Trace metal partitioning in hydrothermal magnetite

Hydrothermal ore deposits host significant resources of iron and base, precious, and critical metals. Understanding the complex processes of ore formation is a smart way to identify unexplored geological zones where unidentified ore deposits may exist. The ubiquitously occurring ore mineral magnetite has become an important study objects in the course of finding new ore deposits, because it is known that its chemical composition is a sensitive recorder of ore forming processes. The concentration of certain trace metals in magnetite can inform about temperature, pressure, and chemistry of the fluid magnetite precipitated from, but only if the partitioning behavior of a metal between fluid and mineral at various conditions is well known. However, this fundamental knowledge is missing to a great extend, and therefore a rigorous investigation of the mechanism and controls of metal partitioning in magnetite in relation to ore forming conditions and the hydrothermal fluid is needed. In this project we will investigate the quantitative distribution of metals into the mineral magnetite from a hot fluid from which magnetite precipitated. The approach is dual, meaning we obtain data from perfectly controlled laboratory experiments and more complex natural ore sample. The approach using both natural and synthetic samples allow for critical information feedback and data validation. To detect the distribution of trace metals at the micro- to nano-scale and to quantify the trace metal chemistry of mineral and fluid, we apply a multi-analytical program. Analytical techniques includes state of the art electron, X-ray, Raman beam and laser ablation mass spectrometry micro-analyitics, allowing the spatially controlled mineralogical and chemical analyses of minerals and fluids (latter are preserved as tiny inclusion in minerals). The new datasets allow earth scientists to determine the ore genetic conditions and to approximate trace element abundances of given ore-forming paleofluids from magnetite chemistry. The project can advance to become an exemplary study in hydrothermal ore genesis research. Successful experimental procedures will open paths for similar studies to come, including the investigation of other minerals and a diversity of fluids. Main researchers involved in this project are Dr. Thomas Angerer (PI at GeoSphere Austria), a postdoctoral researcher (at GeoSphere Austria), Ao. Prof. Ronald Bakker and Prof. Frank Melcher, both co-PI at Montanuniversity Leoben (fluid inclusions and mineral laser ablation mass spectrometry). Collaborating researchers are Prof. Liane Benning and Dr. Vladimir Roddatis, GFZ (transmission electron microscopy), Prof. Max Wilke, Uni Potsdam (synchrotron X-ray analytics), Prof. Etienne Deloule, CRPG-CNRS (oxygen isotopes), Dr. Tobias Fußwinkel, RWTH Aachen (fluid inclusion laser ablation mass spectrometry), Dr. Bastian Joachim-Mrosko, Uni Innsbruck (alternative experimental setups), Dr. Christin Kehrer, TU Freiberg, and Prof. Robert Marschik, LMU Munich (research collections). This project is thematically linked to DFG Sonderforschungsprogram SPP 2238 Dynamik der Erzmetallanreicherung (DOME) and project members will be closely affiliated and interacting with DOME through meetings, workshops, and conferences.