Preliminary exploration project of the Khur and Zirvaght manganese deposits (Central Khorasan)
The Report of 1:5000 geology map
At north of the Taknar fault in the Khorasan Province, in the Khur and Zirvaght areas, oldest exposed volcano-sedimentary rocks are followed by the lower Cretaceous limestones and Paleocene conglomerate. These rock units are laid upon the younger units along the fault. An ophiolitic complex belonging to the Sabzevar ophiolite trend includes these units:
1- intensely serpentinized periodotite with diabasic and andesitic dykes
2- basic to intermediate marine volcanic rocks of upper Cretaceous containing pillow basalts, spilite, andesite, and rhyodacite
3- radiolarite, pillow basalt and pelagic limestone
Tertiary deposits occur as conglomerate and conglomeratic limestone with nummulite fossils. Tuff, green tuff breccia and volcanic rocks are following the former limestone. Toward east, this unit finds a flysch facies with little evaporate.
Last magmatic activity in the area includes sub-volcanic intermediate intrusions. Manganese has occurred due to marine volcanism of the Late Cretaceous as discontinuous lenses in the Khur and Zirvaght areas. Numerous faults caused the rupturing and fragmentation of ore bearing lenses.