Asmari Limestone Research Articles

Assessment of the hydrogeochemical and isotopic characterization and hydraulic behavior of the Izeh complex karstic area, Khuzestan province, southwest Iran

Proper water resources management requires recognizing and evaluating the factors that affect the quantity and quality of water resources. The Ilam-Sarvak (Upper Cretaceous) and Asmari (Oligocene to Miocene) limestone- dolomite formations in the Zagros structural belt have formed a promising karst groundwater horizon. In the present study, the hydraulic relationship between the karst structures of the Izeh territory in the northeast of Khuzestan province was investigated using hydrogeochemical and isotopic information of springs and wells. The results enabled to understand various components influencing the recharge of water resources. In this study, samples were collected from the karst springs and wells of Mongasht, Shavish-Tanosh and Kamarderaz anticlines and Naal-e-Asbi (Horseshoe) syncline and meteoric water to understand the hydrochemical and isotopic characterization, and hydrogeological and hydraulic behavior of the Izeh karst system. The meteoric and groundwater samples were analyzed to determine major and minor ion concentrations and δ18O and δ2H isotope ratios. Isotopic content ranged from -31.6 to -2.9‰ and from -6.32 to -1.87‰ for δ2H and δ18O, respectively, and d-excess values were high and positive. The study of the isotopic content of water samples of springs and wells in the region shows three groups of water sources. The first group, related to the Mongasht anticline springs, has lower isotopic values, indicating that it is recharged by rainfall at high altitudes and snow melting. The isotopic value of the second group is richer than that of the first group, indicating rainfall recharge as well as groundwater mixing (ex­amples of Naal-e-Asbi syncline and Shavish-Tanosh anticline). The highest value in the third group (samples of Kamarderaz anticline) is attributed to evaporation and longer distance from the recharge site to the discharge point, as well as to the diffu­sion system. The trend of decrease in Sr+2 and increase in Ba+2 in the samples of dolomitic limestone formations (Shavish Ta­nosh and Mongasht anticlines) compared to the water samples of Kamarderaz anticline and Naal-e-Asbi syncline indicates the possibility that karst aquifers of the region are recharged from the Mongasht anticline and that there is a hydraulic relation­ship between these structures. D-excess and δ18O show a linear trend, illustrating the effect of altitude difference on isotopic content and recharge sources. The major and minor changes in the concentration of ions, the isotopic content of groundwa­ter and the relationship between TDS and δ18O and d-excess and δ18O indicate the mixing and recharging of karst aquifers (Shavish-Tanosh, Kamarderaz and Naal-e-Asbi aquifers) from the Mongasht karst aquifer and their hydraulic connection.

Determining the appropriate sealing conditions through a permeability and groutability evaluation: a case study of the Sivaki Dam, Iran

The Sivaki Dam is an earth dam that is located near Yasuj city, 5.3 km NW of Sepidar village. During excavations at the dam construction site, the high potential of water seepage from the foundation and its abutments has been proven. Some cavities and dissolution have been observed on both sides of the dam, suggesting the possibility of karstification at greater depths. Most of the rocks cropping out in the study area comprise Asmari Limestone. These rock masses, despite their medium–high strength, have provided unfavourable conditions in terms of permeability and weathering. In this study, the foundation and both abutments of the dam were evaluated and analysed to determine the permeability and groutability characteristics. To achieve this goal, the engineering characteristics of the rock mass of the construction site were examined by performing rock mass rating (RMR) and geological strength index (GSI) classifications. The Lugeon test, secondary permeability index (SPI), rock quality designation (RQD) and monitoring hydraulic flows were used for this purpose. According to the results of this study, for abutments of the dam and in the case of alluvial substrates, a grout curtain and cutoff wall, respectively, are the best and most compatible methods available.

