Magmatism and alteration zones of Meshkin Shahr
A 130 Km2 wide area in the northwest and west of Meshkin Shahr , northwest Iran was studied for mineral exploration at 1996. The study includes sampling for petrography, heavy mineral and geochemical analyses, assessment of different magmatic phases and facieses and the boundary between alteration zones, determining the alteration and magmatism trends and preparation of geology map of alteration zones.
At whole 120 samples were taken for mineralography and petrography. 50 samples from alteration zones were analyzed by XRD method. 180 heavy mineral samples also were taken. Each sample was primarily 20 Kg that washed and dressed to 10-20 g samples. These samples were studied using binocular microscope. XRD and Cu-anticathode methods were used for mineralogy and phase detection.
The result of study shows that:
- Intrusive and volcanic rocks have the same origin with geochemical correlation, i.e. they are comagmatic. The diversity of facies is due to magma differentiation and different crystallization condition.
- Magmatism is in relation to E-trending faults. It shows granular to porphyry textures.
- Gabbroid rocks are Eocene in age, because theirs xenoliths exist in the granitoids.
- Magnetite, hematite, and manganese mineralizations are in relation with diorite, quartz diorite, and granodiorite rocks (Skarn type).
- Monzonite and quartz monzonite bodies contain polymetal mineralization (Cu, Mo, Pb, Au and Ag).
- Pegmatites contain B-bearing tourmalines.
- Rhyolitic, dacitic and andesi-basalt domes are younger than Oligocene, showing lesser weathering.