Zagros

Open Access Article

1 - The geometric and kinematic analysis of the Kabir-Kuh and Chenareh anticlines in the Zagros Fold-Thrust Belt
فاطمه زینعلی mohammad hosein goudarzi

20.1001.1.17357128.1394.9.34.2.6

Kabir-Kuh and Chenareh anticlines are located in the Lurestan Province of the Zagros fold-thrust belt. The geometry and kinematic evolution of folds in the Zagros fold-thrust belt are controlled by thrust faults. In this paper, the geometry of the Kabir-Kuh and Chenareh More

Kabir-Kuh and Chenareh anticlines are located in the Lurestan Province of the Zagros fold-thrust belt. The geometry and kinematic evolution of folds in the Zagros fold-thrust belt are controlled by thrust faults. In this paper, the geometry of the Kabir-Kuh and Chenareh anticlines is investigated in order to analyze their deformation style. To analyze the deformation style of these anticlines, five structural cross-sections were measured perpendicular to the axial surface trace of the anticlines. Based on geometric and kinematic analysis, Kabir-Kuh and Chenareh anticlines have a geometry similar to faulted-detachment folds with multi-detachment levels. The detachment level above which the folds formed is probably located in the Lower Paleozoic series. Also structural cross-sections represent an important contribution of the Dashtak Formation as intermediate level in the development of deformation in this part of the Lurestan Province. Manuscript profile

Open Access Article

2 - Structural analysis of elevated Sabzkuh syncline in High Zagros
yasser narimani Elham Asadi Mehmandosti

High Zagros zone located in the northeast of Zagros Fold-Thrust Belt and comprises of NW-trending thrust faults. In Sabzkuh area, these thrust faults as forethrust and backthrust have accompanied with positive and negative triangle zones. These zones cause formation of More

High Zagros zone located in the northeast of Zagros Fold-Thrust Belt and comprises of NW-trending thrust faults. In Sabzkuh area, these thrust faults as forethrust and backthrust have accompanied with positive and negative triangle zones. These zones cause formation of the elevated Sabzkuh syncline on the hanging wall of the Dopoulan and Solaghan-Avardegan Fault as well as the Choghakhor embayment at footwalls of the Main Zagros and Solaghan-Avardegan faults. The horizontal bedding in the Ilam-Sarvak formations in the main faults footwall can be used as an evidence for the formation of the embayment. The elevated Sabzkuh syncline is associated with accommodation of limb wedge thrusts on the fold limbs. These structures show complexity of thrust faults geometry in the high Zagros and imply their initiation from the detachment horizons within the Lower Paleozoic/Hormoz Formation. Manuscript profile

Open Access Article

3 - Geochemistry, microfacies and depositional environment of Eocene Deposit in Gach Mountain, in SE Lar Area
محمد حسين آدابي

The Jahrum Formation in Gach Mountain, located near village of Chahar Berkeh, in 30 Km of south- east of Lar City, south- west of Iran (Zagros Basin). This formation with the total thickness of 404.5 m consists of dolomite, calcareous dolomite and limestone. This form More

The Jahrum Formation in Gach Mountain, located near village of Chahar Berkeh, in 30 Km of south- east of Lar City, south- west of Iran (Zagros Basin). This formation with the total thickness of 404.5 m consists of dolomite, calcareous dolomite and limestone. This formation overlies the Sachun Formation. The Asmari Formation with the total thickness of 44.5 m consists of limestone and marly limestone, and covered by evaporite deposits of the Gachsaran Formation. The age of the Jahrum Formation is Late Paleocene to Late Eocene. Eocene deposit in Gach Mountain, based on different facies, foraminifera and other skeletal and non skeletal grains, 7 microfacies were recognized. These microfacies deposited in a carbonates ramp environment with ooid shoal deposits. Analysis of 30 samples of limestones and dolomites for major and minor elements (Ca, Mg, Fe, Mn, Na, and Sr) and oxygen and carbon isotope values were used for carbonate mineralogy, types of dolomites, and diagenetic system. This study indicates that Jahrum carbonates were deposited in a shallow warm water tropical environment and original carbonate mineralogy was aragonite. These carbonates were affected by close to semi close diagenetic system with low water/rock interaction. Diagenetic trend in limestones and dolomite, based on oxygen and carbon isotope variations, shows a burial diagenesis with the presence of origanic matter. Temperature calculation based on heaviest oxygen isotope values (-3.32% PDB) of micrite and δw of Eocene seawater of - 0.85 SMOW, indicate that very shallow burial temperature was around 23˚C. Sequence stratigraphic studies, shows that two depositional sequences, consisting of transgrassive system tract (TST) and highstand system tract (HST). This sequences, shows third order type, with sequence boundaries (SB2). Maximum flooding surface in the Jahrum Formation was determined based on different facies and variation of isotope values. Manuscript profile