Determining the salinity sources of the Barme Jamal karstic spring, Meydavod, Iran

The Barme Jamal is an important karstic spring with mean discharge of 1.3 m3/s, located in the Meydavod county southwestern of Iran. Its outlet appeared in the Asmari limestone formation and drains the karstic limbs of Kuhe-Safid anticline. Naturally, the spring water salinity is more than expected for a karstic spring with EC about 2100 ms/cm. The spring water contains high concentration of SO4 and Cl with Ca–SO4 water type. Therefore, hydrogeochemical studies have conducted to determine the factors controlling the spring water salinity using hydrochemical techniques such as time series of chemical parameters, relative ion concentrations, Br/Cl ratios, TOC and mixing diagrams. The potential salinity sources such as mixing of karst freshwater with evaporites formation water and oil-field brine were investigated to determine the role of each source in the spring water salinity. The results reveal that the mixing of saline waters from evaporite formations is the main source of groundwater salinity. The hydrochemical time series illustrate that EC and Na–Cl are increasing in the spring water with almost constant rate throughout the studying period suggested the evaporites karst development in the spring catchment area and extension of dissolution conduits in the contact of limestone and evaporites formations.

The effects of diagenesis on the petrophysical and geochemical attributes of the Asmari Formation, Marun oil field, southwest Iran

The distribution of good reservoir quality and its causes is the main challenges in carbonate reservoir characterization. This study investigates the effects of diagenetic processes on the reservoir quality of the carbonate successions of the Asmari Formation, in the Marun oil field, southwest Iran. The study applies an integrated approach including core petrography, petrophysical rock typing, stable carbon and oxygen isotopes as well as major and trace elements analyses. Petrographic studies and geochemical analyses express that the Asmari limestones have been affected mainly by compaction, dissolution, recrystallization, calcite and anhydrite cementation and dolomitization. Among those diagenetic overprints, dolomitization and dissolution played an important role to enhance the reservoir quality of the formation. Moreover, four types of dolomites were recognized and the rate of dolomitization increases toward the top of the Asmari carbonate successions. Possible models for dolomitization include mixing zone, brine reflux, seepage reflux and tidal pumping of seawater. Employing Flow Zone Index and Discrete Rock Type concepts led to classification of the Asmari reservoir into seven reservoir rock types. Integrating reservoir rock typing with petrographic studies and geochemical analyses also confirms that reservoir quality of the Asmari Fm. would have been mainly controlled by diagenetic processes. Moreover, stable isotopes, trace elements and facies analyses support the idea that carbonate intervals of the Asmari Formation were deposited in a warm, shallow-water environment under a saline condition.

ArcGIS fuzzy modeling to assess the relationship between seismic wave velocity and electrical resistivity with limestone mass quality (case study: Asmari Formation, southwest Iran)

In this study, seismic-wave velocity (Vp) and electrical resistivity (ER) were used to determine the quality of Asmari limestone in the southwest of Iran. In addition, the efficiency of geophysical methods in prediction of rock mass classification system (Q) and modified classification for sedimentary rock masses (Qsrm) has been compared. Models for the prediction of Q and Qsrm in Asmari limestone were rendered by extracting about 1200 data point sets of studded sections of Seymareh and Karoun 2 Dam Sites (SDS and KDS) in south-west Iran, and using multivariate regression analyses and ArcGIS fuzzy overlay (AFO). Because Qsrm considers bedding, dipping of the layers, texture, and presence of cavities, prediction of Qsrm value by combining geophysical methods has a better prediction of limestone rock mass quality. The coefficient of determination (R2) for empirical equations obtained for predicting of Q and Qsrm 0.49 and 0.66, respectively; and the coefficient of determination 0.82 for the estimated Qsrm from the AFO model was calculated. In addition, root mean square error (RMSE) and mean average error (MAE) were measured for model accuracy evaluation shows that the AFO method was interesting because it had good accuracy for prediction of Qsrm by geophysical methods.

