1:20000 geochemical exploration in the Khoshumi Mountain
Reza Hosseinzade, Bahram Sadeqi
The study area, 52 Km2, is located in the 1:25000 topography map of Darrehanjir, between 55 60' 30" to 55 11' 30" E and 32 22' 30" to 32 27' N. This zone is situated in the Central Iran and Yazd province, between Saghand and Kharanaq villages. Geochemical sampling was done based on grid designed with consideation of lithology, faults, drainage system and etc. Totally, 202 stream sediment (four samples per square kilometer), 58 heavy mineral and 52 rock and mineralized samples were taken. After preparation, the samples were analyzed for Fe, Sb, Cd, Ba, Bi, Sr, As, Hg, Ag, Cu, Zn, Pb, Sn, Mo, W, Au, Sc, V, Cr, Co, Ni and Ti. Au was analyzed by emission spectroscopy, W and Mo by polarography and other elements by XRD. Ti, Fe and Mn were analyzed as oxide.
After data processing, the distribution maps of 15 elements were prepared. Heavy mineral and mineralized samples also were studied to control the identified anomalies. Some thin sections were prepared from old workings and mineralized zones.
This area has good potential for Cu, Pb, Zn, Ag, W and Bi mineralization. But the maximum observed gold content was 2ppm.
The mineral potential of the area is concentration in NW-SE trending zones within two main lithologic units: the marble-limestone of Rizu series with maximum concentration of anomalies, the metamorphosed units of the Tashk formation in the northwestern region.
Final anomalies include 6 zones with 4.5 Km2 areas.
1- Chah Sorkhu abandoned mine and its northern portion (0.6 Km2) with Sr, Sn, Pb, Cu, Cd and Ag anomalies. South of it, there is a Zn anomaly. Heavy minerals include Zn ores, pyrite oxide, scheelite, vanadite, Cu and Zn ores. Mineralized samples had up to 11 ppm Au, 1.5% Cu, 0.5% Pb, 3056 ppm Zn, 29 ppm Ag, 212 ppm W and 2733 ppm Bi. Thin sections contain chalcopyrite, antimonite, sphalerite, pyrite, malachite and iron hydroxides.
2- Around the ChahJamal and Yengehdonya abandoned mines (1.5 Km2) with Zn, W, Sb, Hg, Ag, Au. Heavy minerals include Cu and Pb ores, pyrite oxide, Au, pyrite, scheelite and orpiment. Mineralized samples contained 11 ppm Au, 13.41% Cu, 2.4% Pb, 1.3%Zn, 1016 ppm Ag, 211 Mo and 1175 Bi. Polymetal mineralization is probable in this area. Thin sections contained malachite, azurite, pyrite and ilmenite.
3- Chahjamal in the central area (0.5 Km2) with Au, As, Sr and W anomalies. Heavy minerals include lead ores and pyrite oxide. Rock samples contained up to 2 ppm Au, 105 ppm Ag, 7% Cu, 5% Pb, 4230 ppm Zn, 1040 ppm Bi. Intensive alterations include hematitic, limonitic and gypsum.
4- In the south of the region, Zn, Cd, Au and Mo anomalies exist in the 2 Km2 wide zone. Heavy minerals include gold, pyrite, pyrite oxide, orpiment, scheelite, vanadite and Cu, Zn and Pb ores. A mineralized sample had 254 ppm As and 28 ppb Au.
5- The stream of Zaj mine (0.3 Km2) with W anomaly. Heavy minerals include scheelite, vanadinite, wulfenite, pyrite oxide, orpiment, Cu, Zn and Pb ores.
6- Upstream of sample 92 (0.3 Km2), there is a tungsten anomaly. Heavy minerals include scheelite, vanadinite, wulfenite, pyrite oxide, Pb, Zn and Cu ores and orpiment. A mineralized sample from slicic vein with scheelite, malachite, pyrite and chalcopyrite had 1885 ppm W, 2.63% Cu, 815 ppm Bi, 5.8 ppm Ag and 52 ppb Au.