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1
Vivoda Prodan, Martina, and Željko Arbanas. "Weathering Influence on Properties of Siltstones from Istria, Croatia." Advances in Materials Science and Engineering 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/3073202.
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Slaking and weathering of weak rocks result in slope instability. Siltstones from flysch rock masses are highly susceptible to weathering, which causes rapid changes in the geotechnical properties and durability. This study investigated siltstone samples of different weathering grades from flysch rock masses from the Istria Peninsula, Croatia, and determined the effects of weathering on their engineering properties. Laboratory testing of siltstone samples of different weathering grades was conducted to determine the specific gravity, grain size distribution, Atterberg limits, and uniaxial compressive strength. The standardized slake durability index is not sufficient to classify the durability of weak rock masses such as siltstones. Therefore, the durability of siltstone samples of different weathering grades was quantified from the fragment size distribution after each of five slaking cycles. The tested samples were classified based on the disintegration ratio, and the modified disintegration ratio was used to determine potential long-term degradation of the tested samples. The results indicated that weathering has a significant influence on the plasticity, uniaxial compressive strength, and durability characteristics and thus affects the landslides and erosion processes in siltstones in the flysch zone of the Istria Peninsula.
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Hartono, Edi, Sri Prabandiyani Retno Wardani, and Agus Setyo Muntohar. "The effect of cement stabilization on the strength of the Bawen’s siltstone." MATEC Web of Conferences 195 (2018): 03012. http://dx.doi.org/10.1051/matecconf/201819503012.
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Siltstones are predominantly found along the Bawen toll-road. Siltstone is degradable soil due to weather session. The soil is susceptible to the drying and wetting and the changes in moisture content. Thus, Siltstone is problematic soils in its bearing capacity when served as a subgrade or subbase. The main objective of this study was to investigate the effect of cement stabilization on the strength of Siltstone. The primary laboratory test to evaluate the strength was Unconfined Compression Strength (UCS) and California Bearing Ratio (CBR). The cement content was varied from 2 to 12 per cent by weight of the dry soil. The soils were collected from the Ungaran - Bawen toll road. The specimens were tested after seven days of moist-curing in controlled temperature room of 25°C. The CBR test was performed after soaking under water for four days to observe the swelling. The results show that the mudstones were less swelling after soaking. Cement-stabilized siltstone increased the CBR value and the UCS significantly. The addition of optimum cement content for siltstone stabilization was about 7 to 10 per cent.
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Cheng, Ming, Yuhong Lei, Xiaorong Luo, Likuan Zhang, Xiangzeng Wang, Lixia Zhang, Chengfu Jiang, and Jintao Yin. "Pore Type, Pore Structure, and Controlling Factors in the Late Triassic Lacustrine Yanchang Shale, Ordos Basin, China." Energies 14, no. 11 (May 25, 2021): 3053. http://dx.doi.org/10.3390/en14113053.