Open Access Article

4 - Neotectonic zoning using morphometric indices in Lali – Gotvand area, Khuzestan
Tayebeh Ahmadi Aziz Rahimi Hojahallah Safari Arash Barjasteh

Quantitative assessment forms and effects of the Earth's surface and calculation of morphometry indices of rivers, river channel, and mountain fronts are the best methods for investigation of the active tectonics. The studied area is located in Dezful Embayment zone of More

Quantitative assessment forms and effects of the Earth's surface and calculation of morphometry indices of rivers, river channel, and mountain fronts are the best methods for investigation of the active tectonics. The studied area is located in Dezful Embayment zone of the Zagros Simply Folded Belt. In this study, the tectonics and regional morphotectonics of Lali – Gotvand area are interpreted using digital elevation model. This research analyzed three indices including mountain front sinuosity (Smf), ratio of valley width to valley height (Vf) and stream length-gradient index (Sl). The morphometry indices were analyzed to determine tectonic activity according to general tectonic of Simply Folded Zagros and Dezful Embayment in Lali - Gotvand region in the north east of Khuzestan. After calculating the noted indices and information integration layers, the neotectonic zoning map were prepared as tectonic activity in 4 categories: very active, active, relatively active and non-active. According to these results, maximum tectonic activities have occurred in the North East based on stream length-gradient index, in East, North East, South East based on ratio of valley width to valley height and in North East, South East and central part based on mountain front sinuosity, respectively. The neotectonic zoning map shows the highest activity in the North, North East and Center and the lowest activity in the South of the study area. Manuscript profile

Open Access Article

5 - The role of tectonic structures in conducting groundwater inflow to the second part of Zagros water tunnel – Kermanshah province
HamidReza Nasseri Narges Bayat Lili Izadi Kian Farshad Alijani

High local groundwater flow into rock tunnels is a technical and environmental problem for underground constructions. Geological structures such as faults, open fractures, and dissolution channels could play important roles in conducting ground waters to the tunnels. Ho More

High local groundwater flow into rock tunnels is a technical and environmental problem for underground constructions. Geological structures such as faults, open fractures, and dissolution channels could play important roles in conducting ground waters to the tunnels. However, prediction of groundwater inflow from these structures using analytical and empirical method often failed due to given hydrogeological assumptions and simplification such as a homogeneous and isotropic porous medium around the tunnel. The Zagros water tunnel is located in the northwest of Kermanshah province. A huge amount of groundwater flow into the tunnel through fractures occurred during drilling of the second part of tunnel. The second part of tunnel passes through Pabdeh and Gurpi formations. A considerable amount of groundwater flushed into the tunnel when the Ilam Formation was penetrated, causing numerous problems and great damage to the drilling operation. The goal of this study is to identify the factors that influenced water flows into the tunnel. To this purpose, geological features of high flow rate zones have been identified and investigated. The highest input rate (800 l/s) was recorded in the zone Hz23 located in Kurdighaseman anticline. The relationship between geological features and the groundwater inflow into the tunnel indicated that faults play conveying role for ground water into the tunnel. Evaluation of high local groundwater inflow to rock tunnels based on characterization of geological structures is more reliable compared to available analytical and empirical estimation. Manuscript profile

Open Access Article

6 - Determining the deposits attributed to the Gurpi Formation based on the calcareous nannofossil located in SW Borojen, Chahar-Mahal and Bakhtiyari provinces
Saeideh Senemari Fariba Foroughi

20.1001.1.17357128.1398.13.50.1.5

Calcareous nannofossils are useful in determining the relative age of the Cretaceous strata. In this study, the Gurpi Formation with a thickness of 445 m at the Kuh-e Sabz syncline located in southwest of Borojen city is investigated based on the calcareous nannofossils More

