Sedimentology
Hoda bavi; Reza Moussavi-Haramia; Mohamad Hosein Mahmudy Gharaie; Hamed Zand-Moghadam; Asadollah Mahboubi; Mohammad Reza Tohidi
Abstract
The geochemical separation pattern and environmental behavior of ΣREE have been investigated in five different sedimentary systems related to Dar-e-Allo copper mine. For this purpose, the total concentration and sequential patterns of ΣREE elements were determined using multi-acid digestion ...
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The geochemical separation pattern and environmental behavior of ΣREE have been investigated in five different sedimentary systems related to Dar-e-Allo copper mine. For this purpose, the total concentration and sequential patterns of ΣREE elements were determined using multi-acid digestion and mBCR selective extraction method. The normalization patterns of ΣREE are drawn based on the NASC and UCC. concentration changes in the five sedimentary systems are very similar and the concentration of LREEs is higher than that HREEs, Opposite of the changes in the concentration of ΣREEs, more enrichment is seen in HREEs compared to LREEs. The geochemical separation patterns of ΣREEs in natural sediment and samples containing iron and manganese oxides is mainly dominated by the residual fraction. considering the different conditions of formation and stability in the samples taken from the waterways leading to the mine, evaporite deposits and sediments washed from the rock dump, the separation pattern of ΣREEs is controlled mainly with two parts soluble in Acid and reducible fraction. The trend of mobility and bioavailability from LREEs to HREEs increases with an upward slope. These results show that speciation, geochemical segregation pattern and environmental behavior for ΣREE lead to misinterpretation without considering key environmental factors.
Sedimentology
Sedigheh Amjadi; Hamid Alizade Lahijani; Mohamad Hosein Mahmudy Gharaie; Razieh Lak; Nick Marriner
Abstract
AbstractAlthough the second deadliest tsunami in the Indian oceans was triggered in the Makran zone, our knowledge in regard to the number of tsunami events through the Holocene is negligible. In this study the sedimentary environment palaeo-tsunami have reconstructed and identified by Gulf of Oman deep ...
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AbstractAlthough the second deadliest tsunami in the Indian oceans was triggered in the Makran zone, our knowledge in regard to the number of tsunami events through the Holocene is negligible. In this study the sedimentary environment palaeo-tsunami have reconstructed and identified by Gulf of Oman deep sea cores. Sedimentation trends and effective factors on seabed sediments transportation by tsunami events were identified based on sedimentological parameters, foraminifera shells identification, magnetite susceptibility changes and palaeo-ocean currents reconstruction. The results of this study demonstrated that evidence of sea bed sediments transportation due to the strong earthquake in the Gulf of Oman were different through time and location. The palaeoenvironmental studies and historical tsunami events suggested at least five considerable submarine landslides through last 2500 cal. yr BP. The number of the events have dramatically increased during last thousand years. Rendering to the results and historical data, almost seven strong earthquakes were happened in the studied area that their traces have illustrated in this study. According to the city expansion in the southeast coast of Iran and increases number of earthquake events in the Makran zone adoption management plans in order to decrease probably tsunami damages are required.
Sedimentology
Shirin Samani; A. Uromeihy; Amirhossein Enayati; Imandokht Mostafavi; Misha Pezeshki
Abstract
Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical ...
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Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical modeling and its application in the exploitation-development of hydrocarbon fields, it is necessary to find out how lithological characteristics affect its rock mechanical behavior. In this study, the impact of two diagenetic processes (Dolomitization and Anhydrite cement) on the physical and mechanical characteristics (such as Uniaxial Compressive Strength, Young’s modulus, Cohesion, and Internal friction angle) of carbonate reservoirs of the Kangan Formation, are addressed. The evaluations have been done in two phases: i.e. lithological studies and rock mechanical tests. The results show that changes in mechanical properties are strongly influenced by diagenetic processes. The two main influential features on mechanical characteristics are dolomitization and anhydrite cementation, which strongly affect porosity, dominant pore type, and mineralogy. The results show that dolomitization in the studied samples has caused an increase in porosity and a decrease in strength and elasticity. While the presence of anhydrite has caused an improvement in the resistance characteristics with an opposite effect.
Sedimentology
Ali Hossein Jalilian; Mohammad Ali Kavoosi
Abstract
The Hauterivian-Barremian Gadvan Formation represents the depositional sequence in central and eastern regions of Zagros Mountains. Field and petrographic investigations of this formation in Khaneh-Kat anticline togheter with wireline logs and cuttings analysis of two drilled wells in the Dashtak and ...
