Salt Plugs Research Articles

Water Biogeochemistry of a Mangrove-Dominated Estuary Under a Semi-Arid Climate (New Caledonia)

Mangrove water biogeochemistry has been frequently studied under tropical climates, but less is known regarding mangroves in semi-arid climates. In this study, we examine the carbon and nutrient biogeochemistry in a mangrove tidal creek and in the main branch of a semi-arid estuary in New Caledonia. Porewater seepage represents a source of nutrients (DON, NH4+, and DIP), carbon (DOC and CO2), and alkalinity for the water column, but seawater dilution of the mangrove inputs is observed. Spatial and tidal variations in CO2 fluxes along the tidal creek suggest that porewater seepage is a driver of CO2 emission into the atmosphere. Large seasonal and spatial differences in the biogeochemical functioning of the main channel are observed and are mainly related to the seasonal rainfall pattern. During the rainy season, the watershed influences the entire estuary, which exhibits a typical positive circulation. During the dry season, the estuary turns into a salt-plug region with positive and negative circulations in the upper and lower reaches, respectively. In this case, the upper and lower reaches seem to function independently, and the biogeochemical functioning of their water column is not controlled by the same processes. Surprisingly, pCO2@27 °C values tend to be higher during the dry season, as do the total alkalinity (TAlk) values, while the pH values exhibit an opposite trend. Moreover, the TAlk values are higher in the lower reaches during the wet season and in the upper reaches during the dry season. These results indicate high in situ biogeochemical reactions and high porewater influence during the dry season, likely because of a low flushing rate and high water residence time after salt plug establishment. Although our results suggest that salt plugs may significantly affect the water column’s biogeochemistry and may promote CO2 emissions of mangrove-derived carbon, further investigations, especially mass balance studies, are required to quantify their role in the biogeochemical functioning of such estuarine systems.

Salinity and suspended sediment transport in a shallow estuary on the east coast of India

Velocity, salinity, tidal depth and suspended sediment concentrations were monitored at the two stations located at the mouth and head of the Muthupet estuary during the spring and neap tides of post-monsoon, pre-monsoon and monsoon seasons. There was a pronounced seasonal variation in the salinity and suspended sediment concentration during the study period. The total transport of salt at the station near the mouth varied between 4.78 kg/s/m and 0.038 kg/s/m. The transport of suspended sediments was in the range of 0.021 kg/s/m and 0.121 kg/s/m. The direction of transport of salt and suspended sediments also varied over a seasonal scale. The transport of salt and suspended sediments occurred in the downstream direction during the post-monsoon and monsoon, while it was in the upstream direction during the pre-monsoon. Fluvial advection was identified as the main controlling factor in the transport of salt and suspended sediments. The formation of salt plug during the pre-monsoon affected the transport of salt; the transport of salt was from the location of salt plug to the upstream and downstream directions. The spatial variability in the transport of suspended sediments was evident, with higher transport at the downstream station than that at the upstream station. The transport of salt was correlated with the concentration of Fe in the estuary obtained from previous studies. Further, it was observed that the concentration of Cd and Cu was dependent on the resuspension of sediments due to tidal action. The study proved that all the suspended sediments transported towards the upstream from the downstream reaches do not reach the upstream station, but are removed from the water column; the transport of suspended sediments were correlated with the settling velocity established from previous studies.

Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary.

Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. The formation of a salt plug in response to changes in river discharge was investigated using a conductivity-temperature-depth (CTD) recorder during spring and neap tides in the dry and wet seasons in 2014. An exportation of saline water from the Shibsa River Estuary (SRE) to the PRE through the Chunkhuri Channel occurred during the dry season, and a salt plug was created and persisted from December to June near Chalna in the PRE. A discharge-induced, relatively high water level in the PRE during the wet season exerted hydrostatic pressure towards the SRE from the PRE and thereby prevented the intrusion of salt water from the SRE to the PRE.

