A Heavy Mineral Exploration in Allahyar Alluvial FanSediments of East Iran
|Category||Economic geology & mineral exploration|
|Location||21th symposium on geosciences|
|Holding Date||21 May 2008|
The studied area, the Allahyar alluvial fan sediments, is located in the south of Birjand city, east Iran which is limited by the 59 00 00 and 59 07 00 degrees of east longitude and the 32 41 00 and 41 49 00 degrees of north latitude. The whole region is a part of Sistan block that is separated by the Hirmand fault from the Afghan block in the east and is also separated by Nehbandan fault from the Lut block in the west. The ophiolitic rocks such as pillow lavas, dolerites, gabbros, dunites, harzburgites, and lherzolites cover the studied area where the Allahyar fan sediments have been originated from it.
The preliminary assessments were carried out and it was found that Allahyar fans may be subject of a semi-detailed exploration program. 30 samples were taken from the depth of 50 cm in the main streams and channels of the fan. Samples of the minus 120 mesh fractions were subjected to heavy mineral separation by water washing. The identification of the magnetic and non-magnetic heavy minerals were done by using SEM, Scanning Electron Microscope The - 120 mesh fractions of the 30 original samples were also subjected to analysis by AAS, Atomic Absorption Spectrometry, for the elements Fe, Cu, Cr, Ni and Pb. The results indicate that the range of Fe contents vary from 1800 ppm to 80000 ppm. Cu contents ranges from 100 ppm to 400 ppm (C.V.= %56). The threshold of Cu is 239 ppm implying that the central, north and south part of the area have some potential for further investigations. Cr contents vary from 100 ppm to 400 pp. The threshold of Cr is 260 ppm indicating some potential in the southwest in the north of area. Ni contents vary from 100ppm to 400ppm. The threshold of Ni is 333ppm indicates some potential in the north and west of the area.
The presence of the anomalies for the elements Cu, Cr, Fe and Ni are related to the occurrences of their corresponding heavy minerals which in turn may be originated from the overlying ophiolitic rocks of the studied area.