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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The Proterozoic Mount Isa Fault Zone, northeastern Australia: is it really a ca. 1.9 Ga terrane-bounding suture?
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The Proterozoic Mount Isa Fault Zone, northeastern Australia: is it really a ca. 1.9 Ga terrane-bounding suture?

机译：澳大利亚东北部元古代的伊萨山断裂带：真的吗？ 1.9跨界缝合线？

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In marked contrast to Palaeoproterozoic Laurentia, the location of sutures and boundaries of discrete crustal fragments amalgamated during Palaeoproterozoic formation of the North Australian Craton remain highly speculative. Interpretations of suture locations have relied heavily on the analysis of regional geophysical datasets because of sparse exposure of rocks of the appropriate age. The Mount Isa Fault Zone has been interpreted as one such Palaeoproterozoic terrane-bounding suture. Furthermore, the coincidence of this fault zone with major shale-hosted massive sulphide Pb-Zn-Ag orebodies has led to speculations that trans-lithospheric faults may be an important ingredient for the development of this deposit type. This study has integrated geophysical and geochemical data to test the statute of the Mount Isa Fault as a terrane-bounding suture. Forward modelling of gravity data shows that basement rocks on either side of the Mount Isa Fault have similar densities. These interpretations are consistent with geochemical observations and Sm-Nd data that suggest that basement lithologies on either side of the Mount Isa Fault are geochemically and isotopically indistinguishable from each other, and that the Mount Isa Fault is unlikely to represent a suture zone that separates different Palaeoproterozoic terranes. Our data indicate that the crustal blocks on both sides of the Mount Isa Fault Zone must have been in within close proximity of each other since the Palaeoproterozoic, and that the Western Fold Belt was part of the (ancestral) North Australian Craton well before the similar to1.89-1.87 Ga Barramundi Orogeny. It appears that deep crustal variations in density may be related to the boundary between a shallowly west-dipping high-density mafic to ultramafic plate and low-density basement rocks. This interpretation in turn impacts on crustal-scale models for the development of shale-hosted massive sulphide Pb-Zn mineralisation, which do not require trans-lithospheric faults to tap deep-seated metal reservoirs and/or mantle plumbing systems. The approach applied herein demonstrates the value of multi-disciplinary investigations to the critical assessment of long-lived Proterozoic fault systems which, in the absence of methodical analysis, are commonly assumed to represent terrane-bounding sutures. (C) 2004 Elsevier B.V. All rights reserved.
机译：与劳伦西亚古元古代形成鲜明对比的是，北澳大利亚克拉通古元古代形成过程中合并的离散地壳碎片的缝合位置和边界仍然具有高度的推测性。缝合位置的解释在很大程度上依赖于区域地球物理数据集的分析，因为适当年龄的岩石稀疏暴露。伊萨山断裂带已被解释为一种这样的古元古代地界缝合线。此外，该断层带与主要的页岩寄主块状硫化物Pb-Zn-Ag矿体的重合导致人们推测，跨岩圈断层可能是形成这种矿床类型的重要因素。这项研究已经整合了地球物理和地球化学数据，以测试伊萨山断层为地层缝合线的法规。重力数据的正向建模表明，伊萨山断裂带两侧的基底岩石具有相似的密度。这些解释与地球化学观测和Sm-Nd数据一致，表明伊萨山断层两侧的基底岩性在地球化学和同位素上是彼此无法区分的，而且伊萨山断层不太可能代表分离不同缝线的缝合带。古元古代地层。我们的数据表明，自古元古代以来，伊萨山断层带两侧的地壳必须彼此靠近，并且西部褶皱带早在类似的时代就已经是北澳大利亚克拉通的一部分。到1.89-1.87 Ga肺鱼造山带。似乎深层地壳密度的变化可能与浅西向高密度镁铁质至超镁铁质板块和低密度基底岩石之间的边界有关。这种解释反过来对页岩型块状硫化物铅锌矿化发展的地壳尺度模型产生了影响，该模型不需要跨岩圈断层来开采深层金属储层和/或地幔管道系统。本文所采用的方法证明了多学科研究对长寿元古代断层系统的关键评估的价值，在缺乏系统分析的情况下，通常认为这代表了地界缝合线。 （C）2004 Elsevier B.V.保留所有权利。

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