Petrography and petrology of latest stage of Savalan volcanic rocks
Subject Areas :
Mahnaz
fathollahi
1
(کارشناس ارشد پترولوژی پژوهشکده سازمان زمین شناسی)
mohamad hashem
emami
2
(عضو هئیت علمی پژوهشکده علوم زمین سازمان زمین شناسی و اکتشافات معدنی کشور)
monireh
kheyekhah
3
(عضو هئیت علمی سازمان زمین شناسی و اکتشافات معدنی کشور)
Keywords: Sabalan, crustal partial melting, intermediate rocks, fractionation, magma mixing,
Abstract :
In the latest stage of Savalan volcano formation, the Magmatism following the Subsidence of caldera Cause theformation of acidic and intermediate Dooms and viscose lava flows along fractures and within the margin ofCaldera. mainly having composed of plagioclase, clinopyroxene, amphibole, biotite, potassic feldspar andquartz, Textural and mineralogy relations that are observed in studied microscopic sections, such asglomeroporphyric and glomerochristic occurrence of Mafic minerals as well as the presence of non equilibriumtextures such ac sieve texture, bimodal composition of phenocherists of plagioclase, heterogenic composition ofmatrix, presence of basic micro pillows and enclaves in a acidic rocks, zenolites with reactional rims and alsoscattering and different trends observed in the geochemical reveals that fractionation, magma mixing and crustalcontamination has been play important role in formation of this magmas. On the other hand The intermediaterocks of the region form do to of the mixing of basaltic magmas with fractionated sections , that have beencontaminated with Crust during the ascent phase. Base on Petrographic and geochemical evidence presentedhear, we show that the acidic rocks vastly in the area have a different origin than andesitid and trachy andesitidlavas. Likely that these rocks are the result of partial melting of the crust, while the replacement of basic magmasin crustal magma mixing phenomena has also been made between the two.
