Gypsum Rocks Research Articles

Pore characterization of 3D-printed gypsum rocks: a comprehensive approach

With advancements in additive manufacturing, now 3D-printed core plugs can be duplicated in order to replace natural rock samples. This can help us to control their parameters to be used in different types of experiments for model verifications. However, prior to such substitutions, we should ensure they can represent natural rock samples through characterizing their physical properties. In this paper, synthetic samples made up of gypsum powder are 3D-printed and then characterized for essential pores properties. The analysis included structures of the pores, quantitative porosity evaluation, pore size distribution, pore surface area, pore shape distribution, and corresponding anisotropy. Mercury injection porosimetry (MIP) and helium porosimetry (HP) combined with X-ray micro-computed tomography were performed to provide us with detailed information about the pores. Porosity was measured 32.66% from micro-CT based on watershed thresholding, which was found comparable with MIP and HP results, 27.90 and 28.86%, respectively. Most of the pores lay in the range from 4 to 10 μm in diameter with relative frequency of 92.04%. The pore shape distribution indicates that 3D-printed gypsum rocks host more spherical pores and fewer blade-shaped pores. In addition, pore anisotropy of the sample that was analyzed by collecting pore orientation in orthogonal axes represented the vertical transverse isotropy.

Geothermal flux and phreatic speleogenesis in gypsum, halite, and quartzite rocks

Geothermal flux and phreatic speleogenesis in gypsum, halite, and quartzite rocks

Theoretical and Numerical Investigation of the Cavity Evolution in Gypsum Rock

AbstractWhen water flows through a preexisting cylindrical tube in gypsum rock, the nonuniform dissolution alters the tube into an enlarged tapered tube. A 2‐D analytical model is developed to study the transport‐controlled dissolution in an enlarged tapered tube, with explicit consideration of the tapered geometry and induced radial flow. The analytical model shows that the Graetz solution can be extended to model dissolution in the tapered tube. An alternative form of the governing equations is proposed to take advantage of the invariant quantities in the Graetz solution to facilitate modeling cavity evolution in gypsum rock. A 2‐D finite volume model was developed to validate the extended Graetz solution. The time evolution of the transport‐controlled and the reaction‐controlled dissolution models for a single tube with time‐invariant flow rate are compared. This comparison shows that for time‐invariant flow rate, the reaction‐controlled dissolution model produces a positive feedback between the tube enlargement and dissolution, while the transport‐controlled dissolution does not.

Alteration mineralogy of eocene volcanic and volcaniclastic rocks from Sivas basin in Turkey

The study area covers volcanic-volcanosedimentary units of Eocene age in the Sivas-Ulas area from Turkey. The pyroclastic (tuffaceous claystone/siltsone/sandstone, crystal ash tuff) and volcanic (basalt, basaltic andesite, andesite) rocks of the Karacalar member from the Kalekoy Formation include volcanogenic (plagioclase, augite, hornblende, biotite), diagenetic (K-feldspar, mixed-layered chlorite-smectite/C-S, chlorite, analcime) and post-volcanic (calcite, dolomite, quartz) minerals. The volcanogenic (plagioclase), diagenetic (K-feldspar, C-S, chlorite), postvolcanic (quartz, calcite, dolomite) and detrital (illite) minerals were observed in the epiclastic (shale, siltstone, calcareous siltstone, sandstone, calcareous sandstone) and chemical (limestone, gypsum) rocks of the Yapali member from this formation. C-S + K-feldspar zoning is widely developed by due to the interaction between sea-water and volcanic glass in basic-intermediate composition, on the basis of optic and electron microscopes and also X-rays data. This zone corresponds to the deeper parts of the Sivas basin in the Eocene period and show vertically a transition into zeolite zone in approximately northern parts of the basin (Yavu area).

