QE29 : Petrology and geochemistry¬ of igneous rock of Shahr-e- Firoozeh region (west of Neyshabuor) and their related mineralization
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2009
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Abstarct: The studied area (Shahr-e- Firoozeh), located in the 20 km west of Neyshabour and in the Northwest of Sahr-e- Firoozeh. This area is part of northern part of central IRAN structural zone. In this area, plutonic and sobvolcanic igneous rocks with compositional range include andesite, thrachyandesite, despite and hyalite have been outcropped. These rocks are manifested in the form of dike, stock and small domes, and in general they have NW- SE trend. Host rocks are Volcaosedimentary and volcanic rocks of Paleocene and Eocene. There are intercalations of Nummolite bearing limestone between Volcano-sedimentary rocks which confirm the middle to upper Eocene age for the host rocks. baxsed on, Field observation, the younger than Oligocene rocks (Pliocene conglomerate) have been not intruded by the studied igneous bodies. These are part of Post- Eocene magmatism which some their outcrop available from north of Sabzevar to south of Ghouchan or Esfarayen. Petrography studies indicate that these rocks mainly composed of plagioclase, hornblende, biotite, quartz and a little apatite, magnetite, zircon and sphene. Typical textures of the studied rocks are porphyry, microlitic porphyry, gelomeroporphyry and crossion gulf. Opacitization has been observed clearly around of brown hornblende and drak brown biotite. Some of the another typical phenomena are as follows: the evolvtion of hornblende to biotite, biotite to muscovite, Plagioclase to sericite or epidote, and ferromagnesian minerals to chlorite, sphen and iron oxides. baxsed on geochemical diagrams for nomen calturing of extrusive igneous rocks, the studied rocks were plotted in the compositional limites of andesite, thrachyandesite ,dacite and rhyolite. This subject confim the petrogeraphic studies and field observations. The mentioned rocks have middle potassium calc-alkaline and mextaluminous nature. In geochemical diagrams (bivarieant diagrams such as oxide-oxide, trase element and rare elements versus each others or versus the other oxides) the studied rocks indicate a approximately linear trend which confirm the fractional crystallization process. Also with respect to AFC diagram (Esperanca et. al., 1992 and Depaolu et. al., 1960), these rocks have been suffered contamination, in addition of Fractional crystallization. The presence of host rocks (tuffaceous sandstone and shale) enclaves in the studied igneous bodies, confirm the mentioned contamination. Mean while the presence of the mafic microgranular enclaves persits on the took placed magma mixing during the evolution of magma of the studied rocks. Rare earths elements, patterns and spider diagrams confirm the mentioned subjects. Negative anomaly of Nd,Ti and positive anomaly of Sr and Pb in the spider diagrams, fractioned patterns of LREES/HREES and LILES/HFSES indicats that the studied rocks bave been evolved by Fractional crystallization process. Investigation of geochemical characteristic of the mentioned rocks and their comparison with adakities, show that they have very similarities with actual adakite and also they belong to high silica adakites. baxsed on geochemical and petrogenetic diagrams, The studied rocks are the result of 10-20 percent partial melting of a young and hot oceanic lithosphere of sabzevar ocean which have been mextamorphosed up to Amphibolite facies then the resulted magma ascended to upper level of continental crustal and emplaced in the form of dike, stock and dome.
Keywords:
#Neyshabour #Shahr-e- Firoozeh #plutonic and sobvolcanic igneous #geochemical #adakite #petrogenes Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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