Low-temperature corrosion in co-combustion of biomass and solid recovered fuels

Lowering flue gas temperatures to recover more energy is of great interest. One of the limiting factors in lowering the flue gas temperature is low-temperature corrosion. In this work the causes of low-temperature corrosion was studied in a full-scale bubbling fluidized bed boiler combusting mixtures of bark, sludge, and solid recovered fuel. The presence of sulfuric acid in the flue gases may lead to severe low-temperature corrosion if the temperature of the pre-heaters and the flue gas duct parts are below the acid dew point. Measurements of H2SO4(g) were performed in the second pass and stack with a technique where SO3 or H2SO4 is captured in a KCl salt plug located in the tip of a sampling probe. Additionally, short- and long-term corrosion probe measurements were conducted to study the corrosion rate of carbon steel at a material temperature of 100°C, under different operational conditions of the boiler. The windward, leeward, and side deposits on the corrosion rings were collected and analyzed by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray fluorescence spectroscopy (XRF). The work revealed that the risk of acid dew point corrosion was minimal; the H2SO4(g) concentration was below 0.3ppmv, both in the second pass and stack. This implies that any SO3 formed in the furnace was captured by ash constituents such as calcium and alkali. Interestingly, the deposits on the corrosion rings showed high calcium and chlorine contents, suggesting the presence of calcium chloride (CaCl2). Calcium chloride is an extremely hygroscopic salt and absorbs water from the flue gas to form a wet deposit at a significantly higher temperature than the pure water dew point. Corrosion was observed in the cases when the flue gas water vapor concentration was high and could be explained by water uptake by the hygroscopic deposit and subsequent wet corrosion.

Salt Tectonics in the Southern Iran

Based on geographic distribution and geological setting of salt plugs in southern Iran, three salt diapiric provinces have been distinguished. These provinces include the Hormuz, Shiraz-Kazerun and Nyriz-Jahrum sub-basins. There are more than hundred salt plugs which they have been formed and developed in the southern margin of Iran. The salt structures that originated from Hormuz formation in these areas have been restricted and separated from each other for the first time in this paper. Salt diapirism of these provinces has been triggered earlier by Halokinesis in the Zagros and Persian Gulf basins, but it has affected later by tectonic forces, because orientation, shape and position of salt plugs have been followed from convergence regime (especially in the Zagros hinterland). In the other hand, based on our results from salt plugs in Persian Gulf foreland basin and the Zagros hinterland, Halokinesis triggers has been affected more than Halotectonic forces.

GROUNDWATER GEOCHEMISTRY OF PETROLEUM DEPOSITS OF THE NORTH SIBERIAN SEDIMENTARY BASINS

Sedimentary basins of northern Siberia regions have a unique hydrogeology. Transitive type of the section (salt-free to salt-laden sediments) changes from the Yamal Peninsula in West Siberia through the regional Yenisei-Khatanga basin to the Anabar-Laptev basin, where salt plugs are located. Synthesis of vast factual data of the West Siberian basin and the Northern Siberian Craton has allowed specifying features of regional hydrogeochemical patterns, nature of local and zonal anomalies in hydrogeochemistry, and establishing their spatial correlation with oil-and-gas occurrences. The West Siberian megabasin has sulfate-free brackish groundwaters and brines (as high as 70 g/L in the study area), elevated concentrations of dissolved OM and hydrocarbon gases in the formation waters of a Mesozoic hydrogeological unit. The Anabar-Laptev basin studied brines have sodium chloride composition with the TDS from 52.3 to 350 g/L. Comparative analysis of groundwaters and brines in Northern Siberia has revealed a group of sodium chloride samples with the TDS > 250 g/L, being the genetic type of brines originating from rock salt leaching within the salt-cores. Composition of brines has varied dramatically with increasing of their evolution. The most evolved calcium brines (Ca/Cl ratio up to 0.33) were detected in the Vendian-Cambrian and Riphean aquifer systems in the Anabar-Laptev basin and Cambrian sediments of the Anabar Shield (Ca/Cl is 0.50-0.65). Mesozoic groundwaters and brines of West Siberia have been only in the beginning of their chemical evolution.

