Gypsum Deposits Research Articles

Contractional fold amplification through bed-parallel gypsum vein (“beef”) formation

Field observations and structural analysis of a 50-m-wavelength gentle anticline document bed-parallel fibrous gypsum veins (“beef”) and calcite veins associated with contractional folding in the Boquillas Formation, east of Langtry, west Texas. Gypsum beef veins with bed-perpendicular fibers accommodated vertical extension of 13% in the anticline, diminishing to 0% in adjacent synclines. Bed-parallel calcite veins accommodated 0–4% vertical extension across the structure, with no clear correspondence of vein distribution to structural position. Homogenization temperatures from two-phase fluid inclusions in calcite veins indicate trapping depths of 2.0–2.7 km. Source rock analysis from unoxidized organic-rich mudrock at the site shows that the rocks never reached hydrocarbon maturation conditions, therefore vein formation cannot be explained by in situ hydrocarbon expulsion. Bed-parallel veins with vertical or bed-perpendicular fibers document a thrust faulting stress regime during contractional folding near the frontal limit of Laramide deformation. Gypsum vein formation may be related to meteoric water interacting with pyrite or H2S to form sulfuric acid, dissolution of carbonate, and deposition of gypsum as an auxiliary mineral. Switching between calcite and gypsum mineralization suggests opening and closing of fault and fracture controlled fluid pathways during deformation.

Regression of the Tethys Sea (central Asia) during middle to late Eocene: Evidence from calcareous nannofossils of western Tarim Basin, NW China

Calcareous nannofossil assemblages from middle to upper Eocene sediments of the western Tarim Basin indicate two important episodes of marine incursion into the basin. The first episode represents a period of shallowing upward in the Wulagen Formation, which is dated as Zone CNE13 (Lutetian) by the co-occurrence of Discoaster bifax, Chiasmolithus solitus, and common Reticulofenestra umbilicus. The presence of a diverse assemblage of discoasters in the basal Wulagen suggests deposition occurred in oligotrophic, warm water with a connection to the open ocean. Progressive shallowing over time led to the formation of a restricted basin in which only Coccolithus pelagicus could survive. The second major episode of marine incursion is preserved in the middle part of the Bashibulake Formation, which is dated as Zone CNE17 (Bartonian/Priabonian) based on the presence of common Cribrocentrum erbae. The interval between the two marine incursions was dominated by subaerial exposure and evaporation, resulting in the deposition of gypsum at the top of the Wulagen Formation. Although maximum regression at the end of the Lutetian is followed by sea-level rise at the beginning of the Bartonian globally, it is clear that local tectonics played a crucial role in regional marine incursions into the Tarim Basin during deposition of the Wulagen Formation.

Ostracods from the Pingyi Basin (eastern China) and their significance for the K/Pg boundary

Abstract The Pingyi Basin is a late Mesozoic to Cenozoic fault basin in East China, containing a good record of Cretaceous to Paleogene non-marine carbonate and gypsum deposits. Abundant microfossils including gastropods, ostracods, charophytes and palynomorphs have been reported from this basin. A taxonomic study of ostracods from the Gejiazhuang section in the Pingyi Basin reveals a total of 17 species assigned to 11 genera. A further ostracod biostratigraphic correlation suggests the K/Pg boundary lies within Member 1 of the Bianqiao Formation in the Gejiazhuang section, which is supported by charophyte biostratigraphy.

