Genesis and evolution of the San Manuel iron skarn deposit (Betic Cordillera, SW Spain)

The San Manuel magnesian skarn is an iron deposit hosted in dolomitic marbles from a tectonic slice imbricated within the Ronda peridotites, westernmost part of Betic Cordillera, Spain. According to dominant mineral assemblage, subdivided into three different zones, (1) forsterite ± calcite skarn, (2) chlorite serpentine and (3) Ca-amphibole skarn. main ore ? 2.5 m thick, massive body situated middle sequence. In this paper, we firstly report comprehensive major trace element composition, texture, microstructure, mineralogy characterization for zoned magnesioferrite-magnetite grains using combination laser ablation inductively coupled plasma mass spectrometer, focused ion beam combined with transmission electron microscopy, back-scattered diffraction. We have defined four generations. A complete sequence zoning includes cores magnesioferrite (Mag-1; MgO up 10.6 wt%) overprinted by successive generations magnetite, namely Mag-2, Mag-3, Mag-4. Mag-2 (MgO < 4 wt%), hosts composite inclusions, consistently high Si, Ca, Sr (average: 8204 ppm, 8980 49 ppm respectively) contents detected situ (LA-ICP-MS). Mag-3 replacing former Mag-1 nanometric spinel gahnite exsolutions microscope (FIB-TEM), which consistent its Al, Ti, V, Ga 5073 368 20 concentration. Mag-4 Fe-richest magnetite (up 94.16 wt% FeOtotal) forming outermost rims grains, exhibiting lowest total contents. Approaches temperature estimations employing magnetite-spinel suggest that minimum prograde stage reached temperatures below 700 °C, whereas should be formed during retrograde stage. Magnetite microstructure studied backscatter diffraction (EBSD) suggests formation under fluid-assisted dynamic conditions, evolution emplacement. propose pulsed hydrothermal fluids derived anatexis crustal rocks peridotite emplacement, promoting re-equilibration processes led zoning.