nb–Ta and positive εHf(t) values (10.3–15.0). Accordingly, they are interpreted as being derived from the melting of subducted oceanic crust mixed with minor sediments in an island arc setting. Magmatic zircons from dacite yield a weighted 206Pb/238U mean age of 326.8 ± 1.6 Ma, constraining the crystallization age of the dacite as well as the timing of the oceanic crust subduction. The Lasite intrusion that intruded the Heishantou Formation is K-feldspar granite, exhibiting pronounced I-type affinity and a high potassic calc-alkaline series. This granite shows low Na2O and Mg# (36.9–40.3) values; low Zr and Y contents as well as 10,000 × Ga/Al ratios; high LREE, K and Pb contents; and a depletion of Nb and Ta. Altogether, the low (87Sr/86Sr)i (0.7037–0.7043) and positive εNd(t) (6.22–6.36) and εHf(t) (10.1–15.5) values suggest that the granites were derived from the partial melting of a juvenile lower crust affected by mantle materials in a subduction setting. The zircon weighted 206Pb/238U mean age of 316.6 ± 2.8 Ma represents the intrusive age of the granite and related subduction during the late Carboniferous. All of the above geochemistry and geochronology of the magmatic rocks constrain the subduction–accretion tectonics in the Sawur Mountains of the northern West Junggar during ~ 327–317 Ma and confirm the subduction of the Paleo-Asian Ocean (PAO) lasted until the late Carboniferous in this region. © 2020, Geologische Vereinigung e.V. (GV).
英文关键词	Carboniferous magmatic rocks; Central Asian Orogenic Belt; Geochemistry and geochronology; Subduction; West Junggar
语种	英语
scopus关键词	accretion; Carboniferous; geochronology; geological mapping; igneous geochemistry; magma; orogenic belt; orogeny; subduction; China; Sawur Mountains; West Junggar; Xinjiang Uygur
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147706
作者单位	State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Northern Taibai Road 229, Xi’an, 710069, China; Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits MNR, Xi’an Center of Geological Survey, Eastern Youyi Road, Xi’an, 710054, China; China Geological Survey, Fuwai Road, Beijing, 100037, China
推荐引用方式 GB/T 7714	Weng K.,Dong Y.,Xu X.,et al. Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains; northern West Junggar; NW China: implications for accretionary orogeny[J],2020,109(2).
APA	Weng K.,Dong Y.,Xu X.,Ma Z.,Chen B.,&Cao K..(2020).Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains; northern West Junggar; NW China: implications for accretionary orogeny.International Journal of Earth Sciences,109(2).
MLA	Weng K.,et al."Geochemistry and geochronology of Carboniferous magmatic rocks in the Sawur Mountains; northern West Junggar; NW China: implications for accretionary orogeny".International Journal of Earth Sciences 109.2(2020).