Unmixing the hydrothermal and detrital components from a metalliferous sediment core from the eastern Southwest Indian Ridge - Insights from mineral magnetism

Mineral magnetic and geochemical investigations were carried out on a short sediment core collected from the eastern Southwest Indian Ridge (ESWIR) to study the variations in the source components. The magnetic concentration parameter chi arm (representing the concentration of stable single domain (SSD) sized grains), magnetic grain size ratios chi arm/chi lf, chi arm/SIRM, geochemical ratios Fe/Ti, Co/Zn, and Zn/Fe and Ba content serve as hydrothermal indicators, all of which show a distinct top - bottom variability. The magnetomineralogical parameters S-ratio and coercivity (Hc) also follow these variations, suggesting an increased contribution of hydrothermal components in the top 15 cm of the core. Significant enrichments of Fe, Mn, and Mg in the samples, along with depletions of detrital elements Al, Si, Rb, Zr, Hf, and Nb in the element/Upper Continental Crust (UCC) values, show that the majority of the detrital component is locally sourced. Thermomagnetic measurements of samples indicate that the major remanence carrier is magnetite in the core, along with minor contributions from titanomagnetite, hematite, and iron sulfides.