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Organic-rich lacustrine shales in the Upper Triassic Yanchang Formation with thermal maturity mainly in the oil window are the main shale oil and shale gas system in the lacustrine strata of the Ordos Basin, China. Pore systems are important for the storage and transfer of shale oil and gas. The main objectives of this study are to identify the pore types and pore structures and investigate the controlling factors for pore types, pore structures, and total porosities of the lacustrine Yanchang Shale. In this study, organic-rich mudstones, mudstones with siltstone interlayers, siltstone, and sandstones were selected from 15 wells in the southern Ordos Basin. X-ray diffraction, pyrolysis, scanning electron microscopy (SEM), low-pressure nitrogen adsorption analysis, and helium porosimetry were conducted to investigate the mineral compositions, pore types, pore structures, porosities, and controlling factors. Siltstone and sandstone interlayers heterogeneously developed in the Yanchang Shale. The petrology, mineral composition, geochemistry, pore type, pore structure, and porosity of siltstone interlayers are different from those of mudstones. The siltstone and sandstone interlayers usually have more quartz and feldspars, greater detrital grain sizes, and relatively better grain sorting but are lower in clay minerals, total organic carbon (TOC), amount of free liquid hydrocarbons values (S1), and total residual hydrocarbons values (S2), compared to mudstones. Interparticle (interP), intraparticle (intraP) pores, and organic pores (OPs) were developed in both siltstones and mudstones. OPs were observed in samples with lower thermal maturity (e.g., 0.5–0.85%). The inorganic pore size is greater than that of OPs. Additionally, the inorganic pore diameters in siltstone interlayers are also greater than those in mudstones. Organic-rich mudstones generally have higher pore volumes (PVs) of pores with sizes less than 10 nm, pore volumes of pores with sizes between 10 and 50 nm (PV, 10–50 nm), and specific surface area (SSA), but they have lower PVs of pores with sizes greater than 50 nm, total PV, and porosity when compared to siltstone and sandstone interlayers. The dominant pore type in mudstones is OPs and TOC (first order), sources and OM types (second order), and thermal maturity (third order), while the abundances of rigid grains with greater sizes and grain sorting are the main controlling factors of pore structures, SSA and PV. Both inorganic pores and organic pores are abundant in the siltstone interlayers. The pore size distribution (PSD), PV, and porosity of siltstone interlayers are related to the abundance of rigid grains (first order), grain sorting (second order), grain size (third order), and carbonate cement content. The total PV and porosity of Yanchang Shale reservoirs may have increased with the increased abundance of siltstone and sandstone interlayers.
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Hurst, J. M., and R. K. Pickerill. "The relationship between sedimentary facies and faunal associations in the Llandovery siliciclastic Ross Brook Formation, Arisaig, Nova Scotia." Canadian Journal of Earth Sciences 23, no. 5 (May 1, 1986): 705–26. http://dx.doi.org/10.1139/e86-070.
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The Llandovery siliciclastic Ross Brook Formation of Arisaig, Nova Scotia, comprises three broadly defined sedimentary facies. These are a mottled silty mudstone facies (facies A), a laminated shale facies (facies B), and a laminated siltstone facies (facies C). Facies A consists of variably bioturbated silty mudstones, muddy siltstones, and fissile shales. It developed in relatively shallow water conditions; mudstones were presumably deposited from suspension, and siltstone laminae and thin layers were formed by increased wave and current activity. Mottling resulted from bioturbation by epifaunal and, particularly, infaunal benthic organisms. Within facies A, two subfacies are recognized: A(i) is mudstone dominated, and A(ii) is fine-grained siltstone dominated. Facies B consists of alternating laminae of undisturbed mudstone and fine-grained siltstone probably produced as a result of deposition from suspension during a temporary upward expansion of the oxygen-minimum layer. Facies C consists of 0.5–30 cm thick fine- to coarse-grained siltstones, which occur in lenses or layers of single, composite, or amalgamated units. Internally they are extremely variable, but all are interpreted as a result of deposition from storm-generated currents.The Ross Brook Formation formed on a shallow-marine, storm-influenced, subtidal inner–mid muddy shelf and is dominated by extensive but stratigraphically variable developments of facies A and facies C. Absolute water depth per se is difficult to assess, and although fluctuations occurred, much of the sequence is believed to have accumulated at or in the immediate vicinity of fair-weather wave base in water depths estimated to have been between 30 and 60 m. Silt supply was generally low, possibly reflecting great distance from source or the presence of a mud-dominated shoreline.Five brachiopod-dominated associations, which are stratigraphically the Eocoelia hemisphaerica, the Eocoelia intermedia – Eocoelia curtisi, the Visbyella nana, the "Camarotoechia" rossonia, and the Eocoelia sulcata associations, occur through the sequence. Associations change where die sum of the facies characteristics change, suggesting that the major physical controlling factor was substrate type and related environmental parameters. The development of discrete but intergrading associations is viewed as a consequence of the long-term persistence of a set of conservative animal–sediment relationships, superimposed on which is the evolutionary pattern of immigration and extinction of individual species.
