Writers : Pourlatifi,Ali; supervisor:M.H. Emami; advisor: A. Aghanabati
Refference : M.Sc Thesis _ Islamic Azad university,North Tehran Branch;236p.
Publishing Year : 1383

Abstract :

The Northern Ferdows investigations span the North end of central Iran Basin and include part of the Kalat, Gorgou, Doghol-kuh and Ghalifuk Mountains. It is underlain by a basemeni terrane comprising Paleozoic and mesozoic metamorphic rocks, plutonic rocks and Cenozoic hypabyssal volcanos. The Paleozoic and Mesozoic terranes are capped by a widespread Latc Tertiary to early Quaternary volcano surface preserved in remnants in the Northern part of Kalat, Doghol-kuh and Ghalifuk Mountains and buried beneath late Cenozoic deposits ir soutwestern part of Kalat Basin. A sequence of at least three Quaternary pediments are planed into the soutwestern part of Kalat Mountains, each in turn overlain by successively youngei residual and alluvial deposits. The Tertiary volcanic rocks are deformed and broken b .northeast-southwest-trending, high-angle, dip-slip faults in the Mountains and an northwest southeast trending system of high-angle dip- and left-slip faults. In quadrangles around th Ferdows quadrangle, faults of the both sets displace Tertiary sedimentary rocks and volcanic deposited on the Tertiary surface and Pliocene and (or) Pleistocene deposits that accumulated .on the oldest pedimentThe volcanic rocks of "Ferdows area, are characteristic of Calk-alkaline lavas as Basali Andesite, Trachyte, and Rhyolite Groups and represent individual eruptive centers with possibk multiple vents. Two pyroclastic units have been separated at the study area based on texturai and compositional features as well as their stratigraphic positions. The western part of lava comprises basal accidental lithic rich tuff breccias and unsorted, weakly bedded lapilli tuffi inferred to have been deposited by Rhyodacite deposition of fall back tephra and/or higF concentration pyroclastic density currents from vent opening phreatomagmatic explosions neai vent. Above this unit, is Andesitic rocks by high-concentration pyroclastic density currents. Ir the eastern side of the area a large and complex Agglomeratic volcanic rocks and pyroclastic sequence developed by phreatomagmatic explosion generated pyroclastic density currents of decreasing energy and efficiency followed by magmatic explosion generated fall-out Accidental lithic fragments in the pyroclastic beds are derived from pre-volcanic strata that arc not now preserved in the vicinity of The vents but which are inferred to have been present at thc ,site at the time of eruption. be existing in the area during the volcanism -The Ferdows volcanic rocks are characteristic of Continental rift magmatism on the west northern margin of the Kavir-e Loot plain. These rocks extrudes on the Palaeozoic-MesozoicSardar and Shemshak formations and are unconformably overlained by Upper Quaternar clastics. Composition of these rocks are Alkaline changed to calc-alkaline and calcic ir character. Plots of maj or-element oxides against Index differentiation (ID) indicate fractionatior trend for these rocks, The Ferdows volcanic rocks have Potassic-type characteristics based or geochemical compositions. LILE elements are enriched compared to the HFS elements and spider-diagram patterns are similar to those of continental rift zone rocks. The geochemical date also imply that the Ferdows volcanic rocks are composed of magmas, derived from mantk sources that have undergone limited contamination. On tectono-magmatic discriminatior diagrams, the Basalts plot in the continental within plate fields and thus can be classified a post-Orogenic relaxations. Geochemical comparisons of the Ferdows volcanic rocks are witF Kenia (within plate rift zone) from the East African plate. This suggests that the rocks arc ,comparable in the tectonic processes which led to their formation.

Subject List : volcanism and volcanic rocks