فهرست مطالب

Geopersia - Volume:8 Issue: 2, Summer- Autumn 2018

Geopersia
Volume:8 Issue: 2, Summer- Autumn 2018

  • تاریخ انتشار: 1397/09/08
  • تعداد عناوین: 12
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  • Aliakbar Momeni *, Gholamreza Khanlari, Mojtaba Heidari, Seyed Saeed Hashemi Pages 143-156
    In this study, the salt weathering effects on engineering properties and weight loss potential of three types of granitoid rocks were investigated. Sodium and magnesium sulfates tests were performed on core and aggregate samples. The cyclic salt weathering tests on core samples were done up to 90 cycles, while these tests on aggregate samples were done up to 40 cycles. The results showed that deterioration effect of magnesium sulfate on weight loss was more remarkable than sodium sulfate. However, deterioration effect of sodium sulfate on weakening of physico-mechanical properties was more considerable than magnesium sulfate. Porphyroid monzogranite was far more affected by the salts in comparison with other rock types which were tested in the current study. The results showed that ultrasonic wave velocity parameter was more appropriate than other engineering parameters to demonstrate the damage processes. Finally, a crack development weathering pattern and a corrosive damage pattern were observed for sodium sulfate and magnesium sulfate respectively.
    Keywords: Salt weathering, aggregate, engineering properties, weathering pattern
  • Fatemeh Goleij, Asadollah Mahboubi *, Mohammad Khanehbad, Reza Muossavi Harami Pages 157-170
    Travertine deposits are a kind of continental carbonates that form in specific chemical, physical and biological conditions. Garab travertines in southeast of Mashhad are studied based on field, geochemistry (elemental and stable isotope analysis) and hydro-geochemistry analysis. Field and petrographic characterization led to recognize of crystalline crust, raft, foam, shrub, laminated, black mud and tufa lithofacies. These lithofacies are composed of calcite and aragonite mineralogy. They have high concentrations of Ca, Mg, S, Fe, Na and Sr and low concentration of Mn, P and Si. These lithofacies are enriched with respect to δ13C and depleted with respect to δ18O that can be related to algal origin and meteoric water, respectively. The type of Garab springs water is Ca- HCO3- - SO42- and Na- Cl. This water is saturated with respect to bicarbonate and sulfate. The water composition and dissolved ions have a close relation to geological units (carbonate and evaporite) in Garab area.
    Keywords: Travertine, lithofacies, carbonates, Garab
  • Seyed Naser Raissosadat * Pages 171-197
    Representative ammonites of the Family Heteroceratidae have been studied in this paper. The following forms are recorded from the Koppeh-Dagh Basin: Heteroceras cf. colchicus Djanelidze, Heteroceras spp., Martelites cf. tenuicostatus (Kakabadze), Martelites securiformis (Simonovich, Bastevich and Sorokin), Martelites cf. tinae (Eristavi), Martelites sp.1, Martelites sp. 2, Argvethites sp., Imerites sparcicostatus Rouchadze and Paraimerites sp. A Late Barremian age is suggested for beds containing these forms. The Heteroceras sp. and Martelites securiformis Zones are proposed for the Upper Barremian Sub-Stage in the Koppeh-Dagh Basin. Dispressal paleobiogeographic pattern of Heteroceratidae family and relation between Koppeh-Dagh basin and surrounding basin have been discussed during Late Barremian.
    Keywords: Late Barremian, Ammonite, Heteroceratidae, Koppeh-Dagh Basin, Iran
  • Farhad Aliani, Zeinab Daraeezadeh * Pages 199-212
    The Kermanshah ophiolite complex is a part of the Mediterranean–Zagros–Oman Tethyan ophiolites, located in the structural–tectonic zone of western Iran in the northern part of the Zagros main thrust. Doleritic sheeted dykes are well exposed within the ophiolite in the south of Sahneh. These dykes contain high MgO, Na2O, low TiO2 (<0.1 wt %), P2O5, and K2O contents, and high FeOt/MgO and LILE/HFSE ratios. The geochemical data show that the parent magma of these dykes was an initial melt, tholeiitic subalkaline in nature; with LIL elements-enriched signature. N-MORB-normalized multi-element plots indicate nearly flat patterns for HFSE and enrichment in LILE; patterns of incompatible trace elements demonstrate an island arc affinity for these dykes. The enrichment of the LILE in comparison with HFSE suggests the involvement of a crustal component driven by fluids along the subduction zone. Several geochemical parameters suggest that the dykes of Kermanshah Ophiolite exhibit transitional characteristics between mid-ocean ridge basalt and island-arc tholeiite. High LILE/HFSE ratio negate suggest a mid-ocean ridge setting for these dykes; it is, therefore, proposed that the dykes may have originated in a back-arc basin tectonic setting or supra-subduction zone.