Water driven processes and landforms evolution rates in mountain geomorphosites: examples from Swiss Alps

Geomorphic processes driven by water are particularly active in mountain environments, especially under the current climate conditions. Erosion and dissolution processes shape meaningful landforms, in different kinds of deposits and rocks, and in some cases they are classified as geomorphosites. Such landforms, especially earth pyramids and rock pillars, are usually characterized by a high scientific value (e.g., representativeness, ecologic support role) and by additional values (e.g., cultural and aesthetic value) contributing to the local geoheritage. Mountain geomorphosites are growing in importance within scientific community and their morphological evolution can affect the global value of the site itself (e.g., integrity). In this paper, after a first review on the terminology used for classifying landforms modelled by water runoff and on their meaning within the mountain environment, the results of a detailed research performed at two sample sites, included in the Swiss National Inventory of Geosites, are presented. The two study sites are representative respectively of: i) water runoff on glacial deposits shaping earth pyramids (Pyramides d'Euseigne); ii) water dissolution on gypsum rocks, modelling articulate karst landscapes (Pyramides de gypse du Col de la Croix). For each site, landforms evolution was investigated and denudation rates were estimated by means of different methods: iconographic material analysis, quantitative geomorphology and dendrogeomorphology on exposed roots. Despite the long-term, average rates obtained by means of roots exposure for both water runoff on glacial deposits (e.g., 5.8mm/y) and dissolution on gypsum rocks (5.6mm/y) are comparable. Moreover, a strict relation between the activity degree of processes, the integrity of the site and the assignment of geomorphosites to a specific category (i.e., active, passive or evolving passive) emerged from the results.

Study on the Corrosion Model of Tunnel Lining Structure in Gypsum Rock

Study on the Corrosion Model of Tunnel Lining Structure in Gypsum Rock

Characterization and modeling of long-term stress–strain behavior of water confined pre-saturated gypsum rock in Kurdistan Region, Iraq

In order to understand the effects of soaking time and confined water pressure on the strength of rock due to dissolution of gypsum, rock samples with 96% of gypsum content collected from Kurdistan Region in northern Iraq were investigated. Laboratory tests were then performed on the normal gypsum rock samples under pre-saturated condition to obtain their uniaxial compressive strength (UCS) values. The pre-saturated samples were submerged in distilled water for 35 d, 70 d and 105 d, respectively, under confined water pressures of 0–0.5 MPa. The gypsum content decreased by 11% after 105 d of soaking under confined water pressure of 0.5 MPa. The UCS of the normal gypsum rock was 19.6 MPa and it decreased to 6.3 MPa and 2 MPa after 105 d of soaking under confined water pressures of 0 and 0.5 MPa, respectively. A nonlinear constitutive model was used to simulate the experimental stress–strain relationships of rock samples under various conditions. The constitutive model parameters were sensitive to the gypsum content.

Assessment of the geostress field of deep-thick gypsum cap rocks: A case study of Paleogene Formation in the southwestern Tarim Basin, NW China

Gypsum rocks have extremely low permeability and good pressure sealing capability, and they are widely distributed in different strata all over the world. A deep-thick gypsum cap rock is developed in the Paleogene formation of the southwestern Tarim Basin in China. The regions below the gypsum rocks have huge potential for oil and gas resources. Casing deformation and blockage during tripping operations often occur during the drilling process in the gypsum bed, which severely affects the efficient drilling of deep oil and gas. Therefore, it is necessary to comprehensively assess the geostress field of gypsum cap rocks under high-stress background conditions. Through triaxial synchronized mechanical and acoustic testing experiments, high-stress formation environments were simulated and the mechanical parameters of gypsum rocks were obtained. We used dispersion correction technology to transform the measured high-frequency (1MHz) wave velocities of the samples to the wave velocities of well-logging frequency (20kHz). The transformed wave velocities can be used for the well-logging assessment of rock mechanical parameters and geostress. We built well-logging interpretation models for the shear-wave slowness, mechanical parameters and geostress of the Paleogene gypsum rocks. Each model showed high assessment accuracy. Combined with the paleomagnetic analysis of the Paleogene gypsum bed and the results of the fast shear-wave direction analysis, radial expansion position analysis and induced fracture analysis on the reservoir below the Paleogene gypsum bed, we suggest that the direction of geostress in the study region is NW10°. Three-dimensional finite element method was used to simulate the geostress field of the gypsum bed. The Paleogene formation in the study region does not have faults. The geostress distribution of the gypsum rock layer is mainly controlled by structural relief, burial depth, and lithology. This study provided a typical example of a comprehensive assessment of the geostress field of deep-thick gypsum cap rocks.

