Detailed lithogeochemical exploration in the Barzhuk area (1:5000); Northwest Khoy
Based on a contract between the Geochemical Exploration Project of Khoy and Kawoshgaran Consulting Engineers, lithogeochemical sampling, trenching and exploration were conducted at northwest of Khoy County, in an area that is 47 Km2 wide. This area is located between 44 27' 53" to 44 33' 8" eastern longitudes and 38 35' 48" to 38 39' 42" northern latitudes. The area has a cold mountainous climate and high elevations. It is a NW-SE trending mountainous region that belongs to the Western Alborz-Azarbaijan structural zone.
Rock units of the area which encompasses the Khoy ophiolites can be classified into three zones; northern marine basalts, middle ultrabasic rocks and southern gabbro intrusions.
The Barzhuk ophiolite sequence includes serpentinized harzburgite, serpantinite, dunite and pyroxenite. There is a xenolithic marble layer in the sequence that indicates the disruption of it. Doleritic and rodingitic dykes are abundant in the sequence. Intrusive rocks include gabbro and microgabbro that caused the alteration of ultrabasics. Volcanic rocks include basalt and andesite porphyry of Cretaceous. These rocks are thrust over the ophiolitic sequence. The ultrabasic rocks have altered to listvenite. Cenozoic rocks also are present in the region that involve Eocene limestone, marl and conglomerate the cover the ophiolite unconformably.
There two fault system in the area including NE-SW Palangu and NW-SE trending Barzhuk faults.
The geochemical exploration was done by sampling from eight N-S trending sections. Each sample was analyzed for elements that selected based on the lithology. For example, the harzburgites analyzed for Cr, Ni, Co, V and Cu; rodingites for Cr, Ni, Co, V, and Cu; pillow basalts for Zn, Pb, As, Hg and Cu; gabbros for Zn, Pb, V, Ti, Fe and Cu and listvenites for Au, Cu, Hg and As.
The geochemical data show that harzburgites as well as rodingites have anomalous quantities of elements. However basalts are relatively normal in content of elements. Gabbros show a little Ti enrichment; but the listvenites are normal. At whole, harzburgites, rodingites and gabbros have anomalous content of selected elements; however harzburgites are important rocks for chromium mineralization. Based on the prepared anomaly maps, against Ni and Co, the Cr anomalies are not correlated well with rock exposures in the trenches.
Harzburgites contains chromite lenses in which 11 trenches have been excavated. Chromite has occurred as small exposed lenses and also banded layers with nodular texture. The deposit type is podiform. The result of analysis of samples shows that the available chromite is a second and third grade mineral. The ore reserve is 21000 tons with 16.9 to 46.9% chromite. The are requires further investigation.