The Central European, Tarim and Siberian Large Igneous Provinces, Late Palaeozoic orogeny and coeval metallogeny
The Central European, Tarim and Siberian Large Igneous Provinces, Late Palaeozoic orogeny and coeval metallogeny
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DOI：
10.1127/0163-3171/2013/0008
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发表时间：
2014-01
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通讯作者：
H. D. Boorder
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作者：
H. D. Boorder
早二叠世中欧和塔里木大火成岩省（LIPs）的形成分别与华力西造山带和南天山造山带的消亡相吻合。早三叠世西伯利亚陆壳是在晚二叠世西阿尔泰造山带之后形成的。这些过程与大多数已知的晚古生代和早中生代热液和岩浆矿床在相应的造山域中的发展相吻合。镍-铜（-PGE）沉积物直接来自构成LIP的（超）镁铁熔体的演化。在西西伯利亚，Noril'sk-Talnakh Ni-Cu（-PGE）矿床中伴生贵金属和贱金属的多样组合表明，这些金属也有其来源于地幔域，（超）镁铁质熔体就是从地幔域产生的。同样的金属元素也进入了已不存在的华力西造山域和南天山造山域的热液矿床。这些矿床传统上被认为是造山作用的结果。然而，它们的时代，以及它们当时的陆内构造控制的时间和性质，导致造山带的作用不确定。从它们与西伯利亚LIP的地幔来源来看，地幔对造山带晚古生代热液矿床的贡献可能比以前认为的更重要。造山运动对地幔复合体熔融和成矿作用的贡献可能在于大洋岩石圈俯冲对次大陆地幔域的早期修改。在这三种情况下，控制造山终止、LIP形成和成矿的构造背景主要是跨岩石圈走滑变形，可能与造山塌陷和岩石圈拆沉相结合。鉴于它们的重现性，造山带-唇序列可能不是偶然的。控制走滑断层是导致泛古陆合并的岩石圈尺度动力学框架的主要元素。在这个尺度上，西伯利亚LIP异常巨大的体积，除了岩石圈的走滑切割外，可能与超大陆边缘的大陆岩石圈的伸展有关（参见图1）。Gutierrez-Alonso等人，2008年）。外周延伸与其中心的压缩相关。对这些大火成岩省的解释不需要活动地幔柱的概念，因为与造山构造的破坏有关的深部走滑变形、造山塌陷和岩石圈拆沉可能引起次大陆地幔大区域的减压熔融。
The formation of the Central European and Tarim Large Igneous Provinces (LIPs) in the Early Permian coincided with the demise of the Variscan and the Southern Tianshan orogens, respectively. The Early Triassic Si- berian LIP was formed in the wake of the Western Altaid orogeny in the Late Permian. These processes coincided with the development of the majority of known Late Palaeozoic and Early Mesozoic hydrothermal and magmatic ore deposits in the corresponding orogenic domains. Nickel-copper(-PGE) deposits followed directly from the evo- lution of the (ultra-)mafi c melts which make up the LIPs. In Western Siberia, the diverse assemblage of associated noble and base metals in the Noril'sk-Talnakh Ni-Cu(-PGE) deposits suggests these metals also had their source in the mantle domain from which the (ultra-)mafi c melts were generated. The same metals variably found their way into the hydrothermal ore deposits in the defunct Variscan and Southern Tianshan orogenic domains. These ore de- posits have traditionally been viewed as a result of orogenic processes. However, their ages, together with the timing and nature of their by then intracontinental tectonic control cause uncertainty concerning the role of the orogens. In view of their mantle sources in their association with the Siberian LIP, the mantle contribution to these Late Palaeo- zoic hydrothermal ore deposits in the orogenic belts may have been more signifi cant than previously thought. An orogenic contribution to melting of mantle complexes and to mineralisation may have resided in the earlier modifi - cation of subcontinental mantle domains by subduction of oceanic lithosphere. In all three cases, the controlling tectonic setting of orogenic cessation, LIP formation and mineralisation was dominated by translithospheric strike- slip deformation, possibly in combination with orogenic collapse and lithosphere delamination. In view of their re- currence, the orogen-lip sequences were probably not fortuitous. The controlling strike-slip faults were principal elements of the lithosphere-scale dynamic framework that led to the amalgamation of Pangaea. At this scale, the exceptionally large volume of the Siberian LIP may, in addition to the strike-slip dissection of the lithosphere, have been related to extension in the continental lithosphere of the margin of the Supercontinent (cf. Gutierrez-Alonso et al. 2008). The peripheral extension was associated with compression in its centre. The explanation of these Large Igneous Provinces does not require the concept of an active mantle plume because deep-reaching strike-slip defor- mation, orogenic collapse and lithosphere delamination involved in the destruction of the orogenic edifi ces can have caused decompression melting in large domains of the subcontinental mantle.