Stratigraphic position, mineralogy and distribution of the main elements in manganese oxide minerals of Mohammadabad deposit in the Late Cretaceous volcano-sedimentary sequence, southwest of Sabzevar

Mohammadabad manganese deposit is located in the Sabzevar zone and in the Late Cretaceous volcano-sedimentary sequences. This volcano-sedimentary sequence is located inside a 100 km long folded structure with northeast-southwest trend. Mohammadabad deposit is formed in the southern edge of the southern anticline. The geometry of this deposit is stratiform and manganese mineralization is limited to the marly tuff-limy tuff host rock. Ore facies in this deposit are divided into three types feeder zone, bedded and massive ore facies. The high-grade mineralization is formed in the western part of the deposit and in the massive ore facies. Manganese oxide-hydroxides are the main ore minerals in Mohammadabad deposit. Mineral structure and texture are observed in the form of massive, laminae, nodules, disseminated and replacement of manganese minerals in the inner cells of foraminifera and radiolarite fossils. The mineralogy of the minerals includes pyrolusite, psilomelane (romanchite) and manganite minerals. Chlorite, carbonate and argillic alterations observed in the Mohammadabad deposit with related of ore facies. In order to accurately determine the chemical composition of the mineral phases, SEM studies were performed and using the elemental distribution map, the oxidation of manganese minerals was confirmed, which indicates that silica is the main cement of manganese-bearing nodules.