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  Economic Geology
Perlite and Pumice
Title book : Perlite and Pumice
Author : Mansour Qorbani
Publisher date : February 2000
Chapter title : Chapter 4 – pumice and mineral gangs in Iran
Data title : 4-4-Sistan and Baluchistan Regions, North Jazmurian (Taftan Axis, Bazman and Shahsavaran Mount

-Geographical Position and conditions

Taftan , Bazmon and shahsavaran Mount. has extent  in south eastern terminal of Orumieh Dokhtar Zone , to south  lout Block and North Jazmurian and with a trend of E-W with a length of 200 km and in width of 10 to 60 km . This volcanic can be in Pakistan in the Mountain.

According Jiro and Conrad Writings (1976) Moinvaziri (1985), Amin Sobhani (1357) and age of most rocks is volcanic and these volcanoes are plio- guaternary and their lithological compostion changes from basalt to rhyodacite but their west volume rock is andesite and dadcite.

Taftan and Shahsavaran volcanoes are southern east terminal of Urumieh – Bazman Volcanic stripe that it is located among lout and Jazmurian depression. Thick Bazman volcanic Body and Shahsavaran Mount is an oval body with a trend of E – W with length of 120 km and in width of 60 to 70 km.

Young volcanic activities have been contrnued in shahsavarn Mount .with basaltic volcanism and chah shahi Mount.(North Iranshahr), Taftan and kuhsultan in Pakistan.

According to Jiao and Conrad writings (1976) Moinvaziri (1985), Amin Sobhani (1357) have determined age of these  volcanic material , rocks in these volcanic Plio – Quaternary and their litho logical composition is basalt to rhyodacite but  most volume of their rock is andesite and dacite (fig 4-4 ) Bazman volcanic Body and Shahsavarn Mount. is limited to south by Jazmuraion Depression .Eocene flisches  which are depressed towards body of a basin (Stoklin , 1975 ) All of these formations in Pliocene towards south part so that distance of Shahsavarn mount toward west by dextral fault of nay band is border     

According to Harison, slope of movement of Nayband fault is near to 120 km..

It is assumed that fault is yet active in western part and Eocene Flisch series from Zagros Limestone series and Chaman Fault is sinistral in Pakistan and it is mirror of dextral Nayband (Volman , 1965 ) are estimated in slope of drover movement of Chaman Fault near to 500 km .

Volcanic activity of Shahsavaran is initiated from 12.000.000 years ago and it is continued up to Quaternary (Jiro and Conrad, 1976) and lava in this volcano is located in angular inequality on Eocene and Oligocene volcanic Rocks in Shahsavaran Mount .More than granodiorite  intrusive bodies and volcanic and volcanic Eo – Oligacene Rocks have been eroded and they have been covered up to Mio – Plio – Quaternary ( Jiro and ZConrad , 1976 )


Petrography

According to Jiro and Conrad , Plioquaternary lava have been differentiated  in Shahsavarn mount.This series included basalts full of alomine, andesite, dacite, rhyodacite with nature of calc alkaline. Basalt is less than other volcanic rocks and old eruptions and first region Basalts are seen in body of extensive and regular bodies .Acidic rocks are separated among both flown with acidic volcanic rocks from each other.

Andesite makes over 50% of Shahsavaran volcanic body and they are very young because some andesite lava is preserved on recent deposits and some volcanic cones have been preserved well.

In Bazman Mount Andesites are seen in body of breccia, not cloud, pumice – bearing tuffs and ignimbrite which are representative of explosive eruptions.

Basalts with fixed mineralogical composition have thoroughly basic plagioclase phenocrysts (core of phenocrystal is 85% to 90% Anorthite ) Augite Olivine  (with react ionic margin of orthopyroxene) and a martial caused by plagioclase , alkaline feldspar and quartz from chemical aspect  , these  basalts are full of Alomine and phenocrystals  are plagioclase (30 to 90% Anorthite ) so that it is not vitric, embedding  Oligoclase –Andesine , orthopyroxene  quartz (Tridimite ) + augite + feldspar +  iron – oxide grains.

Dacite and rhyodacite are more abundant in Bazman Mount is more abundant shahsavaran mount. Hence acidic rocks are important to East shahsavaran Mount: More than this point and acidic tuffs in a body between layers with dacite and rhyodacite lava.


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