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The deep-burial Ordovician carbonate reservoirs in the Yangshuiwu area (Jizhong Depression) have shown significant hydrocarbon potential since 2016. In this paper, based on the systematic investigation of characteristics and diagenesis of the reservoirs using cores, thin sections, logging, drilling, and geochemical analysis, their controlling factors and formation mechanism were discussed. The three high-quality reservoir belts (RBs) developed in the Ordovician strata are named RB1 (karst reservoirs), RB2 and RB3 (dolostone reservoirs) from top to bottom, each with its own set of pores, vugs, caves, and fractures. The results show that dolostones have relatively higher porosity and permeability than limestones and breccias. Unfilled and partly filled fractures, in particular, multiply enhance reservoir permeability. Additionally, the diagenetic paragenesis developed in marine, meteoric, and burial environments leads to the porosity evolution of Ordovician carbonates, mainly including compaction, calcite cementation, dolomitization, dissolution, and fracturing. Notably, sedimentation and dolomitization controlled by sea-level fluctuations are critical for the reservoirs formation. The tidal-flat sequence of each cycle of sea-level fluctuations influences their distribution. Subaerial meteoric water dissolution triggered by the Late Ordovician uplift plays an important role in the RB1, but has a negligible effect on the RB2 and RB3. Most importantly, the conductive high-angle fractures induced by the activities of the Yangshuiwu and Hexiwu faults from the Eocene to Pliocene can enhance all RBs potential, contributing to the ultimate reservoir quality. Therefore, a four-stage theoretical development model of the Ordovician reservoirs was established in combination with the tectonic background. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the adsorption process of a new composite adsorbent prepared from chitosan (Ch) and dolomite (Do) for removal of lead ions from aqueous solutions. The adsorption process of Pb2+ions onto Ch-Do composite adsorbent as initial Pb2+ concentration, solution pH, temperature, contact time and desorption was investigated. From the results, it has been observed that the highest removal efficiency is approximately 89% at contact time of 6 h, initial Pb2+concentration of 500 mg L−1, adsorbent dosage of 100 mg and agitation speed of 150 rpm at pH 4.0. Langmuir isotherm has a better fit with the experimental isotherm data (R2 = 0.920). The maximum Pb2+adsorption capacity from the Langmuir model was found as 0.332 mol kg−1 at 25°C Also, it performs pseudo-second-order superior performance in kinetic behaviour compared to other used kinetic models (R2 = 0.904). Thermodynamic parameters showed the Pb2+adsorption onto Ch-Do was endothermic, spontaneous and possible. The desorption studies have shown that Ch-Do composite adsorbent has a good adsorption/desorption performance for Pb2+ions. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the effective use of high calcium fly ash (HCFA) and dolomite powder in geopolymer mortar (GPM) and concrete. Trail HCFA GPM mixes were made with 10%, 20%, 30% and 40% dolomite powder. The alkaline liquids used for polymerization are sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). To prepare different mixes, 8 M, 10 M, 12 M and 14 M concentration of NaOH solution, NaOH to sodium silicate ratio 2.5 and liquid to binder ratio 0.5 were selected. Ambient temperature was used to cure the specimens. Test results show that HCFA GPM mix with 20% dolomite powder and 14 M NaOH concentration yielded remarkably higher compressive strength with 41.95 MPa at 28 days than the other mixes. Further, experimental work on HCFA geopolymer concrete (GPC) using 20% dolomite powder demonstrated more excellent strength properties than those demonstrated by control mix cement concrete. [ABSTRACT FROM AUTHOR]

Limestone is a widely used natural building material, and its physical and mechanical properties can change greatly when exposed to high-temperature heat sources. In this paper, limestone samples from Linyi City, Shandong Province, were selected and some of them were heated to 650 °C at different heating rates (4, 6, and 8 °C min−1), while the rest of the samples were heated cyclically (200, 300, 400, 500, 600, and 650 °C) at a heating rate of 8 °C min−1, and the acoustic emission (AE) signals were recorded throughout. The results show that the AE signal rate increases with increases in temperature, and the AE signal increases rapidly at 300 °C and 500 °C because of the thermal decomposition of dolomite and calcite. There is a negative correlation between the heating rate and the AE signal rate. The high-frequency data and high-amplitude data generated by AE are negatively correlated with the heating rate. With the increase in the heating rate, AE counts and cumulative AE counts decrease significantly. [ABSTRACT FROM AUTHOR]

This paper describes the stratiform fluorite and fluorite–base-metal mineralization within the Baikal area, Aldan Shield, Sette-Daban Ridge, and Omulyovka uplift in the Kolyma region. It is assumed to have developed in the Bureya, Khanka, and East Chukchi massifs. Fluorite was concentrated in terrigenous–carbonate rocks of the predominant dolomite range, in the shallow shelf zones separated from the open sea by coral reefs. The fluorite accumulation within layers and horizons at the diagenesis stage was followed by its redistribution with the formation of commercial ore bodies at the catagenesis stage. The Baikal stratiform fluorite mineralization is typical for stratiform deposits of fluorite–base-metal ores. The Aldan type occurs as deposits of high-quality fluorite ores in the carbonate cover of the Siberian Platform. The examples of typical deposits are considered and the forecast fluorite resources are estimated. [ABSTRACT FROM AUTHOR]

In the reverse flotation of fluorapatite and dolomite, high-efficiency depressors of fluorapatite have received considerable attention. In this paper, the depression mechanism of hydroxy ethylene diphosphonic acid (HEDP) was studied for the first time as a novel fluorapatite depressant on the surface of fluorapatite. The effect of HEDP on the flotation behavior of the two minerals was studied by single and mixed minerals in flotation tests. HEDP exhibited an excellent depression effect on fluorapatite flotation, whereas its adsorption on dolomite surface was minimal. Fluorapatite and dolomite were effectively separated by applying sodium oleate as a collector and HEDP as a depressant at pH 6.0. The depression mechanism of HEDP on fluorapatite was further analyzed via contact angle measurement, zeta potential and X-ray photoelectron spectroscopic (XPS) analysis. We found that HEDP seriously hindered the adsorption of sodium oleate (NaOL) on the fluorapatite surface and had a minimal effect on the dolomite surface. XPS analysis results indicate that the strong adsorption of HEDP on the fluorapatite surface can be attributed to the strong chelation between the electron-rich groups of HEDP and Ca ions on the fluorapatite surface. Therefore, HEDP is used as a selective depressant of fluorapatite in the fluorapatite–dolomite flotation–separation process. [ABSTRACT FROM AUTHOR]

