Hot spring geochemistry from the Cordillera Blanca and Cordillera Huayhuash, Peru, reveal the influence of crustal‐scale structures on geothermal fluid circulation in an amagmatic region located above a flat‐slab subduction zone. To test the influence of contrasting modes of faulting in these regions, springs were targeted along the Cordillera Blanca detachment fault, within its hanging wall, in the footwall of the detachment, and in the Cordillera Huayhuash. Hot springs along the Cordillera Blanca detachment fault zone are associated with recent extension and normal faulting, and those in its footwall and the Cordillera Huayhuash are located in the Marañon fold and thrust belt where compressional structures dominate. Springs along and in the hanging wall of the Cordillera Blanca detachment fault yield brackish‐saline, alkaline‐chloride waters, with oxygen, hydrogen, carbon, and chlorine stable isotope values that suggest mixing between meteoric groundwater and saline brine affected by high water‐rock interaction. Geothermometry reservoir temperature estimates (RTEs) of 91–226°C indicate maximum flow path depths of 8.7 or 11 km, depending on geothermal gradient, associated with the Cordillera Blanca detachment fault. In contrast, springs in the footwall and in the Cordillera Huayhuash exhibit a wide range of water types with an isotopic affinity to meteoric water, suggesting a greater influence from shallow groundwater and less water‐rock interaction. For these springs, RTEs of 40–98°C correspond to much shallower circulation (1.6–4 km). Results indicate that the Cordillera Blanca detachment system accommodates significantly deeper circulation of crustal fluids compared to other regional compressional structures.

中文翻译：

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秘鲁平板俯冲带上方地壳流体循环和温泉地球化学的结构控制

来自秘鲁科迪勒拉·布兰卡和科迪勒拉·瓦伊瓦什的温泉地​​球化学揭示了地壳尺度结构对平板俯冲带上方一个岩浆区域地热流体循环的影响。为了测试这些地区的断层对比模式的影响，沿科迪勒拉布兰卡脱离断层，悬挂壁内，该支队的下盘壁以及科迪勒拉瓦伊瓦什地区进行了弹簧定位。山脉山脉断裂断层带的温泉与近期的伸展和正常断裂有关，其下盘壁和山脉Huayhuash的温泉位于Maraon褶皱和逆冲带中，其中压缩构造占主导地位。沿着白色山脉分离断层的悬壁和悬壁的泉水，产生咸淡盐水，碱性氯化物水，具有氧，氢，碳和氯的稳定同位素值，表明流星地下水和受高水-岩相互作用影响的盐水之间的混合。根据地热梯度，地热测定法储层温度估计值（RTE）为91–226°C，表明最大流径深度为8.7或11 km，这与白山脉分离断层有关。相比之下，下壁和科伊迪亚什山脉的泉水表现出多种水类型，它们与陨石水具有同位素亲合力，表明浅层地下水的影响更大，水岩相互作用较小。对于这些弹簧，RTE为40–98°C时，对应的循环较浅（1.6–4 km）。