Facies

Open Access Article

1 - Robustness of fuzzy c-mean method for delineation of hydrochemical facies distribution of groundwater in Varamin Plain
Mohammad Nakhaei Mehdi Talkhabi Meysam Vadiati

In this paper, classification of a large hydrochemical data set from Varamin plain is done by using fuzzy c-means (FCM) and hierarchical cluster analysis (HCA) clustering techniques. Then its application to hydrochemical facies delineation is discussed. Groundwater samp More

In this paper, classification of a large hydrochemical data set from Varamin plain is done by using fuzzy c-means (FCM) and hierarchical cluster analysis (HCA) clustering techniques. Then its application to hydrochemical facies delineation is discussed. Groundwater samples were grouped into three classes according to the optimum number of the classes and fuzziness exponent by using the fuzzy c-mean. The data set includes 90 deep and moderate deep well samples from groundwater data set and 9 hydrochemical variables were used. Results from both FCM and HCA clustering produced cluster centers that can be used to identify the physical and chemical processes creating the variations in the water chemistries. The optimum cluster in FCM method determined by optimization function, but in HCA method by trial and error. The FCM method is potentially useful in establishing hydrochemical facies distribution and may provide a better tool than HCA for clustering large data sets when overlapping or continuous clusters exist. Plotting the cluster membership value contours on a map demonstrated the existence of three spatially continuous, well-defined clusters of groundwater samples. The results showed that the FCM method is more sound for investigating threshold data rather than HCA method (that represents sharp and abrupt variations). Manuscript profile

Open Access Article

2 - Geomechanical zonation of the Faraghan, Zakeen and Sarchahan formations based on incorporation of rock mechanical and sedimentological studies, in one of the Persian Gulf oil fields
Mehran Kalhori Hooshang Mehrabi Ebrahim Sefidari Hasan Eshraghi Behnam Vaez Livari

Geomechanical studies have important applications in various topics such as wellbore stability, well completion, well orientation, hydraulic fracturing plans and operations, sand production and hydrocarbon fields subsidence. It is necessary to prepare earth mechanical m More

Geomechanical studies have important applications in various topics such as wellbore stability, well completion, well orientation, hydraulic fracturing plans and operations, sand production and hydrocarbon fields subsidence. It is necessary to prepare earth mechanical model of the well in the field. In addition, one of the necessary subjects to prepare mechanical earth model (MEM) is providing continuous rock mechanical parameters in the well. Rock mechanical parameters change by any variation in lithology. In this study, rock mechanical parameters are provided in continuous form, for Faraghan, Zakeen and Sarchahan formations for a field in the Persian Gulf and these parameters are clustered. Clustering resulted in recognizing six clusters with various rock mechanical characteristics. Petrographic study (i.e. determining facies, cementation and diagenesis) recognized five facies with different petrographic and cementation characteristics. These facies include quartz arenite and arkosic sandstones, shales, red mudstone and carbonates. A correlation between sedimentary and geomechanical facies was found. According to petrographic and geomechanical studies, the studied interval was divided into 7 sections. Accordingly, variation of rock mechanical parameters with regard to change in lithology was investigated. In addition, the impact of rock composition, cementation and compaction changes on rock mechanical parameters were evaluated as well. Manuscript profile

Open Access Article

3 - Facies and depositional model in siliciclastic Chelken Formation, South Ghaemshahr City
هوشنگ مهرابی عبدالحسین امینی وحید توکلی مرتضی فرخی Seyed Mohad Zamanzadeh

20.1001.1.17357128.1399.14.55.7.8

Siliciclastic Chelken Formation (Lower and Middle Pliocene) with a siliciclastics nature in Javarom Section (south of the Ghaemshahr city) was studied. This formation comprises three sets of conglomerate, sandstone and mudstone, which are usually arranged in fining upwa More

Siliciclastic Chelken Formation (Lower and Middle Pliocene) with a siliciclastics nature in Javarom Section (south of the Ghaemshahr city) was studied. This formation comprises three sets of conglomerate, sandstone and mudstone, which are usually arranged in fining upwards sequences. According to the nature of fining upward sedimentary sequences, sedimentological characteristics and structural features, it is proposed that Chelken Formation deposited in a fluvial environment. Conglomeratic facies are mainly grain-supported in nature, sandstone facies are represented by quartz arenite and lithic arenite in nature and Mudstone facies are carbonate in nature. The paleo-currents analyses represent a north and northeastward direction Manuscript profile

Open Access Article

4 - Facies studies and depositional environment of Sahand volcanic complex (NW of Iran)
Farhad Pirmohammadi alishah Ahmad Jahangiri