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Hardisty, Laynie, Matthew J. Pranter, Deepak Devegowda, Kurt J. Marfurt, Carl Sondergeld, Chandra Rai, Ishank Gupta, et al. "Stratigraphic variability of Mississippian Meramec chemofacies and petrophysical properties using machine learning and geostatistical modeling, STACK trend, Anadarko Basin, Oklahoma." Interpretation 9, no. 3 (August 1, 2021): T987—T1007. http://dx.doi.org/10.1190/int-2020-0169.1.
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Mississippian Meramec deposits and reservoirs in the Sooner Trend in the Anadarko (Basin) in Canadian and Kingfisher counties (STACK) play of Oklahoma are comprised of silty limestones, calcareous sandstones, argillaceous-calcareous siltstones, argillaceous siltstones, and mudstones. We used core-derived X-ray fluorescence (XRF) data and established environmental proxies to evaluate the occurrence of specific elements (Al, K, Ti, Zr, Sr, Ca, and Si) and to illustrate their stratigraphic variability. For the Mississippian Meramec, six indicator elements or element ratios serve as proxies for clay (Al and K), detrital sediment (Ti and Zr), carbonate deposits (Sr and Ca), calcite cement (Sr/Ca), and quartz (Si/Ti and Si/Al). We used an unsupervised K-means classification to cluster elemental data from which we interpret three chemofacies: (1) calcareous sandstone, (2) argillaceous-calcareous siltstone, and (3) detrital mudstone. We used random forest to relate core-derived chemofacies to well logs and classify chemofacies in noncored wells with an accuracy of up to 83% based on blind tests. We integrated core-derived XRF, conventional well logs, and chemofacies logs to produce a cross-sectional chemofacies model that trends from the northwest to the southeast across the STACK trend. Chemofacies distribution indicates an upward increase of detrital mudstone from parasequences 1 to 3. Parasequence 3 is capped by a maximum flooding surface. From parasequences 4 to 5, an increase in argillaceous-calcareous siltstone and calcareous sandstone reflects the progradational stacking. Porosity is low in calcareous sandstones primarily due to calcite cement. Water saturation is high in argillaceous-calcareous siltstone, moderate in calcareous sandstone, and low in detrital mudstone. Interpreted biogenic quartz from element profiles corresponds to the calcareous sandstone chemofacies, which can be estimated from well logs and mapped. Effective porosity and water saturation models reflect the stratigraphic variability of chemofacies and rock types and can be predicted within the defined chemostratigraphic framework.
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Tedesco, Julia, Joice Cagliari, and Carolina Danielski Aquino. "Late Paleozoic Ice-Age rhythmites in the southernmost Paraná Basin: A sedimentological and paleoenvironmental analysis." Journal of Sedimentary Research 90, no. 8 (August 19, 2020): 969–79. http://dx.doi.org/10.2110/jsr.2020.54.
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ABSTRACT Fine-grained rhythmites are a recurrent sedimentary facies in glacially influenced marine and lacustrine sequences throughout geological time. Paleoenvironmental interpretation of these ancient deposits has been a challenge, because similar rhythmites may have formed in different depositional contexts. In the Paraná Basin, the Itararé Group contains numerous successions of fine-grained rhythmites, deposited in the Carboniferous during the Late Paleozoic Ice Age (LPIA). The described rhythmites are characterized by the intercalation of fine-grained sandstones and siltstones with clay and clayey siltstones. We have identified two distinct types of rhythmites based on the contact between couplets, couplets thickness, sedimentary structures, and geochemical proxies. Type 1 rhythmites are characterized by intercalation of very fine-grained sandstone–siltstone (60–90%) with claystone (40–10%) and normal grading. Type 2 rhythmites are characterized by couplets of siltstone (50%) and claystone (50%), with a sharp contact within couplets. Type 1 rhythmites are interpreted as turbidity-current deposits, and Type 2 as distal deposits of hypopycnal flow. Geochemical proxies suggest deposition of the rhythmites under marine conditions, in a period of rising temperature and humidity, and with intensified chemical weathering. These paleoenvironmental characteristics are in agreement with the interglacial period. The preservation of thick rhythmite successions of the Itararé Group in the southern part of the basin was controlled by the constant creation of accommodation space inside paleovalleys.
