Geochemical exploration in 1:100000 sheet of Ayask
The 1:100000 map of Ayask is located in northeast of Iran (south of Ferdows county). It is bounded to 58? to 58? 30' eastern longitudes and 33?30' to 34? northern latitudes. This region is part of Lut block. It is mostly covered by 2000-3000 meters thick Cenozoic volcanic rocks including andesite, basalt, and dacites. Neogene-Quaternary terrestrial deposits are the youngest unit of the region. The extent and thickness of Paleogene volcanic rocks are lesser than Neogene. Their composition varies between andesite and dacite. These rocks are main responsible for mineralization in the region. Neogene volcanic rocks, andesite-basalt in composition, are very abundant in the region and show lesser tectonic deformation. Other exposed rock units in the area involve Jamal carbonate deposits of Permian, Triassic arenite, limestone and shale of Nayband, Shemshak arenite-shale formation of Jurassic, Baghamshah shale, marl and sandstone of Jurassic, Qaleh Dokhtar and Esfandiyar formations of Jurassic, Cretaceous limestones, Paleogene andesite, dacite, rhyolite and marl, and Neogene-Quaternary tuff, andesite, volcanic glass, ignimbrite, trachite, basalt, diabase, sandstone and deposits.
Rock layers in the region are gently folded. High angle strike slip with few oblique slip faults exist in the area.
Volcanic activities and hydrothermal fluids have caused vein-type antimony mineralization in Shourab and Gallehchah abandoned mines and associated mineral indications. Mineral indications of bentonite and kaolinite occurred due to weathering of rhyolite and dacitic tuff, especially at northeast and southeast of the sheet. Sandstones of Qaleh Dokhtar formation show evidence of iron mineralization at south of Chahgarik and northwest of Chahqoli.
The geochemical survey was conducted by analysis of stream sediment samples for 23 elements including Mo, Ni, Ob, Sc, Sn, Sb, Sr, Ti, Ag, As, Au, Bi, Ba, Co, Cu, Cr, Cd, Fe, Hg, Mn, V, W and Zn. Statistical analyses, rock classification, calculation of enrichment index, normalization, and other required processes were done on obtained data from analysis. As a result, several anomalies identified, among which the most important cases are summarized in below table.