Behavior of volatiles and ore-forming metals during high-pressure differentiation of arc magmas

一些研究提出，地壳中矿床形成和定位的一个关键因素是存在一个富含矿石金属的源区，这些金属随后从源区被输送到矿体中，最终富集。其中一个潜在的金属丰富的来源援引，特别是关于形成大型金矿省，是一个交代的次大陆岩石圈地幔（SCLM）。因此，该项目的主要目标是了解地幔交代作用、SCLM中肥沃区域的生成以及最终与弧相关的岩浆热液矿床的形成之间的关系。在这种情况下，巴塔哥尼亚提供了一个理想的位置来研究地幔过程（例如，部分熔融和交代作用），影响了活跃俯冲带附近的SCLM，因为在整个地区发现了丰富的超镁铁质地幔捕虏体。此外，几个浅成低温热液金银矿床分别位于巴塔哥尼亚南部和北部的北巴塔哥尼亚和Deseado火山岩的侏罗纪火山岩中。然而，这些矿床似乎在巴塔哥尼亚南部更为常见，最近有报道称，在世界最南端的成矿区Deseado Baglif下方的SCLM中存在自然金。与北巴塔哥尼亚地块相比，南部地块的金属丰度明显较高，这可能反映了它们各自SCLM的地球化学差异。在这个项目中，我们将研究样品的超镁铁质捕虏体的地球化学北巴塔哥尼亚岩石圈地幔，特别关注其亲铜元素Se和Te的浓度，除了他们的Se同位素签名，调查亏损/富集过程中记录的巴塔哥尼亚SCLM和它们的联系与亲铜金属轴承系统。最终，这些信息将与巴塔哥尼亚南部捕虏体的现有数据相结合，以调查其独特的地幔储层与地壳矿床形成之间的可能联系。

Several studies have proposed that a critical factor in the formation and localization of ore deposits in the Earth's crust is the existence of a source region rich in ore metals, from where these metals are then transported to concentrate in orebodies finally. One of the potential metal-rich sources invoked, particularly concerning the formation of large auriferous provinces, is a metasomatized subcontinental lithospheric mantle (SCLM). Therefore, the main goal of this project is to understand the relationship between mantle metasomatism, the generation of fertile domains in the SCLM, and, ultimately, the formation of arc-related magmatic-hydrothermal ore deposits. In this scenario, Patagonia provides an ideal location to investigate mantle processes (e.g., partial melting, and metasomatism) affecting the SCLM near active subduction zones, as abundant ultramafic mantle xenoliths are found throughout the region. Moreover, several epithermal Au-Ag deposits are hosted in Jurassic volcanic rocks in the North Patagonian and Deseado massifs, two large massifs located in the south and north of Patagonia, respectively. However, these ore deposits seem to be more common in southern Patagonia, where recently, the presence of native gold in the SCLM beneath the Deseado massif, the world's southernmost metallogenic region, was reported. This apparent higher abundance of metals in the southern Massif compared to the North Patagonian Massif may reflect the geochemical differences of their respective SCLM. In this project, we will study the geochemistry of ultramafic xenoliths that sample the North Patagonian lithospheric mantle, with a particular focus on the concentration of their chalcophile elements Se and Te, in addition to their Se isotope signatures, to investigate depletion/enrichment processes recorded in the Patagonian SCLM and their links with the chalcophile metal-bearing systematics. Ultimately, this information will be combined with available data from southern Patagonian xenoliths to investigate possible links between their distinct mantle reservoirs and the formation of ore deposits in the crust.