    Keywords: Sheeted dykes, Tholeiite, Back-arc-basin, Island arc, Kermanshah Ophiolite
  • Mohammad Javad Hassani *, Fatemeh Hosseinipour Pages 213-232
    This paper focuses on the quantitative analyses of Early Miocene ostracods in south and north of the Sirjan area, southwest of Kerman. Detailed studies resulted in identification of 23 species of ostracoda. The coexisting benthic foraminifera and comparing the identified microfauna assemblages with previous studies confirms the Early Miocene age for the strata. The quantitative analysis show a low diversity in the ostracoda assemblages, in compare with other areas. The ostracoda community is classified into seven morphogroups. Several communities are recorded in the ostracoda morphogroups, which reflects basic changes in the basin condition. The morphogroups analysis also reveals that the basal parts of the sections are deposited in shallow and poorly ventilated waters, while a normal condition prevailed through upward. A period of instability is predominant after the normal condition and final stages of deposition took place in the near shore environment, which reflects the end of sea life. The stratigraphical position and structural history of the basement suggest that syndepositional tectonic activities were responsible for the fluctuations in the environmental conditions. This suggestion is confirmed by comparing the studied area with adjacent areas, where similar deposits are deposited on different basements
    Keywords: Ostracods, Lower Miocene, Basin evolution, Sirjan, Kerman
  • Mohammad Hossein Gharaie *, Behnaz Kalanat Pages 233-244
    A late Cenomanian-early Turonian interval (Hamam-ghaleh section) adjusted with the transition of Aitamir and Abderaz formations has been investigated in the east of Koppeh-Dagh Basin to examine environmental perturbations related to the oceanic anoxic event 2. The dark shale of the upper Aitamir Formation indicate higher organic matter concentrations especially in the two intervals at the end of Rotalipora cushmani biozone and the middle part of Whiteinella archaeocretacea biozone. These intervals are characterized by higher detrital input (quartz and feldspar) and chemical alteration (high kaolinite/illite ratios), which suggest a warm-humid condition coeval with high productivity during the OAE2. The Aitamir Formation also shows higher total sulfur values associated with deposition of framboidal pyrite reflecting an oxygen deficiency.The warm and humid periods in the study section were followed by the cooler and drier intervals associated with decreased TOC values and chemical weathering. These cooling periods might be caused by falling of atmospheric CO2 due to large amount of carbon burial in sediments and high silicate weathering. The δ13Corg positive excursions of around 1‰ are other characteristics of these cooler-drier intervals, which were result of high burial of light carbon in the organic matter and lower isotopic differentiation in low atmospheric pCO2.
    Keywords: Aitamir-Abderaz transition, Anoxic Ocean, Cenomanian, Turonian boundary, Koppeh-Dagh, OAE2
  • Narges Daneshvar, Mohammad Maanijou *, Hossein Azizi, Yoshihiro Asahara Pages 245-259
    The granitic intrusives in southwest Saqqez are located in the northern Sanandaj Sirjan zone. These granites can be divided into mesocratic and leucocratic granites. The external morphology and internal structures of zircon from these granites have been investigated employing the classic Pupin method supplemented by electron microscope analysis. The zircon crystallization is a function of temperature, chemical composition, water content of magma, velocity of crystallization and Zr saturation of magma. So, we have focused on the study of zircon to evaluate the chemical characteristic of these bodies. The minimum temperature of crystallization in mesocratic granite based on morphology of zircon crystal ranges from 784 to 847°C and for leucocratic granite ranges from 704 to 785°C, which show good correlation with calculation of saturation temperature of zircon (755 to 866°C for mesocratic granite; 755 to 832°C for leucocratic granite). Crystal growth {101} in most of zircon crystals in case study indicating I-type source of magma. Also, crystal growth {100} shows high temperature which confirm the result of thermometry. Also, absent of apatite and monazite inclusions in zircons and intergrowth hydrothermal zircons indicating dry I-type magma which correspondent with geochemical data, mineralogical survey and field observation.
    Keywords: Zircon, thermometry, morphology, Saqqez, Iran
  • Bita Javidfakhr *, Seiran Ahmadian Pages 261-278
    Alborz Mountains is a region of active deformation within Arabia-Eurasia collision zone. The study fault system in western Alborz comprises abundant evidence of active faulting accompanied by occurrence of historical earthquakes. Active tectonics of Manjil-Rudbar fault zone whose movement caused destructive 1990 Manjil-Rudbar earthquake was concentrated in this article through geomorphic and structural analyses. Satellite images were used to improve the visualization of fault traces in order to constrain their geometry considering structural linkage between different fault segments. Faults are supported by field geologic data and kinematic measurements. There are left-lateral strike-slip and oblique reverse movements observed all over the fault zone corresponding to recent fault activities of Rudbar, Manjil, Kelishom and Jirandeh (Kashachal) faults. A more complete catalogue of earthquake focal mechanisms is presented to consider general seismic framework of the region. Fault plane solutions indicate a radial pattern of thrusting in western Alborz. We analyzed drainage offsets and Quaternary alluvial fans along major structures in order to understand precise role of major faults in ongoing deformation processes. Most river offsets along active faults are small (about 100m), while left-lateral displacement of up to 500m is also observed in streams cut along major faults.