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The Hauterivian-Barremian Gadvan Formation represents the depositional sequence in central and eastern regions of Zagros Mountains. Field and petrographic investigations of this formation in Khaneh-Kat anticline togheter with wireline logs and cuttings analysis of two drilled wells in the Dashtak and Bandubast gas fields (Interior Fars area) indicate important events in the basin evolution, especially the changes in the sedimentation regime and platform evolution during the time period. The key point is upward grading of the thick-bedded, feature forming Berriasian-Valanginian carbonates into shale, marl and argillaceous limestone interbeds of the Gadvan Formation. The vertical changes is consisten with a prominent decrease in carbonate production and a definite change in the nature of the Fars platform. The intense bioturbation and mostly mud-dominated texture of skeletal limestones indicate Gadvan Formation deposited in a mixed carbonate-siliciclastic platform. In the drilled wells, these changes correspond to a significant increase in gamma-ray and sonic wireline logs. The Khalij Member shows the regional continuity, indicates an increase of carbonate production in the mixed platform. Considering tectonic quiescence of Fars area during Early Cretaceous, the mentioned changes can be the result of interplay between tropical climate and short-term fluctuations in the context of global sea level rise.
Sedimentology
Afshin Karimkhani-Bahador; Sadat Feiznia; Mohsen Aleali; Mehran Arian
Abstract
To prepare sedimentological data, 98 surface sampling stations have been designed from the seabed in the continental shelf in the southern part of the Caspian Sea and along the coast of Iran. Indicators such as the type and amount of sediment load transported to the sedimentation environment, the energy ...
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To prepare sedimentological data, 98 surface sampling stations have been designed from the seabed in the continental shelf in the southern part of the Caspian Sea and along the coast of Iran. Indicators such as the type and amount of sediment load transported to the sedimentation environment, the energy of waves and sea currents, as well as how the slope of the seabed changes, play a role in the production and diversity of the sedimentary facies. 9 sedimentary facies are the most abundant in the surface deposits of this area and on average, in the sediments of the continental shelf, there are 1% by weight of coarse-grained particles, 25% by weight of medium-grained particles and 74% by weight of fine-grained particles. The composition of sedimentary facies in this area is controlled by indicators such as the size of sedimentary particles, the amount of sedimentary load carried to the environment, the energy of waves and sea currents, and how the slope of the seabed changes. In the marine environment of the study area, sub-sedimentary environments, Backshore, Foreshore, Shoreface, Offshore transition zone and offshore can be identified. The two facies of slightly gravelly Mud and Mud are more abundant than other facies.
Sedimentology
Alireza Vaezi; Vahid Tavakoli; Abdolmajid Naderi-Beni
Abstract
In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with ...
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In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with high values of δ13COM, and Paq indicate a wet period in Jiroft. evidence indicates a relative decrease in humidity between about 3900 and 3293 cal yr BP. Between 3293 and 2897 cal yr BP, Jiroft was dry and dusty. The results show very dry conditions with a significant increase in the amount of dust around 3200 cal yr BP. A long-wet period from about 2897 to 2302 cal yr BP can be recognized with high Paq values. The highest Ti/Al values along with the lowest δ13COM values indicate increased wind activity and dry conditions between 2100 and 1650 cal yr BP. Jiroft experienced wet conditions between 1540 and 1315 cal yr BP. With the relative decrease of rainfall, a semi-humid climate prevailed in Jiroft between 1315 and 854 cal yr BP.
Sedimentology
Mahmoud Sharafi; Mahdi Jafarzadeh; Aram Bayet-Goll; Razieh Lak
Abstract
The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for ...
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The Urmia Lake, which is a tectonic depression in the northwest of Iran, has received a lot of eroded sediments of the geological records of the lake watershed. Because of the constant drought in the recent years, sediments have been subjected to the wind erosion and thus are an important source for local and regional emission during dust storms. In this research the south and west sediments of the Urmia playa lake have studied on the parent rock issue. Bivariate plots such as Th/Co versus La/Sc and TiO2 versus Al2O3 and comparison proportion of the trace elements such as La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th display mainly the felsic and partly basic rocks source for the studied sediments. Major and trace spider plots of the studied sediments display their depletion with respect to Sc, V, Cr, Ni and enrichment with respect to Th and Sr, confirm mainly a felsic and partly mafic and ultramafic source rocks. Geochemistry of the major elements shows the dry climatic conditions during deposition of Urmia Lake sediments, suggested by bivariate plots of SiO2 against the sum of Al2O3, K2O and Na2O as well as the amount of chemical index of weathering.
Sedimentology
Mahshid Sarookhani; Mahboubeh Hosseini-Barzi; Ali Mobasheri
Abstract
The Qom Formation with Oligocene-Miocene age which is important due to its hydrocarbon reservoirs in some areas, is outcropped with a 330 meters thick mixed siliciclastic-carbonate sequence in Dastjerd area that uncomfortably overlain the Lower Red Formation and is conformably underlained by Upper Red ...
