فهرست مطالب

Geopersia
Volume:14 Issue: 1, Winter-Spring 2024

  • تاریخ انتشار: 1403/03/07
  • تعداد عناوین: 12
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  • Sadegh Zahiri, Davood Jahani *, Ali Rahmani Pages 1-21
    Maastrichtian to Thanetian carbonate platforms comprise the outcrops of scarcity, especially in Tethys, Zagros Foreland Basin of which is hardly documented. A carbonate platform-to-basin transect in Zagros Basin was done, consisting of two important outcrops, and large cliffs with a vast landscape and good photographic capacity. Based on large benthic foraminifera (LBF) and planktonic foraminifera, these carbonate platforms are referred to as Tarbur and Taleh Zang formations, which are dated to the Maastrichtian and Paleocene (Thanetian-Selandian). Multiple stratigraphic approaches, along with the facies analysis, were used to build the carbonate platform architecture and figure out the most conspicuous factors controlling the evolution of these platforms through time. Ten sedimentary facies belts were identified, ranging from the basin to the proximal and distal shallow-water contexts with carbonate ramps. The distribution of grain-associations in the spatial and temporal scale, facies belts, apparent stratal geometry, and biological evolution accompanied by age dating led to identifying two distinct carbonate models: Maastrichtian distally steepened ramp and Paleocene carbonate ramp, belonging to Tarbur and Taleh Zang carbonate formations, respectively. Due to the first dominating community of Cenozoic Zooxanthellate corals associated with red coralline algae as separate patches, the Paleocene Taleh Zang carbonate ramp was divided into two carbonate modes: Danian-lower Selandian and upper Selandian.
    Keywords: Carbonate Platform, Maastrichtian-Paleocene, Zagros Foreland Basin, Tarbur Fm, Taleh Zang Fm
  • Saeed Nejati, Mashalah Khamehchiyan *, Mohammadreza Nikudel, Ahmad Zalooli Pages 23-44

    This study compares rock porosities measured using petrographic image analysis (PIA) and saturation-buoyancy (SB) methods. To this end, the fresh block samples from sandstone and limestone were collected from Upper Red and Asmari Formations, respectively. Next, cylindrical core specimens from those were prepared using a coring machine. Afterward, the porosity values of sandstone and limestone samples were measured using PIA and SB methods. In the next step, the physical and mechanical properties of samples, including water absorption (W), P wave velocity (PWV), uniaxial compressive strength (UCS), Young’s modulus (E), point load strength index (PLSI), and Brazilian tensile strength (BTS), were determined. Results showed that PIA underestimates the porosity in both rocks. These conservative results can be attributed to the incomplete filling of micropores with blue-dyed epoxy resin in sandstone cement and limestone matrix or petrographic microscope limitation to differentiate micro-pores in cement and matrix. Furthermore, results demonstrated that SB in upper red sandstone has a good correlation with W, E, and BTS and a moderate correlation with PWV, UCS, and PLSI. Besides, porosity of limestone samples showed strong relation with W, PWV, and BTS, while UCS and E data versus porosity showed a scattering pattern. Finally, a strong relation was established between PIA porosity and UCS, E, and PLSI, a poor correlation was established in the cases of W, PWV, and BTS. Overall, PIA is a strong method for investigating the interior pore system of rocks, especially isolated pore spaces, although it underestimates rocks porosity compared to the SB method.

