All existing bench and tunnel vein and fault structural data with identified mineral infill, acquired in Chuquicamata, were georeferenced, digitized, and, according to their mineralogy, assigned to one or more of the major alteration events developed between 35 and 31 Ma. Veins and faults were separated into two main stages: (1) the late magmatic and potassic stage that comprises the background potassic and the propylitic alteration and (2) the hydrothermal stage composed by early (intense potassic), main (principal and late sericite; hydrothermal stages H1 through H4), and late (advanced argillic alteration) hydrothermal events. The spatial distribution of the propylitic to late-hydrothermal events that plotted within the major fault framework indicate these had either permeable or impermeable (±barrier) behavior through time. The area of the deposit was divided into 600 square grids measuring 100 × 100 m, and a stress orientation analysis was carried out for every propylitic to late-hydrothermal alteration event. The analysis indicates that the local principal horizontal stress (σH) trajectories are nonlinear and noncoaxial through the successive alteration events, differing from the previous and following stages, and in the majority of cases do not coincide with the approximate east-northeast orientation of the inferred tectonic far-field stress orientation. The differences between the stress trajectories, away from the far-field stress orientation throughout the evolution of the system, are considered to be principally related to the dynamic variations experienced by the stress components, such as thermal-magmatic stresses linked to temperature fluctuations due to cooling or heating by progressive igneous/hydrothermal activity and/or elastic, overburden-related stresses associated with reaccommodations developed during uplift and erosion. The estimated stresses resulting after erosional unroofing and decreasing temperature indicate that the maximum horizontal stress varied as the system evolved from the commonly accepted depth of emplacement of ~6 km. During the late magmatic, background potassic, and intense potassic stages, the calculated differential stress was contractional, decreasing to an isotropic state at the contraction-extension stress reversal that hosted the main hydrothermal H1 through H3 events, to finally become extensional at the shallow late-hydrothermal event. The most significant mineralization occurred at the time of stress reversal, coincidental with the sericite and quartz-sericite events (H1-H4), associated with hydrothermal fluid accumulation, overpressuring, and multiple-orientated hydraulic fracture development.The Chuquicamata study suggests that the local stress control involved in the emplacement of porphyry copper systems is fundamentally related to variable and progressive heat energy release, associated with igneous and hydrothermal activity, and to the elastic stresses derived from uplift and unloading, rather than to a constant far-field tectonic stress. The continuous local stress fluctuations led to bulk stress readjustments and cyclical stress-fluid interactions for local fault reactivation, damage zone modification, brecciation, permeability creation/destruction, and fluid focusing, as well as the discharge of hydrothermal fluids throughout the evolution of the system.

中文翻译：

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智利北部丘基卡马塔铜钼矿床蚀变阶段的结构控制

在丘基卡玛塔（Chuquicamata）获得的所有现有的已确定矿藏填充物的台架和隧道静脉和断层结构数据，都经过地理定位，数字化处理，并根据其矿物学分配给35至31 Ma之间发生的一个或多个主要蚀变事件。静脉和断层分为两个主要阶段：（1）岩浆和钾的晚期阶段，包括背景钾和丙酮酸蚀变；（2）由早期（强钾），主要（主要和主要绢云母）组成的热液阶段； H1至H4的热液阶段）和晚期（先进的泥质蚀变）热液事件。在主要断层框架内标绘的丙炔事件至晚水热事件的空间分布表明，这些事件随时间具有渗透性或非渗透性（±阻隔）行为。将沉积物的区域划分为600个100×100 m的方格，并对每一个丙炔化至晚水热蚀变事件进行应力取向分析。分析表明，通过连续的变化事件，局部主水平应力（σH）轨迹是非线性且非同轴的，这与之前和之后的阶段有所不同，并且在大多数情况下与推断的近似东-东北方向不一致。构造远场应力取向。在整个系统的演化过程中，远离远场应力方向的应力轨迹之间的差异被认为主要与应力分量所经历的动态变化有关，例如，由于渐进的火成/水热活动和/或与隆起和侵蚀过程中产生的适应作用相关的与覆盖层相关的弹性应力，与因冷却或加热而引起的温度波动相关的热岩浆应力。侵蚀性屋面和温度降低后产生的估计应力表明，最大水平应力随系统从公认的大约6 km的进深变化而变化。在岩浆，背景钾肥和强烈钾肥的晚期，计算得出的压差是收缩的，在收缩-延伸应力逆转过程中下降到各向同性状态，该逆转是主要的热液H1到H3事件，最终在浅水后期变成张性。 -热液事件。最显着的矿化发生在应力逆转时，与绢云母和石英绢云母事件（H1-H4）同时发生，与热液流体蓄积，超压和多向水力压裂发展有关.Chuquicamata研究表明斑岩型铜系统的位移所涉及的应力控制从根本上与可变的，渐进的热能释放有关，与火成岩和热液活动有关，并且与隆起和卸载产生的弹性应力有关，而不是与恒定的远场构造应力有关。持续的局部应力波动导致整体应力重新调整和周期性的应力-流体相互作用，从而导致局部断层重新激活，破坏带改造，破裂，渗透性产生/破坏以及流体聚焦，