Calcareous nannofossils are useful in determining the relative age of the Cretaceous strata. In this study, the Gurpi Formation with a thickness of 445 m at the Kuh-e Sabz syncline located in southwest of Borojen city is investigated based on the calcareous nannofossils. As a result of this study, 20 genera and 37 species of calcareous nannofossil were identified. Based on distribution of these index calcareous nannofossils, seven bio-zones were recognized including: Calculites obscurus Zone (CC17/ late Santonian- early Campanian), Aspidolithus parcus Zone (CC18/ early Campanian), Calculites ovalis Zone (CC19/ late Early Campanian), Ceratolithoides aculeus Zone (CC20/ late Early Campanian), Quadrum sissinghii Zone (CC21/ early Late Campanian), Quadrum trifidum Zone (CC22/ late Late Campanian) and Tranolithus phacelosus Zone (CC23/ latest Campanian–early Maastrichtian), that corresponding to upper part of NC17 - NC20 and UC13-UC17. Based on the identified zones, the age of the studied intervals is Late Santonian/Early Campanian to latest Campanian/early Maastrichtian. The study of the Gurpi Formation in the Kuh-e Sabz syncline, shows that the sedimentation began at the Late Santonian/Early Campanian time and continued up to the latest Campanian/early Maastrichtian. Then, with a sudden drop in the depth of sedimentary basin, the Tarbur Formation gradually deposited on the top of the Gurpi Formation. Manuscript profile

Open Access Article

7 - Petrology and geochemistry of basic rocks of the Piranshahr Ophiolitic complex in Zagros belt (NW Iran), compared with the similar rocks from Iraqi Zagros ophiolitic complex
Maryam Yazdani

The Piranshahr ophiolitic complex is located in NW Iran and in the north west of Piranshahr town. Tectonically, the NW Piranshahr ophiolitic complex is severely mingled and the boundary of different units in this complex is indistinguishable. Piranshahr ophiolite includ More

The Piranshahr ophiolitic complex is located in NW Iran and in the north west of Piranshahr town. Tectonically, the NW Piranshahr ophiolitic complex is severely mingled and the boundary of different units in this complex is indistinguishable. Piranshahr ophiolite includes ultramafic, mafic, sedimentary and metamorphic rocks. Basic rocks with basalt and diabase compositions are exposed in several parts of the region. In this paper, whole rocks geochemistry and petrogenesis of basic rocks were studied in the Piramshahr ophiolite (in the Mashkan and Gerdikavalan areas) and were compared with the geochemistry of basic rocks located in the west of Mawat ophiolite in Iraq (in the Hasanbag, Walash and Neopurdan regions). Composition of basic rocks of Mashkan area in Piranshahr ophiolite and Hasanbag area in Iraq ophiolite is calc-alkaline in nature and depleted with respect to MREE, HREE,Zr, Hf, Y, Ti elements and enriched in Rb, Cs, Ba, U, Th, Pb, LREE elements with negative Ta, Nb anomalies. These geochemical features show that the source of magma was generated in the supra-subduction zone tectonic settings. Composition of basic rocks of Gerdikavalan area in Piranshahr ophiolite and similar rocks in the Walash-Neopurdan areas in Iraq ophiolite represent tholeiitic nature. Tholeiitic nature in these areas show both MORB and volcanic arc affinity. It seems that the tholeiitic magma was probably generated in the lithospheric extension over on subduction zone and these features conform asupra-subduction setting for basic rocks in Piranshahr ophiolite and similar rocks in western continuation of Iraq ophiolitic complex. Manuscript profile

Open Access Article

8 - Investigating rate of Doroud fault zone tectonic activity (southwest of Iran) by using geomorphologic data analysis (fans, basins and drainage system)
محمدرضا سپهوند Zahra Kamali Tokhmechi MahmoudReza Hayhat Roshandel Kahoo Hamid Nazari Ahmadi Noubari Mohammad Mahdi Khatib

Morphotectonic analysis with the help of geomorphic indices is considered as a tool for the identification of new and active structures affected by tectonic movements in special areas. For this purpose, indicators such as Mountain Front Sinuosity index (Smf), (Vf), (Af More