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Tokarev, Yury, Grigory Yakovlev, Zarina Saidova, Valery Grakhov, Alexander Buryanov, and Ali Elsaed Mohamed Mohamed Elrefai. "A STUDY ON MECHANICAL PROPERTIES AND STRUCTURE OF ANHYDRITE BINDER MODIFIED BY ULTRA-DISPERSED SILTSTONE." Engineering Structures and Technologies 11, no. 3 (February 3, 2020): 78–86. http://dx.doi.org/10.3846/est.2019.11950.
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This research is devoted to modification of physical and mechanical properties and structure of a binder based on natural anhydrite. A sedimentary rock siltstone was added into the composition as a mineral ultrafine additive. The presence of aluminosilicate minerals proves that finely ground siltstone can be used as a mineral additive in the composition of the anhydrite binder, accelerating crystallization of gypsum new formations and densifying the structure of gypsum stone. For the first time, the effectiveness of using sodium and ammonium phosphates as hardening activators of an anhydrite binder was shown. Siltstone, added to the composition in the amount from 0 to 5%, lead to up to 40% increase in strength, which is due to the action of siltstone particles as “crystallization centers” and formation of crystalline hydrates of calcium sulfate dihydrate on their surface. Combined action of calcined siltstone and lime leads to a 45% increase in strength due to the additional compaction by new hydration products formed in the course of metakaolin and lime interaction. Microstructural analysis showed that samples with calcined siltstone and lime have a more dense and uniform structure with a lower porosity, compared to those with only natural siltstone.
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Hosseini, S. H., S. Feiznia, and H. R. Peyrovan. "Assessment of marl properties effect on sediment and runoff rate at different rainfall intensity under field rainfall simulator." Glasnik Srpskog geografskog drustva 89, no. 4 (2009): 85–94. http://dx.doi.org/10.2298/gsgd0904085h.
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The objective of this study is to assess the effect of physical and chemical properties of Marl's formations on sediment and runoff rates at different rainfall intensities, based on using field rainfall simulator. For this purpose, first Marl's formations (Neocene's units) were separated to five units including Halite siltstone(NgSiH), Siltstone (NgSi), Mudstone (gy1C), Gypsum mudstone (gy1CG) and Halite clay stone (gy2CH), based on physical and chemical properties. Then runoff and sediment rates were determined in each unit at two intensities (30 and 60 mm/h) using rainfall simulator. Analysis of variance and Duncan's tests showed that Halite siltstone unit has produced the highest amount of runoff and sediment rates and then the runoff and sediment rates of other subunits in decreasing order are as follows: Siltstone, gy2CH, gylCG and gy1C are 5% significant level. The trend of induced runoff and sediment rates at different times showed that in Halite siltstone and Siltstone units the runoff amounts were fixed rapidly at 2nd ten minutes. And, on the other units, the runoff amounts were fixed at 3rd ten minutes and sediment yield was increased rapidly at 3rd ten minutes.
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VINN, OLEV, and URSULA TOOM. "Borings in phosphatized Cambrian siltstone pebbles, Estonia (Baltica)." Geological Magazine 153, no. 4 (November 20, 2015): 635–42. http://dx.doi.org/10.1017/s001675681500076x.
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AbstractThe earliest known macroborings (Trypanites) from Baltica occur in early Cambrian phosphatized siltstone pebbles from Kopli quarry in Tallinn, Estonia. Trypanites borings also occur in Furongian phosphatized siltstone pebbles in northern Estonia. The intensity of bioerosion on these Cambrian pebbles is low compared to analogue substrates from Ordovician deposits of Baltica. These bored phosphatized siltstone pebbles show that bioerosion of hard substrates occurred in relatively cold climate epicontinental seas during Cambrian time.