This paper focuses to the thermo-chemical conversion of sewage sludge into valuable products using pressure of 0.1 and 1.0 bar, and temperatures of 500 and 900°C in a tubular reactor. Both the reactor pressure and pyrolysis temperature had a significant effect on the product yields and composition. Higher gas yield was found at higher temperature and lower pressure. The lower reactor pressure resulted higher heating values of the gas fraction. Due to its significantly higher carbon monoxide content, more syngas (hydrogen and carbon monoxide) was observed using 0.1 bar pressure. Regarding the char, their composition can be also significantly affected by the reactor pressure, however their morphology differed slightly. To enhance the product yield and affect their properties natural sourced dolomite was also used. It was concluded, that the dolomite mixing into the raw material can enhanced the dry reforming reactions and increase the syngas yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel collector DDALA is developed based on dodecylamine (DDA) structure. • The reagent system composed of DDALA and xanthan gum has better flotation selectivity for apatite/quartz. • DDALA/oleic acid combined collector exhibits different competitive adsorption configurations on apatite and dolomite surfaces. • DDALA/oleic acid molecular aggregates on apatite surface dictate its weakened capturing ability. This paper introduces a novel amphoteric collector, N -dodecyl-β-alanine (DDALA), derived from the molecular structure of dodecylamine, with the incorporation of a propionic acid group. In the study, flotation experiments are undertaken to examine the selectivity of DDALA in apatite flotation. Results demonstrate that DDALA, in combination with xanthan gum (XG) depressant and oleic acid collector successfully accomplishes the reverse flotation separation of apatite from quartz and dolomite. In addition, the synergistic application of zeta potential experiments, X-ray photoelectron spectroscopic tests, and first-principles calculations has been employed to delve into the action mechanisms of DDALA collector and XG depressant. By combining the results with existing research, the paper proposes that the selective adsorption of XG between apatite and quartz surfaces facilitates the selective separation of these two minerals by DDALA collector. Moreover, the intermediate collecting ability of DDALA/oleic acid combined collector for dolomite results from the competitive adsorption of DDALA neutral molecules and oleic acid anions on dolomite surface. Furthermore, the formation of hydrophilic molecular aggregates between DDALA neutral molecules and oleic acid anions on apatite surface diminishes the collecting ability of DDALA/oleic acid combined collector for apatite compared to the individual use of each collector. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to propose a method to predict shear-wave velocities in the process of AVO (amplitude variation with offset) inversion, to interpret seismic converted-wave data, and to match reservoir engineering information with seismic data in regions without shear-wave velocities. During CO2 flooding and sequestration, the shear-wave velocity varies with the pressure that is caused by fluid injection. Predictions of how the shear-wave velocity changes with pressure can be used to interpret 4D seismic monitoring data during different stages of CO2 injection. To verify the calculations, the authors used the characteristic parameters of the Marly dolomite and Vuggy limestone units of the Weyburn Oilfield reservoir in Canada. The Digby's model and Gassmann's equation were used to evaluate the dependence of the shear-wave velocity on the pressure in the carbonate rock formation. The authors have developed a new method for calculating the coordination number of the model and supplement the results with a shale correction, enabling the prediction to match the measured shear-wave velocities more closely. Our method is verified by dipole sonic logging data and petrophysical test data from the Weyburn Oilfield. When applied to petrophysical test data, the average error is below 5%. When the method is applied to well log data, the average error in the porous media is 3.014% in the Marly unit and 6.288% in the Vuggy unit. [ABSTRACT FROM AUTHOR]

A study of dolomite rock material failure using a simple small-scale blast setup is presented. Laboratory tests were conducted using disc specimens drilled with a borehole in the center. A detonation cord and a blasting cap were fitted inside the borehole to induce cracking and fracturing of the specimens. The specimens were inserted between two steel plates, which were compressed against the specimen using bolt screws. Prior to testing, the most suitable screw torque for constraining the vertical displacement of the specimen surfaces without compressing the specimen was selected based on numerical simulations. Then, the experimental tests with the blasting cap were simulated using the Johnson--Holmquist II (JH-2) material model, and the properties of the blasting cap were determined and verified in two special tests with a lead specimen. Possessing the validated model, the influence of specimen thickness on the cracking patterns was finally analyzed. This paper presents a relatively easy method for studying rock material behavior under blast loading and for validating the numerical and constitutive models used for rock simulations. [ABSTRACT FROM AUTHOR]

Taking dolomite and limestone in Guilin and Liuzhou regions in the north of Guangxi Province as research objects, this paper analyzed their mineral composition and chemical composition and proposed a digital assessment method for multi-source factors on corrosion characteristics in the Karst areas. Specifically, the chemical corrosion test, the corrosion test under the chemical-temperature actions, and the corrosion test under the action of vibration load are carried out from the digital view, respectively. Four aspects can be found in digital assessment results. Firstly, the dolomite in northern Guangxi mainly has a fine crystalline texture and a massive structure with low content of acid-insoluble matters, while limestone mainly has a powder crystalline texture and a massive structure with high content of acid-insoluble matters, and the purity of both dolomite and limestone are very high. Secondly, the difference of corrosion between dolomite and limestone mainly depends on the ratio of CaO/MgO in their chemical composition and the content of silica and acid insoluble matters. Thirdly, the corrosion rates of pure dolomite and pure limestone are basically the same under the same external conditions. Finally, temperature and vibration load have a relatively large influence on the corrosion rates of dolomite and limestone, and the corrosion rates of dolomite and limestone increase with the increase of temperature, but the influence of vibration load on the corrosion rate is more significant than temperature. This research can provide theoretical basis and technical support for large-scale engineering construction and prevention of karst geologic disasters in karst stone mountainous areas in northern Guangxi. [ABSTRACT FROM AUTHOR]

The paper aims to understand the effect of light-burned dolomite powders (LBD) on ordinary Portland cement (OPC) and evaluate the influence of LBD dosages and fineness levels on the mechanical properties and hydration properties of OPC. The LBD/OPC pastes were prepared by OPC blended with LBD at various replacement dosages and fineness levels. The mechanical properties were studied by flexural and compressive strength tests, while the hydration properties were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and reaction degree of LBD. Experiment results indicated that the flexural and compressive strength of LBD/OPC samples were higher than reference sample at all ages. The fineness levels of LBD was C (C-LBD) with 0.5–1.5 wt% dosages, and the fineness levels of LBD was B (B-LBD) with 1.5–2.5 wt% dosages can significantly improve the strength of cement-based materials. The main mineral components of LBD are MgO and CaCO3, of which MgO could react with water to form Mg(OH)2 quickly, and CaCO3 could hydrate with C3A to from hydrated calcium carboaluminate (C3A·CaCO3·11H2O), which prevents the conversion of AFt to AFm. [ABSTRACT FROM AUTHOR]

