A Multi Source Origin Of Manganese For The Montaña De Manganeso Deposit, Central Mexico: Evidence From Geochemistry

Abstract:

The Montaña de Manganeso manganese deposit is a vein-type deposit spatially associated with ophiolitic remnants of the Guerrero tectonostratigraphic terrane. The study of the rare-earth element and ytrium (REY) geochemistry coupled with major and trace-element geochemical characteristics of the Montaña de Manganeso provided insight into the controls on ore-forming processes. The deposit is characterized by low trace elements (Co, Cu and Ni) contents, high Mn/Fe ratios (< 455) and high Ba (>10 000 ppm) contents typical of hydrothermal deposits. REE normalized profiles , Low ∑REE abundance (18.7 to 103 ppm), negative Ce anomalies (0.2 to 0.6), positive Y anomalies (1.00 to 2.34) and mostly positive Eu anomalies (0.6 to 4.4) indicate hydrothermal source for the Montaña de Manganeso deposit. ∑REE vs (Cu+Ni+Co), Zr vs (Cu+Ni+Co), Ce/Ce* vs Nd, Ce/Ce* vs Y/Ho discrimination plots also indicate a hydrothermal source and predominantly oxidative conditions during deposition. The Mn-Fe-(Ni+Cu+Co), MnO₂-MgO-Fe₂O₃, (Cu/Zn)/Fe₂O₃vs (Zn/Ni)/MnO₂, Na-Mg discriminating diagrams as well as comparison of the Montaña de Manganeso manganese deposit with continental and submarine hydrothermal manganese deposits reported in literature shows that the Montaña de Manganeso deposit displays both marine and terrestrial geochemical signatures. The deposit formed through a two-stage hydrothermal process involving formation of primary manganese oxides by hydrothermal/diagenetic processes on the sea floor. Subsequent to accretion of the Mn enriched ophiolite sequences of the Guerrero terrane onto the continental Mexico, continental hydrothermal activity remobilized the primary oxides which were then redeposited upon mixing with shallow meteoric waters.