Rare-earth element distribution and genesis of manganese ores associated with Tethyan ophiolites, Iran: A review

Abstract

The Zagros orogenic and metallogenic belt is characterized by the widespread occurrence of manganese and ferromanganese deposits. These deposits are spatially associated with radiolarian cherts and basaltic rocks, which cap the ophiolite sequences. The present work provides a review on the rare-earth element (REE) geochemistry coupled with major- and trace-element geochemical characteristics of the Nasirabad and Abadeh Tashk manganese deposits (associated with the Neyriz ophiolite), and Sorkhvand manganese deposit (associated with the Kermanshah ophiolite). These data are used to gain an insight into the primary ore-forming processes that control the deposition of manganese ores. All of the selected manganese deposits have consistently high Ba contents and low concentrations of trace elements (Co, Cu and Ni) with high Mn/Fe ratios typical of hydrothermal activity. A relatively low REE abundance, Lan/Ndn ratios (>3), and position on a Lan/Cen vs. Al2O3/(Al2O3 + Fe2O3) discrimination plot indicate a distal hydrothermal source for almost all of the selected manganese deposits. Most of the deposits are characterized by Ceanom < –0.1 which reflects the prevailing oxidative conditions during the deposition of manganese ores. Importantly, this is consistent with the occurrence of non-sulfide oxic Mn mineralization in all the manganese deposits of the Zagros orogeny. The comparison of the Sorkhvand, Abadeh Tashk and Nasirabad manganese deposits with other manganese deposits elsewhere in the world indicates that major- and trace-element characteristics, as well as the REE composition of the Zagros manganese deposits are analogous to those typical of hydrothermal deposits.

The Coal-Forming Environment at the End of the Late Permian and Its Control on Trace Elements: The Upper Xuanwei Formation in Eastern Yunnan, China

“…Rare earth elements (REEs) are often used to indicate the redox conditions of the paleoenvironment due to their sensitivity to changes in the sedimentary environment. The Ce anomaly parameter (Ce anom ) proposed by Elderfield et al has been widely used in the identification of paleoredox conditions [53,54]. Generally, Ce anom > −0.1 indicates a reducing environment, while Ce anom < −0.1 indicates an oxidizing environment.…”

Mineralogical and Geochemical Characterization of Asbestiform Todorokite, Birnessite, and Ranciéite, and Their host Mn-Rich Deposits from Serra D’Aiello (Southern Italy)

“…Geochemical features of marine siliceous sediments, in particular the abundances of quartz and/or of its polymorphs common in deep-ocean floor sediments and in ophiolite sequences [67,68], have been studied to obtain information about their sources and depositional environments [69,70].…”

Critical Metal Mineralogy: Preface to the special issue of Mineralogical Magazine

“…Finally, as demand for manganese is growing, there is an interest in a wider range of deposit types. Zarasvandi et al (2016) present a study of the manganese deposits associated with Tethyan ophiolites in Iran, and use their geochemistry to investigate their origin.…”