Petrology
Zeinab Rahmanian; Gholam Reza Ghadami; Hamid Ahmadipour; Mohammad Poosti
Abstract
Dalfard granitoids are located in the south-east of Kerman province and in the margins mainly include quartz diorite. Quartz diorites contain main minerals plagioclase, amphibole and biotite and this work reveals that the rocks in this area are I type granitoides and they belong to calc-alkaline ...
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Dalfard granitoids are located in the south-east of Kerman province and in the margins mainly include quartz diorite. Quartz diorites contain main minerals plagioclase, amphibole and biotite and this work reveals that the rocks in this area are I type granitoides and they belong to calc-alkaline magmatic series. The enrichment of LREE relative to HREE, high contents of LILE relative to HFSE and anomalies of Nb and Ti in spider diagrams show that the Dalfard quartzdiorites are formed in an arc setting environment. The CaO/(MgO+FeOt) and Al2O3/(MgO+FeOt) ratios (0.55 and 1.36 respectively) show that the parent magmas were formed by the partial melting of basaltic rocks of the lower crust and mantle fluids/melts also participated in their formation. Based on geochemical data such as La/Yb(N) and Th/Yb(N) ratios (4.4 and 6.5 respectively), these magmas are related to pre-plate collision environment and formed in the mature Volcanic arc setting at a depth of about 40 km at the supra subduction zone of the Neothetys oceanic lithosphere and then, they ascent to the higher levels of the crust and passed fractional crystallization.
Stratigraphy and Palaeontology
Zahra Khajehjavaran; Gholam Reza Ghadami; Mohammad Poosti; Abbas Moradian; Behrouz Karimi Shahraki
Abstract
Andesites are located in the north of shahr-e-babak , central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of ...
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Andesites are located in the north of shahr-e-babak , central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of calc- alkaline series formed in a volcanic arc setting. Based on geochemical studies, the rocks show enrichment in LREE rather than HREE. The lack of significant Eu anomalies in REE pattern indicates oxidation state of magma during crystallization. Based on geochemical studies, the clinopyroxenes are Augite and have been crystallized from magma with almost 10% H2O. Fe3+ values of the clinopyroxenes reveal high oxygen fugacity in the magma. Based on the mineral chemistry data, pressure estimates from the clinopyroxenes in the range of 6-10 Kbr and composition yield the crystalization temperatures that range from 900-1100 OC. Typically, clinopyroxenes occure at calc-alkaline orogenic igneous rocks. The plagioclase composition yield the crystalization temperatures that range from 650-750 OC. According to the present study, the rocks are probably the result of the subduction of the Neo-Tethys oceanic lithosphere below the Sanandaj-Sirjan zone, during the Eocene and in a volcanic arc environment.
Petrology
Atefeh Nimroozi; gholamreza ghadami; Jamshid Hassanzadeh; Mohammad posti
Abstract
The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate ...
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The study area is located near Abarkoh city and in Sanandaj –Sirjan zone. The volcanic activity of this region is in the form of dacite and rhyolite domes and lava flow and in the petrographic studies includes coarse plagioclase, quartz and hornblende. The volcanic rocks are considered as the separate units interlayered with calcareous sedimentary units. Geochemical classification confirms the rhyolitic and dacitic composition of the volcanic unites and show their belonging to the calc-alkaline magmatic series, which is the characteristic of the subduction tectonic setting. Significant characteristics observed in spider and multi-element diagrams, such as their enrichment in LREE, high LREE / HREE ratio, Nb and Ti trough, and enrichment of Pb, Rb and Th elements demonstrate the continental crustal contribution to the development of the volcanics and their formation in the subduction environment in the active continental margin setting. Tectonic setting diagrams confirm this idea and determined a continental arc setting for the volcanic rocks of the area. The dating studies on zircon minerals yield the age of about 17.7.2 ± 7.6 ma equivalent to Jurassic for this part of the Sanandaj-Sirjan zone, which matches with the subduction stage of the Neotethyan Ocean below the central Iran zone.