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Wanniarachchi, Ayal, Ranjith Pathegama Gamage, Qiao Lyu, Samintha Perera, Hiruni Wickramarathne, and Tharaka Rathnaweera. "Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study." Energies 12, no. 1 (December 21, 2018): 14. http://dx.doi.org/10.3390/en12010014.
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Hydro-fracturing is a common production enhancement technique used in unconventional reservoirs. However, an effective fracturing process requires a precise understanding of a formation’s in-situ strength behavior, which is mainly dependent on the formation’s in-situ stresses and fluid saturation. The aim of this study is to identify the effect of brine saturation (concentration and degree of saturation (DOS)) on the mechanical properties of one of the common unconventional reservoir rock types, siltstone. Most common type of non-destructive test: acoustic emission (AE) was used in conjunction with the destructive tests to investigate the rock properties. Unconfined compressive strength (UCS) and splitting tensile strength (STS) experiments were carried out for 78 varyingly saturated specimens utilizing ARAMIS (non-contact and material independent measuring system) and acoustic emission systems to determine the fracture propagation. According to the experimental results, the increase in degree of pore fluid saturation (NaCl ionic solution) causes siltstone’s compressive and tensile strengths to be reduced through weakening and breakage of the existing bonding between clay minerals. However, increasing NaCl concentration in the pore fluid generally enhances the compressive strength of siltstone through associated NaCl crystallization effect and actually reduces the tensile strength of siltstone through the corrosive influence of the NaCl ions. Moreover, results show that AE capture and analysis is one of the most effective methods to understand crack propagation behavior in rocks including the crack initiation, crack propagation, and final failure. The findings of this study are important for the identification of fluid saturation dependent in-situ strength conditions for successful hydro-fracturing in low permeable reservoirs.
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Vivoda Prodan, Martina, and Željko Arbanas. "Analysis of the Possible Reactivation of the Krbavčići Landslide in Northern Istria, Croatia." Geosciences 10, no. 8 (July 31, 2020): 294. http://dx.doi.org/10.3390/geosciences10080294.
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The Krbavčići landslide occurred in January 1979 near the town of Buzet, Croatia, after a long period of heavy rainfall. It is located in Northern Istria in the area built of flysch rock mass where numerous mass movements in the past and recent history have been recorded. A flysch rock mass is highly susceptible to weathering, which leads to material disintegration, changes in geotechnical properties, and shear strength decrease, finally resulting in instability processes in flysch slopes. This paper describes existing information about the Krbavčići landslide occurrence, laboratory testing of siltstone samples from a flysch rock mass, and numerical slope stability analyses of a possible landslide reactivation caused by possible long rainy periods and further weathering of the flysch rock mass. Slope stability analysis using the Rocscience, Slide software, as well as landslide numerical simulations using the LS-Rapid simulation software were performed on the basis of the digital elevation model (DEM) and laboratory test results of siltstones with different weathering grades. A DEM of the Krbavčići landslide was obtained on the basis of the unmanned aerial vehicle (UAV) survey conducted in March 2016. The residual shear strength of siltstones to predict a reactivation of landslides is of highest importance and was determined by ring shear and direct shear tests on siltstone samples with different weathering grades. The results of the numerical simulations show that an increase of the groundwater level in the landslide body in combination with the further weathering of the flysch rock material at the sliding surface would have the main influence on a possible landslide reactivation and the further development of the landslide displacement.
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Marshall, Nathan, and Carlton E. Brett. "Siltstone: a key to cyclicity in mixed siliciclastic–carbonate successions: example from Upper Ordovician Kope Formation (Ohio, Indiana, Kentucky)." Canadian Journal of Earth Sciences 53, no. 8 (August 2016): 823–35. http://dx.doi.org/10.1139/cjes-2015-0207.