PALEOENVIRONMENTAL ANALYSIS OF A LOWER CRETACEOUS PALEOLAKE FROM THE IGUATU BASIN BASED ON ITS OSTRACOD FAUNA AND XRF DATA

ABSTRACTThis paper presents the results of a paleoenvironmental study of two Hauterivian–Aptian adjacent sections (Transnordestina A/B) of the Iguatu Basin using ostracods and aided by X-ray fluorescence (XRF), total organic carbon (TOC), total sulfur (S), and spectral analyses. Cluster analysis divided the 10 genera found into two main groups: one composed of Alicenula-Pattersoncypris?-Brasacypris-Hastacypris-Ilyocypris?, and the second composed of Cypridea-Looneyellopsis-Rhinocypris?. The first group is interpreted as representing paleoenvironments with permanent waterbodies, such as lakes, and the second as being indicative of ephemeral settings, such as temporary pools in an inundation plain. XRF analysis using the positive peaks of Ca/Ti and Ca/ΣTi, Fe, Al ratios show a few dry periods, particularly in the lower and middle part of Transnordestina A, between 0 to 175 m and 385 to 475 m, which also display a small number of ostracods. Total S shows several high peaks which might be indicative of gypsum deposition during droughts. Spectral analysis of molar Ti/Al ratio shows two intervals with different sedimentation rates, between 0 and 233 m, and 233 to 836 m. For the first interval, six 100 ka eccentricity cycles were identified; the low number of ostracods for the interval and highly variable Ca/Ti and Ca/ΣTi, Fe, Al values indicate a different sedimentation rate in a drier environment. For the second interval, ten 405 ka cycles were identified; its higher ostracod count and more stable Ca/Ti and Ca/ΣTi, Fe, Al values could be indicative of increasing humidity.

Inhibitory effect of novel green polymer (Aspartic-citric acid) on the process of nucleation during gypsum scale formation

The presence of metal salts in the process fluid in industries leads to scale deposition over the heating or cooling surfaces and causes an significant increase in the overall process and product cost of the product. This further reduces the efficacy of the equipment and the quality of the product is compromised. Hence, in order to avoid this various conventional additives containing nitrogen, phosphorous and sulphur are used as antiscaling agents due to their superior scale inhibition properties. However, excessive use of these antiscalants has created an imbalance in the ecosystem. Hence, there is a necessity to look for more reliable compounds that are as equally efficient as the conventional ones and are eco-friendly, biodegradable and cost effective. In the present study, homo and hetero polymers of aspartic acid and citric acid have been synthesized using condensation method and their antiscaling properties against gypsum deposition is been evaluated. Characterization of the synthesized polymers and deposited scale was performed by FTIR, GPC, SEM and XRD. The polymer showing the highest efficiency in the preliminary screening test was further evaluated to study its effect on the process of nucleation and crystal growth. The synthesized polymers were found to be efficient in inhibiting the scale deposition process at additive concentration as low as 3 ppm. The presence of additive (PAS-co-CA2) increased the induction time, surface free energy of formation, critical nuclei size and number of molecules per critical nuclei. Hence, rate of nucleation was reduced. Molecular weight and functional groups were the crucial factors in determining the scale inhibition properties of the polymer. The process of crystal formation and deposition was significantly retarded in presence of the additive with a change in the crystal morphology of the deposited crystals.

The Messinian evaporites of the Mesaoria basin (North Cyprus): A discrepancy with the current chronostratigraphic understanding