20.1001.1.17357128.1400.15.58.3.7

Sahand volcanic complex is located in the south of Tabriz and east of Urmia Lake and includes an alternation of lava, igneous materials and clastic sediments that were affected by many folds and fractures. Sahand volcano is relatively young in age (Miocene to Pliocene) More

Sahand volcanic complex is located in the south of Tabriz and east of Urmia Lake and includes an alternation of lava, igneous materials and clastic sediments that were affected by many folds and fractures. Sahand volcano is relatively young in age (Miocene to Pliocene) and its structure is somewhat intact. Consequently, where there is a good lateral continuity, facies and volcanological studies can be carried out in the upper part of the complex. Based on these studies, it was determined that the Sahand volcanic structure can be divided into four central, near, medium and distant facies. Facies studies show that the structure of Sahand Volcano was created by several explosive phases, some of which were associated with water intrusion and there was not much time between eruptions. Characteristics, such as severe welding and discoloration of pyroclastic deposits show that these units had a high temperature at the time of formation and were formed on land. Overall, Sahand volcanic eruptions were more explosive, and thus, the number of pyroclastic deposits is much higher than lava flows. In the central, near and middle facies of Sahand, no traces of younger hydrothermal activities can be found, and only in the distant facies, there is a hot spring (Bostan Abad), the relationship of which needs further study to prove the connection of these springs with the Sahand Volcano. Manuscript profile

Open Access Article

5 - Basic steps in determining the provenance of terrestrial sedimentary sequences, with examples from central and north west of Iran
عبدالحسین امینی

20.1001.1.17357128.1400.15.60.5.3

By stating the fundamental differences between terrestrial and detrital facies, this paper emphasizes on the limitations of provenance studies in terrestrial facies. Considering the presence of coarse-, medium- and fine-grained facies in most of terrestrial sedimentary More

By stating the fundamental differences between terrestrial and detrital facies, this paper emphasizes on the limitations of provenance studies in terrestrial facies. Considering the presence of coarse-, medium- and fine-grained facies in most of terrestrial sedimentary sequences, the differences in textural and mineralogical characteristics, their study methods and possible differences in the provenance of these facies, the basic and necessary steps in studying these facies for determining the sedimentary provenance was investigated. In explaining these steps, some examples from terrestrial formations of Central Iran (Upper Red Formation) and north west of Iran (Zivar Formation) are presented. The role of diagenesis, structural deformation and paleogeography in the provenance study and their importance in this type of studies are explained. Finally, it is discussed how to proof the accuracy of the interpretations for the studied sedimentary sequences. Manuscript profile

Open Access Article

6 - An investigation on sedimentary facies and hydrochemistry characteristics of carbonate deposits in the Ab-e Ask region, Southeast of Damavand volcano
S. Rahmani Javanmard Mohsen Ranjbaran V. Amiri

20.1001.1.17357128.1401.16.62.5.4

Calcareous springs of Ab-e Ask are located 85 km northeast of Tehran, in the southern range of the Damavand volcano. Microscopic studies represent the existence of four abiotic and two microbialite facies in the Ab-e Ask travertines. The travertines are the main deposit More

Calcareous springs of Ab-e Ask are located 85 km northeast of Tehran, in the southern range of the Damavand volcano. Microscopic studies represent the existence of four abiotic and two microbialite facies in the Ab-e Ask travertines. The travertines are the main deposit types of these springs. Based on sedimentation sequence and lithofacies these travertines are categorized as first type (vent and channel), second type (pound, dam, and cascade), and third type (laminated) travertines. On a δ18O versus δ13C plot (VPDB), these travertines are plotted in the oncoid and crystalline crust lithofacies fields. These facies show the character of hydrothermal spring and set the spring in the thermogenic group. Positive values of the Langelier Saturation Index (LSI) for Pashnak, Nadaali, and Zagh springs indicate that these water samples are supersaturated with respect to calcium carbonate, which leads to considerable sedimentation around the springs. In contrast, a negative LSI value at the Sare Pole spring indicates the water is undersaturated with respect to calcium carbonate. Therefore, this spring has a lesser role in travertine deposition compared to the other springs. Also, the position of the samples on the modified Gibbs and Van Wirdum diagrams, suggests that the interaction of water with carbonate and to some extent silicate rocks is considered as the most important source of Ca and Na. Manuscript profile

Open Access Article

7 - Facies analysis and sedimentary environment of the Jeirud Formation in Garmabdar section, central Alborz: with emphasis on paleoredox conditions during deposition of black shales
Nahid Karimi Najmeh Etemad-Saeed Aram Bayet-Goll Afshin Zohdi Tomas Kumpan

20.1001.1.17357128.1401.16.63.4.5

The late Devonian has been associated with major global climate changes, widespread anoxia events, and the Hangenberg Crisis. The main aim of this study is to explore the relationship between paleoenvironment and paleoredox condition during deposition of the lower Devon More

