The Southern Andes margin hosts active and fossil volcanic, geothermal, and mineralized systems documenting intense geofluid migration through the crust. Fluid flow is also spatially associated with crustal faults that accommodate the bulk deformation arising from oblique plate convergence. Although recognized, the precise local mechanical interaction between faults and crustal reservoirs is yet to be better understood. Here we present 3D numerical models of a magmatic reservoir and a fault zone set about 4 km apart, inspired by the Tatara-San Pedro volcanic complex in the Southern Volcanic Zone (~36°S), which displays a geothermal field and a margin-parallel dextral active fault zone constrained by published magnetotelluric profiles and crustal seismicity respectively. We investigate elasto-plastic deformation and stress patterns in the intermediate bedrock space between the reservoir and the fault zone and test how shear stress, volumetric strain, and plastic strain develop. We also test the potential of enabling brittle failure of their counterpart by imposing either (1) a strike-slip displacement along the fault zone, or (2) a magmatic overpressure at the cavity walls. Parametric tests of Young's modulus and frictional strength provide the conditions for macro-scale brittle failure and show the development of diffuse domains of dilational strain of the order of 10⁻⁵ –10⁻³ in the intervening bedrock. This dilation is a proxy to the opening of voids or volumetric cracking in the bedrock, which tends to increase porosity and permeability allowing over-pressurized geofluids to migrate within these domains. Our results show that a minimum of 60 m of fault displacement is required to trigger brittle failure of an upper crustal cavity if the bedrock is stiff, whereas, for a more compliant bedrock, more than 100 m of localized slip motion is required. This implies that it is rather the accumulated effect of repeated crustal fault displacement that potentially favors fluid pathways upwards, rather than a single seismic event. On the other hand, a minimum of 7.5 MPa of fluid overpressure is required for a mid-crustal cavity (15 km depth) to trigger brittle failure of the fault zone. This threshold overpressure increases up to 50 MPa when the cavity is shallower (6 km depth). Our results show that in general, shallow reservoirs must be very close to fault zones (less than 1–2 km apart) to reactivate them. The models show that localized strike-slip tectonics and magma intrusions build a dilational stress field at the scale of several kilometers, that promotes fluid pathways to the surface. Further combining this interaction with the regional transpressional stress field may explain observations of transient fluid pathways on seemingly independent timescales along the Andean margin.

安第斯山脉南部边缘拥有活跃的化石火山、地热和矿化系统，记录了地壳中强烈的地质流体迁移。流体流动在空间上也与地壳断层相关，地壳断层容纳了倾斜板块会聚引起的整体变形。尽管已经认识到，断层和地壳储层之间精确的局部机械相互作用还有待更好地理解。在这里，我们展示了岩浆储层和相距约 4 公里的断层带的 3D 数值模型，其灵感来自南部火山带（~36°S）中的 Tatara-San Pedro 火山复合体，该模型显示地热场和边缘 -分别受已发表的大地电磁剖面和地壳地震活动约束的平行右旋活动断层带。我们研究了储层和断层带之间中间基岩空间的弹塑性变形和应力模式，并测试了剪应力、体积应变和塑性应变是如何发展的。我们还通过施加 (1) 沿断层带的走滑位移或 (2) 腔壁处的岩浆超压来测试其对应物发生脆性破坏的潜力。杨氏模量和摩擦强度的参数测试为宏观脆性破坏提供了条件，并显示了 10 级膨胀应变扩散域的发展 我们还通过施加 (1) 沿断层带的走滑位移或 (2) 腔壁处的岩浆超压来测试其对应物发生脆性破坏的潜力。杨氏模量和摩擦强度的参数测试为宏观脆性破坏提供了条件，并显示了 10 级膨胀应变扩散域的发展 我们还通过施加 (1) 沿断层带的走滑位移或 (2) 腔壁处的岩浆超压来测试其对应物发生脆性破坏的潜力。杨氏模量和摩擦强度的参数测试为宏观脆性破坏提供了条件，并显示了 10 级膨胀应变扩散域的发展⁻⁵ –10 ⁻³在介入的基岩中。这种膨胀是基岩中空隙或体积开裂的代表，这往往会增加孔隙度和渗透率，使超压地质流体在这些区域内迁移。我们的结果表明，如果基岩坚硬，至少需要 60 m 的断层位移才能触发上地壳空腔的脆性破坏，而对于更柔顺的基岩，需要超过 100 m 的局部滑动运动。这意味着它是重复地壳断层位移的累积效应可能有利于向上的流体通道，而不是单个地震事件。另一方面，中地壳空腔（15 公里深）至少需要 7.5 兆帕的流体超压才能触发断层带的脆性破坏。当空腔较浅（6 公里深）时，该阈值超压增加至 50 MPa。我们的结果表明，一般来说，浅层储层必须非常靠近断层带（相距小于 1-2 公里）才能重新激活它们。模型表明，局部走滑构造和岩浆侵入在几公里的范围内建立了一个扩张应力场，促进了流体通道进入地表。进一步将这种相互作用与区域压应力场结合起来，可以解释沿安第斯边缘看似独立的时间尺度上对瞬态流体路径的观察。模型表明，局部走滑构造和岩浆侵入在几公里的范围内建立了一个扩张应力场，促进了流体通道进入地表。进一步将这种相互作用与区域压应力场结合起来，可以解释沿安第斯边缘看似独立的时间尺度上对瞬态流体路径的观察。模型表明，局部走滑构造和岩浆侵入在几公里的范围内建立了一个扩张应力场，促进了流体通道进入地表。进一步将这种相互作用与区域压应力场结合起来，可以解释沿安第斯边缘看似独立的时间尺度上对瞬态流体路径的观察。