The etching and hydraulic conductivity of acidized rough fractures

Acid fracturing is one of the eligible techniques for increasing productivity of hydrocarbon reservoirs. Laboratory tests are performed on reservoir rock samples to improve understanding of acid fracture performance. Fractures formed by hydraulic fracturing or acid fracturing before acid etching are rough, therefore in this study, an acid injection cell was developed to study surface etching in rough fracture acidizing on Asmari limestone samples (one of Iran's reservoir rocks). In this research, the effects of acidizing at different times on roughness evolution and also conductivity of fractures with rough surfaces were investigated experimentally and numerically. Conductivity of fractures in low stresses was determined using permeability test. In the case of high stresses, conductivity was determined using a penetration model and local aperture (derived from surface scan) and a numerical finite element code developed in MATLAB. Results showed that increase in the initial roughness coefficient and the linear roughness of fracture surface resulted in higher surface etching and higher dissolved rock equivalent conductivity (DREC). With increase in fracture surfaces mismatch, fracture aperture and eventually initial fracture conductivity also increase. In this study, for the first time, mismatch in acidized fracture has been defined as linear roughness difference and roughness coefficient difference of lower and upper fracture surfaces. Increase in acidizing time resulted in higher difference in roughness coefficient, linear roughness of the two surfaces of fractures, and higher initial conductivity. Also, increase in rock embedment strength clearly increased final conductivity for samples with 20 min acidizing time. However, for samples with 10 min of acidizing time, final conductivity of fractures depends on roughness distribution. Measuring normal deformation of fracture emergent from applied normal stress showed that longer durations of acid injection exhibit more normal deformation and lower final conductivity. Final conductivity increases with decrease in kurtosis of roughness distribution and maximum fracture closure. Eventually, a logarithmic relation for decreasing rate of conductivity with closure stress (C2 in Nierode and Kruk's equation) was approximated using rock embedment strength for Asmari limestone.

Estimation of Uniaxial Compressive Strength and Modulus of Deformability of the Asmari Limestone, Using Neuro-Fuzzy System

The uniaxial compressive strength (UCS) and modulus of deformability (E s) of intact rocks are essential parameters in rock engineering and engineering geology projects. Because of the difficulty involved in measuring these parameters, indirect methods are often used to estimate these parameters. In this research, some predictive models using multiple regression analysis and Adaptive Neuro-Fuzzy Infrence System (ANFIS) were developed for predicting UCS and E s of the limestone outcropped of Asmari formation in Lordegan, Chaharmahal and Bakhtiari Province, Iran. For this purpose, a series of important and easy-to-obtain parameters, such as density, porosity, and indirect tensile strength (Brazilian test) were used as the model inputs. Because the measured values of UCS and E s of samples varied in a wide range, rock samples were classified as medium- to high- and very high-strength rocks according to the ISRM UCS classification (1978), and then, the ANFIS models were improved for these groups. The variation of coefficient of determination (R 2), Variance Accounted For (VAF), and Root Mean Square Error (RMSE) were calculated for the UCS and the modulus of deformability obtained from the multiple regression and the neuro-fuzzy models. The results revealed that the forecasting performance and accuracy of the neuro-fuzzy system are very higher than those of multiple regression models.

Assessment of brittleness and empirical correlations between physical and mechanical parameters of the Asmari limestone in Khersan 2 dam site, in southwest of Iran

The determination of brittleness and geomechanical parameters, especially uniaxial compressive strength (UCS) and Young's modulus (ES) of rocks are needed for the design of different rock engineering applications. Evaluation of these parameters are time-consuming processes, tedious, expensive and require well-prepared rock cores. Therefore, compressional wave velocity (Vp) and index parameters such as point load index and porosity are often used to predict the properties of rocks. In this paper, brittleness and other properties, physical and mechanical in type, of 56 Asmari limestones in dry and saturated conditions were analyzed. The rock samples were collected from Khersan 2 dam site. This dam with the height of 240 m is being constructed and located in the Zagros Mountain, in the southwest of Iran. The bedrock and abutments of the dam site consist of Asemari and Gachsaran Formations. In this paper, a practical relation for predicting brittleness and some relations between mechanical and index parameters of the Asmari limestone were established. The presented equation for predicting brittleness based on UCS, Brazilian tensile strength and Vp had high accuracy. Moreover, results showed that the brittleness estimation based on B3 concept (the ratio of multiply compressive strength in tensile strength divided 2) had more accuracy as compared to the B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength) and B1 (the ratio of compressive strength to tensile strength) concepts.