FORMATION CONDITIONS, GENESIS, EVOLUTION, CLASSIFICATION AND SOME FEATURES OF SOILS FORMED ON GYPSUM ROCKS IN THE REPUBLIC OF MACEDONIA

The current paper studies the formation conditions, genesis, evolution, classification, morphological features, mechanical composition and chemical properties of soils formed on gypsum rocks in the Republic of Macedonia. The soils have been formed on mountain relief with steep slopes upon gypsum and anhydrite. Warm continental climate with inconsiderable impact of the Mediterranean climate prevails in the area. The soils occur underneath hill pastures, which are rather poor from a floristic point of view and they are characterized by minor canopy closure. Destruction of the natural forest vegetation and intensive grazing on the hill pastures that have remained following the destruction thereof have caused heavy soil erosion. Our research has ascertained that gypsic rendzic leptosol and gypsic pararen-dzina have been formed on gypsum rocks. Both soil types are distinguished by a light mechanical composition domi-nated by physical sand. Carbonates are present in both soil types in all soil assays while in certain soil assays the gyp-sum has been fully washed.

Using stable isotopes and major ions to identify hydrogeochemical characteristics of karst groundwater in Xide country, Sichuan Province

Karst groundwater is important water resources for local people in southwest China, especially in Xide country, Sichuan Province. Stable isotopes (H and O) that incorporated with major ions of groundwater were used to identify the origin of groundwater, and determine the dominant water–rock interaction processes controlling the hydrogeochemical characteristics of groundwater in the study area. The stable isotopes results indicated that all groundwater derived from meteoric water. The chemical analysis showed that the cold groundwater was HCO3-Ca·Mg type, and the thermal water was HCO3·SO4-Ca·Mg type. The major ions of groundwater combined with the equilibrium stated of the groundwater based on the saturation index (SI), suggested that the hydrogeochemical characteristic of groundwater was mainly governed by dissolution of carbonate minerals and gypsum rocks, and ion exchange. Other factors such as evaporation and anthropogenic activities may also play roles on it. The results revealed the dominant hydrogeochemical processes controlling groundwater water quality in this karst area, which would provide significant insights into the local governments that can make effective policy for groundwater utilization.

Petrology and Alteration of Calcium Sulphate Deposits in Late Paleozoic Rocks of Wang Saphung Area, Loei Province, Thailand

The gypsum-anhydrite deposit in Loei-Wang Saphung (LWS) area of northeastern Thailand is a small evaporite sediment deposit with up to 50 m thick gypsum-anhydrite beds. The evaporite deposits are overlain by cross-laminated and fine-grained siliciclastic and carbonate rocks of the Carboniferous to Permian ages. This paper documents some characteristics of the deposits, including lithologies, textures, and structures of gypsum-anhydrite and associated rocks, based on the stratigraphic core logging of boreholes and lithofacies analysis of selected samples. Morphological and textural mineralogical relationships reveal 10 textures of the evaporite formation viz. alabastrine gypsum, satin spar gypsum, selenite gypsum, gypsarenite, porphyroblastic gypsum, fine lenticular gypsum, crystalloblastic or blocky anhydrite, prismatic anhydrite, epigenetic anhydrite, and felty epigenetic anhydrite. The results also indicate that the LWS sulfate deposit has passed through at least 4 evolutionary alterations; (1) original precipitation as gypsum deposit, (2) gypsum-to-anhydrite transformation resulting from burial diagenesis in response to basinal subsidence, (3) rehydration of anhydrite-to-gypsum, indicated by distorted gypsum rocks, resulting from the increase of volume due to the rehydration from anhydrite to gypsum, and recrystallization of anhydrite and/or primary gypsum to secondary gypsum (4) uplift and re-expose of gypsum, indicated by the karstification and dissolution cavities and gypsarenite veins. The gypsum-anhydrite beds with associated carbonate and mud rocks suggest that these sedimentary sequences form in a subaqueous, probably shallow marine marginal setting during Late Carboniferous.

