Geochemistry, geochronology and Sr–Nd–Hf isotopes of Paleozoic granitoids in the Chinese Altai, NW China: Constraints on the conversion from subduction–accretion to syn/post-collision

IF 2.6 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of the Geological Society Pub Date : 2023-02-13 DOI:10.1144/jgs2022-150

Kai Weng, Yunpeng Dong, Liuqing Jiang, Zhongping Ma, Shuangshuang Wang, Bo Chen

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引用次数: 1

Abstract

The Chinese Altai features abundant granitoids, which can be used to reconstruct the tectonic evolution of the orogen. Here, petrological, geochronological, geochemical and isotopic analyses have been conducted on several representative granitoids from the Altai region. U‒Pb dating revealed ages of 444±3 Ma for gneissic granites, 406±8 Ma for syenogranites, 280±6 Ma for diorites, 278±3 Ma for two-mica monzonitic granites, and 269±3 Ma for muscovite granites. Ordovician gneissic granites have I-type arc-related element characteristics and are derived from volcanic magmas extracted from the mantle wedge metasomatized by subducted sediment in a continental arc. Devonian syenogranites show I-type arc and within-plate granite dual geochemical signatures, suggesting derivation from volcanic magmas extracted from the lithospheric mantle metasomatized by subducted fluid/melt in a back-arc basin. Permian diorites are Mg-diorites derived from a mixed magma source involving residual subducted basaltic oceanic crust and lithospheric mantle; two-mica monzonitic granites are S-type granites originating from crustal recycling of sedimentary rocks; muscovite granites are leucogranites resulting from the anatexis of ancient metasedimentary rocks. Their tectonic setting is syn/postcollision. Combining with previous data, we propose that the Chinese Altai experienced middle–late Ordovician continental arc magmatism, early–middle Devonian back-arc extension, and early–middle Permian arc–arc syn/postcollision. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6420236

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中国阿尔泰地区古生代花岗质岩石的地球化学、地质年代学和Sr–Nd–Hf同位素：俯冲-吸积向同碰撞/碰撞后转换的制约因素

中国阿尔泰具有丰富的花岗质岩石，可用于重建造山带的构造演化。本文对阿尔泰地区几种具有代表性的花岗质岩石进行了岩石学、地质年代学、地球化学和同位素分析。U-Pb定年显示，片麻岩花岗岩的年龄为444±3 Ma，正长花岗岩的年龄是406±8 Ma，闪长岩的年龄是280±6 Ma，两云母二长花岗岩的时间是278±3 Ma。奥陶系片麻质花岗岩具有I型弧相关元素特征，来源于大陆弧俯冲沉积交代地幔楔体中提取的火山岩浆。泥盆纪正长花岗岩表现出I型弧和板内花岗岩双重地球化学特征，表明其来源于弧后盆地中俯冲流体/熔体交代的岩石圈地幔中提取的火山岩浆。二叠纪闪长岩是镁闪长岩，来源于残余俯冲玄武岩洋壳和岩石圈地幔的混合岩浆源；两种云母二长花岗岩是起源于沉积岩地壳再循环的S型花岗岩；白云母花岗岩是由古代变质沉积岩的锐钛矿作用形成的浅色花岗岩。它们的构造背景是同/后碰撞。结合前人资料，我们认为中国阿尔泰地区经历了中-晚奥陶世大陆弧岩浆作用、早-中泥盆纪弧后伸展和早-中二叠纪弧-弧同碰撞。补充材料：https://doi.org/10.6084/m9.figshare.c.6420236

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来源期刊

Journal of the Geological Society 地学-地球科学综合

CiteScore

6.00

自引率

3.70%

发文量

审稿时长

6-12 weeks

期刊介绍： Journal of the Geological Society (JGS) is owned and published by the Geological Society of London. JGS publishes topical, high-quality recent research across the full range of Earth Sciences. Papers are interdisciplinary in nature and emphasize the development of an understanding of fundamental geological processes. Broad interest articles that refer to regional studies, but which extend beyond their geographical context are also welcomed. Each year JGS presents the ‘JGS Early Career Award'' for papers published in the journal, which rewards the writing of well-written, exciting papers from early career geologists. The journal publishes research and invited review articles, discussion papers and thematic sets.