Magnetotelluric imaging of a lithospheric-scale boundary in central Australia has been used to support a model of collision between the North Australian Craton and an exotic continental ribbon referred to as the Warumpi Province during the late Paleoproterozoic Liebig Orogeny ( 1640 Ma). This idea of collision has become an important element to reconstructions of late Paleoproterozoic Australia. In this study, we present mineral equilibria forward models from 1640 Ma metamorphic rocks to delineate the thermal regime associated with the Liebig Orogeny. Liebig-aged cordierite–orthopyroxene–biotite–quartz–plagioclase–K-feldspar–ilmenite–magnetite assemblages constrain peak metamorphic conditions to 4–5 kbar and 770–800 °C. These conditions are indicative of a high geothermal gradient regime and the mineral assemblage evolution shows no evidence for significant pressure changes that would generally support a crustal thickening model. Detrital zircon age spectra for the metasediments in the assumed exotic crust are broadly similar to the age record in the Aileron Province in the southern part of the North Australian Craton. Furthermore, εNd and εHf isotopic data of Liebig-aged granitic rocks make it permissible that they are derived from melting of North Australian Craton crust. This suggests the Warumpi Province was not exotic to the North Australian Craton and was instead a part of it. On the basis of the shared history between the Warumpi and Aileron Provinces and the newly constrained thermal character of 1640 Ma metamorphism, we suggest the Liebig Orogeny was characterised by extensional deformation of the North Australian Craton in the upper plate above a southward retreating subduction system. Tectonically, the Liebig Orogeny is interpreted to record a back-arc regime characterised by sedimentation, mafic and felsic magmatism, and predominantly contact metamorphism, and represents the continuation of a long-lived ( 200 Ma) upper plate system that dictated the evolution of the North Australian Craton during the late Paleoproterozoic.

中文翻译：

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李比希造山运动期间的延伸：澳大利亚中部古元古代的构造环境修正


澳大利亚中部岩石圈尺度边界的大地电磁成像已被用来支持古元古代晚期李比希造山运动（1640 Ma）期间北澳大利亚克拉通与被称为 Warumpi 省的奇异大陆带之间的碰撞模型。这种碰撞的想法已成为澳大利亚古元古代晚期重建的重要元素。在这项研究中，我们提出了 1640 Ma 变质岩的矿物平衡正演模型，以描绘与李比希造山运动相关的热状态。李比希年龄堇青石-斜方辉石-黑云母-石英-斜长石-钾长石-钛铁矿-磁铁矿组合将峰值变质条件限制在4-5 kbar和770-800 °C。这些条件表明存在高地温梯度状态，并且矿物组合演化没有显示出通常支持地壳增厚模型的显着压力变化的证据。假定的奇异地壳中变沉积岩的碎屑锆石年龄谱与北澳大利亚克拉通南部 Aileron 省的年龄记录大致相似。此外，李比希时代花岗岩的εNd和εHf同位素数据表明它们来自北澳大利亚克拉通地壳的融化。这表明瓦伦皮省对北澳大利亚克拉通来说并不陌生，而是它的一部分。根据瓦伦皮省和艾勒隆省的共同历史以及1640 Ma变质作用的新约束热特征，我们认为李比希造山运动的特征是南退俯冲系统上方板块上的北澳大利亚克拉通的伸展变形。 从构造上看，李比希造山运动被解释为记录了一种以沉积、镁铁质和长英质岩浆作用以及主要是接触变质作用为特征的弧后区域，代表了一个长期存在的（200 Ma）上部板块系统的延续，该系统决定了地球演化的过程。古元古代晚期的北澳大利亚克拉通。