Geochemical exploration in 1:100000 sheet of Talkhab 1
The study area is located near the border of Iran and Pakistan, in the Sistan-va-Balouchestan province. It is a sheet in the Narehno quadrangle located between 61?30' to 62? Eastern longitudes and 28?30' to 29? northern latitudes. This sheet includes 1:50000 topography maps of Talkhab, Sharq-e Sangan and Rigmalek. From geological view, the area is located in the Southeastern zone of Iran and Nehbandan-Khash subzone.
Sedimentation in mentioned area was started by flysch type deposits having extensive diversity and thickness in Eocene period. With sea transgression and regression, conglomerate was deposited in Oligocene.
According to existing faults in Eocene and Oligocene-Miocene rocks, and deformation and metamorphism of these rocks, we can expect the orogenic activities at late Eocene and Oligocene-Miocene similar to neighboring regions. During Neogene, a massive polymictic conglomerate and an orange-color tuff unit were deposited that subsequently followed by Quaternary deposits. The conglomerate unit is folded. Based on performed studies on 1:250000 map of Narehno, there is no exposed rock older than Eocene in the area. Existing rock units include Talkhab Neogene conglomerate, Tilk Oligocene conglomerate, and Badamkouh mountain Eocene rock units, Oligo-Miocene metamorphosed and intrusive rock of Shahkouh and Quaternary rock units.
Existing faults system in the area has the general trend of NW-SW. Fold types include normal anticlines and synclines, which have NW-SE trend.
In the study region, an area near 1300 km2, 192 geochemical samples were taken that analyzed for 35 elements involving La, Zn, Cr, Mn, Ba, Au, Sm, Zr, Ag, As, Co, Cu, Cd, Hf, Nd, Mg, K, Ca, Si, Al, Fe, Ti, Sr, Na Ce, Bi, Y, Th, Sn, Pb, Nb, Mo, Sb, W and Ni. Au element measured by spectrograph emission and W and Mo elements by polarograph and other elements by XRF and AAS methods. After processing the geochemical data, three regions indicated as anomalous. 27 Heavy mineral and 8 mineralized samples were also analyzed. Statistical processes on geochemical data include rock classes separation, assessment of Clark values in the exposed rocks of the regions, local field assessment of each rock class and its comparison with whole community, statistical parameters calculation from raw data and their normalization, omitting out of order data, correlation coefficient calculation, uni- and multi-variables statistical analysis, cluster and factor analyses, calculation of enrichment index of each class, anomalies separation from field class by PN method and network data estimation.
After controlling the anomalous areas, sampling for heavy mineral and mineralized zones, and compilation of existing data layer, favorable zones were introduced. In these layers, geochemical and fault data are more important because of special features.
The area at south of Rigmalek village that is located in southwest of 1:50000 sheet of Rigmalek, is 166 km2 wide. Outcropped lithology includes shale, sandstone, limestone, schist, granite, gneiss, metabasics, skarn, slate and garnet schist. Migmatitic gneisses that resulted from metamorphism of the granitic bodies in the area have skarn contact. They are very suitable areas for exploration activity. Observation of gold peaces (2 peaces), scheelite (7 peaces), mimetite (4 peaces), pyrite (20 peaces) and native lead (2 peaces) in heavy minerals is an evidence of this fact.