    Keywords: Petrographic Image Analysis, Porosity, Upper Red Sandstone, Asmari Limestone, Physico-Mechanical Properties
  • Zohreh Sharifi, Gholamreza Lashkaripour *, Mohammad Khanehbad, Mojtaba Rahimi Shahid Pages 45-62

    Uniaxial compressive strength is one of the most important properties of rocks, whose determination is important for rock engineering studies in civil engineering and mining. Determining the uniaxial compressive strength is time-consuming and expensive. In order to reduce the cost and time, you can use the empirical relationships obtained from easier methods. In this research, using the artificial neural network method, experimental relationships have been presented to estimate the uniaxial compressive strength of limestones of the Esfandiar formation in the north of Tabas city. In this method, the physical characteristics of the rock sample as independent variables are the input parameters that are used to calculate the uniaxial compressive strength as a dependent variable. These relationships consist of a general structure with 4 inputs and 1 output, which was performed using a perceptron multilayer neural network. In this research, the root mean square error (RMSE) was investigated. The results of this research show that the amount of error caused by testing, testing, and validation is close to zero and these relationships can be used to estimate the uniaxial compressive strength of limestones of the Esfandiar formation. Also, the results of the artificial neural network have been compared with the results of multivariate regression, and the results show that the value of the confidence coefficient obtained from the artificial neural network is more acceptable.

    Keywords: Physical Properties, Limestone, Artificial Intelligence, East Of Iran, Uniaxial Compressive Strength
  • Alireza Pazhuhandeh, Ali Mohammadi Torkashvand *, Abolfazl Moeini, Ebrahim Pazira Pages 63-71
    This study aimed to investigate the relationship between these factors and soil physicochemical properties for rapid management of watersheds and Multivariate linear modeling of soil properties using soil formation factors. Four watersheds of Qazvin province were studied, namely Juyank, Madan, Niyarak, and Plangeh. First, the unit map was prepared using a geographical information system (GIS) on a scale of 1:25000 based on photogeological investigations and field visits. Then, 101 soil samples were collected and EC, pH, organic matter percentage, sand fraction, silt proportion, and clay percentages were measured. The relationship between soil formation factors and properties wasinvestigated using linear multivariate regression in three methods of Enter, Forward, and Stepwise. Therefore, the 5 soil-forming factors were the independent variables, and the soil's physical and chemical characteristics were set as the dependent variables. The accuracy of these models was validated using two statistics of explanation coefficient and mean squared error (RMSE). The results demonstrated that the highest R2 value of 0.78 with an RMSE of 0.56 was associated with the relationship between pH and soil-forming factors (regression by the Enter method). There was less than a 50% correlation between silt, clay, and electrical conductivity with soil-forming factors.
    Keywords: Soil Formation Factors, Regression, One-Way Analysis Of Variance, Soil Characteristics
  • Fatemeh Dehghan Nayeri, Mohsen Nasrabady *, Mahboobeh Jamshidibadr, Akbar Ahmadvand Pages 73-88
    There are extensive outcrops of regional metamorphic rocks that consist of marble, calcschist, metapelite, and amphibolite in the south Sirjan (southern Sanandaj-Sirjan zone). Garnet, muscovite, biotite, calcite, quartz, and feldspar are the rock-forming minerals of calcschists. Kyanite, garnet, and staurolite constitute the index minerals of the studied metapelites. Amphibole and plagioclase are the main minerals of the massive and foliated amphibolites. The P-T conditions of the regional metamorphic event in the southern SSZ were constrained using conventional (single-reaction) and multi-equilibrium thermobarometry (THERMOCALC software). The average temperature and pressure gained by THERMOCALC software are 8 kb, 643 ˚C, and 9.6 kb, 645 ˚C for Ky-Grt schist and calcschist samples, respectively. Using revised and recalibrated conventional thermobarometry methods result in temperature from 504 to 664 °C and pressure from 6.57 to 7.88 kb for the investigated Ky-Grt schist. Mineralogical paragenesis and thermobarometry results of the investigated metamorphic rocks are in accordance with a medium P/T- type metamorphic gradient. Presumably, Neotethys subduction beneath the Sanandaj-Sirjan block and resulting crustal thickening event led to such a metamorphic gradient during Eo-cimmerian orogeny. Medium P/T metamorphic rocks of the southern Sanandaj-Sirjan zone and accompanying high P/T metamorphic rocks of the north Hajiabad could be defined as a pair of metamorphic belts that were constructed during Zagros orogeny.
    Keywords: Medium P, T Metamorphism, Eocimmerian Orogeny, Southern Sanandaj-Sirjan
  • Shahrbanoo Ousta, Afshin Ashja-Ardalan, Abdollah Yazdi *, Rahim Dabiri, Mohammadali Arian Pages 89-111

