The Carboniferous Arc of the North Pamir
The Carboniferous Arc of the North Pamir
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DOI：
10.2113/2021/6697858
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发表时间：
2021-01
期刊：
影响因子：
2.4
通讯作者：
Johannes Rembe;E. Sobel;J. Kley;R. Zhou;R. Thiede;Jie Chen
中科院分区：
文献类型：
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作者：
Johannes Rembe;E. Sobel;J. Kley;R. Zhou;R. Thiede;Jie Chen
在这项研究中，我们调查了在中亚的中国，吉尔吉斯斯坦和塔吉克北帕米尔发现的火山弧岩的年龄和地球化学变化。新的地球化学和地质年代学数据，以及从文献中汇编的数据给出了一个整体的看法，早中石炭纪洋内弧保存在东北帕米尔。北帕米尔火山弧杂岩包括其西部延伸的大陆条，并转变为具有弧岩浆岩的科迪勒拉式碰撞带。这些部分由泥盆纪至石炭纪的洋壳和塔吉克斯坦埃迪卡拉纪（最大沉积年龄）的变质Kurguvad基底块体所承载。我们讨论了石炭纪俯冲相关的玄武岩和侵入英云闪长岩的银接近中国城镇马扎是同一弧的一部分。LA-ICP-MS U-Pb测年的锆石，连同整个岩石的地球化学来自英云闪长岩花岗闪长质侵入体，揭示了一个主要的Visean Bashkirian侵入相之间的340和320 Ma前。这明显晚于西昆仑古生代弧岩浆活动约100 Ma。这一观察结果，沿着地球化学证据表明，在北帕米尔石炭纪弧岩浆岩中有更明显的地幔成分，与从西昆仑到北帕米尔的连续昆仑带的共同模式不一致。此外，古生代海洋单位年轻于和西部的塔里木海盆地壳挑战的想法，一个连续的海盆塔里木-塔吉克大陆之下的帕米尔。
In this study, we investigate the age and geochemical variability of volcanic arc rocks found in the Chinese, Kyrgyz, and Tajik North Pamir in Central Asia. New geochemical and geochronological data together with compiled data from the literature give a holistic view of an early to mid-Carboniferous intraoceanic arc preserved in the northeastern Pamir. This North Pamir volcanic arc complex involves continental slivers in its western reaches and transforms into a Cordilleran-style collision zone with arc-magmatic rocks. These are hosted in part by Devonian to Carboniferous oceanic crust and the metamorphic Kurguvad basement block of Ediacaran age (maximum deposition age) in Tajikistan. We discuss whether a sliver of Carboniferous subduction-related basalts and intruded tonalites close to the Chinese town of Mazar was part of the same arc. LA-ICP-MS U-Pb dating of zircons, together with whole rock geochemistry derived from tonalitic to granodioritic intrusions, reveals a major Visean to Bashkirian intrusive phase between 340 and 320 Ma ago. This clearly postdates Paleozoic arc-magmatic activity in the West Kunlun by ~100 Ma. This observation, along with geochemical evidence for a more pronounced mantle component in the Carboniferous arc-magmatic rocks of the North Pamir, disagrees with the common model of a continuous Kunlun belt from the West Kunlun into the North Pamir. Moreover, Paleozoic oceanic units younger than and west of the Tarim cratonic crust challenge the idea of a continuous cratonic Tarim-Tajik continent beneath the Pamir.