Tectonomagmatic history and ore-forming triggers at the Titiribi and La Mina porphyry-epithermal deposits, Colombia

斑岩铜矿是工业和社会铜(以及金和钼)的主要全球来源，也是矿业公司勘探的首要目标。地质学家现在很好地了解了这些矿床的形成和产状的一般模式，涉及热的金属流体从上地壳结晶岩浆(岩浆-热液流体)中出溶；释放这些流体的“富饶”岩浆通常形成于汇聚板块边界的俯冲带上方，如南美洲的安第斯山脉和北美西部的科迪勒拉。然而，对是否形成经济金属矿床(而不是低品位矿床或贫瘠系统)的最终控制并没有受到很好的约束，而且确实可能是随机的(因为除非从概率的角度来看，它们可能是不可预测的)。值得注意的是，斑岩系统中的成矿作用发生在源岩系统的整个历史上的短而单一的时间段(~10万年)(100~500万年)，通常涉及爆炸角砾化和浅层岩浆侵位，但许多岩浆系统没有显示出这种事件的证据。这表明，一种戏剧性的、或许是灾难性的变化偶尔会影响原本被动结晶的弧岩浆系统，从而导致成矿。大型矿床的本质是它们表现出广泛的叠印和蚀变，因此可能揭示这些触发过程的早期结构被破坏。因此，我们计划研究哥伦比亚相对较小的Titiribi和La Mina斑岩矿床，那里的叠印程度较少，早期角砾岩和岩浆结构保存良好。这将使我们能够严格限制岩浆侵位、热液释放和矿石沉积之间的相互作用，目的是确定这些过程的潜在触发因素。尽管成矿可能仍然是随机的，但了解关键控制因素将提高可预测性，从而提高目标勘探的能力。

Porphyry copper deposits are major global sources of copper (as well as gold and molybdenum) to industry and society, and are premier targets for exploration by mining companies. The general mode of formation and occurrence of these deposits is now well understood by geologists, and involves the exsolution of hot metalliferous fluids from crystallizing magma in the upper crust (magmatic-hydrothermal fluids); the "fertile" magma that releases these fluids is typically formed above subduction zones at convergent plate boundaries, such as the Andes of South America, and the Cordillera of western North America. However, the ultimate controls on whether an economic deposit of metals is formed (as opposed to a low-grade deposit or barren system) are not well constrained, and indeed may be stochastic (inasmuch as they may not be predictable except in a probabilistic sense). It is noticeable that ore formation in porphyry systems occurs over short and singular periods of time (~100,000 years) in the overall history of the source magmatic system (1 to 5 million years), and commonly involves explosive brecciation and shallow magma emplacement, and yet many magmatic systems to not show evidence of such events. This suggests that a dramatic, perhaps catastrophic change occasionally affects otherwise passively crystallizing arc magmatic systems, leading to ore-formation. The nature of large ore deposits is that they display extensive overprinting and alteration, such that early textures that might reveal these triggering processes are destroyed. Therefore, we plan to study the relatively small Titiribi and La Mina porphyry deposits in Colombia, where the degree of overprinting is less, and early breccia and magmatic textures are well preserved. This will enable us to tightly constrain the interplay between magma emplacement, hydrothermal fluid release, and ore deposition, with the objective of identifying the underlying triggers for these processes. Although, ore formation may still be stochastic, understanding the key controls will improve predictability, thereby improving the ability to target exploration.