Large volume of evaporites were deposited during the Messinian Salinity Crisis (MSC) across the Mediterranean. These evaporites are currently outcropping on land and are interpreted by seismic profiles beneath the Mediterranean floor. Biostratigraphic, magnetostratigraphic and astrochronologic data recovered from sediments below and above outcropping evaporites, together with gypsum facies associations and stratigraphic cyclicity, are the cornerstone of what is known as the MSC ‘three-stage’ model: Primary Lower Gypsum (PLG) – MSC stage 1, Resedimented Lower Gypsum (RLG) - MSC stage 2, and Upper Gypsum (UG) – MSC stage 3. Although this litho- and chronostratigraphic model is mainly based on the gypsum succession in Sicily, it is being currently applied by many investigators across the Mediterranean. The Mesaoria basin, in North Cyprus, hosts well exposed MSC gypsum deposits of the Kalavasos Fm. Two informal units are distinguished in the gypsum succession. The lower unit, largely consisting of clastic gypsum deposits, is conformably overlaid by the upper unit, mostly consisting of ‘in situ’ vertically-oriented selenite deposits. Based on the lithostratigraphic gypsum succession, the lower unit could be tentatively assigned to RLG - MSC stage 2, while the upper unit could correspond to UG - MSC stage 3. However, our lithologic and geochemical (δ 34 S sulfate δ 18 O sulfate , 87 Sr/ 86 Sr) data in gypsum points that the upper unit fits with those of the PLG – MSC stage 1. For the first time, thick vertically-oriented selenite beds with lithofacies and geochemical signatures diagnostic of PLG deposits lay conformably over clastic gypsum successions diagnostic of RLG deposits in the currently accepted ‘three-stage’ model. In North Cyprus, ‘in situ’ selenite platforms and ‘clastic’ gravity-flow gypsum deposits are coeval involving erosion and redeposition during the same evolutive stage. The complete gypsum succession in North Cyprus must be considered as MSC Lower Evaporites in the ‘two-step’ model (Lower Evaporites and Upper Evaporites) classically proposed prior to the ‘three-stage’ model. We show how nearby Messinian evaporite basins in the same island (North and South Cyprus) can produce different sedimentary records. Our data cast doubts on the systematic application of the ‘three-stage’ litho- and chronostratigraphic model to North Cyprus and other MSC Mediterranean evaporite successions. This work highlights the importance of local processes in the sedimentation and distribution of MSC evaporites in active tectonic settings, and alerts against extrabasinal MSC correlations based on gypsum facies distribution. • North Cyprus hosts important Messinian Salinity Crisis (MSC) evaporite deposits • MSC gypsum successions in North and South Cyprus are different • Geochemical data assigns North Cyprus evaporites to the MSC Lower Evaporites • The MSC gypsum succession in North Cyprus differs from the three-stage model • Extension of the Sicily based three-stage model to other basins is questionable

Synchronous onset of the Messinian salinity crisis and diachronous evaporite deposition: New evidences from the deep Eastern Mediterranean basin

We present a basin-wide correlation of the pre-evaporitic succession across the deep Levant basin, based on integrated bio- and cyclostratigraphy. The onset of Messinian salinity crisis (MSC) can be placed in all studied wells where foraminifers suddenly disappear and normal marine calcareous nannofossils are replaced by opportunistic assemblages. These changes mark the base of the Foraminifers Barren Interval (FBI), a 10s-of-m-thick (below seismic resolution), evaporite-free, shale unit that records the entire duration of the first stage. Moving towards the basin margin the FBI is progressively truncated on top by the Messinian erosional surface (MES), a regional-scale discontinuity sealed by a thin clastic evaporite units overlain by thick halite deposits. Our results confirm previous hypothesis suggesting that the crisis started in deep- as well as in shallow-water settings at 5.97 Ma and pointing to a synchronous onset of the MSC but diachronous deposition of evaporites. During stage 1 of the crisis, coeval with gypsum deposition in marginal basins, the salinity in deep basins progressively increased (with possible oxygen reduction) hindering the life of marine organisms. Then, at 5.60 Ma, when salinity in deep basins exceeded halite saturation, massive halite precipitation started, and a nearly 2-km-thick salt sequence accumulated in deep basins within a short period of 60 kyr. At that time (stage 2), sedimentation rate jumped by an order of magnitude reaching a few cm/yr. Similar sedimentation rates are inferred for the Realmonte salt mine (Sicily) and observed in the modern Dead Sea and artificial salinas.

Resistance of blended alkali-activated fly ash-OPC mortar to mild-concentration sulfuric and acetic acid attack.