Shale oil reservoirs are dominated by micro- and nanopores, which greatly impede the oil recovery rates. CO2 and N2 injection have proven to be highly effective approaches to enhance oil recovery from low-permeability shale reservoirs, and also represent great potential for CO2 sequestration. Therefore, a better understanding of the mechanism of shale oil recovery enhanced by CO2 and N2 is of great importance to achieve maximum shale oil productivity. In this paper, the adsorption behavior of shale oil and the mechanism of enhancing shale oil recovery by CO2 and N2 flooding in dolomite slit pores are investigated by performing nonequilibrium molecular dynamics simulations. Considering the shale oil adsorption behavior, mass density distribution is analyzed and the results indicate that a symmetric density distribution of the oil regarding the center in the slit pore along the x-axis can be obtained. The maximum density of the adsorbed layer nearest to the slit wall is 1.310 g/cm3 for C8H18, which is about 2.0 times of that for bulk oil density in the middle area of slit pore. The interaction energy and radial distribution functions (between oil and CO2, and between oil and N2) are calculated to display the displacement behavior of CO2 and N2 flooding. It is found that CO2 and N2 play different roles: CO2 has strong solubility, diffusivity and a higher interaction energy with dolomite wall, and the oil displacement efficiency of CO2 reaches 100% after 1 ns of flooding; however, during N2 flooding, the oil displacement efficiency is 87.3% after 4 ns of flooding due to the lower interaction energy between N2 and dolomite and that between N2 and oil. [ABSTRACT FROM AUTHOR]

This paper presents new age estimates and results obtained by the chemostratigraphic study of dolostones of the Billyakh Group, which consists of the Kotuikan and the Yusmastakh formations. The Billyakh Group forms the upper part of the Riphean section of the Anabar uplift in northern Siberia. The stepwise dissolution technique was used for the first time to determine the 87Sr/86Sr, 206Pb/204Pb, and 207Pb/204Pb isotopic ratios in dolostones. The Rb‒Sr systematics was studied by the chemical removal of about a third of the crushed sample (fraction L1) by the preliminary acid leaching in 0.2 N CH3COOH and the subsequent partial dissolution (fraction L2) of the remaining part of the sample in CH3COOH with the same concentration. The Pb‒Pb isotope systematics of dolostones was studied by the six-step dissolution of crushed samples in 0.5 N HBr. These procedures led to the removal of secondary carbonate material and greatly improved the quality of Sr chemostratigraphic and geochronological information. The initial 87Sr/86Sr ratios of the least altered carbonate material (fraction L2) of the Billyakh Group dolostones are 0.70502 ± 0.00029 in the Kotuikan Formation, 0.70519 ± 0.00026 in the lower subformation of the Yusmastakh Formation, and 0.70511 ± 0.00018 in the upper subformation of the Yusmastakh Formation. The Pb‒Pb age of early diagenesis of Kotuikan and Yusmastakh dolostones (1519 ± 18 Ma at MSWD = 1.8) was calculated from the results obtained for carbonate fractions L3–L6. Secondary carbonate fractions L1‒L2 are characterized by a Pb‒Pb age of 1466 ± 54 Ma at MSWD = 0.6. The δ13C values vary from ‒1 to ‒0.4‰ in dolostones of the Kotuikan Formation and from ‒0.4 to +0.8‰ in those of the Yusmastakh Formation (from ‒0.1 to +0.4‰ in the lower subformation and from ‒0.4 to +0.8‰ in the upper subformation). Comparison of these variations, as well as variations in the initial 87Sr/86Sr ratios in dolostones of the Kotuikan Formation and the Lower and Upper Yusmastakh subformations (0.70460‒0.70499, 0.70450‒0.70525, and 0.70462‒0.70523, respectively), does not make it possible to distinguish these units on the basis of chemostratigraphic characteristics. [ABSTRACT FROM AUTHOR]

The Albian Mauddud Formation is a prolific reservoir in Kuwait and nearby countries such as Iraq and Iran but has received far less attention than the under‐ and overlying units (the Aptian Shu'aiba and Cenomanian Mishrif Formations). Detailed reservoir characterization studies of the formation are required to support field development and improved / enhanced oil recovery (EOR) programmes. In this study, 26 wells penetrating the Mauddud Formation within the Greater Burgan area of Kuwait (Burgan and neighbouring fields) were investigated, integrating the logging of 910 ft of core with petrographic investigations of 113 stained and impregnated thin sections. In the Greater Burgan area, the Mauddud Formation can be divided into a lower Clastic Member and an upper Carbonate Member which is the main focus of this paper. The primary objective of the study was to present a new characterization of this thin, heterogeneous carbonate reservoir by integrating facies analysis and sequence stratigraphy with a detailed petrographic investigation. A second objective was to identify the relative importance of depositional characteristics and diagenesis on the distribution of reservoir properties. Sandstones in the Clastic Member of the Mauddud Formation were deposited on a delta which passed laterally to the north and east into a carbonate platform. During subsequent regional flooding, increased carbonate production resulted in the development of a larger‐scale carbonate platform covering the entire study area. The Burgan field area was part of the proximal zone of this carbonate platform. A number of depositional environments were identified by integrating core and thin section data. These range from outer platform to mid‐ and inner platform, the latter including both high‐ and low‐energy settings (shoal, shoreline; and lagoonal respectively). Mud‐supported textures characteristic of low‐energy inner‐platform and mid‐ to outer‐platform settings are volumetrically dominant in the Mauddud Carbonate Member. Sequence stratigraphic analysis suggests that the Mauddud Carbonate Member is part of a major regressive phase (or highstand systems tract) of a third‐order sequence, with the regional‐scale K110 MFS positioned close to the transition with the underlying Clastic Member. Two 4th order transgressive – regressive (TR) cycles or sequences, M1 and M2, were identified within the Carbonate Member. The top‐Mauddud surface corresponds to a sequence boundary with long‐lasting subaerial exposure during the latest Albian and is characterized by both micro‐ and macroscopic karst features (calcite dissolution vugs and recrystallization in thin sections; and cavities in cores). This study demonstrates that the Burgan field area experienced significant uplift, with increased differential erosion and/or non‐deposition of the upper M2 TR cycle towards the southwest. Eogenetic marine and meteoric calcite cements partially fill macropores close to the tops of the TR cycles and remaining macropores were occluded by shallow‐burial calcite cements. Cementation by ferroan dolomite cement, which resulted from the increased overburden and associated chemical compaction, has almost entirely occluded residual macropores in the lower part of the Mauddud Carbonate Member, close to the underlying siliciclastic deposits of the Clastic Member. As a consequence, porosity is mostly preserved in the middle part of the Carbonate Member. The predominance of mud‐supported textures in these intervals together with the effects of diagenesis explain the widespread occurrence of microporosity within both micritic matrix and grains. In the Greater Burgan area, meteoric diagenesis associated with subaerial exposure(s) of the top‐Mauddud preserved and/or enhanced micrite microporosity. Plug porosity may reach 35% or more, but permeability does not exceed 100 mD. The Mauddud Carbonate Member in the Greater Burgan area is a thin, microporous reservoir, with a dual porosity component which is linked to karst alteration and not to tectonic fracturing. The distribution of reservoir properties results from a combination of primary depositional characteristics and a multiphase diagenetic overprint. This study will guide the future development of the Mauddud reservoir in the Greater Burgan area. It also demonstrates the importance of an integrated approach to constrain sub‐seismic heterogeneities in carbonate reservoirs. [ABSTRACT FROM AUTHOR]

