Geochemical and geological assessment of northwest Karaj, volume 1: geochemical survey on the scale 1:50000
Geochemical survey at northwest of Karaj was conducted in an area of 300 Km2 by stream-sediment and heavy mineral sampling, based on the contract between Industries and Mines Organization of Tehran and Tehran Padir Consulting Engineers.
Field work for taking stream sediment and heavy mineral samples was started by photogeology of aerial photos with scale ~1:50000 (NGO). Prepared samples were analyzed by atomic absorption method. At whole 163 sediment and 50 heavy mineral samples were analyzed and studied. The result of survey indicates that:
1- Copper mineralization has occurred in the Eocene volcano-sedimentary rocks, south of Senj village, in the fault zones between Infracambrian and Eocene rocks at northeast of the area. The copper anomalies have malachite, azurite, and chalcopyrite heavy minerals. Copper shows positive correlation with Pb, Zn, Ag, and Co with 99% confidence.
2- Pb-Zn mineralization mostly occurred in the fault zones within Eocene volcanics with barite veins. Also a dyke in the Infracambrian rocks at north of the area contains Pb-Zn bearing baritic veins. Related heavy minerals include galena and pyromorphite.
3- Arsenic mineralization has occurred in the Eocene rocks. Also old carbonate rocks show little concentration of arsenic.
4- Cobalt mineralization has occurred in the Eocene rocks.
5- Ag enrichment has occurred in the Eocene rocks and older carbonate rocks. Anomalies number I, II and IV are more important.
6- Gold, bismuth and molybdenum donít show notable enrichment.