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The Upper Ordovician (mid-Katian) Kope Formation provides an example of how a detailed study of fine-grained siliciclastic sediment can provide sedimentological insights. The Kope Formation is an exemplar of mixed siliciclastic–carbonate cyclicity; however, most of the sedimentological research to date has focused on the fossiliferous limestone beds. Conversely, this paper provides a detailed investigation of siltstone within 42 metre-scale cycles from 26 locations spanning a large geographic area. The objective of the study is twofold: (i) to confirm the mineralogical nature of silt-sized sediment. Currently, silt-sized sediment is irregularly defined as being either carbonate or siliciclastic rich. This paper uses X-ray diffraction, thin-section, and elemental analyses to determine the mineralogy of the silt; (ii) to determine the stratigraphic distribution of siltstone beds. If a distinctive and reoccurring distribution of siltstone can be found, then it can provide additional information about environmental energy changes that led to cyclic fossiliferous limestone formation. This study finds that silt within the Kope Formation is siliciclastic and siltstone, therefore, records periodic minor pulses of coarser terrigenous sediment. Predominantly, metre-scale limestone–shale cycles show an increasing abundance of siltstone beds in the upper half of the shale interval, with a marked decrease just before the capping limestone. This finding supports the idea that limestone formation occurred during slowing sedimentation, perhaps at a time of maximum sea-level rise. Furthermore, decametre-scale fluctuations in siltstone abundance are similar in pattern to previously documented faunal variations, indicating that fauna assemblage might be more controlled by turbidity and not depth.
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Jackson, J., I. P. Sweet, and T. G. Powell. "STUDIES ON PETROLEUM GEOLOGY AND GEOCHEMISTRY, MIDDLE PROTEROZOIC, McARTHUR BASIN NORTHERN AUSTRALIA I: PETROLEUM POTENTIAL." APPEA Journal 28, no. 1 (1988): 283. http://dx.doi.org/10.1071/aj87022.
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Mature, rich, potential source beds and adjacent potential reservoir beds exist in the Middle Proterozoic sequence (1400-1800 Ma) of the McArthur Basin. The McArthur and Nathan Groups consist mainly of evaporitic and stromatolitic cherty dolostones interbedded with dolomitic siltstone and shale. They were deposited in interfingering marginal marine, lacustrine and fluvial environments. Lacustrine dolomitic siltstones form potential source beds, while potential reservoirs include vuggy brecciated carbonates associated with penecontemporaneous faulting and rare coarse-grained clastics. In contrast, the younger Roper Group consists of quartz arenite, siltstone and shale that occur in more uniform facies deposited in a stable marine setting. Both source and reservoir units are laterally extensive (over 200 km).Five potential source rocks at various stages of maturity have been discovered. Two of these source rocks, the lacustrine Barney Creek Formation in the McArthur Group and the marine Velkerri Formation in the Roper Group, compare favourably in thickness and potential with rich demonstrated source rocks in major oil-producing provinces. There is abundant evidence of migration of hydrocarbons at many stratigraphic levels. The geology and reservoir characteristics of the sediments in combination with the distribution of potential source beds, timing of hydrocarbon generation, evidence for migration and chances of preservation have been used to rank the prospectivity of the various stratigraphic units in different parts of the basin.
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Arrieta, Rafael Gómez, Camila de Andrade Carvalho Gualberto, Thiago Siqueira Prudente, Gustavo Alves Santos, Luiz Henrique Silveira, Bruno Nicchio, and Hamilton Seron Pereira. "Glauconitic Siltstone as a Source of Potassium, Silicon and Manganese for Flooded Rice." Journal of Agricultural Science 12, no. 9 (August 15, 2020): 96. http://dx.doi.org/10.5539/jas.v12n9p96.
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The objective of this study was to evaluate the efficiency of glauconitic siltstone as a multi-nutrient source for flooded rice. Two experiments were carried out under greenhouse conditions, one using a Ferralsol and the another an Arenosol. Glauconitic siltstone was applied in different doses (0, 5, 20, 40, and 80 mg dm-3 K2O) and potassium chloride, wollastonite, and manganese sulfate were respectively used as standard sources, at doses of 80 mg dm-3 K2O, 270 mg dm-3 Si, and 2 mg dm-3 Mn. The sources were incubated for 90 days on the two soil types and, after the incubation period, rice plants were sown, and two consecutive rice growths were performed. The application of glauconitic siltstone in tropical soils promotes increases in the plant and grain dry matter of rice plants, as well as K, Si and Mn contents in soil samples and accumulated in plants. Greater effects following the application of glauconitic siltstone are obtained after the second rice growth due to its gradual release.
