Geochronological and geochemical constraints on Late Cryogenian to Early Ediacaran magmatic rocks on the northern Tarim Craton: implications for tectonic setting and affinity with Gondwana
Geochronological and geochemical constraints on Late Cryogenian to Early Ediacaran magmatic rocks on the northern Tarim Craton: implications for tectonic setting and affinity with Gondwana
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DOI：
10.1080/00206814.2019.1581847
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发表时间：
2019-03
影响因子：
2.6
通讯作者：
Yang Xiao;Guanghui Wu;T. Vandyk;L. You
中科院分区：
文献类型：
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作者：
Yang Xiao;Guanghui Wu;T. Vandyk;L. You
摘要 塔里木克拉通提供了罗迪尼超大陆破碎和冈瓦纳大陆随后组装的地质记录。然而，这些截然不同的构造过程的时间和相互作用仍然存在争议。这场争论的一个关键部分围绕着克拉通北缘的晚成冰纪-埃迪卡拉纪火成岩，特别是它们是否记录了与罗迪尼碎裂有关的超级地幔柱或冈瓦纳造山运动。为了解决这个问题，我们提供了塔里木克拉通北部晚成冰世到早埃迪卡拉纪花岗岩的锆石 U-Pb-Hf 同位素数据和全岩石地球化学数据。 U-Pb 锆石年龄揭示了塔里木北缘的三个岩浆期：大约660–640 Ma、635–625 Ma 和 620–600 Ma，与小规模长英质和镁铁质岩浆有关。这些花岗岩具有 A2 型亲和力，富含碱性元素，但缺乏 Nb、Ta、Sr、P 和 Ti。元素数据和普遍为负的εHf(t)值（-13.96至1.65）表明它们主要源自塔里木北部活动大陆边缘软流圈地幔上涌引发的富集、俯冲改造的岩石圈地幔部分熔融。我们认为，在新元古代晚期的大部分时间里，塔里木克拉通作为一个孤立的板块移动，靠近罗迪尼亚的外部以及随后的冈瓦纳大陆。在此期间，它受到局部和周期性的俯冲相关侵入和喷发的影响。然而，在本研究的样本中，没有U-Pb-Hf同位素和全岩地球化学证据来支持与超羽流相关的裂谷（即罗迪尼期断裂）或泛非造山运动（即冈瓦纳组装）。
ABSTRACT The Tarim Craton provides a geologic record of both the fragmentation of the Rodinian supercontinent and the subsequent assembly of Gondwana. However, the timing and interactions of these radically different tectonic processes remain contested. A critical part of this debate revolves around the Late Cryogenian-Ediacaran igneous rocks along the Craton’s northern margin, specifically, whether they record super-plume related Rodinian breakup or Gondwanan orogeny. To address this issue, we present zircon U-Pb-Hf isotopic data and whole rock geochemistry from Late Cryogenian to Early Ediacaran granitoids of the northern Tarim Craton. U-Pb zircon ages reveal three magmatic periods along the northern Tarim margin: ca. 660–640 Ma, 635–625 Ma and 620–600 Ma, associated with small scale felsic and mafic magmas. These granitoids have an A2-type affinity and are enriched in alkalines, but are depleted in Nb, Ta, Sr, P and Ti. Elemental data and generally negative εHf(t) values (−13.96 to 1.65) suggest that they were mainly derived from partial melting of enriched, subduction-modified lithospheric mantle triggered by upwelling of the asthenospheric mantle along the active continental margin of northern Tarim. We suggest that the Tarim Craton travelled as an isolated plate for much of the Late Neoproterozoic, near the outer part of Rodinia and subsequently Gondwana. During this time it was affected by localized and periodic subduction-related intrusion and eruption. However, within the samples of this study, there is no U-Pb-Hf isotopic and whole-rock geochemical evidence to support either super-plume-related rifting (i.e. Rodinian breakup) or Pan-African orogeny (i.e. Gondwanan assembly).