The nobleman Achille De Zigno (1813–1892) was an Italian geologist and naturalist who studied the geological and paleontological features of the Veneto and Tirol regions. His field notes were accompanied by a great number of extremely detailed drawings. His eight notebooks were written between 1841 and 1890, starting when he was 28 until shortly before his death in 1892. He sketched mountain sections, maps, geological outcrops, and he made ink drawings of fossils together with archeological and landscape views. The most impressive features in De Zigno's notebooks are the illustrations of a great number of 'strati'. These testify to the great effort he made to understand the age and stratigraphic order of the main geological sections in the mountains which he visited. In the spring of 1846, De Zigno crossed the already renowned Dolomites and described in detail in his notebooks the geology of the area, providing a state-of-the-art account of the geological kowledge of the Dolomites during the mid-nineteenth century. Using a geological map prepared by Leopold von Buch, De Zigno travelled from Auer (Ora) to Bozen (Bolzano), walking through all the western Dolomites, including a site in the village of Predazzo. The former locality, described by Giuseppe Marzari Pencati in 1819, was renowned for its rock layer sequence which contradicted neptunism, a dominant stratigraphic theory of the early 19th century. De Zigno, in sketching the 'Stratified rocks' underlying the so-called 'Primitive rocks' that therefore were not placed at the base of the entire stratigraphic sequence, made a significant contribution to the history of geology of the Dolomites of that time. [ABSTRACT FROM AUTHOR]

The structure and properties of the glass can be modified by introducing appropriate additives. Dolomite is one of the primary raw materials modifying the properties of glass, in which the essential component is calcium-magnesium double carbonate CaCO3∙MgCO3. The paper presents the research results on glasses obtained by smelting pure amphibolite and amphibolite modified with 10 and 20% dolomite additives. The raw material used was mined in the Poland region of Lower Silesia. The glass melting process was carried out in an electric furnace at 1450 °C for 2 h. The structure and properties of the glasses and crystallization products were determined by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy—Energy Dispersive Spectroscopy (SEM-EDS). Viscosity and Vickers microhardness were also measured. It was found that the modification of amphibolite glass by adding dolomite affects the glasses' properties and structure. The research results determined the effect of dolomite addition on the properties of alumino-silicate glasses in terms of the mineral fibre products used in the construction industry. [ABSTRACT FROM AUTHOR]

This paper presents a device used to measure and register temperature for long-term subsoil measurements in boreholes. The borehole of this study is located in Gijón (Asturias, Spain). The measurements were made through two fixed sets of sensors coupled to the geothermal pipe, constituting two independent installations: (a) a commercial device called "Hobo", which uses TMCx-HD-specific sensors based on resistors with variable resistance; and (b) a device built by this research group, which uses DS12B20 Maxim sensors, a bus 1-wire, and a recording device based on a conventional Arduino board. Temperature was registered every 5 min across several years. These measurements were used to thermally characterize the subsoil, determining the apparent thermal diffusivity, and to study the thermo-hydrogeology of the Lower Jurassic Gijón's formation made of Liassic limestones and dolomites. This work is part of the Q-Thermie group's research called "Shallow Thermal Energy". [ABSTRACT FROM AUTHOR]

In this paper, the depositional environment, age, and tectonic context of the Sub-Himalayan Kuldana Formation are discussed in detail. To determine the Kuldana Formation's depositional environment, age, and tectonic setting, sedimentological, palaeontological, and petrographic investigations have been conducted accordingly. The Kuldana Formation lithologically consists of both siliciclastic and carbonate rocks. Petrographically, the Kuldana Formation's sandstone is divided into litharenite and feldspathic litharenite petrofacies. The sandstone plots on the QtFL and QmFLt suggest that the sandstone of the Kuldana Formation derived from a recycled orogen provenance field that developed during the collision of the Indian and Eurasian plates in the Lesser and Higher Himalayas. The plots in the diamond diagram further demonstrate that the detritus of the Kuldana Formation was derived from low and middle-to-upper rank metamorphic rocks of the Himalayas. Throughout the deposition of sandstone, paleo-climate conditions were semi-humid to semiarid. Dolostone and limestone are the two main types of carbonate rocks found in the Kuldana Formation. According to Dunham's Classification, the Kuldana Formation limestone is classified as mudstone, wackstone, and packstone. These petrofacies suggest that the limestone was deposited in an inner-outer ramp setting. The bioclasts include bivalves, brachiopods, crinoid, gastropods, Globigerinoides spp., Lockhartia pustulosa, miliolids, Nummulites atacicus, Nummulites discorbina, Nummulites mamillatus, Nummulites djodjokartae, Nummulites vascus, and ostracods suggesting that the age of Kuldana Formation is Middle Eocene-early Oligocene. The Kuldana Formation was deposited during the initial stages of the Himalayan Orogeny as a result of the Ceno-Tethys Ocean's regression and transgression, as revealed by a succession of siliciclastic and non-clastic rocks. [ABSTRACT FROM AUTHOR]

Dolostone is widely distributed and commonly used as concrete aggregates. A large number of studies have shown that there are significant differences in the expansibility of different dolostones, and the key factors determining the expansibility of alkali carbonate rocks have not been clarified. In this paper, rocks were selected from five different geological ages: Jixianian, Cambrian, Ordovician, Devonian, and Triassic ages. The ordering degree and the content of MgCO3 of dolomites in rocks of different geological ages were determined by X-ray diffraction (XRD). The degree of dedolomitization reaction in rocks cured in 80 °C, 1 mol/L NaOH solution was determined by quantitative X-ray diffraction (QXRD). The morphology of dolomites in rocks was determined by a polarizing microscope. The products of the dedolomitization reaction were determined by field emission electron microscopy (FESEM-EDS). According to the test results, the following conclusions are drawn. There is a good positive correlation between ordering degree and the molar fraction of MgCO3 of dolomites. When the MgCO3 mole fraction of dolomites varies from 47.17% to 49.60%, the higher the MgCO3 mole fraction, the greater the ordering degree of dolomite. By analyzing the degree of the dedolomitization reaction of different dolostone powders cured at 80 °C in 1 mol/L NaOH solution, it is found that the older the geological age of dolostone, the slower the dedolomitization reaction rate and the lower the degree of dedolomitization reaction. The lower the ordering degree of dolomite crystal in the same geological age, the faster the rate of dedolomitization reaction and the higher the degree of dedolomitization reaction. [ABSTRACT FROM AUTHOR]