Seasonal dynamics of turbidity maximum in the Muthupet estuary, India

Results are presented of the longitudinal and vertical profiling of salinity and suspended particulate matter (SPM) at the Muthupet estuary, India, during a one year period under widely varying freshwater flow conditions. Freshwater flow was available during post-monsoon and monsoon. An up-estuary shift in the location of estuarine turbidity maxima (ETM) was observed during the transition from post-monsoon to pre-monsoon and further it shifted downstream during the transition from pre-monsoon to monsoon, thereby exhibiting a pronounced seasonal cycle. The salinity intrusion was dependent on the freshwater discharge and was expressed as a power function of freshwater flow, explaining 97% of the variance. The formation of a salt plug in Muthupet estuary and its seasonal dynamics were observed, which is not an identified feature of any of the Indian estuaries studied so far. The geographical positions of salt plug and ETM core were more or less the same during their formation. The occurrence of two ETM during the LW of post-monsoon and the absence of ETM during monsoon explains the strong seasonal variation in the formation of ETM. The primary factor affecting the formation of ETM was identified as the freshwater flow over an annual cycle; the resuspension of sediments by tidal current affecting the formation on a flood/ebb cycle was secondary. The extent of shift of ETM was found to be an inverse logarithmic function of the freshwater discharge. The separation between ETM intrusion and salinity intrusion increased two fold with the increase in ETM intrusion.

New method for evaluating antiperspirant efficacy using the skin surface biopsy technique to extract aluminum salt plugs from axillary and back eccrine sweat ducts

New method for evaluating antiperspirant efficacy using the skin surface biopsy technique to extract aluminum salt plugs from axillary and back eccrine sweat ducts

Influence of pre-existing salt diapirs on 3D folding patterns

The 3D detachment folding instability gives rise to a wide variety of fold shapes (e.g. from dome shape structures to long en-echelon or straight anticlines) as a result of interactions between growing fold segments. The 3D growth of these folds, as well as the wavelength and lateral propagation of folds, is controlled by the physical parameters of a detachment layer and its overburden. However, the existence of initial heterogeneities, such as pre-existing salt plugs within the sedimentary cover, might affect fold development as well.We use numerical modeling to investigate how the fold pattern is affected by pre-existing salt structures. High-resolution 3D folding simulations (with and without pre-existing salt structures) were performed, in which we varied the shape, height and spacing of pre-existing diapirs. In a first geometric setup, we employed a multilayer setup and synthetic diapir distributions in order to study the influence of diapir spacing on fold spacing and patterns. In a second geometric setup, we use a diapir distribution that fits the observed exposed diapir distribution in the southeastern Zagros.Results show that the presence of diapirs does not considerably change the wavelength of the folds, which is in all cases close to the dominant folding wavelength that develops in the absence of diapirs. Yet, the presence of pre-existing structures speeds up the folding instability in those locations and also affects folding patterns as the diapirs localize the initial deformation by accommodating folding above them, which results in the diapirs being located in the core of the folds. If diapir spacing is much smaller than the dominant folding wavelength, diapirs are located in different structural positions such as fold synclines or flanks.

A Three-Dimensional Multi-Body Inversion Process of Gravity Fields of the Gheshm Sedimentary Basin

Understanding the response of a particular exploration target necessitates modelling the response from other sources that are of less interest. Three-dimensional (3D) modelling can provide accurate results of targets of interest with less calculation error due to the simultaneous computations of the responses from anomalous sources. This paper presents a 3D multi-body model to match the observed gravity data in the seashore and shallow waters from east of the Gheshm Island to the Hormoz Island and its northern seashores. A commercial software called ModelVision Pro was used to perform modelling process to determine the geometry and physical properties of geological structures and oil traps. The 3D modelling results were compared with the geological and depth information from wells. The results of anomaly separation identified few gravity lows due to the salt plug intrusion. The depth of the anomalous sources and other geological structures were determined. An approximate depth of 1,800 m was predicted for depth to the top of the source N next to the Gheshm salt plug. This correlates fine with the depth obtained from well Gh 2 (1,660 m); showing a relative error of 8.4 %. The results obtained from this research can provide useful information about the likely oil traps in the study area.

