The role of third order basins in accumulation of heavy minerals in N-W of Dez area, Boroudjerd

Because of transportation of the sedimentary materials from the surface of continents,the continental environments have a significance importance among the other river environments. The quantitative study of these environments is done on the basis of their driange basins. This study is also done on the basis of the same aspect, with a special attention to the influences of the sub-basin on the accumulation of the heavy minerals. The proposed basin is the NW part of Dez basin that is located between two different geological zones, called Sanandaj–sirjan and Zagros crush zone.These geological zones are seperated by Boroudjerd- Dorood plane.The strahler grading order was used for ranking. Due to our knowledge, third – order sub- basins were selected as concentred places of heavy minerals for further studies. The main basin of the proposed area was a six –order type, that is a relatively high degree. Four drinage anomalys were seen in this area, that one of them was affected by the lithology characters of area and other were affected by the faults. The results show that faults have significant rules on the formation of third- order sub- basin. The proposed area has a suitable maturation, due to the high rank of it and existence numerous of the low- order sub- basins of the higher altitudes,so that number of the high – order sub-basins is 25 % relative to low-order sub – basins.Further studies showed that, the main heavy minerals are andalusite and kyanite in the third- order sub – basins that belong to sanandaj- sirjan zone. Finally, it was revealed that the six – order basin was a consequent type.