    Keywords: earthquake, Alborz, Manjil, Rudbar, Quaternary
  • Akram Ostadhosseini, Mehrdad Barati *, Peyman Afzal, Insung Lee Pages 279-292
    The purpose of this study is to determine geochemical anomalies on lithogeochemical data from Ardestan area, Central Iran, using concentration-number (C-N) fractal modeling and staged factor analysis. Staged factor analysis is used to the recognition of genetic correlation and elimination of non-indicator elements in three steps. Factor scores of elements were calculated and geochemical data classified by the C-N fractal model. According to the anomaly values, the distribution of elemental concentration for Mn and F1-3 were divided in four classes and five geochemical groups of Cu, Ag, Fe, F2-3 and F3-3 have been identified. Main geochemical anomalies are located in the NW, NE and SE of the study area. Obtained results from fractal and factor analyses is confirmed by field observations, petrographic and mineralographic studies, indicating pyrite, chalcopyrite, chalcocite, covellite, argentite, malachite, azurite, magnetite, hematite and pyrolusite are main ore minerals hosted by andesites and basaltic andesites.
    Keywords: Concentration–Number (C-N) fractal model, Staged factor analysis, Polymetallic mineralization, Ardestan
  • Haji Karimi *, Ezzatollah Raeisi, Abolfazl Rezaei Pages 293-305
    The karstic Rijab Spring with an average discharge of 3290 l/s is located in the Alvand River basin in the northwest of the Zagros, Iran, which drains Asmari formation. To investigate groundwater flow in the catchment area of the Spring, the physicochemical parameters include major cations and anions, discharge, EC, pH, and temperature were studied from September 2000-2002. The results indicate that the karst aquifer has a diffuse-conduit flow system since the diffuse condition supplies mostly base flow whereas the conduit system, providing quick flow, activates mostly during snowmelt period at late-winter and early-spring. The spring hydrograph shows two recession coefficients in both 2000-01 and 2001-02 water years. In both years, the steep recession coefficient (α1=0.0225 on average) which occurs in the wet season is related to the conduit flow system whereas the gentle recession coefficient (α2=0.00685 on average) corresponds with the dry period and related to the diffuse flow. Moreover, the temporal variations of EC, major ions concentrations and saturation indices of the calcite and dolomite also suggest diffuse-conduit flow system. Furthermore, investigation of both the hydrograph and chemographs of the Rijab Spring indicates that about half of the spring catchment area is distributed out of surface catchment boundary.
    Keywords: Karst, diffuse-conduit flow system, physicochemical parameters, Alvand basin, Rijab Spring
  • Rahim Dabiri *, Heydar Hagdoust, Reza Arjmandzadeh Pages 307-317
    The Chah-Shaljami polymetal ore deposit contains heavy metal anomalies in various mineralization zones. Geochemical distribution and correlation of elements in surficial soilsindicate that sulfide, sulfate, sulfosalt and silicate mineral occurrences (e.g. Pyrite, chalcopyrite, galena, sphalerite, molybdenite, enargite, hornblend and biotite) in mineralization and stockwork zones resulted in the strong correlation between some elements such as Fe, Mn, Mg, Ni, Pb, Zn, Cr, Sn. In addition, there is a relatively strong correlation between Cd, Ti, Ba, Al which may be related to the vein-veinlets and the intrusives. Contamination indexes (enrichment factor, geoaccumulation index (Igeo), contamination factor and modified contamination degree) were used to assess the soil and sediment enrichment in Chah-Shaljami ore deposit. These indexes indicate enrichment of S, Sb, Mn, Pb. Sulfide, sulfate and sulfosalt minerals cause strong sulfur enrichment. Cadmium is weakly contaminated as can be inferred from its paragenetic association with Pb-Zn minerals in polymetal ore deposits.
    Keywords: heavy metal, enrichment factor, Contamination, Chah-shalgami
  • Leila Rostami, Seyed Hamid Vaziri *, Davood Jahani, Ali Solgi, Morteza Taherpour Khalil Abad, Ivana Carevi, Ahmad Yahyaei Pages 319-329
    The Dorood oilfield is located offshore in the northern part of the Persian Gulf. It partly underlies the Kharg Island. The Neocomian Fahliyan Formation represents the high-quality reservoir in the oilfield. It includes five carbonate members: The Manifa, Middle and Upper Yamama, Khami and Lower Ratawi. The Fahliyan Formation in the studied well attains a thickness of 378.1 m and mainly consists of thin-bedded limestones. It unconformably overlies the evaporate Hith Formation and conformably underlies the Gadvan Formation. An integrated biostratigraphic (benthic foraminifera and algae) and lithostratigraphic study is presented. Paleontological studies led to the identification of 19 genera and 29 species of benthic foraminifera and 10 genera and 9 species of calcareous algae. Two biozones of Berriasian through Valanginian age have been recognized. These are Lithocodium aggregatum-Salpingoporella muehlbergii assemblage zone (Valanginian) and Pseudocyclammina lituus- Coscinoconus assemblage zone (Berriasian-Valanginian).
    Keywords: Fahliyan Formation, Foraminifera, Calcareous algae, Berriasian-Valanginian, Dorood oilfield