This paper reports the first detailed microscopic and geochemical investigations of multiphase dolomitization in Devonian Shogram Formation, North-Western Karakorum constraining nature and origin of dolomitizing fluids. Field and petrographic studies revealed 4 different types of replacive dolomites, which are (i) fine grained anhedral dolomite (D1), (ii) medium grained subhedral to anhedral dolomite (D2), (iii) medium grained euhedral dolomite (D3), and (iv) coarse grained anhedral dolomite (D4) along with cement phase saddle dolomite (SD). These dolomites had high Fe and Mn concentraions and low Sr content. Stable isotope studies indicated high light isotope δ18O values for D1 and D2, higher lighter isotope δ18O value for D3, and highest lightest isotope δ18O values for D4 and SD, respectively. Petrographical and geochemical data suggested that D1 and D2 are likely formed in compactional flow regime in early stages prior to chemical compaction at shallow burial depths, whereas D3 is formed in late diagenetic deep burial settings. Lastly, D4 and SD are formed from high temperature hydrothermal fluids. These fluids could be related to widespread tectonic activity in the Karakorum region during collision or post-collisional time. Reshun fault acted as an important pathway that channeled Mg-rich hydrothermal fluids from underlying strata into carbonates, which caused intense dolomitization. [ABSTRACT FROM AUTHOR]

The marine shale in the Sinian Doushantuo Formation of Qinglinkou outcrop section is well developed, but the current characterization methods for outcrops are unsatisfactory. In this paper, the data of outcrop in the field study area were collected by Unmanned Aerial Vehicle, then processed and interpreted by oblique photography technology combined with manual investigation. Subsequently, we established a quantitative geological knowledge database of the shale formations and carried out the typical section of anatomy analysis. The results showed that the high-precision image information captured by unmanned aerial vehicle oblique photography technology can be well coupled with a three-dimensional coordinate system. The three-dimensional digital model was used to characterize the lithologic assemblage, thickness and distribution characteristics of the target reservoir. Based on this digital model, we established the three-dimensional lithology and the total organic carbon models of the outcrop area. The spatial distribution characteristics of interbedding between marine dolomite and shale in the outcrop area were displayed, and the distribution of total organic carbon was revealed under lithological constraints. The models are beneficial for the analysis and prediction of the lithology and total organic carbon, which is of great significance to the understanding of shale gas sweet spots. [ABSTRACT FROM AUTHOR]

This paper deals with relationships between vegetation of Macedonian pine (Pinus peuce) and soils developed on different parent materials on the territory of North Macedonia. We analysed the floristic composition at localities on limestone, on scree of dolomite marble and on scree of silicate. On limestone and scree of dolomite marble, rendzinas on hard limestone and dolomite have developed, and on silicate parent material brown forest soils. The vegetation was sampled according to the Braun-Blanquet approach. DCA and indicator values were used for ecological interpretation of the vegetation patterns. The mechanical and chemical properties of soil and textural classes were also processed. An evident increased presence of carbonates in the soil of scree of dolomite marble on Nidže Mountain was observed, unlike that on Shar Mountain which has formed on typical limestone. Although it is a forest community dominated by the same species, differences between the massifs, the precipitation regime, geology, differences in soil properties in relation to the appearance of carbonates and pH values, and other factors, result in differences in their floristic composition and are the reason for the distinction between the two groups. On silicate on Nidže Mountain, Macedonian pine forests have also developed on brown forest soils, with a different floristic composition to that of the other group on carbonate (dolomite and limestone). [ABSTRACT FROM AUTHOR]

Lower Cambrian Xiaoerblak Formation is one of the major exploration targets in Cambrian pre-salt Tarim Basin; however, the exploration breakthrough is restricted by insufficient understanding of its sedimentary evolution and reservoir genesis. In this paper, based on a systematic description of the outcrop in the Xiaoerblak section, northwestern Tarim Basin, some samples were selected for tests of stable carbon and oxygen isotopic compositions, strontium isotopic composition, order degree, trace and rare earth elements, U-Pb isotopic age and clumped isotope. It is found that the Xiaoerblak Formation mainly develops nine types of dolomites, i.e., laminated microbial dolomite, thrombolite dolomite, stromatolite dolomite, foamy microbial dolomite, grain dolomite, etc. According to the lithofacies associations, it can be divided into three members: Xi 1, Xi 2, and Xi 3, of which member Xi 2 is subdivided into three submembers. The characteristics of lithofacies assemblage formed bottom to top indicate that it can be described as a third-order sequence. The Xiaoerblak Formation was deposited in a nearshore shallow seawater environment characterized by high water salinity and temperature under a warm and humid climate during the Early Cambrian, giving rise to the sedimentary sequence of inner ramp lagoon, subtidal microbial mound shoal and tidal flat in the carbonate ramp setting from bottom to top. Its dolomitization occurred in the penecontemporaneous–shallow burial period when the temperature was relatively low and high-salinity seawater acted as the main dolomitizaiton fluid. The reservoir space mainly comprises primary microbial framework pores and vugs formed by the atmospheric freshwater dissolution. Reservoirs were controlled by lithofacies, high-frequency sequence boundary and early dolomitization. The research results are of great significance for presalt Cambrian lithofacies paleogeographic mapping and reservoir prediction. [ABSTRACT FROM AUTHOR]

In this paper, the dolomitic limestone determined as alkali–carbonate-reactive by various methods is used as an aggregate. Inhibition experiments were carried out on the basis of the concrete microbar method (RILEM AAR-5 standard), in which 10%, 30%, and 50% fly ash and metakaolin were used to replace cement. Thermogravimetric–differential scanning calorimetry (TG-DSC), X-ray diffractometry (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM-EDS) were used to analyze the inhibition mechanism of fly ash and metakaolin on ACR. The results show that the expansion of samples at the age of 28 days are less than 0.10% when the fly ash contents exceed 30% and the metakaolin contents exceed 10%, which proves that the ACR is inhibited effectively. Meanwhile, the Ca(OH)2 content of the samples was reduced and the pore structure of the samples was optimized after adding fly ash and metakaolin. The dolomite crystals in the samples containing 50% fly ash and metakaolin are relatively complete. [ABSTRACT FROM AUTHOR]