석고 모형재와 고무인상재의 젖음성이 지르코니아 코핑의 변연적합도에 미치는 영향

Purpose: This study examined the effect of wettability of gypsum materials and rubber impression material on the marginal fitness of zirconia copings. Methods: Three commercially available gypsum materials(Fugirock EP, Snow Rock, Tuff Rock) and three zirconia blocks(iJAM Emerald, LUXEN Smile block, ICE Zirkon transluzent) were studied. The zirconia copings were fabricated by using dental CAD/CAM system. Contact angles on the impression materials were measured with contact angle measuring device. Silicone replica method was used to measure the marginal fitness and cutting was performed on the bucco-lingual and mesio-distal sides. It were observed with a stereomicroscope at &#x00B0;&#x00F8;40 magnification. The data were statistically analyzed with One-way ANOVA. Results: Mean values of contact angles were <TEX>$58.3{\pm}0.7^{\circ}$</TEX> for Tuff Rock, <TEX>$77.5{\pm}0.5^{\circ}$</TEX> for Fugirock EP and <TEX>$87.8{\pm}0.5^{\circ}$</TEX> for Snow Rock and the difference between them was statistically significant(p<0.05). The smallest values of marginal fitness for the JF groups were <TEX>$30.7{\pm}3.0{\mu}m$</TEX> for bucco-lingual direction, <TEX>$29.3{\pm}3.0{\mu}m$</TEX> for mesio-distal direction. One-way ANOVA showed statistically significant difference between groups for marginal fitness(p<0.05). Conclusion: Tuff rock gypsum material had superior wettability to others. The mean marginal fitness of the Tuff rock gypsum material group were significantly better than other groups. Thus they can be also expected to show clinically satisfactory marginal fitness.

Польсько-україїнський семінар "Звітрювання гіпсів і ангідритів"

It is a review of the Polish-Ukrainian seminar “Weathering of gypsum and anhydrite rocks”, which was held in Warsaw.

Analytical and Laboratory Evaluation of the Solubility of Gypsiferous Soils

Gypsum soil is one of the problematic soils because of considerable solubility for Gypsum particles in contact with water. In this research the effects of three factors including; gypsum percent, hydraulic gradient and soil texture were studied on solubility of gypsum soils. To do this, samples of gypsum soils were provided artificially by adding various rates of natural gypsum rock including 0, 5, 10, 20 and 30 percent weight of 3 kinds of soil textures including clay, silty clay and sand. Totally, 15 types of gypsum soils were prepared. Then each of gypsum soils were leached under five hydraulic gradients levels 0.5, 1, 2, 5 and 10. The results of the test indicated that the rate of Gypsum in the soil had direct effect on the rate of soluble and by increasing the percent of Gypsum, the rate of solubility was increased. In addition, by increasing hydraulic gradient, the speed of water existing soil media in a specified time was increased and also higher rate of Gypsum was derived. Also the soil texture has a considerable effect on the rate of solubility of soil. In this study, rate of solubility of gypsum soils with sandy soils was determined as 1.5 to 2 times more than the rate of clay soils. The statistical results show the highest impact of gypsum percentage and lowest impact of hydraulic gradient soil on solubility of particles in different types of soils and it has no significant effect on the overall equation of the soil texture.