Morphotectonic analysis with the help of geomorphic indices is considered as a tool for the identification of new and active structures affected by tectonic movements in special areas. For this purpose, indicators such as Mountain Front Sinuosity index (Smf), (Vf), (Af), (S), (Sl), (T), form factor basin, basin shape, slenderness ratio and stretch ratio index of basin (Bs) associated with alluvial fans, including fan of bending β, fanning coefficient and longitudinal profile were calculated. The tools in this study include: the topographic maps, field geology invesigations, satellite imagery, digital elevation model (DEM), IRS satellite images of the region, GIS and Global mapper softwares. The results of the analysis of topographic data, evidences from field observations and data obtained from geomorphic indicators, all suggested that the area is active from neotectonics viewpoint. Based on the classification of LAT, the study area is classified in class 1, which indicates intense tectonic activity. Based on the results, the northern part of the Dorud fault is more active than the southern section in terms of neotectonic movements. Manuscript profile

Open Access Article

9 - Geometrical parameter, Anticline, Sarkan, Zagros, Lurestan
Reza Alipoor امیرحسین‌ صدر farid shahmoradi عارف شمس‌زاده

20.1001.1.17357128.1399.14.55.8.9

The Sarkan anticline is located in the Lurestan sedimentary-structural zone and in the Zagros fold and thrust belt. Geometry and kinematic of the fold of this zone are controlled by thrust faults and detachment levels. The exposed formations in this anticline are the up More

The Sarkan anticline is located in the Lurestan sedimentary-structural zone and in the Zagros fold and thrust belt. Geometry and kinematic of the fold of this zone are controlled by thrust faults and detachment levels. The exposed formations in this anticline are the upper Cretaceous and Cenozoic formations. In this research, geometry and deformational style analysis of the anticline and role of the detachment levels on folding style have been investigated using drawing four structural cross-sections, interpretation of the seismic profiles and calculation of geometric parameters. The structure of this anticline is affected by two detachment horizon, which is the flysch Amiran, and shaly Garu formations as the upper and middle detachment levels, respectively. The high thickness of the upper detachment level caused displacement of the surface anticline axis to the SW with respect to the deep anticline axis. The study of geometrical parameters and structural cross-sections of the Sarkan anticline exhibit that this structure is an asymmetric and noncylindrical anticline, and from tightness and aspect ratio view is ranked in the open to gentle and wide category, respectively. Manuscript profile

Open Access Article

10 - Sudden drowning of the Late Cretaceous carbonate platform in central Zagros basin: a case study from the shaley Laffan Member in one of the Oil Fields of Abadan Plain, SW Iran
maryam kianifard علی حسین جلیلیان nasser arzani

20.1001.1.17357128.1399.14.56.1.4

Rapid sea-level rise and drowning of carbonate platforms is one of the important geological events in the Late Cretaceous and after the Turonian global unconformity. This transgression in central and western Zagros Basin is represented as shaley sediments of the Laffan More

Rapid sea-level rise and drowning of carbonate platforms is one of the important geological events in the Late Cretaceous and after the Turonian global unconformity. This transgression in central and western Zagros Basin is represented as shaley sediments of the Laffan Member, which were deposited over the Sarvak Formation. The stratigraphic position and the occurrence of the Charophytes-Ostracods biozone indicate the late Cretaceous, Coniacian age for the Laffan Member, which is stratigraphically equivalent to the Surgah Formation in Lurestan area in the west of Iran. The Laffan Member is mainly shaley in lithology with intercalations of thin-bedded argillaceous limestones and is the caprock over the reservoir of the Sarvak Formation in some oil fields in SW Zagros. Microfacies, sedimentary environments, biostratigraphy and sequence stratigraphy of the Laffan Member in two wells of Azadegan Oil Field located in Abadan Plain were investigated. Petrographic data revealed the presence of a shaley facies and two carbonate microfacies including charophitic mudstone-wackestone to bioclastic planktonic foraminiferal wackestone. These microfacies were deposited in transitional-brackish to deep marine environments. Marine transgression over the eroded palaeotopography of the Cenomanian-Toronian carbonates resulted in estuaries as channels and transitional environments. In these estuaries, mixture of the fresh and marine waters resulted in deposition of the lower parts of the Laffan Member and graded upward into the marine deposits of the upper parts of this Member.The sudden change of shallow-transitional facies to deep marine sediments in the Laffan Member indicates drowning of the carbonate platform of central Zagros Basin in Coniacian. The evidence like erosional base, deepening-upward sequences, frequency of mudstone facies (shale) and continuity with marine carbonates confirm this conclusion. Investigation of vertical changes of the microfacies with gama-ray well log data indicate the Laffan Member is part of a sequence as lowstand deposits (LST), transgressive deposits (TST) which grade upwards into maximum flooding surface (MFS) and high-stand deposits (HST) which comprise a third-order sequence. This sequence begins with an erosional unconformity and follows up with the formation of the estuary and deep sea sediments. The latter package is covered with the carbonate sediments of the lower part of the Ilam Formation (Santonian) which represents carbonate platform deposits of high-stand system track (HST). Manuscript profile