    Fudge dikes of diorite and microdiorite are penetrated in the Mio-Pliocene sedimentary-volcanic series in the northeast of Bam. In terms of lithology, these dikes are placed in two categories: gabbro-diorite. The primary minerals of the dikes are plagioclase, amphibole (hornblende), and augite, and secondary minerals such as chlorite, biotite, and sericite. Also, their textures are granular, ophitic, and microgranular. From the geochemical point of view, gabbro-diorites have sub-alkaline and met aluminum with enrichment of LILE and HREE and depletion of Nb and Ta elements. The parental magma of the gabbro-diorites is obtained from the melting of a part of the subcontinental lithospheric mantle affected by the subduction producers and in equilibrium with lherzolite spinel. The characteristics of incompatible element patterns include LILE enrichment and HFSE depletion compared to REE similar to subduction zone igneous rocks. These rocks show the intermediate geochemical characteristics of the volcanic arc magmatism of arc islands and margins, consistent with the formation of these rocks in active continents. Geochemical evidence, as well as the association of igneous rocks with green tuffites and other shallow sea sediments, indicate the occurrence of an extensional basin behind the continental arc.

    Keywords: Swarm Dike, Extensional Basin, Miocene, Southeast Bam
  • Behrooz Esrafili-Dizaji * Pages 113-143
    Dolomite reservoirs flourished during arid climatic periods in the Middle East, primarily in the Permo- Triassic, Upper Jurassic, and Oligo-Miocene formations. These dolomitized reservoirs are frequently linked to evaporites, exhibit isotopically enriched signatures, and tend to occur predominantly in the more restricted regions of carbonate platforms. These observations strongly support their origin through sabkha and evaporative reflux processes. Consequently, dolomite formation and distribution are primarily influenced by early diagenetic processes and climatic conditions during arid periods. Dolomitization has exerted a significant influence on reservoir properties within the studied carbonateplatforms. Porosity distribution and variation are jointly controlled by several factors, including dolomite content, texture, crystal size, anhydrite abundance, dolomite cementation, and the extent of burial compaction. While dolomite textures can vary from fabric-preserving to fabric-destroying, the overall reservoir properties exhibit an ascending pattern from intertidal to shoal facies. This trend is primarily determined by the proximity to the source of dolomitizing brines. The downward percolation of brines, coupled with decreasing dolomitizing potential, leads to an increase in dolomite crystal size within depositional cycles as one moves further away from the anhydrite facies. Proximal areas, characterized by fine-grained intertidal and lagoonal facies, are more susceptible to anhydrite cementation and overdolomitization, resulting in significant porosity reduction. Conversely, in more distal regions, reservoir quality substantially improves, particularly in areas dominated by sucrosic dolomite or grain-rich facies. While this trend may be altered by compaction during burial, itunderscores the crucial role of dolomitization in preserving porosity, especially in deeply buried carbonate reservoirs
    Keywords: Dolomite Reservoirs, Dehram Reservoirs, Upper Surmeh Reservoirs, Asmari Reservoirs
  • Abdorrahman Rajabi *, Pouria Mahmoodi, Carles Canet, Mohammad Pirouei, Pura Alfonso, Amir Mahdavi, Shojaeddin Niroomand, Mehdi Movahednia, Sara Momenipour Pages 145-163
    Framboidal pyrite is common in marine sediments and organic matter-bearing sedimentary rocks. It has also been reported in many ‘sediment-hosted ore deposits’, such as shale-hosted massive sulfide (SHMS) or clastic-dominated Zn-Pb deposits, volcanogenic massive sulfides (VMS), Irish-type Zn-Pb, sediment-hosted stratabound copper (SSC), and sandstone-hosted Pb-Zn and U, as well as in coal deposits, whereas it is absent or rare in some others (e.g., Mississippi Valley Type, MVT). Spherulitic pyrites are more common in Cambrian pyrite-rich SHMS Zn-Pb deposits, hosted in organic matter-rich black shales and siltstones. Framboid textures can be observed in other minerals as well, such as magnetite, hematite, goethite, limonite, magnesium ferrite, chalcocite, cobaltite, digenite, and arsenopyrite. However, it is possible that these non-pyrite framboids are either formed due to the oxidation of pyrite or the replacement of pyrite by other minerals. The recognition of different morphology types of pyrite framboids and spherulites and their relationship with other sulfides are useful in determining the time of formation of these ore deposits, especially in sediment-hosted Zn-Pbmineralizations. Although framboidal pyrite usually has a sedimentary origin, in some sediment-hosted ore deposits (e.g., Koushk, Chahmir, Zarigan, Hossein-Abad, Eastern Haft-Savaran, Tiran, and Irankuh), where it occurs in association with fine-grained sphalerite and galena, and also in the hydrothermal alterations, its origin is influenced by hydrothermal fluid inputs. Whatever its origin, framboidal pyrite allows us to approach the redox conditions of the sedimentary environment, based on a detailed morphometric analysis in each (ore) facies. Suggesting an analogy with modern euxinic sedimentarybasins, the large number of framboidal pyrite indicates euxinic to anoxic conditions in the Chahmir,Koushk, Zarigan, Hossein-Abad, Eastern Haft-Savaran, and Ab-Bagh ore deposits, which is consistent with the geochemical proxies of the host rocks
