The Têt fault is a major crustal-scale fault in the eastern Pyrenees (France) along which 29 hot springs emerge, mainly within the footwall damage zone of the fault. In this study, $(\mathrm{U}-\mathrm{Th})/\mathrm{He}$ apatite (AHe) thermochronology is used in combination with rare-earth element (REE) analyses in order to investigate the imprint of hydrothermal activity around two main hot spring clusters (Thuès-les-Bains and St Thomas) and between them. The main goal is to better define the geometry and intensity of the recent thermal anomalies along the fault and to compare them with previous results from numerical modelling. This study displays 99 new AHe ages and 63 REE analyses on single apatite grains from samples collected in the hanging wall (18 to 43 Ma) and footwall (8 to 26 Ma) of the Têt fault. In the footwall, the results reveal AHe age resetting and apatite REE depletion due to hydrothermal circulation along the Têt fault damage zone, near the two hot spring clusters, and also in areas lacking present-day geothermal surface manifestation. These age resettings and element depletions are more pronounced around the Thuès-les-Bains hot spring cluster and are spatially restricted to a limited volume of the damage zone. Outside this damage zone, new modelling of thermochronological data specifies the thermal evolution of the massifs. The footwall model suggests the succession of two main phases of cooling: between 30 and 24 Ma and a second one around 10 Ma. In the hanging wall, little evidence of hydrothermal imprint on AHe ages and REE signatures has been found, and thermal modelling records a single cooling phase at 35–30 Ma. Low-temperature thermochronology combined with REE analyses allows us to identify the spatial extent of a recent geothermal perturbation related to hydrothermal flow along a master fault zone in the eastern Pyrenees, opens new perspectives to constrain the geometry and intensity of geothermal fields, and provides new regional constraints on the cooling history of the footwall and hanging-wall massifs.

中文翻译：

---

利用（U-Th）∕ He磷灰石热年代学和稀土元素（REE）分析跟踪地壳断层的地热异常：Têt断层的例子（法国比利牛斯）

Têt断层是东比利牛斯（法国）的一个主要的地壳尺度断层，沿着该断层出现了29个温泉，主要位于断层的下盘破坏带内。在这个研究中，$（\mathrm{ü}--\mathrm{钍}）/\mathrm{他}$磷灰石（AHe）热年代学与稀土元素（REE）分析结合使用，以研究两个主要温泉团簇（Thuès-les-Bains和St Thomas）及其之间的热液活动烙印。主要目标是更好地定义沿断层的近期热异常的几何形状和强度，并将其与数值模拟的先前结果进行比较。这项研究显示了从Têt断层的上盘（18至43 Ma）和下盘（8至26 Ma）收集的样品中的单个磷灰石晶粒的99个新的AHe年龄和63 REE分析。在底盘中，结果显示由于沿Têt断层破坏带的热液循环，两个温泉团簇附近以及缺乏当今地热表面表现的区域，AHe年龄复位和磷灰石REE耗尽。这些年龄重置和元素消耗在Thuès-les-Bains温泉群附近更为明显，并且在空间上受到损害区域的限制。在损坏区域之外，新的热年代学数据模型指定了地块的热演化。底盘模型表明了冷却的两个主要阶段的相继：在30和24 Ma之间，第二个阶段在10 Ma附近。在吊壁上，几乎没有证据显示在AHe年龄和REE签名上有热液烙印，热模型记录了在35-30 Ma的单个冷却阶段。低温热年代学与REE分析相结合，使我们能够确定近期与比利牛斯山脉东部主要断裂带上的热液流有关的地热扰动的空间范围，