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

一些研究表明，地壳中矿床的形成和定位的一个关键因素是存在一个富含矿质金属的源区，这些金属从那里被输送到矿体中。一个潜在的富金属来源，特别是与大型含金省的形成有关的来源之一，是交代次大陆岩石圈地幔(SCLM)。因此，这一项目的主要目标是了解地幔交代作用与SCLM富矿区域的产生，以及最终与弧相关的岩浆-热液矿床形成之间的关系。在这种情况下，巴塔哥尼亚为研究活动俯冲带附近影响SCLM的地幔过程(如部分熔融和交代)提供了理想的位置，因为整个地区都发现了丰富的超镁铁质地幔包体。此外，在位于巴塔哥尼亚南部和北部的两个大地块--北巴塔哥尼亚地块和德塞多地块的侏罗纪火山岩中，产有几个浅成低温热液金银矿床。然而，这些矿藏似乎在巴塔哥尼亚南部更为常见，最近有报道称，在世界最南端成矿区Deseado地块下的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更高，这可能反映了它们各自的SCLM的地球化学差异。在这个项目中，我们将研究巴塔哥尼亚北部岩石圈地幔样品的超镁铁捕虏体的地球化学，特别是其亲硫元素Se和Te的浓度，以及它们的Se同位素特征，以研究巴塔哥尼亚SCLM记录的亏损/富集过程及其与亲硫金属系统学的联系。最终，这些信息将与来自巴塔哥尼亚南部捕虏体的现有数据结合起来，以调查其独特的地幔储集层与地壳中矿藏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.