    Keywords: Sediment-Hosted Ore Deposits, Sedimentary-Exhalative (SEDEX), Euxinic, Anoxic, Mineral Texture, Framboids, Spheroidal
  • Mohammadreza Hajiannezhad *, Behnam Rahimi Pages 165-182
    The Astaneh Fault is one of the active and seismic faults in the Shahroud sinistral fault system. Fault gouges can be seen in a completely pristine and unchanged form in the portions of this fault that have affected the carbonate rocks. Fault gouges are the direct product of lithology and are formed as a result of the fault slip from the host rocks. Studying these rocks for type, composition, mineralogical phases and structure can provide results on how the fault slip and gouge process occurs. The result of a seismic slip in faults, and especially in gouges, are different types of deformations, such as mineralogical and compositional deformations, depending on the conditions of their formation. From this deformation model, we can mention the thermal decomposition of calcite and dolomite, as well as the presence of siderite in gouges. In this article, by studying the combined [aggregated] microstructures in the Astaneh fault gouge, their relationship with seismic slip has been investigated. According to previous research, the Astaneh Fault is certainly a seismic fault. The presence of the resulting thermal decomposition of calcite and dolomite (calcium and magnesium oxide or periclase) and the welding of particles due to heat may be the key to seismic slip in this fault.
    Keywords: Active Fault, Fault Gouge, Thermal Decomposition, Seismic Slip
  • Peyman Sudegi, Rahim Bagheri *, Hadi Jafari, Somayeh Zarei Pages 183-198
    The potable groundwater crisis has escalated in Davarzan crucial alluvial aquifer due to over-exploitation and poor management, though it acts as a reliable resource during the drought situations. Davarzan crucial aquifer is located near the salty playa and ophiolite complex in a desert area at northern Iran. The main aims of the paper were determining groundwater potential zoning and exploitation management of potable groundwater using the quality instruments associated with implementing multi-quantity-hydrogeology criteria. The trend of increasing EC values and groundwater flow direction are from the northern to the southern adjacent desert. Based on the GIS modeling, the two potable groundwater potential zone maps were produced using the qualitative (pollution and salinity) and quantitative layers. Both layers have made most of the groundwater unsuitable in the central and southern parts of the area. Although most of the north and northwest parts of the area falls under the good groundwater potential zone for potable usage, overexploitation of the groundwater has caused the groundwater level to decline and salinity increase towards the aquifer. Therefore, for exploitation management of potable groundwater without causing additional storage loss in this desert region, sustainable yield is advised and it could be turning potable water wells into agricultural wells. The results of this research have significant implications in exploitation management of potable groundwater in desert regions.
    Keywords: Groundwater Budget, Overexploitation, Qualitative Layer, GIS, Davarzan, Iran
  • Fatemeh Vaez-Javadi *, Nasrollah Abbassi Pages 199-212
    Miocene miospores in the Upper Red Formation, Zanjan, northwestern IranAbstractThe Upper Red Formation has extensive outcrops in the southern and western parts of the Zanjan province, northwestern Iran. Here, we studied a sequence of lowermost part of this formation near Mehr-Abad village, northwestern Zanjan. Lithostratigraphy, sedimentology and ichnology of the URF have been studied in recent decades but palynology of this formation has not been investigated. This article is a preliminary report of miospores. The palynofloras comprise thirty species including three algae spores (in three genera), seven fern species (in seven genera), various type of gymnosperm (thirteen species designated to nine genera), and angiosperm pollen species (seven species designated to six genera); for example, Botryococcus sp., Closteritetrapidites magnus, and Diagonalites diagonalis of algal spores; Echinatisporis muelleri, Magnastriatites sp. cf. M. grandiosus, and Polyapodiaceoisporites potoniei of fern; Cathayapollis scheuringii, Cedripites sp., Ephedripites tertiarius, Pinuspollenites lobatus, P. minimus, Cupressacites spp., Tsugapollenites spp. of gymnosperm, and Acidanthera brevicollis, Calliandra spp., Fagopsis longifolia, Monoporopollenites sp., and Retitricolporites sp. of angiosperm evidenced herein. Moreover, botanical affinity of miospores considered. Therefore, Botryococcaceae/ Dictyosphaeriaceae, Closteriaceae, Zygnemataceae (algae); Marattiaceae, Pteridaceae, Polypodiaceae (fern); Cupressaceae, Ephedraceae, Pinaceae (gymnosperm), and Fagaceae, Fabaceae, Iridaceae, and Poaceae (angiosperm) identified.Keywords: Miocene, Upper Red Formation, spore, pollen, Zanjan, NW Iran.
    Keywords: Miocene, Upper Red Formation, :Miospore, Zanjan
  • Ashkan Seydi, Maysam Abedi *, Abbas Bahroudi, Hosein Ferdowsi Pages 213-229