Open Access Article

11 - Calcareous nannofossil biostratigraphy in the upper part of the Garau Formation in the Sheikh Saleh section in Northwest of Kermanshah, Lurestan Province (Zagros Basin)
سعیده سنماری

20.1001.1.17357128.1400.15.58.4.8

In this study, the upper part of the Garau Formation with a thickness of 24 m in the section of Sheikh Saleh anticline located in the northwest of Kermanshah was investigated from the calcareous nannofossils. In this section, the Garau Formation is mainly composed of me More

In this study, the upper part of the Garau Formation with a thickness of 24 m in the section of Sheikh Saleh anticline located in the northwest of Kermanshah was investigated from the calcareous nannofossils. In this section, the Garau Formation is mainly composed of medium bedded argillaceous limestone. In order to introduce the index species and biozones, 17 slides from the Garau Formation were studied, which resulted in the identification of three biozones. As a result of this study, 20 species and 15 genera of calcareous nannofossils were identified. Based on the obtained biozones, the age of the upper part of the Garau Formation in the studied section is suggested the late early Cenomanian to the late late Cenomanian. This age is corresponding to the upper part of Eiffellithus turriseiffelii Zone (CC9), Microrhabdulus decorates Zone (CC10), lower part of Quadrum gartneri Zone (CC11) from the Sissingh (1977) zonation and UC1, UC2, UC3, and lower part of UC7 from the Burnett (1998) zonation. Manuscript profile

Open Access Article

12 - Physiochemical characteristics of oOre-bearing fluids for celestite occurrence in the Zagros fold-thrust belt: using microthermometry studies
رضوانه حمیدی Hojjat Ollah Safari مهاسا روستایی

20.1001.1.17357128.1400.15.60.3.1

Oilgocene-Miocene celestite occurrences are observed across the carbonate-evaporite formations of Asmari and Gachsaran in the Zagros fold - thrust belt. The aim of this research is the study of fluid inclusions in our celestite deposits (Tortab, Tarak, Likak and Babamoh More

Oilgocene-Miocene celestite occurrences are observed across the carbonate-evaporite formations of Asmari and Gachsaran in the Zagros fold - thrust belt. The aim of this research is the study of fluid inclusions in our celestite deposits (Tortab, Tarak, Likak and Babamohamad) to reveal the nature of ore-forming fluids. Abundant structures including: geodic and vein-like structures as open-space filling along with replacement textures like mosaic and vein-like in a carbonate matrix are present. Moreover, celestite, calcite, gypsum and anhydrite are observed as the major minerals in this deposits. Based on petrographic studies, 5 groups of fluid inclusions were recognised, which are categorized as: Liquid mono phase (L), vapour mono phase (V), liquid-rich two phase (LV), vapor-rich two phase (VL) and multi-phase fluids (LVS). The results obtained from the study of microthermometry data show 134.3 to 291.8°C as homogenisation temperatures and salinities of 2.5-18.17 wt%, NaCl equ, all are involved in forming celestite. Based on the results of microthermometry data, it can be deduced that formation mechanism of celestite is resulted from reaction between fluid and rocks of the area. Moreover, tectonic activities such as uplift and diagenesis of beds along with dissolution of minerals have caused release of strontium in the fluids responsible for ore-forming. This has generally undertaken by two fluids of meteoric and brine origins over different stages of ore-formation, replacing anhydrite with strontium at high temperatures during late- diagenetic and epigenetic processes. Manuscript profile

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