The traditional cementitious product is prone to suffer from a high degree of deterioration in the case of exposure to acid solutions because of the decomposition of the binder network. However, the degradation of concrete structures in service by mild concentrations of acid under conditions involving sewage, industrial waters, and acid rain is more common and results in a significant environmental problem. The utilization of alkali-activated materials has been seen to potentially offer an attractive option with regard to acceptable durability and a low carbon footprint. With the aid of visual observation, mass loss, compressive strength tests, X-ray diffraction, Fourier transform infrared spectroscopy, and field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, the acid resistance of alkali-activated fly ash mortars in which the precursor was partially replaced (0-30% by mass proportion) with ordinary Portland cement (OPC) was evaluated after 180 days of exposure to mild-concentration sulfuric and acetic solutions (pH = 3). A conventional cement mortar (100% OPC) was used as a reference group. The results demonstrate that the addition of OPC into the alkali-activated system causes a significant increase in compressive strength (around 16.08-36.61%) while showing an opposite influence on durability after acid attack. Based on a linear mean value and nonlinear artificial neural network model simulation, the mass losses of the specimens were evaluated, and the alkali-activated pure-fly ash mortar demonstrated the lowest value (i.e., a maximum of 5.61%) together with the best behavior in the aspect of discreteness at 180 days. The results from microstructure analysis show that the coexistence of the N-A-S-H and C-S-H networks in the blend system occurred by both OPC hydration and FA. However, the formation of the gypsum deposition within the fly ash-OPC blend systems at sulfuric acid was found to impose internal disintegrating stresses, causing a significant area of delamination and cracks. In addition, alkali metal ion leaching, dealumination, as well as the disappearance of some crystalline phases occurred in specimens immersed in both types of acids.

A Messinian Gypsum Deposit in the Ionian Forearc Basin (Benestare, Calabria, Southern Italy): Origin and Paleoenvironmental Indications

This study reports the first accurate record of the Messinian Resedimented Gypsum in the forearc and back-arc basins connected to the Calabrian-Peloritan orogen. A multidisciplinary approach has been used to investigate a gypsum deposit located in the Benestare’s area (Calabria, Southern Italy). Such deposit is made of bedded gypsrudites displaying clastic selenite with chaotical textures. On the top, the gypsrudites are interspersed with gypsum lenses belonging to the branching-like facies. Despite these two facies seem different macroscopically, they show petrographic features, fluid inclusions, organic matter and Strontium isotopic values very similar to each other. On the other hand, both facies show fractured and folded crystals. Crystals are only locally corroded and preserve primary structure relict as well as allochthonous (organic debris) and autochthonous putative microbial remains. All crystals are rich in fluid inclusions but these are visibly affected by stretching and leaking (re-equilibration processes) suggesting a moderate plastic deformation during re-sedimentation and subsequent burial. Minimal transport of the deposit is testified by subangular shapes of the gypsum crystals. The gypsrudite and branching-like facies reveal an 87Sr/86Sr average value of 0.709045 and 0.709082, respectively. These values suggest a strong connection with the global Ocean and reduced freshwater input. The Benestare’s deposit originated from the partial to complete dismantling of selenite crystals related to the first stage (5.97–5.60 Ma) of the Messinian Salinity Crisis through gravitational collapse due to local controlling factors.

Hydroclimatological Patterns and Limnological Characteristics of Unique Wetland Systems on the Argentine High Andean Plateau

High-elevation wetlands in South America are not well described despite their high sensitivity to human impact and unique biodiversity. We describe the hydroclimatological and limnological characteristics of 21 wetlands on the High Andean Plateau of Argentina, synthesizing information gathered over ten years (2010–2020). We collected physical-chemical, phytoplankton, and zooplankton data and counted flamingos in each wetland. We also conducted an extensive analysis of climatic patterns and hydrological responses since 1985. These wetlands are shallow, with a wide range of salinity (from fresh to brine), mostly alkaline, and are dominated by carbonate and gypsum deposits and sodium-chloride waters. They tend to have high nutrient concentrations. Plankton shows a low species richness and moderate to high dominance of taxa. Flamingos are highly dependent on the presence of Bacillariophyta, which appears to be positively linked to silica and soluble reactive phosphorus availability. Climatic conditions show a strong region-wide increase in average air temperature since the mid-1980s and a decrease in precipitation between 1985–1999 and 2000–2020. These high-elevation wetlands are fundamentally sensitive systems; therefore, having baseline information becomes imperative to understanding the impact of climatic changes and other human perturbations. This work attempts to advance the body of scientific knowledge of these unique wetland systems.

