Geochemical Survey in the 1:100000 sheet of Spakeh
This report is about systematic geochemical survey in the Spakeh sheet (1:100000) that is located in the Sistan and Baluchestan Province, between 60 to 60 30' E and 26 30' to 27N. It falls within 1:250000 quadrangle of Nikshahr and includes four 1:50000 sheets of Surmich, Jaks, Chanf and Spakeh.
Geologicaly, the area is part of the Southeast Iran flysch and ophiolite zone that contains a complex assemblage of ophiolite, colored melange, flysch and alluvium. The area situated within Western Makran that is a oceanic-continental convergence boundary. The area has importantn NE-SW, E-W and N-S faults such as Lashar and Pip.
The survey was done by stream sediment sampling method. The sampling network was designed on the base of weight center of drainage basins. For this, topography maps and aerial photographs were used. Other factors such as tectonics, intrusions, alterations and faults were also important in the network design. At whole 807 samples were designed to be taken from 2160 square kilometers, but during sampling, only 528 samples were taken because of accessibility and security problems in the area.
Each samples consisted of 500 g of 80 mesh stream sediments of which 100 g has been analyzed and the rest was archived. The samples were milled to 200 mesh and then analyzed. All samples were analyzed for 23 elements including Zn, Cr, Ti, Mn, Sr, Ba, Au, As, Sb, Bi, Hg, W, Pb, Ni, Mo, Sn, V, Cd, Sn, Ag, Co, Fe and C. Au was analyzed by atomic absorption, Mo and W by polarography and the other elements by XRF.
After obtaining the analysis data, they were processed to determine the geochemical anomalies in the area. 21 geochemical anomalies identified in the shet. To check the anomalies in the filed, we used heavy mineral sampling method. Considering the extent of the area, 177 samples were collected from alluviums with density of one sample per 15 Km2. As the result of the project, several promising zones were identified that are described in the report.