In this paper magnesium oxychloride cement (MOC) is prepared from dolomite by calcinations process. The effect of different ratios of additive prepared from magnesite MOC (0.5, 1 and 1.5%) on the mechanical properties of dolomite MOC is recorded at 7, 14 and 28 days. Infrared spectroscopy (IR-spectra) is used to characterize the effect of magnesite MOC additive on the mineralogy of dolomite MOC mixes air cured at 28 days. The results indicated that one-part MOC additive posted the mechanical compressive strength of dolomite MOC mix at addition rate of 0.5 and 1% and was declined at 1.5%. The water resistance of MOC increased with increase of additive in mix. The micro structural investigation revealed that the mechanical performance of MOC was predominantly dependent on abundance and crystals size of phase 5. [ABSTRACT FROM AUTHOR]

For a low grade dolomite type fluorite ore in the Hebei province, it was observed that the depressant CK102, a mixture of sulfuric acid, sodium silicate and aluminum sulfate, can effectively inhibit the gangue mineral dolomite in the flotation of fluorite. However, the inhibition mechanism of the depressant is still unclear. In this paper, the flotation separation performance and underlying mechanism of CK102 inhibiting dolomite were investigated through mineral flotation tests, adsorption measurements, infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The flotation results showed that the inhibition effect of CK102 on dolomite flotation was much more remarkable than that of fluorite flotation under optimum conditions. Adsorption measurements revealed that there was competitive adsorption between the depressant and collector and that the adsorption of the depressant CK102 prevented the collector modified sodium oleate from adsorbing onto the surface of minerals. The FT-IR and XPS results showed that the co-oxygen cross-linked component of the depressant CK102 chemisorbed on the surface of dolomite; the CaSiO3 precipitation was generated from the reaction of CK102 with Ca2+ groups on the surface of the dolomite; Al2MgO8Si2 precipitation was also generated from Mg2+ reacting with the sodium silicate and aluminum sulfate of CK102. The above adsorptions and reactions enhanced the hydrophilicity of the dolomite surface and the dolomite was effectively depressed. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to analyze a modern and unique technological system producing common aggregates at the Imielin Dolomite Mine. The installation was built on the basis of inventions of AGH UST and consists of an impact crusher, innovative screens WSR and WSL, light fraction separator SEL and hard fraction separator SET, low-pressure hydrocyclone NHC and infrastructure. The study was carried out on the crusher and screen on the example of production of aggregates with grain size 8–16 mm from dolomite, granite, limestone, sandstone, and gravel. The results showed that cubic aggregates with a low content of irregular grains of less than 1% can be produced in this technological system. [ABSTRACT FROM AUTHOR]

The main aim of this study was focused on the Method of testing alkali-carbonate reaction activity to avoid alkali-carbonate reaction damage. In this paper, the alkali-carbonate reaction activity and alkali-silica reaction activity of ten kinds of aggregates were determined and analysed by existing standards and methods, by making specimens with aggregates of 2.5–5 mm and 5–10 mm particle size, cured in 1 mol/L tetramethyl ammonium hydroxide solution at 60 °C and 80 °C. Tetramethyl ammonium hydroxide solution was used to exclude the expansion caused by alkali-silica reaction. Effects of aggregate particle size and curing temperature on the expansion of samples were systematically investigated to determine alkali-carbonate reactivity of aggregates. In order to explore the relationship between stress and strain of aggregates, these aggregates were prepared into compacted bodies to test their stress and try to discover the pattern. The results showed that the expansion of the mould specimen prepared by the aggregate of 5–10 mm particle size, cured in 1 mol/L tetramethyl ammonium hydroxide solution at 80 °C was greater than 0.1% after 42 days, which could be used as a reference criterion to determine the alkali-carbonate reaction activity of the aggregate. In addition, the expansion stress test suggest that the alkali-carbonate reaction can generate expansion stress. The expansion stress of aggregates with alkali-carbonate reaction activity were much larger than that of aggregates without alkali-carbonate reaction activity. Through SEM and EDX analysis of the products of the alkali-carbonate reaction, it was shown that the dolomite crystals in the dolomitic aggregates reacted with the TMAH solution and resulted in alkali-carbonate reaction, forming calcite and brucite. [ABSTRACT FROM AUTHOR]

Karst water quality degradation has been a challenge for domestic and industrial water supplies worldwide. To reveal the possible factors response for karst water quality degradation, Baotu karst spring system is studied as an representative example. In this study, a hydrogeochemical investigation and mathematical, statistical, and geochemical modeling was conducted together to identify the major hydrochemical processes involved in the degradation process. It is found that the karst water is normally fresh, neutral-to-slightly alkaline, with calcium and magnesium as the predominant cations, and bicarbonate and sulfate as the predominant anions. The abnormally high chloride (95.05 mg/L) and nitrate concentrations (148.4 mg/L) give clues to the potential source of contamination in some karst water. The main hydrochemical facies of karst water are HCO3-Ca and HCO3 × SO4-Ca, accounting for 76% of water samples. The water hydrochemistry is controlled mainly by the dissolution of carbonate minerals (calcite, dolomite), followed by the dissolution of silicate and gypsum. The dissolution of calcite and dolomite mostly happens in the recharge area. In the discharge area, the karst water is basically in equilibrium with calcite. The negative SI value of gypsum represents that the water–gypsum interaction is dominated by dissolution along the whole flow path. Cation exchange is observed in the karst water in the indirect recharge area. Along the flow path, the contents of chloride, sulfate, nitrate, and TDS (Total dissolved solids, abbreviated TDS, indicates how many milligrams of dissolved solids are dissolved in one liter of water) vary significantly, which is mostly affected by pollution from human industrial and agricultural activities. The concentrations of major ions were maintained at a low level (<20 mg/L) in the 1960s in karst water. The fast elevation of the parameter values has occurred in the past two decades. The temporal elevation of some pollutants in karst water suggest that global changes (acid rain) and human activity (such as overusing fertilizer) are main factors resulting in the degradation of karst water quality in the study area. The results of this paper provide invaluable information for the management and protection of karst water resources in the urban and rural areas. [ABSTRACT FROM AUTHOR]

In the Transdanubian Range (Hungary), a wide spectrum of Triassic dolomites is known. Mechanism of dolomitization of the platform carbonate successions was subject of a number of studies but the study of dolomitization of basinal carbonates is very limited. Petrographical and isotope–geochemical characteristics of the Upper Triassic dolomitized carbonate deposits, formed in a fault-controlled intraplatform basin, and interpretation of the dolomite-forming processes are presented in the current paper. From the latest Carnian to Middle Norian under semi-arid climatic conditions density-driven flux of seawater derived mesohaline fluids was the dominant mechanism of the near-surface pervasive dolomitization of the thick platform carbonate succession. In the late Middle Norian incipient rifting of the Alpine Tethys led to establishment of an extensional structural regime and onset of the formation of the Kössen Basin. In the study area, above the dolomitized platform carbonate succession, platform-derived carbonate sediments were accumulated in a fault-bounded, semi-restricted sub-basin of the Kössen Basin, whereas talus breccias and debrites were deposited near a basin-bounding master fault. The basin deposits (lower and upper members of the Rezi Dolomite Formation) were subject of early diagenetic dolomitization in shallow burial setting. Enhanced salinity seawater was the dolomitizing fluid; the synsedimentary fracturing may have promoted the fluid flow and thereby the dolomitization. Thick-bedded carbonates (middle member of the Rezi Dolomite Formation) representing a progradational tongue of the ambient platform are intercalated between the basin deposits. The dolomitization of this unit can be explained by the reflux model. [ABSTRACT FROM AUTHOR]