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The Qom Formation with Oligocene-Miocene age which is important due to its hydrocarbon reservoirs in some areas, is outcropped with a 330 meters thick mixed siliciclastic-carbonate sequence in Dastjerd area that uncomfortably overlain the Lower Red Formation and is conformably underlained by Upper Red Formation. In this study, the deposits were studied for petrography, microfacies and sedimentary environment, sea-level changes and mixing mechanism. Based on the frequency and distribution of the skeletal and other constituents of the carbonate deposits of Qom Formation in the studied section, six microfacies associated with three facies belt (open marine, shoal & lagoon) were identified related to a carbonate ramp. Mixing and hybridization of carbonate deposits of Qom Formation with different amounts of siliciclastic inputs in sand, silt size in through the thickness and laterally in the depositional basin of this sediments, is related to the tectonic activity and erosion of older rocks such as the Lower Red Formation and associated Paleogene volcanic rocks, deposited in the backarc basin of a subduction system. According to the microfacies analysis of the studied sediments, two cycles of sea level changes were recognized. The first cycle is associated with unstability of the basin floor and fluctuations in the relative sea-level, which leads to the deposition of a thick layer of sandstone regarded to the high tectonic activity and the second cycle is coincident with more stability of the basin which ultimately tends to a shallowing condition.
Sedimentology
Zeinab Sheikholeslami; , Mahmoudreza Majidifard; Seyed Mohsen Aleali; Mohammad Javanbakht; Morteza Taherpour Khalilabad
Abstract
A unique basement of Kopeh Dagh sedimentary basin is located and investigated in Agh-darband area, northeastern Iran. The second formation of the Agh- darband group, the Nazarkardeh Formation is cropped out in the area by carbonate and volcanogenic successions. This Formation with Anisian age is ...
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A unique basement of Kopeh Dagh sedimentary basin is located and investigated in Agh-darband area, northeastern Iran. The second formation of the Agh- darband group, the Nazarkardeh Formation is cropped out in the area by carbonate and volcanogenic successions. This Formation with Anisian age is overlaid by the Sina Formation, Ladinian age with a sharp boundary and is underlaid by the Sefidkuh Formation with late Scythian in age by a gradual boundary. During this research, four stratigraphic sections are measured from petrology, sequence stratigraphy, microfacies and sedimentary basin points of view. Next this measurement, 300 samples are token and 100 thin sections are made. 11 microfacies with 1 hybrid facies and 3 terrestrial facies are determined. By high resolution studies on these data, this Formation is deposited in lagoon, shoal and open marine which is deposited between the Sefidkuh Formation (carbonate ramp) and the Sina Formation (marginal shelf), so that the depositional environment of the Nazarkardeh Formation is determined as a transitional environment from carbonate ramp to marginal shelf. The existence of hybrid facies show the volcanic activities during deposition of this Formation. the existence of intraformation and monomictic conglomerate in the last depositinal stages of this formation, shows the falling and collapse facies next to the deep floor changes of the sedimentary basin. The sea level change graphs in A, B, C and D stratigraphic sections in contrast with sea level change graphs of Anisian (middle Triassic) shows a third level sequence stratigraphy and is markable by a non-erosional boundary (SB2) on the basis on top of the A, B, C and D stratigraphic sections.
Sedimentology
Alireza Rostami; Mohammad Hossein Adabi; Abbas Sadeghi; Seyed Ali Moallemi
Abstract
The Dariyan Formation with the Aptian age is the youngest reservoir formation of the Upper Khami group which is important in terms of hydrocarbon reservoir potential. This formation is 135 meters thick in the Kuh-e-Mish surface section and consists of thin, thick and massive limestone, marl and shale. ...
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The Dariyan Formation with the Aptian age is the youngest reservoir formation of the Upper Khami group which is important in terms of hydrocarbon reservoir potential. This formation is 135 meters thick in the Kuh-e-Mish surface section and consists of thin, thick and massive limestone, marl and shale. Petrographic studies led to the identification of 13 microfacies. These have been deposited in four types of depositional environments, including inner ramp, mid ramp, outer ramp and basin, in a ramp type carbonate platform. Based on petrography, lateral and vertical facies changes, 3 third-order cycles distinguished. An integrated multidisciplinary approach including, petrography, surface gamma-ray spectrometry and trace element analysis have been used for recognition of original carbonate mineralogy and stratigraphic interpretations of this succession. Geochemistry of minor and major elements reveal original aragonitic mineralogy of the Dariyan Formation. Bivariate plot of Mn versus Sr/Ca values illustrated that the Aptian carbonates were affected by semi close diagenetic system with moderate water/rock interaction. Trace elements (Fe and Mn) contents are compared with distribution of sedimentary facies and depositional sequences to investigate and correlate stratigraphic boundaries, which are determined by sequence stratigraphy in shallow marine carbonate platform of the Dariyan Formation. The elemental peaks coinciding with the sequence boundaries and elemental peaks are correlated with maximum flooding surfaces.