The Elements of Fold Style Analysis in the Khaftar Anticline, Zagros, Iran

The Study area is located in the Zagros Simply Folded Belt of Iran and in the interior Fars sub-basin. The Khaftar anticline is located in the West, North-West of Jahrom city in the Fars province (148 km distance from Persian Gulf). The trend of Khaftar anticline has three orientations, consist of North-Northeast, East-West and South-Southwest. This anticline has asymmetric structure and some faults with large strike separation observed in this anticline. In the study area, stratigraphic units are affected by many faults in this area. Also one salt plug cropping out in the middle part of the Khaftar anticline. Maybe this salt plug affected on the stratigraphic units and geometry of structure. Description of fold geometry is important because it allows comparisons within and between folds and allow us to recognize patterns in the occurrence and distribution of fold systems. The main aim of this paper is determination of fold style elements and folding pattern of the Khaftar anticline. This paper presents a part of the results of a regional study of the Fars province in the Zagros Simply folded belt, based on satellite images, geological maps, and well data. Some data, such as geological maps and geological regional data were prepared and provided by the National Iranian Oil Company (NIOC). Because of the Khaftar anticline, has complex structure, the analysis of fold style elements is seems necessary. Therefore, in further studies on this structure the changes of fold style elements will be analyzed and investigated from east to west in the different parts of this anticline. The activity of Nezamabad sinistral strike slip fault in the Khaftar anticline causes changes of axial plane characteristics and fold axis. Some of the results such as folding style analysis, how position of salt plug, changes of fold type and main structural changes (rotation of fold axis and 2.5 km displacement in this anticline) show main changes in the middle parts of the Khaftar anticline. It seems that, these changes have formed by activity of the Nezamabad fault and this fault’s activity same as fault zone.

Retracted: Pierced Salt Domes in the Persian Gulf and in the Zagros Mountain Ranges in Southern Iran and their Relationship to Hydrocarbon and Basement Tectonics

The most enigmatic problems with the nearly 200 salt domes pierced in the Persian Gulf and in the Zagros Mountain Ranges (ZMR) in southern Iran, a unique morphology in the world, have been the matter of this study, which is based on a combination of field work, enhancement of satellite and aerial photographs etc. In the ZMR, structural anomalies are frequently associated with similar facies distribution patterns. In the eastern portion of the region, emergent salt plugs of Infra-Cambrian age exhibit the same alignment patterns. Such trends bear no apparent genetic relationship to the Tertiary folding responsible for the present Zagros fold belt, but rather indicate their affinity with linear basement features which are readily observable on Land sat imagery and aerial photographs. Bending of anticlines in the competent cover rock, combined with minor strike-slip faults and horizontal displacements of parts of folded structures, strongly point to the presence of these basement faults. The salt plugs, which have pierced cover rocks of up to 10000 m thick, are distributed on the Arabian Platform along regional basement faults. The area of diapir outcrops is bounded by the Oman Line to the east and by the Kazerun fault to the west. Pieces of the basement have been brought up to the surface on some of the salt domes. The fragments were transported by rotational ascent of the Hormuz Salt Formation to the present and former land surfaces. The recognition of features related to basement tectonics and realization of their implication in the control and modification of geological processes are important adjuncts to the search for hydrocarbon accumulations in this region. To our best knowledge, data of basement faults in the study area are scarce. Therefore, this study was carried out to determine basement faults and their relation to salt dome distribution. Considering the fold axes bending, the trend of the salt plugs and also the distribution of epicenters of the last century, n umerous new basement faults are introduced in this paper.

FIRST OIL FIELD DISCOVERED BY "NAFTOGAZ OF UKRAINE" NATIONAL JOINTBSTOCK COMPANY IN DNIEPER-DONETS DEPRESSION

In 2013 National Joint-Stock Company Naftogaz of Ukraine has discovered an oil field named "Academician Shpak oilfield". Significant reserves of this oil field are confined to the trap rimming the Runovshchyna salt plug that located in the central part of the Dnieper-Donets basin. The discovery testifies that resource potential of hydrocarbon prospects related to the traps sealed by salt plug or its canopy remains rather high and development of that exploration trend gives an impetus to increase hydrocarbon production in the East Ukrainian petroleum province.