Similarities and distinctions in the genesis of salt-affected soils in different regions of the south of Eastern Siberia

Soil salinization is determined by a set of factors, which can be subdivided into sources and mechanisms. The south of Eastern Siberia is characterized by the mountainous topography with numerous intermontane depressions, a large number of tectonic faults and springs. Hydromorphic surface-saline soils of sulfate and chloride-sulfate chemistry predominate. In Tuva, the share of chloride salinity increases, which is associated with the presence of salt rocks, and the percentage of soda-saline soils decreases sharply. In Buryatia, the percentage of soda salinity is higher than in other regions. In Khakasia, despite the gypsum deposits, the percentage of soda-saline soils is also significant, which is related to irrigation practices. Sharper differences are observed in individual basins of the regions, the salinity of which is determined by the presence of salinization sources in the given area, as well as by the mechanisms and conditions of soil salinization. For example, the presence of permafrost prevents the leaching of chlorides from the profile leading to the development of chloride salinization, or an increase in the alkalinity associated with the magnesium bicarbonate in slightly arid intermontane depressions of Buryatia and high–mountain depressions of Tuva.

Gypsum lithofacies and stratigraphic architecture of a Messinian marginal basin (Piedmont Basin, NW Italy)

During the Messinian salinity crisis (5.97–5.33 Ma) the Mediterranean was transformed into the youngest salt giant in Earth history. In marginal Mediterranean subbasins, the first stage of the crisis is recorded by up to 16 lithological cycles made up of shale/gypsum couplets (Primary Lower Gypsum unit, PLG), making a downslope transition to organic-rich shales. Gypsum comprises a wide array of lithofacies, including bottom-grown gypsum, cumulate deposits (i.e., resulting from gypsum nucleation in the water column and subsequent deposition on the seafloor) and the branching selenite. The latter appeared synchronously in many sections of the Mediterranean in the 6th PLG cycle (i.e., at about 5.87 Ma). To investigate the still enigmatic stratigraphic architecture of the lateral lithofacies transition from the shallower basin margin to the depocenter and the paleoenvironmental modifications driving the development of the branching selenite lithofacies, we carried out sedimentological, petrographic and geochemical analyses of the different types of gypsum lithofacies exposed along a margin-to-depocenter transect in the Piedmont Basin (NW Italy), corresponding to the northernmost Mediterranean subbasin. The results of this study suggest that the lateral and vertical distribution of gypsum lithofacies mostly reflects the position of an oxycline with respect to the seafloor. Bottom grown gypsum (cycles PLG1–PLG5) was deposited on a temporarily oxygenated seafloor above the oxycline in the marginal part of the basin. In the case of cumulate deposits (laminar gypsum and gypsiferous mudstones, cycles PLG6–PLG15), gypsum nucleated within the water column at the oxycline and was eventually deposited on an anoxic seafloor. The branching selenite lithofacies corresponds to a syngenetic product formed below the seafloor at the expenses of cumulate gypsum. Deposition of cumulate gypsum and formation of the branching selenite were controlled by the balance between the rate of sulfate reduction in bottom waters and nucleation of gypsum in the water column. The appearance of cumulate gypsum and the branching selenite from the 6th PLG cycle upwards reflects the intensification of water column stratification in response to increased isolation of the basin.