Sedimentology
Hadi Amin-Rasouli; Nasim Haghighat jou; Mahdi Moradi
Abstract
Kraftu cave, 67 km northwest of Divandareh in Kurdistan province, includes four floors. The bottom of the second floor, in the bat hall, is covered by thick guano deposits. SEM–EDX analyses of the guano deposits showed secondary sulfate (gypsum, cesanite), phosphate (phosphammite, brushite, taranakite, ...
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Kraftu cave, 67 km northwest of Divandareh in Kurdistan province, includes four floors. The bottom of the second floor, in the bat hall, is covered by thick guano deposits. SEM–EDX analyses of the guano deposits showed secondary sulfate (gypsum, cesanite), phosphate (phosphammite, brushite, taranakite, francoanellite, whitlockite, leucophosphite, spheniscidite, pyrocoproite), and nitrate (urea, niter) minerals, along with microorganisms and chitin. Occurrence of these minerals is due to changes in the pH (from acidic to alkaline) and moisture (wet and dry conditions) in the presence of microorganisms. Bat guano has accumulated in Karaftu cave during three different paleoclimate conditions, from base to top, including dry, wet, and dry conditions. A comparison between distributions of secondary minerals and Ce-anomalies along the profile represents that taranakite only forms in wet conditions, but whitlockite, urea, and cesanite only occur in dry ones. Therefore, they are significant indicators of climate in the geologic record, but other minerals, because they can be in both conditions, don't be so.Various reactions between the solutions derived from guano with substrate have resulted in phosphatization and dolomitization of bedrock. The abundance of chitin in the Karaftu cave guano deposits indicates that they are feces of insectivorous bats.
Sedimentology
Mohammad Shalalvand; Mohammad Adabi; Afshin Zohdi
Abstract
In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of ...
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In this study, the Late Paleocene Taleh Zang Formation in the southwest of Kermanshah hasbeeninvestigatedfor elemental geochemistry and effective diagenetic processes during burial. The thickness of the studied section is 282 meters that mainly composed of shallow marine limestones with interbedded of marl and dolomite. The main diagenetic processes affecting the TalehZangFormation include micritization, various types of porosity, cementation, dolomitization and compaction. Due to the texture and the abundance of unstable skeletal particles (green algae and bivalve), porosity and cementation aremorecommon among the identified processes. Microscopic and geochemical studies have shown that these processes have taken place in eogenesis and early mesogenesis stages in marine, meteoric and shallow burial environments. Evidences indicate that the carbonates of the TalehZangFormation didnot tolerate deep burial after the deposition during diagenesis. Fluids that affected the lower parts of the formation during burial were mainly marine. Moreover, tothetop ofthe sequence in addition to seawater less meteoric fluids have affected the marine carbonates of the Taleh Zang Formation during diagenesis. The high amounts of Sr/Mn (mean27/51) and Sr/Ca (mean 1/61) and also low Mn (mean 27ppm) and Fe (mean 78ppm) values indicate close digenetic system with low water/rock interaction for the carbonate samples of the TalehZangFormation.
Sedimentology
Hadi Amin-Rasouli; Hossein Azizi; shahla mahmodyan
Abstract
The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and ...
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The Upper Cretaceous succession (UCS) of the north Sanandaj-Sirjan zone consists of five units. The units are 2000 m thick, including shale, sandstone, limestone, intrafomational conglomerate with interbedded basaltic- andesitic lava. This succession is unconformably underlain by Lower Cretaceous and overlain by Paleocene conglomerates. The geochemistry of the samples represents ratios of Al2O3/TiO2 (18-22), La/LuCN (5.43-24.4), La/Sc (0.51-2.53), Th/Sc (0.42-0.68), LREE/HREE (Nd/ErCN > 5), and negative anomalies of Eu/Eu* (0.26-0.89) and Nb/Nb* (0.14-0.82). These characteristics indicate that the samples are immature, first-order sediments, and were eroded from intermediate to acidic arcs in the subduction zone. The volcanic rocks were formed during the intracrustal melting of an altered oceanic slab at high pressures in the garnet-amphibolite facies. The geochemical compositions and vertical lithofacies stacking patterns of the UCS imply that the depositional environment has changed during sedimentation from a trench to trench slope and forearc basins arising from continent-ward migration of the magmatic arc. The activities of Late Cretaceous volcanism resulted in the upwelling of anoxic water, demise of planktonic, and formed pyrite in the deposits. Samples on the Th/Yb-Ta/Yb diagram fall in the ACM and WPVZ fields, indicating tectonic evolution from low-gradient subduction to extensional volcanic conditions.
