Geological assessments in the northwest of Karaj
Tehran Padir Consulting Engineers
Geological survey at northwest of Karaj was conducted in an area of 300 Km2 that result in 1:50000 geology map. The project was done on the base of the contract between Industries and Mines Organization of Tehran and Tehran Padir Consulting Engineers. Field works for geological studies started after geochemical survey to conduct the study toward proper trends of mineralization. The report describes the general geology, geomorphology, lithology, structure and mineral indications in the area. Sampling was done with aims of economic geology and geochemistry aspects. Petrography, mineralogy and chemical analysis studies were done on the samples. The method of analysis was X-Ray analysis. In petrography, both polished and thin sections were used.
The economic geology section of the report mostly focused on the lead and copper metallic deposits plus to barite, coal, and dimension stone as the non-metallic resources.
Filed survey was based on 1:50000 topography maps of National Geographical Organization of Iran (Fashand and Karaj-II) and 1:50000 aerial photographs. 30 samples studied for petrography, 10 samples for paleontology, 15 samples for main oxides, 10 samples for polished-section mineralogy, 10 samples for chemical analysis of metallic elements and 10 samples for XRF.
Generally, the lithology of the area consists of Precambrian – Paleozoic carbonate and siliciclastic rocks. Precambrian Kahar formation is the oldest exposed rock with a basal fault contact. Limestone and dolomite of Soltanieh overlies the Kahar. Cambrian Zagun and Lalun formations show extensive fracturing. These units are cut by younger small dykes that not mapped due to their size. Some fault zones in the area show evidences of mineralization where the sedimentary rocks adjacent to the intrusive rocks are lowly metamorphosed. Dominant rocks in the area are volcano-sedimentary rocks of Karaj formation that include shaly tuff, sandy tuff, limy tuff and conglomerate with andesitic lavas.