Magmatic arcs may play a major role in the initiation, behavior, and abandonment of intra‐arc strike‐slip systems. Here we present zircon U‐Pb and (U‐Th)/He geochronology/thermochronology with new mapping to relate Coastal Cordillera arc magmatism to sinistral shear along the Atacama fault system (AFS) in northern Chile. New dates from 18 intrusions along the AFS between 24.6°S and 27°S compiled with published data record a minor Early Jurassic magmatic pulse (195–175 Ma), broad latest Jurassic to Early Cretaceous (150–120 Ma) pulse, and a minor younger (120–105 Ma) pulse. Mylonitization occurred only along the margins of Early Cretaceous plutons and surrounding Paleozoic metasedimentary rock, whereas Jurassic plutons and metasedimentary rocks away from Early Cretaceous plutons lack mylonitic fabrics. Early Cretaceous magmatism facilitated AFS deformation by thermally weakening the crust with elevated geothermal gradients that enabled mylonitization to take place at ~5‐ to 7‐km depths and low stresses. Spatial variability of pluton emplacement produced significant rheological heterogeneity, giving rise to a highly segmented fault system that did not originate as a regional‐scale shear zone. Synkinematic dikes (~120–117 Ma) cut mylonitic fabrics, and a postkinematic dike (~110 Ma) records the end stages of slip. The cessation of slip coincided with cooling below ~180 °C at ~116–99 Ma as arc magmatism migrated eastward and geothermal gradients relaxed, coeval with a major reorganization in plate motion and the onset of seafloor spreading in the south Atlantic.

中文翻译：

---

智利北部弧内走滑阿塔卡马断层系统的岩浆作用与变形之间的关系

岩浆弧可能在弧内走滑系统的启动，行为和放弃中起主要作用。在这里，我们介绍了锆石U-Pb和（U-Th）/ He地质年代学/热年代学，并提供了新的映射，以将智利北部阿塔卡马断裂系统（AFS）上的沿海Cordillera弧岩浆作用与左旋剪切作用联系起来。从24.6°S到27°S沿AFS的18次侵入的新日期与已公布的数据汇编，记录了较小的侏罗纪早期岩浆脉冲（195-175 Ma），最新的侏罗纪至早白垩纪（150-120 Ma）脉冲，以及较小的年轻（120–105 Ma）脉冲。仅在早白垩纪岩体边缘和古生界准沉积岩的边缘发生了髓系化作用，而远离早白垩纪岩体的侏罗系岩浆和准沉积岩缺少象棉质构造。早期白垩纪岩浆作用通过升高地热梯度使地壳热弱化，从而促进了AFS变形，从而能够在约5至7 km的深度和低应力下进行成岩作用。岩体位置的空间变异性产生了显着的流变异质性，形成了高度分段的断层系统，该断层系统并非起源于区域尺度的剪切带。运动学堤防（〜120–117 Ma）切割了棉麻织物，运动学堤防（〜110 Ma）记录了滑移的结束阶段。滑移的停止与在约116-99 Ma时在〜180°C以下的降温相伴，因为弧岩浆作用向东迁移，地热梯度松弛，同时伴随板块运动的重大重组和南大西洋海底扩散的开始。