Edge detection in gravity field of the Gheshm sedimentary basin

Edge detection and edge enhancement techniques play an essential role in interpreting potential field data. This paper describes the application of various edge detection techniques to gravity data in order to delineate the edges of subsurface structures. The edge detection methods comprise analytic signal, total horizontal derivative (THDR), theta angle, tilt angle, hyperbolic of tilt angle (HTA), normalised total horizontal gradient (TDX) and normalised horizontal derivative (NTHD). The results showed that almost all filters delineated edges of anomalies successfully. However, the capability of these filters in edge detection decreased as the depth of sources increased. Of the edge enhancement filters, normalized standard deviation filter provided much better results in delineating deeper sources. The edge detection techniques were further applied on a real gravity data from the Gheshm sedimentary basin in the Persian Gulf in Iran. All filters specified a northeast-southwest structural trend. The THDR better outlined the structural morphology and trend. Moreover, it indicated the salt plugs much better than other filters. Analytic signal and THDR successfully enhanced the edges of the shorter wavelength residual structures. Normalized standard deviation (NSTD), TDX and hyperbolic of tilt angle (HTA) filters highlighted the likely fault pattern and lineaments, with a dominant northeast-southwest structural trend. This case study shows that the edge detection techniques provides valuable information for geologists and petroleum engineers to outline the horizontal location of geological sources including salt plugs and stand out buried faults, contacts and other tectonic and geological features.

Halite clogging in a deep geothermal well – Geochemical and isotopic characterisation of salt origin

The sandstone formation of the Middle Buntsandstein (Lower Triassic) in the geothermal well Groß Buchholz Gt1, Hanover, Northern Germany, was hydraulically stimulated to generate a heat exchanger surface, using 20000m3 of fresh water. After six months of enclosure the recovered water was oversaturated with respect to halite at surface conditions. Due to cooling induced precipitation a salt plug formed between 655 and 1350m depth in the tubing. While the Na/Br and the Cl/Br ratio of the recovered water reflect the signature of a relic evaporative solution the recovered water contains tritium, indicating a significant proportion of fresh water. Leaching experiments of the reservoir rocks point towards presence of traces of soluble salt minerals in the formation. Therefore we assume that the salinity cannot be attributed solely to halite dissolution nor to the production of a pure formation brine. The recovered water is a result of a combination of both salt dissolution by injected fresh water and of mixing with a formation brine which has undergone water–rock interaction. The calculated fresh water proportion in the recovered water is around 40%. The presence of salt mineral traces in pores of a target formation is a potential threat for the operation of geothermal wells, as cooling-induced salt scaling jeopardizes their performance.

Development of a long-term wellbore sealing concept based on numerical simulations and in situ-testing in the Altmark natural gas field

This paper presents an innovative well abandonment concept developed for the long-term containment of CO2 in depleted Rotliegend gas reservoirs. The new concept aims at amending the conventional standard well abandonment procedure, taking advantage of the natural creeping ability of the thick, homogeneous Zechstein rock salt formation located around 3,000 m in depth (Altmark area) and consists of four main sealing units: (1) a standard sealing element with cement from the reservoir to the impermeable caprock, (2) a salt plug created in the formerly reamed section of casing within the plastic Zechstein (Upper Permian) rock salt formation, (3) two bridge plugs at the bottom and top of the salt plug and (4) a standard sealing element with cement from the top bridge plug until the ground surface. This site-specific study mainly lays emphasis on the development and field testing of the naturally created salt plug, as a key component of the long-term wellbore sealing concept. Comprehensive numerical simulations conducted prior to and during the field test in 2010 and 2011 successfully predicted the evolution of convergence using downhole measurement data. Preliminary results comprise (1) proven convergence of the rock salt formation, (2) a successful coring and (3) restored integrity of Zechstein salt formation, as proven by the formation integrity test. Based on these results, the new long-term sealing concept has been successfully tested at the Altmark natural gas field and successful application of the concept on other sites with similar geological conditions is foreseen to be likely.

Salt deposition from hydrothermal solutions in a flow reactor

A flow hydrothermal setup with a tubular reactor equipped with a plunger pump and back pressure valves is used to study the effects of scaling in the K2SO4-KCl-H2O, K2SO4-K2CO3-H2O, and Na2SO4-NaCl-H2O systems at pressures of up to 270–340 kg/cm2, temperatures of 400–600°C, and flow rates of 5.0 and 2.5 ml/min in order to establish conditions for the formation of salt plugs of type 2 (K2SO4, Na2SO4) in the flow mode at supercritical (SC) state parameters and to explore ways of eliminating such salt deposits by means of hydrothermal solvents, more specifically, high-temperature aqueous solutions of salts of type 1 (KCl, K2CO3, and NaCl). The concentrations of hydrothermal solvents sufficient to prevent the plugging of flow systems with solutions containing 0.26–0.27 mol % K2SO4 or Na2SO4 are determined, and the effects of the flow rate and chemical composition of type 1 salts on this process are studied. The results show that the phenomenon of scaling with the formation of salt plugs, which hinders the practical use of supercritical water oxidation technology, can be eliminated by adding readily soluble electrolytes, salts of type 1, to initial aqueous solution of type 2 salts.