Hydrogeological characterization of the Asmari limestone aquifer, Anar anticline, Zagros Region, Iran

The Anar anticline is located in the Zagros Region, south of Iran. The anticline comprises of the Asmari Formation which is sandwiched between two impermeable formations, the Pabdeh–Gurpi Formation at the bottom and the Gachsaran Formation at the top. There are several freshwater resources (e.g., spring, lake, qanat, and pumping wells) around this anticline without clear known hydrogeological connection of which to the Anar anticline. The comprehensive hydrogeological studies, including the use of the APLIS method, karst hydrogeology, hydrochemistry, and stable isotopes data of the lakes and surrounding springs, were carried out in the study area. Results show that the anticline has no hydrogeological connection with the Haft Barm Lakes, but hydrogeologically, there is potential for hydraulic connection with the Chehel Cheshmeh Spring. The study shows that the catchment area of the Mashayekh and Deh Gerdoo Springs is located in the northeast and a part of the southwest flank of the Anar anticline. Mean annual recharge rate in the Asmari limestone aquifer is estimated less that 38.5 % based on the APLIS approach that confirmed by water balance.

Sensitivity analysis of effective parameters on water curtain performance for crude oil storage in Iranian URC using the 2k factorial design and numerical modeling

Underground storage of hydrocarbons in unlined rock caverns (URC) has advantages over above-ground storage in terms of safety, environmental protection and economy. However seepage of products can cause many environmental and economical problems. Water curtain system is used as a part of hydrodynamic method to control seepage. Water curtains system is composed of a network of underground galleries and horizontal boreholes drilled from these galleries to establish groundwater pressure artificially. Iranian crude oil unlined storage caverns are to be excavated in Asmari limestone formation. This study aimed to clarify the effects of effective parameters on water curtains performance in the establishment of water pressure. To aim this purpose 2k factorial statistical experimental design and numerical modeling using FLAC3D has been employed to evaluate the performance of artificial water curtain systems under various conditions include equivalent permeability and effective porosity of Asmari limestone, borehole pressure, borehole spacing and elevation, groundwater level and operation time of boreholes before the storage operation. The results showed that borehole pressure, permeability, borehole elevation and porosity have most significant effect in order of magnitude respectively. Regression model for 2k factorial design was presented as well.

Magnetotelluric signature of anticlines in Iran's Sehqanat oil field

The magnetotelluric (MT) method has proved to be an effective tool in hydrocarbon exploration especially in areas with geological structures/formations where seismic reflection provides neither good quality data nor images. The Sehqanat oil field located in the sedimentary zone of Zagros in SW of Iran is a typical example. It is covered by the high velocity and heterogeneous formation of Gachsaran, which is exposed at the surface and has a thickness varying from 500m to more than 2km in the region. Gachsaran is composed mainly of salt and evaporites overlying, as a cap rock, the Asmari limestone formation which is the main reservoir in all oil fields of Iran along the Zagros range. The main geological interface which is targeted to be imaged with the MT method is the contact between the highly conductive evaporites of the Gachsaran formation and the underlying more resistive carbonates of the Asmari formation. MT data at more than 600 stations along five parallel SW–NE profiles crossing the main geological trend of the study area and transient electromagnetic data over 400 stations to be used for static shift corrections of the MT data were available. Dimensionality and strike analysis of the MT data show dominant two-dimensional (2-D) conditions in almost all sites and periods. The 2-D resistivity models resolved the boundary between Gachsaran and Asmari formations as a transition zone from highly conductive to resistive structures. The Sehqanat anticline has also been delineated throughout the 2-D resistivity sections as a resistive dome-shaped body located in the middle part of the MT profiles. There is a considerable correlation between the 2-D resistivity models and the adjacent 2-D reflection seismic sections so that a more reliable interpretation on the hydrocarbon trap of the Sehqanat anticline can be obtained.

A Study on Karst Morphology Forms in Manjil Region of Gilan Province

The purpose of this study is The Study on Karst Morphology Forms in Manjil Region of Gilan Province. Due to geological features and quantity and type of rainfalls in Gilan Province and other effective factors on formation and development of Karst and Karst water resources, it is necessary to study karst morphology forms of this region. This study has studied Manjil region. It has first studied and identified karst forms of the region and then considered their formation in relation to the regional tectonic and creation of water potentials. Karst morphology forms of the region were identified and the cause of their creation was specified. Among them, Dorfak Mountain with an altitude of 2714 m in the south- central part of Gilan Province in Rudbar City near to Manjil can be mentioned as an example. Also Manjil Cheshmeh Bad Cave with an altitude of 1400 m above sea level is among other karst phenomena of the region and is regarded as the most important karst phenomenon in Asmari limestone.

