Although many studies link mineral deposit formation to rifting and hydrothermal processes, we present a study that focuses on the relationship between crustal necking and mineral deposit formation. Necking corresponds to the timing, location, and process of rift localization and abrupt crustal and lithospheric thinning. Although necking is well identified and described from present-day rifted margins and has been modeled numerically, little is known about the necking process and its possible link to ore deposit formation. We present observations from the Mont-Blanc fossil detachment system, one of the few exposed examples of a necking detachment fault. We show that fluids flowed along the fault zone and leached metals (mainly Pb and Zn). This process was associated with the hydrothermal breakdown of feldspar and biotite at temperatures of 200 °C and salinities ranging from 5 to 20 eq. wt% with a H₂O-NaCl (-KCl) composition. The resulting metal-rich fluids reacted with mainly carbonate-rich units to form Pb-Zn ore deposits in basement and sedimentary cover rocks. A direct link can, therefore, be demonstrated between fluid and reaction-assisted breakdown of silicates, metal transfer and trapping along detachment faults, and the overlying sedimentary rocks during necking. Similar ore deposits can be found throughout the inner External Crystalline Massif of the Western Alps, interpreted as the former necking domain of the Alpine Tethys. This leads to the suggestion that necking and Pb-Zn deposit formation may be closely linked, a hypothesis, if correct, that has the potential to predict additional Pb-Zn-Ba-F resources in rifts, rifted margins, and reactivated fossil rifted margins forming collisional mountain belts.

尽管许多研究将矿床形成与裂谷和热液过程联系起来，但我们提出的一项研究重点关注地壳颈缩与矿床形成之间的关系。颈缩对应于裂谷定位以及地壳和岩石圈突然减薄的时间、位置和过程。尽管颈缩已从当今的裂谷边缘得到了很好的识别和描述，并且已进行了数值模拟，但人们对颈缩过程及其与矿床形成的可能联系知之甚少。我们展示了勃朗峰化石分离系统的观测结果，这是少数暴露的颈缩分离断层的例子之一。我们发现流体沿着断层带流动并浸出金属（主要是铅和锌）。该过程与长石和黑云母在 200 °C 温度和 5 至 20 eq 盐度范围内的热液分解有关。 wt%，具有H ₂ O-NaCl(-KCl)组合物。由此产生的富含金属的流体与主要富含碳酸盐的单元发生反应，在基底和沉积盖岩中形成铅锌矿床。因此，可以证明流体和反应辅助的硅酸盐分解、沿滑脱断层的金属转移和捕获以及颈缩过程中上覆的沉积岩之间存在直接联系。类似的矿床在西阿尔卑斯山的内部外部结晶体中随处可见，被解释为阿尔卑斯特提斯山脉以前的颈缩区域。这表明颈缩和 Pb-Zn 矿床的形成可能密切相关，这一假设如果正确，有可能预测裂谷、裂谷边缘和重新激活的化石裂谷边缘中的额外 Pb-Zn-Ba-F 资源形成碰撞山带。