Sedimentology
Mahmoud sharafi; Arsalan Zeinalzadeh; Aram Bayet-Goll; Bijan Biranvand; Mehran Moradpour; Farid Taati
Abstract
Miocene siliciclastic sediments with 338m thick are studied in the southern Neka of Northern Alborz flank. Detailed sedimentology study allows recognition four facies associations consist of delta plain, distributary channel, delta front and pro-delta. Delta plain and tidal flat include heterolithic ...
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Miocene siliciclastic sediments with 338m thick are studied in the southern Neka of Northern Alborz flank. Detailed sedimentology study allows recognition four facies associations consist of delta plain, distributary channel, delta front and pro-delta. Delta plain and tidal flat include heterolithic shale-silt-sand and limestone with fenestral fabric. Distributary channel and delta front associations consist of thin to thick channel shape sandstone, which display coarsening-thickening upward cycles with pro-delta/offshore association. Scares Ophiomorpha nodosa and Thalassinoides in these sandstones indicate a stressful condition such as sandy mobile substrate, turbidity and highly salinity fluctuation in the sedimentary environment. Shale-silty sediments of the pro-delta association with abundant framboidal and chamber filling pyrite and organic material display anoxic condition of the sedimentary substrate. Introducing Miocene hydrocarbon sediments in the neighboring region like Turkmenistan and Russia and sedimentary characteristics of the pro-delta/offshore shale of the studied succession allow us to introduce those as high potential candidate for hydrocarbon source.
Sedimentology
Hadi Amin-Rasouli; N. Haghighat jou; Mehdi Moradi
Abstract
Karaftu Cave is located in the 67 km northwest of Divandareh, Kurdistan province. It includes four floors, which the bottom of the second floor, in the bat’s hall, is covered by thick guano deposits. In this study, the distribution of trace elements plus rare earth elements, as well as age determination, ...
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Karaftu Cave is located in the 67 km northwest of Divandareh, Kurdistan province. It includes four floors, which the bottom of the second floor, in the bat’s hall, is covered by thick guano deposits. In this study, the distribution of trace elements plus rare earth elements, as well as age determination, based on 14C, of guano was investigated. Fresh guano decays through bacterial and fungal metabolism and can release organic and inorganic acids. Interactions between these acidic solutions with guano were caused by leaching and changing the distribution and ratios of elements. The rate of leaching is determined by changes in the patterns of distribution of elements and the ratios of Th/U and LREEs/HREEs. The Eu/Eu* and Ce/Ce* ratios are applied to obtain information about the paleoredox conditions of guano deposition. Based on this study, three different climatic conditions, including dry, wet, and dry terms, have been recognized. Geochemical data of guano samples on the La/Th-Hf and Th-Sc diagrams represent intermediate-mafic source rocks. Plot the samples on the Th-Sc-Zr/10 and La/Th-Sc/Ni diagrams, suggesting that their source rocks evolved in a continental island arc tectonic setting. Based on 14C dating, the onset of guano production is about 14260 ± 50 BP after the Last Glacial Maximum recorded worldwide and close to the study area in Zaribar Lake, Zagros Mountains, and Alpine Mountains. The average accumulation rate of guano deposits has been 3.7 mm/year in Karaftu Cave.
Sedimentology
Parvaneh Faridi; Payman Rezaee; AliReza Piryaei; Mehdi Masoodi
Abstract
Halokinetic Sequences are used for analyzing and connecting endogenous and exogenous influencing factors on the sedimentary sequences around the diapir. The most important effect of the diapir movement is the creation of different sedimentary spaces in the result of uplift and subsidence. So, the Handun ...
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Halokinetic Sequences are used for analyzing and connecting endogenous and exogenous influencing factors on the sedimentary sequences around the diapir. The most important effect of the diapir movement is the creation of different sedimentary spaces in the result of uplift and subsidence. So, the Handun Salt Plug has been selected as a classic example. In the Handun salt plug outcrop Upper Cretaceous to recent sediments. The most important effect of the salt plug movement is during the Eocene of the Jahrum. The initial phase of salt extrusion was observed in the Gurpi Formation. Continuation of salt extrusion carrying on hook forms in the deep- water shale of the Pabdeh Formation in the Paleocene-middle Eocene. In the middle Eocene, when the Jahrum carbonate sedimentation exceeds the salt rise, wedges onlap the salt plug. In addition, thrusting led to the emergence of the salt tongues and forming hook in the Formation. The final phase of salt extrusion has been seen in the hooks in the siliciclastic of the Razak Formation. Finally, ongoing shortening is recorded by Guri member growth strata of the Handun salt plug. Our results provide new insights into using Halokinetic Sequences in tectono-sedimentary analysis of the Zagros diapirs.
