Situated in the western Sierras Pampeanas of San Luis, the Nogolí Metamorphic Complex has become a key geological locality for unraveling the construction of the western Gondwana margin on the South American tectonic plate. This study presents a comprehensive analysis, encompassing new petrological and geochronological data, along with a meticulous structural examination of two distinct regions within the Nogolí Metamorphic Complex. Our primary aim is to assess the age and provenance of the protoliths, thereby shedding light on their geodynamic evolution. Detrital zircon U–Pb ages, obtained from a quartz–feldspathic-schist paleosome within a metatexite exposure in the La Barranquita area, disclosed a polymodal distribution. The predominant age population, centered around 616 ± 11 Ma, suggests a late Neoproterozoic source (Brasiliano–Pan African orogen). A secondary, yet significant, age peak at 542 ± 12 Ma points to a late Ediacaran to Early Cambrian origin (Pampean orogen). Additionally, a peak ranging from 930 to 1144 Ma indicates contributions from an early Neoproterozoic source (Grenvillian–Sunsas orogen). The maximum depositional age was determined to be 533 ± 14 Ma, based on the calculation of the youngest grain cluster at 2σ uncertainty. This polymodal zircon-age spectrum indicates that the sedimentary protolith of the Nogolí Metamorphic Complex derived from a Cambrian-age crystalline basement situated along the western margin of Gondwana. Contrary to models invoking continent–continent collision in western Gondwana during the early Cambrian, our findings better support a ridge–trench collision as the most plausible hypothesis for the origin of the Pampean orogeny.

Graphical abstract

中文翻译：

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阿根廷圣路易斯山脉诺戈利变质杂岩原岩的变形、年龄和来源：冈瓦纳大陆边缘西部寒武纪非碰撞历史的证据

诺戈利变质杂岩位于圣路易斯的潘皮纳斯山脉西部，已成为揭示南美板块上冈瓦纳西部边缘构造的关键地质地点。这项研究提供了全面的分析，包括新的岩石学和地质年代学数据，以及对诺戈利变质杂岩内两个不同区域的细致结构检查。我们的主要目标是评估原岩的年龄和来源，从而揭示它们的地球动力学演化。碎屑锆石 U-Pb 年龄是从 La Barranquita 地区变质岩暴露区的石英长石片岩古体中获得的，揭示了多峰分布。主要年龄群体集中在 616 ± 11 Ma 左右，表明其来源为新元古代晚期（巴西利亚诺-泛非造山带）。542 ± 12 Ma 处的次要但重要的年龄峰值指向埃迪卡拉晚期至寒武纪早期（潘普亚造山带）。此外，930 至 1144 Ma 之间的峰值表明来自新元古代早期源（格伦维尔-苏萨斯造山带）的贡献。根据2σ不确定度下最年轻颗粒簇的计算，确定最大沉积年龄为533±14 Ma。这种多峰锆石年龄谱表明，诺戈利变质杂岩的沉积原岩源自位于冈瓦纳大陆西缘的寒武纪结晶基底。与寒武纪早期冈瓦纳西部大陆碰撞的模型相反，我们的研究结果更好地支持了山脊-海沟碰撞作为潘普亚造山运动起源的最合理的假设。

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