Retreat and advance subduction processes in the Yamansu-Central Tianshan arc (NW China): insights into the long-lasting accretionary orogenesis and final closure of the Paleo-Asian Ocean in the southern Altaids
Kai Wang, Wenjiao Xiao, Q. Mao, He Yang, Wenhua Ji, Nijiati Abuduxun, Miao Sang, Zhihua Wang, Yanguang Li
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引用次数: 0
Abstract
Subduction processes of the Eastern Tianshan are crucial to understand the mechanism of the orogenic evolution of the southern Altaids. To identify whether the tectonic setting of the Late Carboniferous or later was continuous subduction, we present a systematic study on Late Carboniferous volcanic and intrusive rocks exposed continuously in time and space in the Weiya area, which were mainly derived from crustal materials with involvement of mantle-derived materials in a subduction-related setting. Our newly discovered 319 Ma A-type granites imply an extensional environment; 306 Ma diorites were derived from thickened crust. Combined with published data, we propose that rollback of the southward subducted North Tianshan oceanic plate induced subduction retreating and tectonic extension in the Yamansu-Central Tianshan arc from 324 Ma to 318 Ma. It was followed by advancing subduction from 315 Ma to 301 Ma, during which the crust of the arc was thickened, and much more crustal materials were involved in subduction-related magmatism. In the Early Permian, the arc was in an extensional environment followed by a change in the movement direction of the subducting plate, rather than in a post-orogenic setting. The final closure of the North Tianshan Ocean was likely completed in the Middle Triassic.
Thematic collection:
This article is part of the Processes of Pangea construction collection available at:
https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction
Supplementary material:
https://doi.org/10.6084/m9.figshare.c.7038686
东天山的俯冲过程对于了解阿尔泰南部造山演化机制至关重要。为了确定晚石炭世或更晚的构造环境是否为连续俯冲,我们对威亚地区在时间和空间上连续出露的晚石炭世火山岩和侵入岩进行了系统研究,这些岩石主要来源于地壳物质,地幔物质参与了与俯冲相关的环境。我们新发现的319 Ma A型花岗岩暗示了一种伸展环境;306 Ma闪长岩则来源于增厚的地壳。结合已发表的数据,我们认为,从 324 Ma 到 318 Ma,向南俯冲的北天山大洋板块的后退诱发了山海关-中天山弧的俯冲后退和构造延伸。随后,在315Ma至301Ma期间,天山弧地壳增厚,更多的地壳物质参与了与俯冲有关的岩浆活动。在早二叠世,弧处于俯冲板块运动方向改变后的伸展环境中,而非后成因环境中。北天山洋的最终封闭可能在中三叠世完成。 专题文集:本文是 "泛大陆构造过程"(Processes of Pangea construction)专题集的一部分,可从以下网址获取:https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction 补充材料:https://doi.org/10.6084/m9.figshare.c.7038686