Sedimentology
Hamed Hazariyan; Masoumeh Kordi; Mansour Ziaii; Mehrdad Soleimani Monfared; َAhmad Yahyaei
Abstract
The sequence stratigraphic studies provide information regarding the distribution of different facies within sedimentary basins. With determining relationship between reservoir or non-reservoir facies and sequence stratigraphy, dissemination of reservoir zones can be achieved within sequence stratigraphic ...
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The sequence stratigraphic studies provide information regarding the distribution of different facies within sedimentary basins. With determining relationship between reservoir or non-reservoir facies and sequence stratigraphy, dissemination of reservoir zones can be achieved within sequence stratigraphic framework. In this paper, using petrographic studies correlated with Gamma-Ray deviation logs, the sedimentary environment, sequences and systems tracts of the Oligo-Miocene Asmari Formation were revealed in one of the Iranian oil fields. Moreover, based on the wireline logs and petrophysical analyses, the factors controlling reservoir quality including porosity, water saturation and shale volume were invistigated within sequences and their systems tracts. The study showed that in general, the highstand systems tracts have higher reservoir quality than the trangressive systems tracts. Distribution of grain-suported and nearshore facies and also absence of anhydrite facies in the upper parts of transgressive systems tracts and the lower parts of highstand systems tracts resulted in development of the best reservoir quality zones within each sequence. This type of studies is very helpful in analysing the sedimentary basins and discovering distribution of the hydrocarbon reserves, and thus it could assist in management of risk reduction in exploration and development activities.
Sedimentology
Seyedeh Zahra Pourheidar; Mohamad Hosein Adabi; Mir Reza Moussavi Tasooj; Abbas Sadeghi
Abstract
The Elika Formation forms the major part of the Triassic carbonate sediments in the Alborz basin. In this study, facies and sedimentary environments of this formation were studied in Shahmirzad section whith a thickness of 746 meters and in Zereshk-Darreh section whith a thickness of 756 meters in the ...
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The Elika Formation forms the major part of the Triassic carbonate sediments in the Alborz basin. In this study, facies and sedimentary environments of this formation were studied in Shahmirzad section whith a thickness of 746 meters and in Zereshk-Darreh section whith a thickness of 756 meters in the southern part of central Alborz. Based on facies studies, four carbonate facies associations (tidal tlat, shoal, lagoon and open marine) have been identified, including twelve carbonate microfacies and have been deposited in a carbonate ramp. Deposition of sediments in this sequence can be divided into three stages. In the first stage, most of vermiculate limestone deposits are composed of bioturbated mudstone and clotted peloidal mudstone. The high frequency of facies such as laminated stromatolite, intraclastic packstone-grainstone and laminated mudstone are characteristic features of the second stage of sedimentation (middle dolomite) and indicate a decrease in the depth of sedimentary environment. In the third stage, the environment was suitable for the expansion of barriers and formation of packstone-grainstone facies.
Sedimentology
Elmira Shahkaram; Mohammad Hosein Adabi; Davood Jahani; Seyed Hamid Vaziri
Abstract
The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, ...
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The Dalichai Formation is the first rock unit of the Middle Jurassic in the Alborz sedimentary basin that has occurred in a marine environment. The boundary of the Dalichai formation with Shemshak Formation is erosional unconformable while it is concordant with Lar formation. Due to lithological similarity, the boundary of the Dalichai formation with the Lar formation is unclear. It is also very difficult to identify the primary carbonates mineralogy, due to the effects of diagenetic processes solely on the basis of petrographic studies. We studied a section of Sharaf mountain with a thickness of 1420m and 149 samples was studied. The study of the major and minor elements, the Oxygen and Carbon isotopes, and plotting of these values against each other represents that the Dalichai formation have had original aragonite mineralogy, and the nonmarine diagenesis have had the highest impact on them. Plotting the Sr/Ca ratio versus Mn value, shows that these carbonates are affected in a semi-closed to open diagenetic system. Using Sr, Sr/Na, Sr/Ca, Oxygen and Carbon isotopes, the boundary of this formation with the Lar Formation is recognized in thickness of 1200m. The diagenetic environment temperature for this section limestones is 32.9ºC.
