Petrology
Maryam Dorani; Mohsen Arvin; Roland Oberhänsli; Hadi Omrani; Sara Dargahi
Abstract
Bajgan Complex is a part of Iranian Makran including many kinds of metapelites, metabasites, calcsilicates, amphibolites, marbles, meta volcanosediments, felsic, mafic and ultramafic intrusives. The calcsilicates are divided into amphibole bearing epidote schist, epidote - amphibole schist, epidote – ...
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Bajgan Complex is a part of Iranian Makran including many kinds of metapelites, metabasites, calcsilicates, amphibolites, marbles, meta volcanosediments, felsic, mafic and ultramafic intrusives. The calcsilicates are divided into amphibole bearing epidote schist, epidote - amphibole schist, epidote – amphibole - garnet schist and carbonate bearing mica schist. Among of all calc silicates the epidote – amphibole - garnet schist shows the highest metamorphic condition and consists of garnet, amphibole, epidote, calcite, quartz, secondary chlorite and minor amount of titanite, apatite, white mica and magnetite. In this study the mineral chemical compositions, temprature, pressure and fluid activity in different metamorphic stages of epidote – amphibole - garnet schist were detected. In according to chemical data, garnet has almandine, grossular, spessartine and pyrope solid solution (Alm 35-50, Grs 23-31, Sps 14.6-36, Prp < sub> 2.6-9.8 ; mol%) and shows chemical zoning as almandine and spessartine have an increasing and decreasing trend, respectively, from core to rim. Amphiboles are classified in sodic- calcic group and are Barroisite. Chlorites are kown as Ripidolite and epidotes are classified in Clinozoisite subgroup. Peak metamorphic condition of epidote – amphibole - garnet schist has been estimated about 610° C and 8 kbar and molar fraction of Co2 and H2O have been calculated about 0.32 and 0.68, respectively. The retrograde metamorphic condition are about 525° C, 4.5 kbar and molar fraction of Co2 and H2O have been calculated about 0.31 and 0.69, respectively. The epidote – amphibole - garnet schist followed a ‘clockwise’ P–T path during prograde and retrograde metamorphism.
A Shaker Ardakani; M Arvin; B Oberhänsli
Abstract
The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic ...
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The Lower Paleocene felsic plutonic rocks in the N- NE of Ghaleh-Ganj, are located on the western side of the Makran accretionary prism and the Jazmurian Depression and the east side of the Jiroft fault. They are parts of the intrusives in the Ganj complex, which itself is a part of the Jazmurian ophiolitic belt or Inner Makran. Petrographically, the intrusives are quartz diorite, plagiogranite, tonalite, granodiorite, monzogranite and albite granite in composition with mainly equigranular to inequigranular textures and subordinate textures such as micrographic, granophyric, poikilitic and zoning. Mineralogically, the plutonic rocks consist of plagioclase, quartz, orthoclase, microcline, amphibole, biotite and opaques. The plagioclases show normal, reverse and oscillatory zoning and based on their mineral chemistry studies, are mainly albite to oligoclase in composition. Amphiboles are calcic type and magnesiohornblende in composition with affinity to actinolite. The geochemical studies show that the felsic plutonic rocks are trondhjemite to tonalite in composition and belonging to a sub-alkaline magmatic series with calc-alkaline nature, and have characteristics of peraluminous granitoids. Using trace element discrimination diagrams and ocean ridge granites-normalized multi-elements diagram clearly show that the Ganj felsic plutonic massifs are plotted in arc-related granites field with affinity towards ocean ridge granites field. These characteristics along with Nb-Ta negative anomalies are known as evidences for formation of Ganj felsic plutonic rocks in a supra-subduction zone environment.