To characterize the polyphase palaeokarst development of Wumishan formation in Jizhong depression, the data of outcrops, cores, thin sections, SEM, core plugs, drilling relief and leakage, and carbon isotope have been analyzed in this paper. The results reveal that the polyphase palaeokarst was petrography controlled of microbial dolostone and grain dolostone, and was identified as three phases: (1) poly-period eogenetic karst during Wumishan depositional environment, (2) two-period telogenetic karst in Triassic and Cretaceous, and (3) hydrothermal karst in Paleogene. The eogenetic karst was related to high frequent sea level fluctuations with development of vugs and selective dissolution porosities which distributed at the top of microbial dolostone and grain dolostone layers. The origin of the telogenetic karst was related to Indosinian and Yanshan orogeny which formed widespread fold belts and thrust faults, and provided the endokinetic force and a strong topography difference. Each period's telogenetic karst was characteristic of one-period fracture-cave system, and the Cretaceous telogenetic karst was stronger than the Triassic telogenetic karst in karst intensity. Moreover, the karst intensity increased downward in superimposed telogenetic karst zones. Hydrothermal karst was related to volcanic activities and provided the hydrothermal environment for its formation. It was featured by solution-enlarged porosities and new forming porosities. The microbial dolostone and grain dolostone layers with three-phase palaeokarst were the best exploration targets for high-quality reservoirs. This paper rebuilds a suitable karst model to show the palaeokarst evolution process. [ABSTRACT FROM AUTHOR]

Dolomites are well-known minerals; belonging to the Infra-Cambrian Hormuz Series lies within the salt domes of southern Iran. In this paper, the origin and alteration of dolomitic rocks of Paskhand and Deh-kuyeh salt diapirs in the area of Larestan (southern Iran) are investigated. Based on petrographic (size and fabric) studies, we recognize four dolomite types that consist of very fine-to-fine crystalline dolomite (D1), neomorphic dolomite (D2), fine-to-medium crystalline euhedral-to-subhedral dolomite (D3), and pore- and fracture-filling dolomite (D4). The dolomite samples with up to 26% iron can be called ferruginous dolomites. Some igneous rock patches to gehter with hydrothermal iron veins are observable in the salt domes of Larestan. Oxygen and carbon isotope values of black and white, and altered red dolomite of Paskhand and Deh-kuyeh salt domes, are equal to − 12.35 to − 18.78 for δ18OPDB and − 5.48 to − 8.49 for δ13CPDB; values enriched δ180 with low-temperature (~ 70 °C) conditions are related to D1 dolomites and values depleted δ180 with higher temperatures (~ 270 °C) are related to D3 and D4 dolomites. The most important source for secondary dolomites is deeper hydrothermal and catchment sources, which ascended through faults during the intrusion. Meteoric waters can be mentioned as less important sources for these types of dolomites. We reported sassolite B(OH)3 mineral in Deh-kuyeh salt diapir for the first time in this paper. This mineral is only observed in the areas which have famous riftings Fumarol. Therefore, in this paper, the existence of sassolite in the studied area could be considered one of the most important the origin of the composing elements of Hormuz rocks from fumarols which are formed in an extensional regime. [ABSTRACT FROM AUTHOR]

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Geopolymer is widely studied nowadays in various scope of studies. Some of the ongoing studies are the study of the various materials towards the geopolymer strength produced. meanwhile, some of the studies focus on the mixing of the geopolymer itself. this paper discussed the phase analysis of metakaolin/dolomite geopolymer for different solid to the liquid ratio which was, 0.4, 0.6, 0.8, and 1.0, and the properties that affected the geopolymer based on the phases. the constant parameters in this study were the percentage of metakaolin and dolomite used. the metakaolin used was 80% meanwhile dolomite usage was 20%. besides that, the molarity of naoh used is 10m and the alkaline activator ratio used is 2.0. All the samples were tested at 28 days of curing. the results show that the 0.8 solid to the liquid ratio used gave better properties compare to other solid to liquid ratio. the phases analyzed were quartz, sillimanite, mullite, and faujasite. the 0.8 S/l ratio shows the better properties compared to others by the test of phase analysis, compressive strength morphology analysis, and functional group analysis. [ABSTRACT FROM AUTHOR]

The Upper Permian Changhsing Formation is one of the most important gas-bearing formations in the Eastern Sichuan Basin. Nonetheless, the primary factors controlling the reef-shoal gas reservoirs of different regions are diverse. Clarifying the controlling factors for the formation of intra-platform reef-shoal reservoirs will promote the exploration and development process of the Changhsing Formation. By using outcrop data, core observation, thin section identification, scanning electron microscope analysis, physical property study, and logging interpretation, this paper analyse the characteristics and factors controlling the reef-shoal reservoir in Dianjiang area of the Eastern Sichuan Basin. The results show that the reef cap and reef base microfacies fine-to-medium crystalline dolomite reservoir have the best physical properties, and the reservoir spaces are primarily composed of intercrystalline pores, intercrystalline solution pores, karst caves, and fractures. The main lithology of reservoir formation is reef-shoal facies. The results for the carbon and oxygen isotopes show that dolomites of different particle sizes are formed in three environments. Affected by regression in the late Changhsingian Age, the reef-shoal of the Changhsing Formation were subaerially exposed to meteoric water diagenesis environments, resulting in the highly dispersed particles in rocks that formed a honeycomb karst system, which greatly improved the physical properties of the reservoirs. After reflux dolomitization, the honeycomb karst system was well preserved due to strong resistance to pressure and dissolution of dolomite. Therefore, dolomitization in the Changhsing formation contributed to reservoir porosity. Later, tectonic fracturing has adjusted and modified the reef-shoal reservoir. In summary, penecontemporaneous karstification was the key to the formation of the reef-shoal reservoir. [ABSTRACT FROM AUTHOR]