    Birjand region is located in South Khorasan province in the structural-magmatic zone of eastern Iran. This part of the Iranian plateau is the result of subduction during the Cenozoic and subsequent continental collisions. This region is known as important in terms of copper and gold mineralization for various geological reasons. This research aims to develop a map of Au geochemical potential. 1966 geochemical samples were collected in the study area, and a 20-element analysis was performed. After data pre-processing including correction of outlier data and data normalization, and through a graph from the fractal concentration-number (C-N) model to isolate different geochemical populations of Au, As, Sb, Hg, Bi, Mo, Sn, and W with Au targeting, a Prediction-area (P-A) graph was plotted for each variable to determine the weight of each geochemical indicator. The results show that after gold, with an ore prediction rate of 74% and specifying 26% of the studied district as mineralization-prone areas, arsenic with a prediction rate of 72% has covered 28% of the Birjand region as potential mineralization areas while Bismuth and Mercury with a prediction of 64% covered 36% of the Birjand region. In addition, a hybrid indicator map was prepared utilizing a multi-class index overlay method, where the potential geochemical areas were located further south and southeast of Birjand. In addition, there are favourable areas in the middle. Notably, the mineral potential map (MPM) has higher efficiency than any geochemical indicator, with an ore prediction rate of 88% and occupying 12% of the whole prospect area.

    Keywords: Concentration-Number Fractal (C-N), Prediction-Area Fractal (P-A), MPM, Au, Birjand