Sedimentology and sequence stratigraphy of evaporites in the Middle Jurassic Buqu Formation of the Qiangtang Basin, Tibet, China

Qiangtang Basin is a large Mesozoic marine sedimentary basin located on the northern Qinghai-Tibet plateau. Multiple sets of evaporites were observed in the Middle Jurassic Buqu Formation through field outcrop description and thin sections analysis, so as to form the sets of evaporite–carbonate sedimentary sequences. The evaporites in the Buqu Formation are represented by gypsum and anhydrite rocks that contain minor secondary diagenetic features such as massive, rosette, chicken-wire, and satin spar gypsum. Two lithofacies association types were identified in the Buqu Formation, including sparry oolitic limestone–dolomite–gypsum/anhydrite and micrite–carbonaceous mudstone–gypsum/anhydrite. The former was deposited in an intertidal–supratidal (tidal flat) setting and the latter was deposited in a subtidal lagoon setting. Two depositional sequences were distinguished, including Buqu sequence 1 and Buqu sequence 2. Gypsum of the intertidal setting is mainly developed in a lowstand system tract in both Buqu sequences 1 and 2, while gypsum of the subtidal setting is mainly developed in a highstand system tract in Buqu sequence 2. Combining the measured evaporites thickness in the field with sedimentary facies analysis, the distribution of the Middle Jurassic Buqu Formation evaporites is clear in the Qiangtang Basin, which may serve as a local seal for oil and gas plays in this region.

Detachment folding in a Lower Cambrian–Upper Permian karst reservoir: 3D model of the Yubei 3D area (eastern Markit Slope, Tarim Basin, Northwest China)

A three-dimensional (3D) structural modeling of the Lower Cambrian–Upper Permian Yubei 3D area was performed to understand its structural evolution. This model reproduces the present-day structure of the basin and comprises 11 horizons within Lower Cambrian to Upper Permian rocks. The analysis is based on 3D depth views and faults. The results image salt movements due to tectonics and/or burial. From these observations, this paper deduces that salt structures are correlated to the main faults and tectonic events. From the model analysis, we interpret the timing and geometry of Tarim Basin tectonics. The fault geometry can be resolved based on the strike of the fault, the morphology of hanging wall strata, and the stratigraphic distribution. Emphasis is placed on gypsum rock detachment, considering its movements during the Middle Caledonian event and decoupling effects during tectonic evolution. Moreover, we point to the structural control of the Paleozoic basement and the crustal architecture (Yubei 3D Zone) on the geometry of the Tarim Basin.

The role of gypsum and/or dolomite dissolution in tufa precipitation: lessons from the hydrochemistry of a carbonate–sulphate karst system

AbstractThe precipitation of freshwater carbonates (tufa) along karstic rivers is enhanced by degassing of carbon dioxide (CO2) downstream of karstic springs. However, in most karstic springs CO2 degassing is not enough to force the precipitation of tufa sediments. Little is known about the role of dissolution of gypsum or dolomite in the hydrochemistry of these systems and how this affects the formation of tufa deposits. Here we present a monitoring study conducted over a year in Trabaque River (Spain). The river has typical karst hydrological dynamics with water sinking upstream and re‐emerging downstream of the canyon. Mixing of calcium–magnesium bicarbonate and calcium sulphate waters downstream of the sink enhances the dissolution of carbonates and potentially plays a positive role in the formation of tufa sediments. However, due to the common‐ion effect, dissolution of dolomite and/or gypsum causes precipitation of underground calcite cements as part of the incongruent dissolution of dolomite/dedolomitization process, which limits the precipitation of tufa sediments. Current precipitation of tufa is scant compared to previous Holocene tufa deposits, which likely precipitated from solutions with higher saturation indexes of calcite (SIcc values) than nowadays. Limited incongruent dissolution of dolomite/dedolomitization favours higher SIcc values. This circumstance occurs when waters with relatively high supersaturation of dolomite and low SO42− composition sink in the upper sector of the canyon. In such a scenario, the process of mixing waters enhances the exclusive dissolution of limestones, preventing the precipitation of calcite within the aquifer and favouring the increase of SIcc values downstream of the springs. Such conditions were recorded during periods of high water level of the aquifers and during floods. This research shows that the common‐ion effect caused by the dissolution of gypsum and/or dolomite rocks can limit [or favour] the precipitation of tufa sediments depending on the occurrence [or not] of incongruent dissolution of dolomite/dedolomitization. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Sedimentation in a continental high-frequency oscillatory lake in an arid climatic background: A case study of the Lower Eocene in the Dongying depression, China

