Chemical Signatures of Ge in Magnetite of Wugang BIF, China

Abstract

Magnetite is a representative ore mineral found in various deposits. The trace element composition of ore deposits is controlled by several physiochemical factors such as temperature, pressure, and oxygen or sulfur fugacity. The chemical behavior of Germanium (Ge) is distinct in different environments. Consequently, the composition patterns of Ge in magnetite can be used to infer the provenance conditions. This study focuses on the Ge composition in magnetite from the Wugang banded iron formation (BIF) to understand the compositional characteristics of BIF sources and reconstruct of origin of Wugang BIF. The magnetite of the Wugang BIF has a porous texture, indicating high dissolution-reprecipitation processes and easy fluid infiltration, owing to its increased effective permeability. The Ge in the magnetite of the Wugang BIF was incorporated into iron hydroxide from the hydrothermal fluid and seawater during precipitation. The formation period of the Wugang BIF was consistent with significant oxidation events that led to the oxidation of ferrous ions in the Precambrian Ocean. Certain processes promote the chemisorption and coprecipitation of Ge into iron hydroxides or oxides.

Keywords

• germanium
• hydrothermal fluid
• paleo-depositional conditions
• banded iron formation