Investigating the origin of gypsum in Olympia Undae: Characterizing the mineralogy of the basal unit

The Olympia Undae sand sea contains the largest known deposit of gypsum discovered on the surface of Mars. The origin of this gypsum, a hydrated sulfate mineral requiring liquid water for its formation, remains largely unconstrained. We examine the hypothesis that gypsum was derived from the early-Amazonian aged Basal Unit, which is suggested to contain hydrated sulfates. Previous attempts to detect hydrated sulfates in the Basal Unit using CRISM and OMEGA data have been largely inconclusive. In this paper, we characterize the hydrated sulfate mineralogy of the Basal Unit using the Guided Endmember Extraction (GEEn) method which can detect target mineral spectra in mixed environments that obscure absorptions characteristic of certain minerals. In this paper, we outline a novel workflow for the application of GEEn to a set of CRISM images from the Olympia Cavi region and present spectral evidence for the presence of polyhydrated sulfates in the Basal Unit. We validate the applied GEEn workflow using CRISM data from various regions on Mars where sulfates have previously been detected. Non-linear mixture modeling is used to determine that spectra of the Basal Unit are best modeled as a spectral mixture of water-ice, sand/dust, mafic dune material, gypsum, and polyhydrated magnesium sulfate⁎. These sulfate detections could indicate the presence of liquid water in the polar region during the Amazonian.11*Polyhydrated magnesium sulfate here refers to the MICA library spectrum named “Polyhydrated Sulfate”, which according to Vivano-Beck et al., could be representative of a variety of polyhydrated sulfates including epsomite, hexahydrite, amorphous Mg-sulfate, and starkeyite (Chipera and Vaniman, 2007; Wang et al., 2009).

Additives Effects on producing Gypsum plaster in Zurbatiyah area, Eastern Iraq


 
 
 
 Gypsum deposits are wide spread in Zurbatiyah area, Eastern of Iraq, especially in Fatha Formation. Gypsum deposits have been known as a suitable materials for gypsum plaster industry. Sawdust and Palm fibers powders have been added in different ratios to gypsum plaster material mixture to improve their industrial properties. Addition of 0 %,1 %, 5%, 10% and 15 % pass of 4.75 mm size of sawdust and palm fibers powder and 0 %, 1 %, 5%, 10% and 15 % pass of 5.60 mm size of sawdust and palm fibers powder to gypsum plaster material mixture. This ratios showed results of consistency (35-75 ml/gm), setting time (11-20 min) and compressive strength (2.2-4.4 N/mm2) for sawdust powders size 4.75 mm, whereas the results of consistency (35-63 ml/gm),setting time (11-21 min) and compressive strength (2.0-4.2 N/mm2) for palm fibers powders size pass of 4.75 mm. The addition of 1% and 5% pass of 4.75 mm sawdust and palm fibers powder to gypsum plaster material mixture showed an improvements in consistency(37-41ml/gm), (36-40ml/gm) setting time (13-14 min), (12-13 min) and compressive strength (4.2-4.4 N/mm2), and (4.1-4.2 N/mm2) for sawdust and palm fibers respectively. Also the addition of 1 % and 5 % pass of 5.60 mm sawdust and palm fibers powder showed consistency (40-45 ml/gm), (39-44 ml/gm), (14-15 min.), (12-13min.), (3.5-4.2 N/mm2), and (3.0-4.1 N/mm2), for sawdust and palm fibers respectively. In general, the results of current study conform the requirements of the Iraqi standard specification No. 28 (1988) and ASTM C28, C472 (2010) for ordinary gypsum plaster industry.
 
 
 

Messinian bottom-grown selenitic gypsum: An archive of microbial life.