The sedimentary environment, formation conditions, sedimentary characteristics and the basin evolution model of high-frequency oscillatory lake in arid climatic background of the Lower Eocene in the Dongying depression were studied through the analysis of drilling cores, sporepollen, geochemistry and geophysics data. During the sedimentary period of the Eocene Ek1–Es4x formations, because of the frequent alternation between dry and wet climates in the arid climatic background and the gentle paleogeomorphology, the lake level and salinity of the Early Eocene Dongying depression frequently and rapidly increased and decreased, which is referred to as a high-frequency oscillatory lake. The sedimentation and distribution of sediments in this high-frequency oscillatory lake basin were controlled by the frequently alternating dry-wet climates. During periods with relatively wet climate, the seasonal floods and unstable rivers led to the formation of over-flooding lake deltas in the gentle slope belt, and fine-grained clastic sediments, with minor thin layers of gypsum-salt rocks in the sag belt. During the relatively arid climatic periods, sedimentation occurred mainly in the limited area of the sag belt with thick gypsum-salt rocks. Because of the impact of the salinity stratification of the lake water, these gypsum-salt rocks exhibit annular structural features. A sedimentary cycle of the oscillatory lake began with isochronous flood channels and ended with relatively thick gypsum rocks and salt rocks. The thickness of one oscillatory cycle is generally 4–20 m. The superposition of multiple sedimentary cycles of the oscillatory lake constitutes the overall vertical filling sequence of the high-frequency oscillatory lake basin.

Assessment of image processing techniques and ASTER SWIR data for the delineation of evaporates and carbonate outcrops along the Salt Lake Fault, Turkey

ABSTRACTThe Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) multispectral sensor allows a variety of minerals to be diagnosed with the availability of six shortwave infrared (SWIR) bands. The study area located in a semi-arid region in central Turkey was flanked by the Salt Lake Fault in the west. ASTER SWIR bands and the adopted image processing techniques such as decorrelation stretch, band ratio, and feature-oriented principle component selection (FPCS) were applied for mapping both gypsum and carbonate rocks in the study area. Initially, the application of the decorrelation stretch method with a novel band combination successfully delineated the gypsum and carbonate outcrops. In addition to that, the principle component 4 (PC4) image obtained from the FPCS technique applied to a new band selection of ASTER data distinguished explicitly the carbonate outcrops. The resultant images, consistent with the geologic map of the study area, were compared with another and demonstrated that the gypsum and carbonate rocks were clearly identifiable. In addition to that, quantitative analyses of parallelepiped supervised classification images, band 9/band 8 ratio, and PC4 images in particular, yielded very compatible results.

RAVINES AND LANDSLIDES OF THE UFA “PENINSULAR”

The Ufa “Peninsular” since active development is experiencing a shortage of land resources due to intensive dissection of Perm massive, on which the city is situated due to constant expansion of the latter. Structuralgeomorphological analysis, using remote sensing materials, field investigations, and drilling data have shown that Permian gypsum, limestone and sandy-clay rocks composing the territory, are divided by vertical and horizontal crustal deformations into blocks of different sizes. As a result, the rock mass was deconsolidated, which caused the intensifi cation of the formation of ravines and landslides.