The circa 1.60 Ga Isan Orogeny in NE Australia has been ascribed to the collision of Australia and Laurentia (North America), marking the final assembly of the Proterozoic supercontinent Nuna. However, details regarding the tectonic evolution of the orogen remain poorly constrained. To investigate the late orogenic to postorogenic thermal evolution and exhumation history, ⁴⁰Ar/³⁹Ar dating on hornblende, muscovite, and biotite was conducted in the Mount Isa Inlier, NE Australia, where intense crustal imbrication occurred during the Proterozoic continental collision. Published thermochronological results were recalculated using the current decay constant. Petrological examination and calculation of sample‐specific ⁴⁰Ar/³⁹Ar closure temperatures and cooling rates were used to reconstruct the pressure‐temperature evolution of individual structural domains. Diachronous cooling histories are revealed between western, central, and eastern belts through ~525–330°C, mainly between 1.53 and 1.48 Ga. Contrasting cooling across postmetamorphic fault zones records the reactivation of inherited normal (i.e., early basinal) and reverse (i.e., orogenic) faults. Estimated exhumation rates are generally low (< ~0.5 mm yr⁻¹), pointing to a modest local relief of < ~1,000 m which is comparable to modern analogs, and suggest a “soft” collision with limited crust thickening. Exhumation shortly following orogenesis was contemporaneous with felsic magmatism (1.55–1.48 Ga) in the eastern belt. Magmatism transitioning from trondhjemitic to A‐type granitoids over this period suggests progressive heating of the orogen base, ascribed to lower crust delamination. Thus, thermochronological data reveal a regionally heterogeneous exhumation history controlled by orogenic collapse‐related extensional faulting following the final assembly of the supercontinent Nuna.

中文翻译：

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1.6 Ga Nuna组装后澳大利亚东北部伊萨山造山带的异质掘出：高精度40Ar / 39Ar新的热年代学约束

该ca。1.60澳大利亚东北部的Ga Isan造山运动被归因于澳大利亚和劳伦西亚（北美）的碰撞，标志着元古代超大陆努纳的最终组装。但是，有关造山带构造演化的细节仍然受限制。为了调查造山后期至造山后的热演化和发掘历史，在澳大利亚东北部伊萨因内尔山进行了角闪石，白云母和黑云母的⁴⁰ Ar / ³⁹ Ar测年，在元古代的大陆碰撞中发生了强烈的地壳振动。使用电流衰减常数重新计算已发布的热年代学结果。岩石学检验和特定样品的计算⁴⁰ Ar / ³⁹氩气关闭温度和冷却速率用于重构各个结构域的压力-温度演变。西部，中部和东部地带在〜525–330°C之间（主要在1.53至1.48 Ga之间）显示了历时的冷却历史。跨变质后断层带的相反冷却记录了继承的正向（即盆地早期）和反向（即造山带）断层。估计的尸体发掘率通常很低（<〜0.5 mm yr ^-1），指的是小于〜1000 m的适度局部起伏，这与现代类似物相当，并暗示了具有有限地壳增厚的``软''碰撞。造山运动后不久的发掘与东部地带的长英质岩浆作用（1.55-1.48 Ga）同时发生。在这段时期内，岩浆作用由白垩纪转变为A型花岗岩，表明造山带基底逐渐升温，这归因于地壳分层的降低。因此，热年代学数据揭示了超大陆努纳河的最终组装后，受造山塌陷相关的伸展断裂控制的区域异质化石历史。