Petrology and alteration of igneous units within the 1:100000 geological map of Tarq
Systematic exploration project on the Oroumiye – Dokhtar belt
Project Managers: Mohammad Javad Vaez Poor
Producer: Mohammad Reza Sahandi
The study area is located in the tectonic zone Oroumiye – Dokhtar magmatic belt. Igneous rock units include volcanic rocks, pyroclastics and igneous bosdies at north and northeast of the city Tarq. There rocks with a basal conglomerate are located over the older Triassic rocks. Based on the microfossils within them, they are Lower to Upper Eocene in age. The magmatism in this portion is not restricted to the volcanism and pyroclastic rocks, but also there are various compositions of intrusive bodies such as diorite, granite and amphibole granite. The igneous bodies cut the Triassic-Jurassic rocks and have caused contact metamorphism (i.e. epidote hornfels, pyroxene and amphibole hornfels).
Sub-volcanic rocks such as rhyolite, dacite and quartz latite form small dome-like bodies in the Eocene rocks. It seems that they are controlled by faults. Volcanic rocks composition includes olivine basalt, basalt, andesite, latite, trachy-andesite, rhyodacite and pyroclastics. Approximately all of these rocks show alkaline series. Two samples show calc-alkaline series with sodium and little potassium. The diagrams show that the magmatic activity is related to orogenic activity, island arc tholeiitic basaltic lava. Rhyolitic to dacitic lava in within the basic series may be related to the partial melting of continental crust.
The pyroxene diorite body 30 sq. Km outcrop is located near the Tameh village. It has also apophyses in the Eocene rocks and caused contact metamorphism. The composition of the body varies between Quartz monzodiorite and pyroxene diorite. Studied samples show that the body is sub-alkaline and metaluminous related to the VAG setting.
Granite to amphibole granodiorite bodies exist in two places. A granit-granodirotie stock with 18 Sq. Km outcrop at north of Karkas mountain and another body at north of Tameh village. All samples of these bodies lied within the Na and K bearing calc-alkaline series. They are metaluminous and synorogenic.
Occurred alterations include propylitic, argillic and hematitic those are related to intrusion of acid bodies and also travertine forming hot waters. The fault and fracture network promotes the alteration. This sheet has just little copper and iron mineralization as malachite and oligist.