Developing, modeling and in-situ-testing a long-term wellbore seal in the framework of the CO2 -EGR research project CLEAN in the natural gas field Altmark

Abstract In this paper we present a new concept developed to improve the abandonment procedure of wellbores in depleted hydrocarbon fields, amongst others in Enhanced Gas Recovery (EGR) operations. The sealing concept is designed for the long-term containment of CO 2 and considers the creep ability of deep Permian Zechstein salt formations in about 3,000 m depth. It is designed to amend the current standard abandonment procedure and consists of (a) an expansive gel filling in the reservoir formation, (b) a sealing element with cement extending to the impermeable caprock and (c) a salt plug as the major long-term sealing component, compatible in its composition and property to the surrounding caprock (halite). The focus of the project work described here is to develop and to model the last-mentioned long-term salt sealing element. Numerical results show that the creep ability of the mentioned salt formations can close a formerly reamed well section and hence recover the geological salt barrier with or even without using a crushed salt backfill. A field test is conducted in the North German Altmark Rotliegend gas field (Sachsen Anhalt) in order to study the technical feasibility for recovering the initial caprock integrity, to verify numerical models and to proof the sealing capability and therefore the sealing concept.

MULTI‐PHASE HORMUZ SALT DIAPIRISM IN THE SOUTHERN ZAGROS, SW IRAN

In the Zagros orogenic belt in SW Iran, a 14 km thick sedimentary succession is decoupled from crystalline basement by the thick Infracambrian Hormuz complex. The complex consists of evaporites (“Hormuz salt”) together with marls, sandstones, carbonates and volcanic rocks and is known from emergent salt diapirs in the Fars and High Zagros areas. In this paper, we document discrete pulses of halokinetic activity using seismic profiles, well data and recent field studies. The earliest phase of mobilization of the Hormuz salt occurred in the pre‐Silurian. Later pulses of salt movement took place during opening of Neo‐Tethys in Permo‐Triassic times and during ophiolite obduction onto the NE Arabian plate margin in the Late Cretaceous. Halokinesis was intense during the Neogene Zagros orogeny when some salt plugs breached the surface.

Timing of thrust activity in the High Zagros fold-thrust belt, Iran, from (U-Th)/He thermochronometry

[1] Apatite and zircon (U-Th)/He cooling ages are used to quantify the timing of exhumation associated with thrust faulting in the High Zagros fold-thrust belt. Single-grain cooling age data were collected from (1) Cambrian sandstone in various thrust sheets, (2) sandstone and basement clasts derived from structurally controlled salt plugs or fault-bounded slices, and (3) syntectonic Neogene siliciclastics strata. In the northwestern (Kuhrang) and central (Kuh-e Lajin) High Zagros, apatite (U-Th)/He (AHe) ages range from ∼26.7 to ∼0.38 Ma. Most cooling and exhumation occurred in the early to middle Miocene, constrained by AHe ages ∼19–15 Ma from the High Zagros thrust sheet, localized faults, and reset cooling ages from Bakhtiyari deposits. In the southeastern High Zagros (Kuh-e Dinar), cooling occurred later with AHe ages ranging from ∼16.5 to ∼0.79 Ma. Here most cooling and exhumation occurred in the late Miocene, constrained by AHe ages ∼12–8 Ma from the High Zagros fault, and exhumed Paleozoic clasts in synorogenic strata. Zircon (U-Th)/He (ZHe) ages from bedrock samples across the High Zagros are reflective of the precollisional thermal history. The preservation of precollisional ZHe ages limits the pre-Miocene maximum burial temperature of the exhumed strata to < 180°C, and indicate < 7–9 km of maximum exhumation in the central Zagros. This study shows that thrust activity in the High Zagros and continental suturing along the Zagros suture was underway by at least 19 Ma, and initiated no later than latest Oligocene to early Miocene time (∼23 Ma).