Zircon U–Pb geochronology and in situ Hf isotopic compositions of the Madao migmatite: Constraints on the Mesozoic orogeny in the South Qinling belt,Geological Journal

当前位置： X-MOL 学术 › Geolog. J. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Zircon U–Pb geochronology and in situ Hf isotopic compositions of the Madao migmatite: Constraints on the Mesozoic orogeny in the South Qinling belt
Geological Journal ( IF 1.4 ) Pub Date : 2020-09-25 , DOI: 10.1002/gj.4006
Dong‐Sheng Wang ₁ , Zong‐Qi Wang ₁ , Tao Wang ₂ , Xiao Nie ₁ , Jiang‐Hua Gong ₁

Affiliation

To understand the crustal growth of the Qinling orogenic belt and the Mesozoic continental interaction between the North China and Yangtze blocks, it is critical to study the South Qinling accretionary complex belt, which is an important part of the Qinling orogen. Based on detailed zircon U–Pb geochronology and Hf isotopic compositional analyses of the Madao complex, this study presents constraints on the migmatization and tectonic evolution of the South Qinling orogenic belt during the Mesozoic. Zircons from leucosome samples of migmatites were found to have weak oscillatory zoning, and one sample yielded a weighted mean age that reflects the time at which the regional tectono‐thermal event initiated the anatexis (210–217 ± 2 Ma). The Hf isotopic compositions indicate that the Madao migmatites were derived from the ancient middle–Late Palaeoproterozoic crust. Zircons from mesosome samples of the migmatites that varied in age from the Palaeozoic to Neoproterozoic exhibited core‐rim textures with magmatic cores (256–1,329 Ma), indicating that they were derived from multiple sources with sedimentary protoliths. Of the 55 analysis spots on the overgrowth rims that yielded ²⁰⁶Pb/²³⁸U ages of 200–233 Ma, 40 analyses yielded a weighted age of 211.5 ± 1.0 Ma, indicating the time of anatexis due to the regional tectono‐thermal event. Combined with previously reported Mesozoic data from the South Qinling belt, these results suggest that the migmatites were probably controlled by post‐orogenic extension driven by Mesozoic orogenesis and a prolonged melting episode (from ~200 to 233 Ma). This study reinforces the interpretation that the continental crust in the South Qinling belt may have experienced complex interactions with asthenospheric mantle material during the Mesozoic.

中文翻译：

锆石U–Pb地质年代学和马刀云母辉石的原位f同位素组成：南秦岭带中生代造山活动的制约

要了解秦岭造山带的地壳发育以及华北与扬子地块之间的中生代大陆相互作用，研究南秦岭增生带是至关重要的，这是秦岭造山带的重要组成部分。根据详细的锆石U–Pb地质年代学和马刀矿床的H同位素组成分析，本研究提出了对中秦代南秦岭造山带迁移和构造演化的限制。发现来自辉马岩白细胞样本的锆石具有较弱的振荡带，其中一个样本的加权平均年龄反映了区域构造-热事件开始产生食蚁兽的时间（210-217±2 Ma）。f同位素组成表明，马岛云母岩是从古中晚期古元古代地壳衍生而来的。从年龄不同（从古生代到新元古代）的辉石岩的介观样品中的锆石显示出具有岩浆岩芯（256-1,329 Ma）的岩心-边缘纹理，表明它们源自具有沉积原生岩的多种来源。在产生的过度生长轮缘上的55个分析点中²⁰⁶ Pb / ²³⁸ U年龄为200–233 Ma，40次分析得出的加权年龄为211.5±1.0 Ma，表明由于区域构造热事件而发生了厌食症。结合先前报道的南秦岭带的中生代数据，这些结果表明，这些成矿岩可能受中生代造山运动驱动的造山后扩张和融化作用的延长（从约200Ma到233Ma）。这项研究加强了这样一种解释，即南秦岭带的大陆壳在中生代可能经历了与软流圈地幔物质的复杂相互作用。

更新日期：2020-09-25

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南11