United Arab Emirates limestones: impact of petrography on thermal behavior

The thermal behavior of selected limestones from representative localities of the United Arab Emirates is investigated for their suitability for soft-burnt lime production. The limestone samples were collected from the Ghalilah, Musandam, Shauiba, Muthaymimah, Dammam and Asmari formations. The samples were characterized for petrography, mineral and chemical composition, together with physico-mechanical characteristics. Investigative methods included transmitted light microscopy (TLM), cathodoluminescence (CLM) and scanning electron microscopy (SEM), as well as X-ray micro-tomography (μ-CT), XRD, XRF and Archimedes method. The limestone samples were fired in an electrical muffle furnace for 0.25, 0.5, 1 and 2 hours at 800, 900, 1,000 and 1,100 °C. After firing the lime grains were tested to determine their hydration rate and microfabric. The Ghalilah and Musandam limes show the lowest and highest maximum hydration rates, respectively, due mainly to the impure nature of the former, and the smaller lime crystallites and dominance of post-calcination micro-cracks of the latter. The Dammam and Asmari limes preserve a “ghost” microfabric of the original limestone. Higher allochem contents impose lower activation energy requirements for calcination, which implies earlier calcination of the allochems. The Musandam, Shauiba and Muthaymimah limestones may be useful for the production of reactive soft-burnt lime under the applied firing conditions, however, the Dammam and Asmari limestones need more advanced calcination conditions than the applied ones. The Ghalilah limestone was found to be unsuitable for the production of lime.

Preliminary analysis of spatial development of karst using a geostatistical simulation approach

Earth science phenomena are primarily spatially dependent with variations occurring on varying scales. Geostatistics is a well-known approach for the assessment of spatial models of regionalized variables, such as porosity. In this study, we used the results of 953 Lugeon tests (402 tests in exploratory wells and 550 tests in grouting wells) to assess effective porosity and karst development at the Tangab Dam site, Iran. Lugeon values were first normalized, following which the variogram method (i.e., range, sill, and nugget effect) was used to identify the spatial variability of Lugeon values. A high correlation range of 200 m was obtained along the grout curtain galleries, while the range was about 40 m in the vertical direction. The simple kriging method with Gaussian variograms was determined to be the best method for estimating the Lugeon values in the study area using cross validation-criteria (e.g., RMSE = 0.835 and ρ = 0.914). Spatial variation of Lugeon values was mapped using a simulated annealing approach. The analysis revealed: (1) a higher potential for karst development on the left abutment of the Tangab Dam site, (2) the average of simulated Lugeon values decreased from values of about 180 close to the ground surface at 1,440 m a.s.l. to lower values of about 50 at 1,260 m a.s.l., and (3) high Lugeon values in the abutments of the dam site approximately followed the 15° bedrock dip, which confirms the potential development of karst features in the Asmari limestone. A schematic model for development of karst at the Tangab Dam site is proposed based on hydrogeological data and results of simulated Lugeon values around the dam site.

Application of artificial neural networks and multivariate statistics to predict UCS and E using physical properties of Asmari limestones

Geomechanical properties of rocks such as uniaxial compressive strength (UCS) and modulus of elasticity (E) have been essentially evaluated for rock engineering projects as well as dam sites. In this paper, in order to estimate the parameters, some mathematical methods are proposed including multiple linear regression, multiple nonlinear regression, and artificial neural networks (ANNs). These methods were employed to predict UCS and E for limestone rocks in terms of P wave velocity, density, and porosity. The data of 105 rock samples from two different dam sites (located in Asmari Formation, Karun 4, and Khersan 3 dams) were obtained and analyzed for developing predictive models. Comparison of the multiple linear and nonlinear regressions and ANNs results indicated that respective ANN models were more acceptable for predicting UCS and E than the others. Also, it observed that between multiple linear and nonlinear regressions, second case has more capability to predict UCS. It should be noted that there were no strong relationships between the predicted and measured E in the both multiple regressions.