Sedimentology
Navid Qavim; Najmeh Etemad-Saeed; Mahdi Najafi
Abstract
The Mahneshan Basin is one of the syntectonic Neogene sub-basins of the Central Iran. The basin is filled by about 4 km of the Miocene Upper Red Formation deposits, showing a combination of halokinetic and growth strata patterns. To assess the provenance evolution of sediments in north of the Mahneshan ...
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The Mahneshan Basin is one of the syntectonic Neogene sub-basins of the Central Iran. The basin is filled by about 4 km of the Miocene Upper Red Formation deposits, showing a combination of halokinetic and growth strata patterns. To assess the provenance evolution of sediments in north of the Mahneshan basin named the Hesar section, we conducted remote sensing mapping, field survey, as well as petrographical and modal analyses of sandstones. Our results reveal that the sandstones are fine to medium-grained sedarenites (Q46F10Rf44) and mainly derived from fine-grained siliciclastics, metamorphic, carbonate, chert and andesitic volcanic rocks, which were exposed in an orogenic tectonic setting (Qm34F10Lt56 and Qt49F10L41). The combination of provenance data and northeastward paleocurrent direction, reflect that the sediments mainly supplied from basement rocks of the Takab Complex and Qom Formation in southwest of Mahneshan Basin. The unchanged provenance of sediments along the studied succession, indicate that regional shortening and uplift of parent rocks has begun before deposition of the Upper Red Formation (Miocene) and continued during deposition of these sediments. This is in agreement with previous age assumption for exhumation of Takab Complex during Oligocene time.
Sedimentology
hajar ghafleh maramazi; Fardin mousivand; alireza zarasvandi
Abstract
The Gol-e-Zard zinc-lead deposit is located in the Malayer-Isfahan belt of Sanandaj-Sirjan zone in northeast of Aligudarz, Lorestan province. Mineralization occurred as two different ore horizon within metamorphosed Jurassic shale and sandstone. Generally, two ore facieses were distinguished in the deposit: ...
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The Gol-e-Zard zinc-lead deposit is located in the Malayer-Isfahan belt of Sanandaj-Sirjan zone in northeast of Aligudarz, Lorestan province. Mineralization occurred as two different ore horizon within metamorphosed Jurassic shale and sandstone. Generally, two ore facieses were distinguished in the deposit: 1) vein-veinlet/stringer facies, and 2) bedded facies. Primary minerals of the ores involve pyrite, sphalerite, galena and chalcopyrite, and the secondary minerals include cerussite, smithsonite, azurite, malachite and goethite. The gangue minerals are quarts, chlorite, calcite and clay-mineral. In the stringer facies, chalcopyrite replaced mainly pyrite and other minerals indicating influx of a copper-rich hot fluid influx into a pyrite-rich ore called as “zone-refining process”. In the Gol-e-Zard deposit metal and mineralogical zonation was observed. Alteration zones have distinct pattern, silicic-carbonatic at core to chloritic at margins. Based on textures and structures, mineralogical, ore facies, alterations and geochemical characters, the zinc-lead mineralization in the Gol-e-Zard region is of Selwyn-type sedimentary-exhalative (SEDEX) deposits, deformed and metamorphosed by the Late Cimmerian and Laramid Orogenies at green schist facies.
Sedimentology
Ali Hossein Jalilian
Abstract
The Mesozoic sequence in the Zagros Region (SW Iran) consists dominantly of carbonates especially dolomite that play the role of reservoir in many oil and gas fields of the region. To investigate the function of sedimentary and diagenetic processes in the formation of Triassic-Neocomian dolomites of ...
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The Mesozoic sequence in the Zagros Region (SW Iran) consists dominantly of carbonates especially dolomite that play the role of reservoir in many oil and gas fields of the region. To investigate the function of sedimentary and diagenetic processes in the formation of Triassic-Neocomian dolomites of the easthern High Zagros, this study focuses on petrography and geochemistry of the carbonates crop out in the Khaneh Kat anticline. Field and laboratory data led to the recognition of four different dolomitization models within the studied carbonates. The Lower-Middle Triassic and Upper Jurassic dolomites are medium to thick-bedded and composed of fine to medium-grained relatively ordered dolomite. The stoichiometric chemistries and heavier oxygen isotope ratios of these dolomites as well as the considerable presence of evaporites indicate the favorable conditions for the formation of early dolomite due to downward-percolating of concentrated evaporate brines (reflux model). The Upper Triassic dolomitic portion of the Zagros consists of medium to coarse-crystalline, massive-bedded dolomites with relatively light isotopic composition. Mineralogy and geochemistry of these dolomites indicate a high temperature origin as well as their relationship to diagenetic processes, including recrystallization in a deep-subsurface environment (burial model). In the Upper Jurassic portion of the succession, dolomites are ...