Primary gypsum deposits, which accumulated in the Mediterranean Basin during the so-called Messinian salinity crisis (5.97-5.33Ma), represent an excellent archive of microbial life. We investigated the molecular fossil inventory and the corresponding compound-specific δ13 C values of bottom-grown gypsum formed during the first stage of the crisis in four marginal basins across the Mediterranean (Nijar, Spain; Vena del Gesso, Italy; Heraklion, Crete; and Psematismenos, Cyprus). All studied gypsum samples contain intricate networks of filamentous microfossils, whose phylogenetic affiliation has been debated for a long time. Petrographic analysis, molecular fossil inventories (hydrocarbons, alcohols, and carboxylic acids), and carbon stable isotope patterns suggest that the mazes of filamentous fossils represent benthic microbial assemblages dominated by chemotrophic sulfide-oxidizing bacteria; in some of the samples, the body fossils are accompanied by lipids produced by sulfate-reducing bacteria. Abundant isoprenoid alcohols including diphytanyl glycerol diethers (DGDs) and glycerol dibiphytanyl glycerol tetraethers (GDGTs), typified by highly variable carbon stable isotope composition with δ13 C values spanning from -40 to -14‰, reveal the presence of planktic and benthic archaeal communities dwelling in Messinian paleoenvironments. The compound inventory of archaeal lipids indicates the existence of a stratified water column, with a normal marine to diluted upper water column and more saline deeper waters. This study documents the lipid biomarker inventory of microbial life preserved in ancient gypsum deposits, helping to reconstruct the widely debated conditions under which Messinian gypsum formed.

Tiny, glassy, and rapidly trapped: The nano-sized planktic diatoms in Messinian (late Miocene) gypsum

Abstract Primary gypsum represents an excellent paleobiological archive due to its early and fast growth, favoring the preservation of delicate biomineralized structures. The Mediterranean region is renowned for evaporite deposits that formed during the Messinian salinity crisis (MSC), an event that supposedly annihilated most of the marine biota. However, the Messinian evaporites have been scarcely studied for their fossil content. Abundant nano-sized planktic diatoms and associated organic matter are observed for the first time in bottom-grown gypsum crystals that formed during the early stage of the MSC in different marginal basins of the western Mediterranean. This discovery increases our knowledge of the Messinian biota and reveals that nano-sized planktic diatoms played a prominent role in carbon and silicon export during gypsum deposition. The co-occurrence of these diatoms with larger diatoms, possibly associated with a deep chlorophyll maximum, suggests that Messinian gypsum formed in stratified and relatively deep basins (far below the photic zone), typified by marine conditions in the upper water column. The nano-sized planktic diatoms may have taken advantage of the hydrological reconfigurations experienced by the Mediterranean since the onset of the MSC. This study confirms that primary gypsum represents a promising archive of information for elucidating the marine biotic response to an ancient environmental crisis.

On calcium-to-alkalinity anomalies in the North Pacific, Red Sea, Indian Ocean and Southern Ocean

An important factor for predicting the effect of increased CO2 on future acidification of the ocean is a proper understanding of the interactions controlling production and dissolution of calcium carbonate minerals (CaCO3). The production and dissolution of CaCO3 in the ocean can be assessed over large spatial scales by measuring seawater calcium concentrations and total alkalinity (AT), yet past studies suggest that there could be large discrepancies between calcium and AT-based balances of the CaCO3 cycle in the North Pacific and Indian Oceans. Here, we analyse water column samples collected along transects in the North Pacific, Southern Ocean, tropical Indian Ocean and Red Sea for their concentrations of calcium, nutrients, and AT. We find that there is an excess calcium over AT anomaly in the top 1000 m of the tropical Indian Ocean water-column. The source of this anomaly is the dissolution of subsurface gypsum deposits in the Red Sea. We find no evidence for calcium-over-AT anomalies in the North Pacific, in contrast to previous studies. Our results show that, in most cases, calcium and AT data agree well and can be used to reconstruct the marine CaCO3 cycle.

