The Bisciarelle fault is a brittle thrust crosscutting lherzolite of the Voltri Massif (Italy) and is similar to the historical gold veins of the area. This is a 16-m-thick fault showing a large damage zone and a 4-m-wide hydrothermal alteration halo. Its fault rocks interacted with a hydrothermal fluid and host peculiar Au-bearing zones made of concentric and circular dolomite aggregates, which we call spherulites, and chalcedony. To constrain spherulite genesis, we quantify fluid-fault interactions at Bisciarelle combining field and microtextural data, mass transfer calculations, and a multi-technique analytical dataset including element imaging by laser ablation-inductively coupled plasma-time-of-flight mass spectrometry. We show that faulting was coupled with significant transfer of H₂O, CO₂, Ca, Sb, and W from the fault fluid to the protolith, and variable transfers of SiO₂ and some trace elements from the protolith to the fluid. This process deposited Au within the spherulites, caused serpentinization and carbonation of the protolith, and weakened the fault localizing subsequent shearing events and providing components for the growth of spherulites and the other fault rocks.

We interpret Bisciarelle as a permeable epizonal orogenic vein, which formed fast as a result of dilation and top-to-NE shearing. This fault developed via cycles of fluid pressure build-up, opening, fluid effervescence, and mineral precipitation from a H₂O-CO₂ hydrothermal fluid. The fluid transported and deposited a suite of metals including Au and interacted with the protolith. A similar mechanism of faulting and reactive fluid flow could have generated the other Au deposits of the area.

Bisciarelle 断层是Voltri Massif（意大利）的一个脆性逆冲横切二长石，与该地区历史上的金矿脉相似。这是一个 16 米厚的断层，显示出一个大的破坏区和一个 4 米宽的热液蚀变晕。它的断层岩与热液相互作用，形成了由同心圆形白云石聚集体（我们称之为球晶）和玉髓组成的奇特的含金区。为了限制球晶的成因，我们在 Bisciarelle 结合场和微观结构数据、传质计算以及包括通过激光烧蚀感应耦合等离子体飞行时间质谱法进行元素成像的多技术分析数据集来量化流体-断层相互作用。我们表明，断层与 H ₂ O、CO _{2的显着转移相结合}、Ca、Sb 和 W 从断层流体到原岩，以及 SiO ₂和一些微量元素从原岩到流体的可变转移。这一过程在球晶内沉积了金，导致原岩蛇纹石化和碳化，并削弱了断层定位随后的剪切事件，并为球晶和其他断层岩的生长提供了成分。

我们将 Bisciarelle 解释为可渗透的带外造山脉，由于扩张和自顶向东北的剪切而迅速形成。该断层是通过流体压力增加、打开、流体泡腾和来自 H ₂ O-CO ₂热液流体的矿物沉淀的循环而形成的。流体运输并沉积了一系列金属，包括金，并与原石相互作用。类似的断层和反应性流体流动机制可能产生了该地区的其他金矿床。