In this paper, we describe porosity variations in Miocene to Holocene carbonates off the west coast of Australia and assess their compaction trends. The porosity values were measured using discrete samples of Sites U1459–U1464 obtained by the International Ocean Discovery Program Expedition 356. The carbonate deposits have been influenced by a range of textures and diagenetic conditions throughout a nearly continuous sequence of geological ages from the Miocene to Holocene and at core depths from 0 to 1100 m below the seafloor. The collected samples were mostly grainstone, packstone, wackestone and mudstone textures. Dolostones and dolomitic carbonates were described at the Miocene intervals. Compaction trends were estimated exponentially and linearly based on cored sites, carbonate textures and dominant mineralogies (dolomite, calcite/aragonite). At all six sites, porosity distribution and reduction were generally depth-dependent. The porosity converged to about 30% between 750 and 1100 m, which suggests that the carbonates were close to the densest packing by mechanical compaction at a burial depth of ∼750 m. The porosity deviations are associated with textures and dominant mineralogies. Increasing mud content from grainstone to mudstone is a controlling factor for initial porosity and porosity reduction rate. Dolomitisation, dolomitic cementation, aragonite needle-rich mud and non-skeletal grains cause deviations from the depth-dependent compaction trends. Reflux-related cementation generally decreases porosity in Miocene dolomitic intervals. Higher porosity values of the Quaternary wackestone and mudstone at Site U1461 resulted from the presence of aragonite needle-rich mud hosting abundant micropores and from a high sedimentation rate. The occurrence of non-skeletal grains, such as ooids and peloids, as well as occasional meteoric exposure led to porosity inversion, occluding interparticle permeability and the creation of moldic pores. Porosity variations of Miocene–Holocene carbonates off the west Australian coast are primarily depth-dependent. Mechanical compaction affected porosity reduction down to a value of ∼30% at a burial depth of ∼750 m. Differences in texture-based compaction trends were affected by increasing mud content. Major porosity deviations are associated with dolomitisation, dolomitic cementation, aragonite needle-rich mud and non-skeletal grains. [ABSTRACT FROM AUTHOR]

The dolomite explosion in the terminal Ediacaran period has great geological significance for understanding the paleoenvironmental evolution of the Precambrian-Cambrian transition. However, dolomite origins remain controversial. Abundant dolomites in the Ediacaran Dengying Formation in the northern Yangtze Block provide a window for solving the problem. In this paper, the genesis of dolomites and the paleoenvironment of the terminal Ediacaran were studied by facies, trace elements (including rare earth elements, REEs), and carbon, oxygen, and strontium isotopes of the Dengying Formation in the Xichuan area of South Qinling, Northern Yangtze Block. The results indicate that the Dengying Formation was deposited on a carbonate platform, and four types of dolomite (i.e., micro-crystalline dolomite, fine-medium crystalline dolomite, brecciated dolomite, and saddle dolomite) are identified. According to the differences in the ∑REEs, δ13C, Z value and 87Sr/86Sr values in different types of dolomite, it is concluded that micro-crystalline dolomite mainly formed in the early diagenetic stage, fine-medium crystalline dolomite in the middle diagenetic stage, and saddle dolomite in the late diagenetic stage, while brecciated dolomite formed in the epigenetic stage. Moreover, it is determined that the dolomitization models for the Dengying Formation include the seepage-reflux, mixed water, burial, and hydrothermal dolomitization models. In addition, micro-crystalline dolomite has a Sr/Ba value far greater than 1, the Z value is usually greater than 125, δEu is positive, V/(V + Ni) is less than 0.74, and δ13C is positive, indicating that the Dengying Formation dolomite was deposited in a shallow water environment with high salinity, weak oxidation, and dry and warm climate. By comparing the characteristics of dolomite in other parts of the world in the same period, it indicates that the global climate warmed up, the ocean appeared oxygenation process, and extensive retrogression events occurred in the Precambrian-Cambrian boundary. [ABSTRACT FROM AUTHOR]

Medical X-ray computed tomography (CT) can be used to rapidly and non-destructively characterize structure and density variations of geological specimens. More information about the nature of samples (electron density and elemental composition) can be retrieved using multi-spectral approaches. This paper explores one of them, a stoichiometric calibration method for dual-energy imaging, to identify the most common minerals. A set of 18 calibrating materials was selected to cover a range of variability in effective atomic number (Zeff) and electron density (pe) encountered in geological specimens. The validation of this calibration was performed analyzing 23 common minerals by mapping their respective Zeff and pe in order to identify the one with the closest properties. This study shows that the stoichiometric method correctly identifies the most important and common minerals (quartz, calcite, dolomite) that are usually not distinguishable using a single energy imaging method, although all the 23 studied minerals were not correctly determined. We show that this method previously elaborated for medical purposes is also efficient in earth science. [ABSTRACT FROM AUTHOR]

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This paper addresses the issue of environmental noise from mining operations, focusing on the specific case of a quarry located in the municipality of Trebejov, Slovakia. The study aims to demonstrate an effective approach to reducing noise pollution through the implementation of mobile noise barriers. The research was motivated by the negative impact of noise from the processing line on the wellbeing of the population residing in the vicinity of the facility. The study involved conducting extensive noise measurements at various locations surrounding the quarry. The collected data were analyzed to assess the existing noise levels and identify the areas of highest noise exposure. Based on the findings, the implementation of mobile noise barriers was proposed as a solution. The results of the study demonstrated that the mobile noise barriers successfully reduced the noise levels below the legal limits, significantly improving the well-being of the population living near the quarry. The case study opens up the possibility of using mobile noise barriers in other areas and operations with high noise exposure. [ABSTRACT FROM AUTHOR]

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Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recently, special attention has been drawn to the high-salt argillaceous dolomite reservoir in Jianghan basin, China due to its abundant oil resources with complex geological conditions. However, the current production methods used to develop this reservoir are not efficient with low throughput. Hence, the purpose of this paper is to explore the main possible reasons affecting the oil well productivity and determine suitable field development method for the target oilfield through experimental and numerical simulation approaches. The mercury injection capillary pressure (MICP) test results indicate that the average pore radius of samples is 0.0144 μm, and pore size distribution (PSD) results from MICP indicate that single peaks appeared in the PSD curves of the pore type samples. Permeability peaks of the samples range from 0.01 to 0.03 μm, and mesopores make most of the permeability contribution of the samples, which also reveals the low-permeability and porosity characteristics of the target oilfield. The results of core stress sensitivity tests show that the largest permeability damage rate is 98.97% with an average permeability damage rate of 98.37% while the maximum porosity damage rate is less than 10% with an average damage rate of 5.57% during the process of depressurization. The results of Non-Darcy percolation experiment indicate that threshold pressure gradient testing by water is about 0.03 MPa/m, which is close to the actual situation of the target oilfield. Numerical simulation method that considers the impact of threshold pressure gradient and stress sensitivity were established to study flooding patterns deployment for the research area. The simulation results show that performing water alternating gas flooding (WAG) by using CO2 is recommended for the development of the high-salt reservoir with inverse five-spot flooding pattern made up of 400 m well spacing in X-direction and 150 m row spacing. [ABSTRACT FROM AUTHOR]