The late Devonian has been associated with major global climate changes, widespread anoxia events, and the Hangenberg Crisis. The main aim of this study is to explore the relationship between paleoenvironment and paleoredox condition during deposition of the lower Devonian Jeirud Formation in the Garmabdar section, northeast of Tehran. The Jeirud Formation in the Garmabdar section, with a thickness of about 280 m, is composed of siliciclastics, carbonates, carbonate-siliciclastic hybrids and phosphorite deposits. Sedimentary facies analysis led to recognition of three siliciclastic facies associations related to estuarine environments under the influence of waves, shoreface and offshore and two carbonate facies associations related to intertidal and subtidal environments. Moreover, the geochemical paleoredox proxies (such as U/Th and V/Cr) also suggest prevailing anoxic conditions during deposition of black shales and phosphorites in the studied section. In overall, these results suggest that there is a good agreement between the depth of the depositional environment and anoxic conditions during deposition of black shales of the Jeirud Formation. Manuscript profile

Open Access Article

8 - The history of deposition and post-deposition and their effects on the reservoir quality of Asmari Formation in Ahvaz oilfield
Akbar Heidari Milad Faraji Narges Shokri

The carbonate interval of the Asmari formation along with sandstone deposits were deposited in most areas of the Zagros sedimentary Basin, including the Ahvaz area, in Oligo-Miocene. In this study, the effects of depositional and post-depositional environments on the re More

The carbonate interval of the Asmari formation along with sandstone deposits were deposited in most areas of the Zagros sedimentary Basin, including the Ahvaz area, in Oligo-Miocene. In this study, the effects of depositional and post-depositional environments on the reservoir quality of zone A7 of the Asmari Formation in well No. 4 in Ahvaz oil field were studied. The study of the sequences of the Asmari Formation in this section led to the identification of 11 carbonate facies, one evaporite facies, one mixed carbonate-siliciclastic facies, and one siliciclastic facies. Sedimentary environments of tidal zone, lagoon, coral reef and open sea were introduced for the depositional environment of identified facies. Due to the absence of sudden changes, it seems that the studied deposits were deposited in a ramp-type carbonate platform that was influenced by siliciclastic sediments from the Zagros river systems. The immature sedimentary texture of the sandstone facies indicates the proximity of the origin of the quartz sources to the carbonate basin. Among the diagenetic processes that have affected the examined sequences, the following processes can be mentioned: micritization, cementation, neomorphism, physical and chemical compaction, dissolution, fracture development and filling, dolomitization, and anhydritization. These diagenetic processes occurred in post-depositional marine, meteoric and burial diagenetic environments. Many fractures were filled with petroleum, which indicates that fractures, along with dolomitization, chemical compaction, and fenestral pores, are among the most important post-sedimentation complications to increase reservoir quality. While cementation and anhydritization resulted in reducing the reservoir quality by closing the pore spaces . Manuscript profile

Open Access Article

9 - Reconstruction of Jeirud Formation depositional environment in Aro Section (Central Alborz)
Seyed Mohammad Zamanzadeh M. Ranjbaran K. Ghaffari

In this paper it is attempted to reconstruct the depositional environment of the Jeirud Formation in Aro section. The Jeirud Formation (Late Devonian) is composed of about 45 meters of clastic sedimentary units in the southwest of Firoozkuh city, southern Alborz area. T More

In this paper it is attempted to reconstruct the depositional environment of the Jeirud Formation in Aro section. The Jeirud Formation (Late Devonian) is composed of about 45 meters of clastic sedimentary units in the southwest of Firoozkuh city, southern Alborz area. To carry out this research a field work was done during which a precise and detailed sedimentary log of the section was prepared and 52 samples from different lithologies of the formation were collected. Thin sections were prepared from all conglomeratic and sandstone samples, besides some thin sections were prepared from mudrocks and just 1 sample of paleosoil and then all were petrographically studied. In the study area, both basal and top boundary of the Jeirud Formation is disconformable with Mila and Mobarak formations respectively. All facies in the section include clastics (conglomerates, sandstones, mudstones and a paleosoil horizon). The facies were classified based on Miall classification so that conglomeratic facies comprise Gcm and Gmm; sandstone facies comprise Sh, Sp and Sm and mudrocks include Fl and Fm facies. Combined field and lab studies resulted in identification of two sedimentary facies associations including channel fill and flood plain facies associations. The reconstructed sedimentary environment of the Jeirud Formation in the Aro area represents a braided river depositional environment. The lower parts of this formation represent a finning-upward sequence which indicates deposition within a braided river channel subenvironment (conglomerates and sandstones) and the upper part is dominated with mudrocks with a paleosoil horizon representing deposition in a flood plain subenvironment. Manuscript profile

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