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. Ansari; S. J. Sheikh Zakariaee; S. Dargahi; M. Arvin
Abstract
The Chargonbad batholith is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone . This batholith is acidic to intermediate in composition and intruded into the Eocene volcanic rocks. The main volume of these rocks consisted of granodiorite and monzogranite, but it also consists of ...
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The Chargonbad batholith is located close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone . This batholith is acidic to intermediate in composition and intruded into the Eocene volcanic rocks. The main volume of these rocks consisted of granodiorite and monzogranite, but it also consists of quartzdiorite, tonalite and syenogranite. Their contacts are gradational. They have allotrimorphic granular texture with subordinate porphyritic texture. Their enclaves consist of xenoliths enclaves, microgranular mafic enclaves (diorite to quartzdiorite in composition) and autolith enclaves(tonalite, granodiorite and monzogranite in composition).The Chargonbad batholith rocks are also cut by different types of dykes which are mainly consisted of dykes and veins of pegmatitic stage, microgranular dykes (andesite and andesite basaltic in composition) and microgranular dykes that are similar to mafic enclaves. Evidenc show that the samples represent properties of I-type granitoids. Chargonbad granitoid has magnesium nature and shows cordellarian granites features. Based on the tectonomagmatic environment diagrams, all samples from the Chahargonbad plot in the island arc setting of a subduction zone and show active continental margin setting characteristics .
S Sedighian; S Dargahi; M Arvin
Abstract
Khunrang intrusive complex, as a one of the largest complexes in the southern part of the Sanandaj-Sirjan zone, is located at northwest of Jiroft, in Kerman province. The complex mainly consists of acidic-intermediate rocks such as diorite, quartzdiorite, tonalite, granodiorite, and granite with subordinate ...
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Khunrang intrusive complex, as a one of the largest complexes in the southern part of the Sanandaj-Sirjan zone, is located at northwest of Jiroft, in Kerman province. The complex mainly consists of acidic-intermediate rocks such as diorite, quartzdiorite, tonalite, granodiorite, and granite with subordinate amounts of mafic members such as hornblende gabbro and microgabbro. Field studies together with mineralogical and geochemical evidence show that the Khunrang intrusive complex belongs to calc-alkaline series and its felsic members are metaluminous to weakly peraluminous which display features typical of I-type granites. On the primitive mantle-normalized spider diagrams, all mafic and felsic samples are enriched in LILE (such as Rb, Cs and K) and depleted in Ti, Ta and Nb which is a main characteristic of subduction-related magmas. Based on geochemical data, the mafic rocks seems to be formed by melting of metasomatised mantle wedge; whereas felsic rocks are formed by melting of lower crust metabasic rocks as a result of the injection of mantle derived mafic magmas. It can be concluded that the Khunrang intrusive complex was formed in a volcanic arc setting due to subduction of the Neotethys oceanic crust beneath the Central Iranian Micro-continent in the Middle-Jurassic time.
A.R Shaker Ardakani; S Dargahi; H Amirpour
Abstract
The Ghaleh-Ganj dioritic- quartzdioritic massifs, Post early Eocene in age, located on the west side of the Makran Accretionary Prism and the Jazmurian Depression and the east side of the Jiroft fault, are part of the intrusives in the Ganj Complex, which itself is a part of the Jazmurian Ophiolitic ...
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The Ghaleh-Ganj dioritic- quartzdioritic massifs, Post early Eocene in age, located on the west side of the Makran Accretionary Prism and the Jazmurian Depression and the east side of the Jiroft fault, are part of the intrusives in the Ganj Complex, which itself is a part of the Jazmurian Ophiolitic Belt or the Inner Makran. The diorite- quartzdiorites are intruded into the Lower- Middle Eocene Bidak sedimentary units, which show spheroidal weathering and onion- skin erosion. The presence of feldspar, biotite and secondary minerals (such as clay minerals, secondary biotite and Fe oxides) in the study massifs played an important role in the occurrence of these features. Mineralogically the intrusives consist of plagioclase, clinopyroxene, amphibole, Biotite and opaques. Based on mineral chemistry studies, the plagioclases, oligoclase to labradorite in composition, show evidences of disequilibrium textures (e.g. sieve texture and oscillatory zoning). The clinopyroxenes are augite in composition and belonging to a tholeiitic magmatic series. Referring to linear relation between Ti and AlIV in clinopyroxenes, they seem to be formed in a pressure less than 5 kbs at a depth of less than 15 kilometers. Amphiboles are magnesiohornblende with tendency to actinolite in composition. Based on Zr/TiO2 versus Nb/Y and SiO2 versus Nb/Y diagrams, the intrusives plot in the fields of diorite- quartzdiorite and sub-alkaline, respectively. Their low Nb/Y ratio (0.14-0.16) also point out to their sub-alkaline (tholeiitic) nature. The intrusives are metaluminous and I-type, which referring to HFS and REE element contents, they belong to one group. The absence of a distinct Eu anomaly suggests the insignificance of plagioclase fractionation or oxidation state of the magma. The trace element discrimination diagrams together with chondrite-normalized rare earth element patterns show that the Ghaleh Ganj diorite- quartzdiorites formed in the Maturity Stage of a supra-subduction zone.
D Raeisi; S Dargahi; S.H Moeinzadeh; M Arvin; B Bahrambeigi
Abstract
Gandom-Berian area, located on southern part of the Kavir-e Lut, covers an area around 480 km2 and morphologically is a covered messa by very dark basaltic lava flows. Their major minerals are olivine and clinopyroxene phenocrysts along with plagioclase microlites and their main textures are microlitic ...
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Gandom-Berian area, located on southern part of the Kavir-e Lut, covers an area around 480 km2 and morphologically is a covered messa by very dark basaltic lava flows. Their major minerals are olivine and clinopyroxene phenocrysts along with plagioclase microlites and their main textures are microlitic porphyry to glomeroporphiry with interestal to intergranular groundmass. The in line position of volcanic cones along the line of movements of Nayband fault show its effect on the formation of Gandom-Berian basaltic magma. The genetic realationship of these lava flows with deep seated lithospheric fractures as a result of Nayband fault, the presence of mantle xenoliths and alkaline nature of basalt all reveal a fast deep ascending of magmas. Based on geochemical analysis and occurrence of nepheline in the norm composition the Gandom-Berian basaltic lava flows belong to basanite-tephrite group. The investigation on Gandom-beriyan alkali basalts clearly shows their relationships to an intera-continental extensional environment. Low ratio of Ce/Nb, Th /Nb, U/Nb, Ba/Nb and High levels Zr with mean 234.81 indicate a none depleted asthenospheric mantle source the origin of Gandom-Berian basaltic lava flows. Enrichment and depletion of light and heavy rare earth elements respectively indicate the existence of garnet in the source rock.