Petrology
gholamreza ghadami; Mohammad Poosti
Abstract
The studied area is located in the north of Rudan city, Groom mountain, in the contact area of the Zagros and Makran zones and some part of Kahnuj-Rudan-Minab ophiolite belt. The studied ultramafic rocks include lherzolite and harzburgite, matrix minerals contains olivine, orthopyroxene, clinopyroxene ...
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The studied area is located in the north of Rudan city, Groom mountain, in the contact area of the Zagros and Makran zones and some part of Kahnuj-Rudan-Minab ophiolite belt. The studied ultramafic rocks include lherzolite and harzburgite, matrix minerals contains olivine, orthopyroxene, clinopyroxene and chromian spinel which is a minor mineral. Based on the geochemical data, the amount of CaO, MgO, TiO2 and V, these rocks belong to non serpentinized orogenic ophiolites. According to microprobe data, the high amounts of Mg#(91.15-93.24) in the lherzolite olivines are indicated that these olivines had refractory and restite, also lherzolite clinopyroxenes are also of the diopside quality, but spinels have poor chromian. Detailed microprobe studies on the spinel of these rocks, ndicated of the high amounts of Mg#(71-77) and Al2O3(52.98 to 46.31Wt%) ) and low Cr#(14-22). Cr/Al proporation of in chromian spinels of lherzolites are equal to 0.19 and amount of Fe3+ in the lherzolite spinels is very low (
A. Bahrampour; Gh. Ghadami; H. Atapour; M. Poosti; H. Ahmadipour
Abstract
At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites ...
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At 60km north-east of Kerman city,near Sarashk village (Ravar, Kerman province) and along the Kuhbanan fault, several lamprophyric dikes have been intruded into Carboniferous to Cretaceous sedimentary formations. Petrographically these lamprophyres could be classified into two groups: comptonites and sanaite. Olivine, clinopyroxene, plagioclase and potassium feldspar are the main minerals in all two groups. Mineral chemistry shows that olivines, clinopyroxenes and amphiboles are of chrysolite (Fo = 72.35-79.85)), augite (Wo = 44.3-50.2, En= 37.06-44.4, Fs = 9.24-14.6), and kaersutite (Ca+Na = 2), (Na+K = 0.59-0.95), (Mg/(Mg+Fe2) = 0.63-0.76) composition, respecrively. Geobarometric and geothermometric estimations along with the tectonomagmatic diagrams for clinopyroxenes show that the parental magmas werealkaline in which the clinopyroxenes crystallized at pressure of 11-15 Kbar and temperature of 1150-1300 ◦C.Whole rock chemical analyses of these rocks show that the parental alkaline magma was originated from a metasomatized lithospheric garnet- spinel- lherzolite mantle source and emplaced in a post-collisional environment.
E. Alizadeh; Gh. R. Ghadami; D. Esmaeily; J. Omrani; A. Golmohammadi
Abstract
The Roshtkhar intrusive rocks are located in the northeastern part of the Roshtkhar prospecting area (KhorassanRazavi province), along the eastern edge of the Khaf-Kashmar-Bardaskan volcano-plutonic belt, north of the Dorouneh Fault and on the southern part of the Sabzevar structural zone. The intusive ...