Sedimentology
Mahdi Ghaderi; Mohsen Moayyed; Nasir Amel; Monire Mojarrad
Abstract
The Saray volcano is located on the East of the Urmia Lake. This extinct stratovolcano mainly consists of Leucitite lavas and related pyroclasts. Dykes with composition of Leucite phonolite, Lamprophyre, Trachyte and microsyenite intruded into leucitite. Field evidences indicate that minette and trachytic ...
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The Saray volcano is located on the East of the Urmia Lake. This extinct stratovolcano mainly consists of Leucitite lavas and related pyroclasts. Dykes with composition of Leucite phonolite, Lamprophyre, Trachyte and microsyenite intruded into leucitite. Field evidences indicate that minette and trachytic dykes intruded into each other. A microsyenitic stock and dykes outcrops in the central valley of this volcano. The trachytic pyroclasts eruption is the last activity of the Saray volcano and probably caused the destruction of volcanoe’s caldera and formed its current shape. Leucitites maimly consist of leucite and clinopyroxene phonocrysts, minettes consist of biotite and clinopyroxene phenocrysts and trachytes consist of biotite, sanidine and clinopyroxene phenocrysts. The Saray magmatism has potassic to ultrapotassic nature and its geochemical features indicate that this magma should be originated from a micaceous garnet clinopyroxenite mantle. The coexistance of leucitite, lamprophyre and trachyte, could not be explained only by the function of fractional crystallization in leucitite magma. Sanidine is the most abundant feldspar in the Saray volcano. Sanidine megacrysts crystalize in a medium size magma chamber with continuing temperature cycling, so that the magma temperature remains close to the liquidus temperature of the K-feldspar for a long time.
Sedimentology
keyvan ahzan; Nader Kohansal Ghadimvand; Seyed Mohsen Aleali; Davood Jahani
Abstract
The Jahrum Formation (Paleocene-Mid Eocene) is one of the most important reservoir units in the Zagros basin and the Persian Gulf. The thickness of this formation in Binaloud oil field in Persian Gulf, which mainly consists of limestones and Dolomites, is about 660 meters. In this research, depositional ...
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The Jahrum Formation (Paleocene-Mid Eocene) is one of the most important reservoir units in the Zagros basin and the Persian Gulf. The thickness of this formation in Binaloud oil field in Persian Gulf, which mainly consists of limestones and Dolomites, is about 660 meters. In this research, depositional environment, sequence stratigraphy and effective diagenesis processes on Reservoir quality of the Jahrum Formation were investigated in Binaloud oil field. The Jahrum succession, which consists of crystalline limestones and dolomites, is overlain by the Asmari Formation and is underlian by the Tarbur Formation unconformably. According to study of cutting samples, eleven microfacies that were deposited in four facies belts, have determined . The most important diagenetic process that was observed in this formation as follows: bioturbation, cementation, dolomitization, dissolution, porosity generation and fracture systems wich is worthy to mation bioturbation and anhydrite cement causes the reduce of reservoir quality and dolomitization , dissolution and secondary porosity causes the reservoir quality. improvement most of facies jahrum formation are mud supported and have very low primary porosity. According to sequence stratigraphy studies, a third order sedimentary sequence with type SB1 boundary was identified in Jahrum subsurface succession.
Sedimentology
Javad Anjerdi; Mahdi Jafarzadeh; Adel Najafzadeh; Rahim Mahari
Abstract
In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types ...
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In this research, a combination of petrography, geochemistry and heavy minerals analysis methods are implemented for investigating the provenance of quartzarenitic and subarkosic sandstones of Ilanqareh Formation with Late Devonian age in Azerbaijan, south of Jolfa. Investigation of the quartz types in the studied sandstones, geochemical characteristics of sandstones and shales of Ilanqareh Formation including Al2O3/TiO2 ratio and La/Sc against Co/Th ratios, illustrates that the dominant parent rocks of most of these deposits are granitic igneous ones. The presence of granitic parent rock along with the presence of euhedral zircon and tourmaline among the well-rounded indicate the erosion of uplifted blocks of Iranian basement in the rifted basin of Paleotethys as effective factor in providing sediments. However, geochemistry and heavy mineral assemblages confirm the recycling of sediments from older formations as another source of sediment. The petrography, geochemistry and heavy minerals also indicate the craton provenance and passive margin tectonic setting at the deposition time of the Ilanqareh sediments. According to the present study, one can consider a combination of uplifted source rock (Cadomian basement) and sedimentary recycling of older formations as main sources and Arabian craton as a subsidiary source in the supply of detritus sanstones of Ilanqareh Formation.