Estimation of limestone rock mass deformation modulus using empirical equations

Determining the geomechanical parameters of rock masses at dam sites is a very important task. Different methods of determining these parameters have been proposed, depending on various factors such as the study phase, facilities, budget, and the time available. The deformation modulus is an important input parameter in any analysis of rock mass behavior. In the present study, the deformation modulus of the rock mass at the site of the Khersan II double-arch concrete dam was investigated using different field and experimental methods. The Khersan II Dam is located in the southwest of Lordegan, Chaharmahal Bakhtiary Province, Iran. The predominant formation at the site of the dam is the Upper Asmari limestone. The results of in situ tests such as plate load tests (PLTs) were analyzed to determine the deformation modulus, using the ASTM standard, Unal, and ISRM methods. These results were then compared to one another and interpreted. After that, engineering classification parameters such as RMR, GSI, and Q were evaluated at the same site that the PLTs were performed. Finally, the correlations between these classification ratings and the in situ deformation modulus of the rock mass were assessed, and some formulae for determining the deformation modulus of the rock mass at the Khersan II Dam site were derived. The accuracy and credibility of every formula was evaluated. These formulae for estimating the deformation modulus of the rock mass at the Khersan II Dam site were found to be highly accurate compared to other similar formulae.

The gigantic Seymareh (Saidmarreh) rock avalanche, Zagros Fold–Thrust Belt, Iran

The Seymareh rock avalanche, first described by J. V. Harrison and N. L. Falcon in the 1930s, is the largest known subaerial non-volcanic landslide on Earth. The volume of its debris (44 Gm 3 ) is approximately equal to that of the largest known subaerial landslide of any kind, the 100 ka collapse of Mount Shasta volcano (45 Gm 3 ) and approaches those of gigantic landslides on Mars. Using satellite imagery, SRTM-3 data, and detailed field investigations, we gain a new understanding of the gigantic rock avalanche. The initial failure (38 Gm 3 ), involving a dip slope consisting of a relatively weak interbedded limestone–mudrock sequence capped by resistant Asmari Limestone, had an average thickness of 410 m along a 15.5 km width of the Kabir Kuh anticline. The rockslide transformed into a rock avalanche that travelled 19.0 km with a fahrböschung (the angle between the highest point of the pre-landslide source area topography and the distal limit of the debris) of only 3.6°. Initial failure involved complex planar sliding dictated by four structural elements: (1) bedding-parallel shears and (2) across-bedding break-throughs combined to produce a low-angle (11°) overall sliding surface that (3) broke out through the Asmari carapace at the toe of the failed slope while (4) tectonically weakened bedding-normal joints provided lateral release surfaces. Nine discrete bedding-parallel basal sliding surfaces divided the detached mass into nine stacked plates. The upper plate (23 Gm 3 ) included 20.7 Gm 3 of Asmari Limestone. Analysis of accelerator mass spectrometry radiocarbon dates from this study and by others indicates that the rock avalanche occurred between c . 8710 and 9800 14 C years BP. Supplementary material: A summary of the tectonics, stratigraphy and physiography of the Zagros Fold–Thrust belt together with a description of surficial gravity collapse structures in the region (Harrison & Falcon 1934, 1936) is available at www.geolsoc.org.uk/SUP18612 .

Assessing and Mapping the Vulnerability of Karstic Aquifer Using GIS and COP Model

<p>Vulnerability assessment and production of the risk map of the contamination is considered as a managerial significant technique in the conservation of Karstic water resources. Karst aquifers in semi-arid regions of the West of Iran with respect to the region’s natural conditions are prone to contamination. The present paper aims to estimate the value of vulnerability and to produce the map of the Karst aquifer of Gilan-e-Gharb in the West of Iran against the pollution diffusion, using COP model. The model estimates the vulnerability of the Karst's water resources against the contamination using three parameters: overlying layer (O), density of current (C), precipitation regime (P). The results show that 0.25% of the region's area is located in a very low vulnerability domain, and 25.5% of the region's area is in a low vulnerability domain, which represents a low vulnerability of this Karst aquifer against pollution. Most regions with a low and moderate vulnerability - in the dominion of developed Karsts of the Asmari limestone formation - are located in the high lands. The dominant vegetation of the region is mostly covered by forest and dense pastures, and its total amount of precipitation is more than 600mm. In general, C, P and O parameters play the most significant role in reducing the value of the vulnerability over the area of study, respectively. The C factor plays the most important role in lessening the vulnerability of the region due to the little area of developed Karsts, high district of non-Karst regions, and lack of suitable vegetation. On the other hand, the region’s precipitation is relatively low which results in a decrease in the amount of contamination permeation. The map of (O) factor shows a high and very high vulnerability of the region, which represents the expansion of permeable structures in the region. The high vulnerability value of this factor is adjusted by other two factors, and on the whole, the vulnerability amount of region is kept down through these factors.</p>

