Synchrotron based micro-mapping and XAFS investigation of Fe-Mn and epigenetic intergrowth Within the Cambrian shallow manganese deposits, South Jordan

Abstract EN

The current work investigates the Cambrian Manganese ore deposits from Wadi Dana at central Wadi Araba region.

This investigation aims to unravel the chemistry and microtextures of the mineral paragenetic sequence for these manganese ore deposits.

Particularly the Fe–Mn intimate intergrowth micro texture and the epigenetic Mn mineralization associated with Cu minerals.

The combination of the synchrotron-based X-ray fluorescence (syn-XRF) micro-mapping and X-ray absorption fine structure (XAFS) techniques were used.

They provide a clear picture of the elemental distribution of Mn, Fe, Cu, and Pb and other elements presented within the ore micro textures.

Besides, it determines the exact elemental speciation.

The results obtained gave a better understanding of the elemental atomic structures and eventually the depositional environment.

Particularly, the syn-XRF micro-mapping reveals the existing of many successive evolution stages in the Mn ores.

Besides, the X-ray Absorption Near Edge Structure (XANES) results showed that the micro-rhythmic texture is changing from Mn+4 (Pyrolusite) into Fe+3 (Hematite).

This is evidence for the role of Eh as the main controlling factor during the ore formation.

Eventually, indicating tentatively the paleoceanography setting of the Mn deposits.

This is related to the continuous transgression-regression on the sea level in a semi-closed sea.