Mapping mineralogy in evaporite basins through time using multispectral Landsat data: Examples from the Bonneville basin, Utah, USA

AbstractThe Bonneville basin, located in north‐western Utah, is a vast evaporite basin which is home to the world‐renowned Bonneville Salt Flats international speedway and is a highly valued landscape undergoing rapid change and anthropogenic influence. Air quality, snowpack, the local hydrological system, and state tourism are all impacted by the nature of the surface sediments exposed in the Bonneville basin. Mapping the Bonneville basin over time with remote sensing methods provides insight into the dynamics and impacts of the changing surface landscape. Utilizing the Landsat‐5 Thematic Mapper (TM) and Landsat‐8 Operational Land Imager (OLI) sensors, a set of band math indices are empirically established to map the predominant halite, gypsum, and carbonates mineralogical zones of the Bonneville basin. Spectral comparisons of representative samples from the study area and image‐derived spectra indicate the halite of the Bonneville basin is wet and that gypsum deposits are slightly mixed with halite. The established indices are assessed in four ways, all of which support the ability of the indices to accentuate the associated mineralogical endmembers. Two study areas within the Bonneville basin are investigated temporally from 1986, 1995, 2005, and 2016 and show changing patterns in mineral distribution that align with surface processes active through these timescales. These indices provide a resource for mapping mineralogy though time in evaporite basins globally with diverse applications for questions about land use and environmental change.

The Analysis of Injected Water into O-1 Formation of the Central Block of the Talakan Oil and Gas Condensate Field in Order to Identify and Predict Zones With High Risk of Salt Precipitation

The value of this research work involves the search for newer and best options of salt precipitation prediction in wells for fields in Eastern Siberia using the example of the Cenral Block of the Talakan oil and gas condensate field. The development of this block is complicated by the presence of salt impurities in a pore volume and highly mineralized formation water represented as calcium chloride brine while the source of gypsum deposits is injected water containing excess sulfate ion values. Prediction and control for scale during oil production is essential for practical tasks since the effectiveness of actions for elimination of salt sediments, prevention and protection of oilfield equipment depends on the prediction and timely detection of salt deposits in wells, on pumping equipment, in oil gathering and processing systems. If there is a problem, it is necessary to monitor it and prevent negative events leading to unproductive costs and losses in oil production, especially in the conditions of market relations, when the development of oil fields should be cost-effective.

Sedimentology and isotope geochemistry of transitional evaporitic environments within arid continental settings: From erg to saline lakes

AbstractArid continental basins typically contain a spectrum of coeval environments that coexist and interact from proximal to distal. Within the distal portion, aeolian ergs often border playa, or perennial, desert lakes, fed by fluvial incursions or elevated groundwaters. Evaporites are common features in these dryland, siliciclastic dominant settings. However, sedimentary controls upon evaporite deposition are not widely understood, especially within transitional zones between coeval clastic environments that are dominantly controlled by larger scale allocyclic processes, such as climate. The sulphur (δ34S) and oxygen (δ18O, Δ17O) isotope systematics of evaporites can reveal cryptic aspects of sedimentary cycling and sulphate sources in dryland settings. However, due to the lack of sedimentological understanding of evaporitic systems, isotopic data can be easily misinterpreted. This work presents detailed sedimentological and petrographic observations, coupled with δ34S, δ18O and Δ17O data, for the early Permian Cedar Mesa Sandstone Formation (western USA). Depositional models for mixed evaporitic/clastic sedimentation, which occurs either in erg‐marginal or lacustrine‐marginal settings, are presented to detail the sedimentary interactions present in terms of climate variations that control them. Sedimentological and petrographical analysis of the evaporites within the Cedar Mesa Sandstone Formation reveal a continental depositional environment and two end member depositional models have been developed: erg‐margin and lake‐margin. The δ34S values of gypsum deposits within the Cedar Mesa Sandstone Formation are consistent with late Carboniferous to early Permian marine settings. However, a marine interpretation is inconsistent with sedimentological and petrographic evidence. Consequently, δ34S, δ18O and Δ17O values are probably recycled and do not reflect ocean‐atmosphere values at the time of evaporite precipitation. They are most likely derived from the weathering of older marine evaporites in the hinterland. Thus, the results demonstrate the need for a combination of both sedimentological and geochemical analysis of evaporitic systems to better understand their depositional setting and conditions.