Regional trends in active diapirism revealed by mountain range‐scale InSAR time series

We construct an orogen‐wide InSAR time series over the Zagros Mountains and eastern Markan Subduction Zone in southern Iran from 19 Envisat tracks spanning 2003–2010. We observe active salt diapirism of the infra‐Cambrian Hormuz Salt at 20 locations and identify several diapirs that are not moving. All active diapirs reach the surface within the Asmari Limestone or older rock units while we do not observe any active diapirism occurring within younger exposures, reflecting a complex vertical accumulation of the basal salt and reactivation of diapirs by erosion. Diapir reactivation of this sort may be a critical factor affecting the feasibility of sequestering nuclear waste and CO2 in evaporite sequences over geologic time scales. The distribution of active diapirism is indifferent to increases in mean elevation, suggesting a relatively uniform thickness of the Zagros Fold Belt above the basal salt with steps in topography driven by basement thickening. We do not observe aseismic uplift of anticlines because rates are likely below the detection threshold of our time series. This suggests that uplift is accommodated at small rates (<2–3 mm/yr) over numerous structures instead of focused at the deformation front.

Paleofluid analysis from fracture-fill cements in the Asmari limestones of the Kuh-I-Mond field, SW Zagros, Iran

Kuh-I-Mond field in the Zagros foreland basin is a conventional heavy oil resource and is composed of fractured carbonates whose fractures were filled by calcite, dolomite, and anhydrite cements. Oil inclusions occurred within the fracture-fill cements indicate that fractures were open and played an active role during oil migration and charge. The highest measured values for secondary porosities belong to fractures in Asmari Formation, which is characterized by significant amounts of vug- and fracture-filling cements. Fractures facilitated fluid circulation and subsequently dissolution of allochems and high Mg carbonates. In contrast, fine-grained carbonate facies were less cemented, and thus, porosity enhancement by cement dissolution was insignificant. Temperature profiles of oil inclusions in the dolomite, calcite, and anhydrite minerals characterized by distinct variations in the homogenization temperatures (Th) that are divided into two ranges below 50°C in anhydrites and from 45°C to 125°C in dolomites and calcites. The lower Th ranges for anhydrite suggests that it may have formed at shallower burial depths during early to middle diagenesis. The oil inclusions display trend for increasing temperature downward which conform to Formation geothermal gradient. In other word, the decreasing trend of Th temperatures upward within Asmari Formation that can be observed in Th versus depth plot is consistent with the uplift events at Late Miocene time and later that caused removal of about 1,300 m of the crest of the Kuh-I-Mond anticline. Vitrinite reflectance data from source rock intervals in the field area do not support vertical migration of locally generated hydrocarbons into the Kuh-I-Mond accumulation, and long-distance lateral oil migration and charge from a source kitchen to the southwest is proposed. Vitrinite reflectance data from this dolomite and limestone reservoir suggest low maturation levels corresponding to paleotemperatures less than 50°C. The observed maturation level (<0.5% Ro) does not exceed values for simple burial maturation based on the estimated burial history. Also, homogenization temperatures from fluid inclusion populations in calcite and dolomites show expected good correlation with reflectance-derived temperatures. The Th data represent pore fluids became warmer and more saline during burial. As aqueous fluid inclusions in calcite veins were homogenized between 22°C and 90°C with a decrease in salinity from 22 to 18 eq. wt.% NaCl. The Th values suggest a change in water composition and that dolomite and calcite cements might have precipitated from petroleum-derived fluids. The hydrocarbon fluid inclusions microthermometry data suggest that the reservoir was being filled by heavy black oils in reservoir during Cenozoic. Aqueous fluid inclusions hosted by calcite equant sparry/fossil cavity fills suggest low cementation temperatures (<45°C) and high salinities (19 eq. wt.% NaCl), while those in dolostones are characterized by highly variable homogenization temperature (52°C to 125°C) and salinities (6.5 to 20 eq. wt.% NaCl).