GoldTrace · tracking the origin and transport of gold beneath seafloor arc volcanoes
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-09-01 → 2019-08-31
- EU contribution
- €85,730
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
GoldTrace: tracking the origin and transport of gold beneath seafloor arc volcanoes
Metals are key to master the world’s transitions into a carbon-neutral economy. The discovery of land-based large deposits of strategic metal -such as copper and gold- is becoming increasingly difficult and explorers start to focus on the deep sea to ensure security of supply. We know that high-grade copper, silver and gold deposits on land are often associated with seafloor arc volcanism. Yet little is known about petrogenetic processes that controls the copper, silver and gold budget beneath volcanic arcs. The intra-oceanic Kermadec arc offshore New Zealand is arguably the world’s most hydrothermally active volcanic arc. To isolate slab versus overriding mantle (wedge) contributions, we present high-precision Au, Ag and Cu analyses together with other geochemical data from 65 submarine glasses recovered from the length of the Kermadec arc. The data reveal that Au, Ag and Cu contents (e.g., Au <1 to 15 ppb) are always highest in glasses with the a composition indicative of their origin from the most depleted sub-arc mantle. Therefore, high degrees of partial melting and high temperatures are the defining petrogenetic parameters to produce copper, silver and gold-rich magmas. Re and Pt are also mainly controlled by sub-arc processes whereas other metals, such as Mo, Tl, W, Bi and As are dominated by the influx from a subducting slab component (e.g., sediments and altered oceanic crust). The GoldTrace project therefore helps to define petrogenetic parameters that the formation of metal-rich magmas, pre-requisite to form high-grade volcanic hosted mineralization on the seabed.
Data: CORDIS, © European Union
Project objective
With an increasing importance of green technologies, today’s world relies on an increasing supply of minerals. As the discovery of large deposits of strategic minerals—such as copper and gold—is becoming rare, explorers now focus on the deepsea to ensure demand is met. We know since decades that large copper, silver and gold-rich volcanic-hosted massive sulphide deposits are associated with seafloor arc volcanism. Therefore, understanding arc volcanism and in particular the source and transport of copper, silver and gold in arc lavas is critical in understanding how, when and why these deposits form. The Kermadec arc offshore New Zealand is arguably the world’s most hydrothermally active volcanic arc. Here, hydrothermal mineralization and the highest copper and silver contents occur in southern Kermadec arc lavas formed above thick subducting plateau crust. This suggests that the composition and thickness of the subducting plate strongly affects the flux and transport of these metals beneath arcs. However, the processes surrounding the source and transport of copper, silver and gold remain unknown. To fill this knowledge gap we will analyse, at high precision, copper, silver and gold in volcanic glasses (and melt inclusions) at GEOMAR/University of Kiel and compare the results from the northern and southern Kermadec arc. This will enable us, for the first time, to determine the extent to which the thickness and composition of the subducting slab influences copper, silver and gold contents within arc volcanoes. It will also allow us to quantify the amount of these elements that is being removed from the melt during its evolution and ascent. Understanding the processes behind the source and transport of strategic metals will provide vectors for explorers to discover new mineral deposits. Our GoldTrace project has the potential to provide a globally applicable model delineating where and why explorers can expect to find hydrothermal mineralization on the seabed.
Original text from CORDIS.
Participants
- HELMHOLTZ-ZENTRUM FUR OZEANFORSCHUNG KIEL (GEOMAR) · KielCoordinatorGermany
Links
Data: CORDIS, © European Union