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The Roshtkhar intrusive rocks are located in the northeastern part of the Roshtkhar prospecting area (KhorassanRazavi province), along the eastern edge of the Khaf-Kashmar-Bardaskan volcano-plutonic belt, north of the Dorouneh Fault and on the southern part of the Sabzevar structural zone. The intusive rocks consist mainly ofsyenite to monzonite with minor amount of syenite porphyry, monzonite porphyry, and diorite porphyry with granular and porphyry texture, respectively. According to the geochemical data, the Roshtkhar intrusive rocks are calc-alkaline granitoid series with high-K to shoshonitic affinity, magnesian, metaluminous, and belong to I-type granites.Chondrite-normalized Rare Earth Element and mantle-normalized trace-element spider diagrams display enriched in LILE and LREE and also Th, depleted in HFSE and weak depletion in HREE and Y, along with negative anomalies of Nb,Ta, and Ti, that are characteristic of the post-collisional calc-alkaline rocks along with a continental active margin tectonic setting. In spite of the low ratios of Nb/U, Nb/La and Ce/Pb, the Sm/Yb (2.8-3.9) ratios reveals low contamination of magmas with upper continental crust. According to geochemistry of trace elements and REE, the main cause of magmatism in Roshtkhar area was melting of a metasomatized lithospheric mantle (E-MORB) with spinel lherzolite composition accompanied by in the presence of phlogopite. Multiple element and REE pattern, abundance of K2O/Na2O in Roshtkhar intrusive rocks show contamination and mixing with acidic magma ofamphibolitic lower crust due to temperature of mantle magma and AFC process played important roles in magma evolution. La vs. La/sm diagram illustrate partial melting and also according to K, positive anomalies of Rb, Ba, K, Th, U, and Pb, and the negative anomalies of Nb, Ti, Ta, and Ba associated with high La (La > 29), it seems partial melting of lower continental crust has played an important role in the genesis of the Roshtkhargranitoids rocks. Based on field investigation, petrographic studies, and lithogeochemistry using the granitoids discrimination tectonic setting diagrams, it seems that the Roshtkhar intrusive rocks were generated in a post-collisional extensional environment in a continental margin arc setting with partial melting of the mantle-lower crust within the Khaf-Kashmar-Bardaskan belt.
Gh Ghadami; M Poosti; F Babai
Abstract
Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts ...
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Few More than 5 dacite to andesite volcanic masses with Mio-Pliocene age are exposed to older volcanic rocksat the south and east of the Mozahem volcano, in south-east of Urumieh- Dokhtar magmatic belt, north-east of Shahre-Babak. These rocks show hyaloporphyritic- trachytic texture and consist of pPhenocrysts of plagioclase, amphiboles and biotites. Based on geochemical data and multi elements patterns, these rocks are medium to high K calc-alkaline suite and they show LILE and LREE enriched normalized multi-element patterns, and negative Nb, Ti and Ta anomalies. Chondrite normalized REE patterns display a steep decrease from LREE to HREE without any Eu anomaly. They have higher SiO2 and Sr contents and Sr/Y and La/Yb ratios and low MgO, Y and Yb contents than the normal calc-alkaline volcanic rocks. These volcanic rocks are formed in the a subduction zone in an active margin, and showing full complete of HSA(high SiO2 adakites) characteristics. HREE and Y depleted patterns suggest the existence of garnet and amphibole as a residue in the source. The source of these rocks was probably amphibole-eclogite or garnet-amphibolite possibly generated during subduction or slab break of the Neo-Tethyan oceanic slab beneath the Central Iran microplate in Neogene.
Gh Ghadami; A Moradiane Shahre Babaki; S.M Mortazavi
Abstract
More than 20 tonalitic to granodioritic plutonic domes, Oligo-Miocene in age, have intruded into the older volcanic rocks, in southeast of Urumieh- Dokhtar Magmatic Belt, northwest of Shahr-e-Babak. These rocks have granoporphyritic texture and consist of Phenocrysts of plagioclase, amphiboles and biotites. ...
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More than 20 tonalitic to granodioritic plutonic domes, Oligo-Miocene in age, have intruded into the older volcanic rocks, in southeast of Urumieh- Dokhtar Magmatic Belt, northwest of Shahr-e-Babak. These rocks have granoporphyritic texture and consist of Phenocrysts of plagioclase, amphiboles and biotites. The geochemical data show calc-alkaline affinities of these rocks , which formed in volcanic arc (I type) of an active continental margin. These data also show LILE and LREE enriched normalized multi-element patterns, and depleted of HFSE (Nb, Ta and Ti). Primitive mantle-normalized REE patterns display a dramatic decrease from LREE to HREE without any Eu anomaly. They have higher SiO2, Al2O3 and Sr content and Sr/Y and La/Yb ratios and lower MgO, Y and Yb contents than the normal calc-alkaline rocks, which reveal their adakitic characteristics. The high content of Sr, LREE enrichments, absente of Eu anomaly, HREE depletion, Y and Yb depletion pattern suggest the existence of garnet, amphibole and absence of plagioclase in the source rocks. Our data suggest that the plutons produced by partial melting of amphibole-eclogite or garnet-amphibolite, due to the subduction of Neotethys oceanic slab under the Central Iran continent.
