Geochemical exploration in the Chahsangi sheet of 1:100000
The study area is located in the 1:250000 quadrangle of Jahanabad, between 59 30' to 60 E and 28 to 28 30' N. It includes 1:50000 sheets of Pak, Sharq-e Gahqan, Shomal-e Gandoman and Gahqan. The oldest available information regarding the area includes general geology reports of the NIOC and aerial photographs. The geological mapping of Jahanabad quadrangle was done at 1975-78 in the East Iran project.
This area contains a NW trending anticline and several N-S to NE-SW trending faults. The oldest known units are Miocene sandstone, volcanoclastics, siltstone, tuff, andesite and dacite.
Various factors affect the design of sampling network. So the drainages were mapped using topography maps and aerial photographs. By application of GIS, other factors such as petrology, tectonics, contacts and alteration zones were also considered. The designed network contained 900 sampling points. But only 738 points were sampled because of accessibility and security.
The samples were analyzed for Hg, W, Pb, Ni, Mo, Sn, Ag, Co, Cu, B, Zn, Cr, Bi, Ti, Mn, Ba, Au, As, Sb and Be elements. Au analyzed by spectrography, W and Mo by Polarograph and the other elements by atomic absorption methods.
After processing and analyzing the obtained data, 20 anomalies were identified. The geochemical anomalies were controlled by heavy mineral and mineralized sampling. 84 heavy mineral samples were studied for the Chahsangi sheet. After compilation of different information, two zones introduced for further study.
It is located in the southeast of Gahqan sheet that shows intensive alterations in the andesite, dacite and other rocks. Alterations involve kaolinitic, silicic, hematitic and limonitic. Apatite, barite, spinel, ceruzite, epidote, galena, goethite, andalusite, ilmenite, chromite and several other heavy minerals found in the area. The zone is anomalous for Mo, Pb, Au, Ti, W, Sb, Co, As, Bi, Ni and Ag elements.
Zone II: southeast of Pak sheet
It is located near the Chah Qanbar spring at west of the Chah Qorban mountain. It is anomalous for Ba, As, Bi and Cu. Lithology include olivine basalt, andesite, conglomerate and breccia. Mineralized samples include pyrite and malachite and marcasite mineralizations. Silicic, hematitic and limonitic alterations are extensive. Identified heavy minerals involve apatite, barite, limonite, celestine, pyrite, pyrite oxide, goethite, ilmenite, leucoxene, hematite, magnetite, nigerine, malachite, zircon, oligiste, saphir and rutile.