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Yang, Yiran, Xingping Lai, Tao Luo, Kekuo Yuan, and Feng Cui. "Study on the viscoelastic–viscoplastic model of layered siltstone using creep test and RBF neural network." Open Geosciences 13, no. 1 (January 1, 2021): 72–84. http://dx.doi.org/10.1515/geo-2020-0224.
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Abstract Creep is a fundamental time-dependent property of rock. As one of the main surrounding rocks of underground engineering, layered siltstone is governed by creep to a great extent because of special structure. Based on the structural characteristics of layered siltstone, a viscoelastic–viscoplastic model was proposed to simulate and present its creep property. To verify the accuracy of the model, governing equation of the viscoelastic–viscoplastic model was introduced into finite element difference program to simulate a series of creep tests of layered siltstone. Meanwhile, creep tests on layered siltstone were conducted. Numerical simulation results of the viscoelastic–viscoplastic model were compared with creep test data. Mean relative error of creep test data and numerical simulation result was 0.41%. Combined with Lyapunov function, the radial basis function (RBF) neural network trained with creep test data was adopted. Mean relative error of creep test data and RBF neural network data was 0.57%. The results further showed high accuracy and stability of RBF neural network and the viscoelastic–viscoplastic model.
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Zhang, Guoliang, Haipeng Jia, and Shuaifeng Wu. "Study on Dynamic Mechanical Properties and Damage Evolution Model of Siltstone." Shock and Vibration 2019 (November 22, 2019): 1–10. http://dx.doi.org/10.1155/2019/5174579.
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This paper is focused on exploring the dynamic mechanical properties and damage process of siltstone. For this purpose, different stress wave wavelengths (0.5 m∼2.0 m) and different strain rates (25 s−1∼120 s−1) were applied to siltstone specimens in the SHPB dynamic impact test. The experimental results show that the dynamic compressive strength of siltstone is linearly positively correlated with the strain rate, and the dynamic increase factor is linearly positively correlated with the natural logarithm of strain rate; the peak strain is linearly positively correlated with the strain rate, and the increase in wavelength causes the peak strain to increase. Through multiple impact tests, it is concluded that the cumulative damage to siltstone increases with the number of impacts. The cumulative damage curve exhibits an initial rapid rise, followed by a stable development, followed by another rapid rise. With increasing wavelength of the stress wave, the stable development of the curve gradually decreases, the cumulative damage to the siltstone is intensified, and the number of repeated impacts is reduced. Meanwhile, a model for damage evolution is established based on the inverse of the Gompertz function, and the physical meanings of the model parameters are determined. The model can reflect the influence of both stress wave parameters and impact times. Verification of the model demonstrates the rationality of the model and the correctness of the physical meaning of the parameters. The model could be applied in future studies of damage to sedimentary rocks.
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Rudmin, Maxim, Santanu Banerjee, Aigerim Dauletova, and Aleksey Ruban. "Depositional Conditions of Cretaceous Ironstones Deposit in the Chulym-Yenisey Basin (Western Siberia)." Minerals 11, no. 9 (September 16, 2021): 1008. http://dx.doi.org/10.3390/min11091008.
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This study reconstructs the depositional conditions of ironstones within the Chulym-Yenisey basin and assesses the iron source. The detrital minerals of the studied deposits include quartz and feldspar. The authigenic minerals are goethite, siderite, aragonite, dolomite, calcite, apatite, barite, and pyrite. The clay components include minerals of the chlorite group (possible chamosite), nontronite, kaolinite, illite, and beidellite. Local bacterial sulfate reduction led to the formation of pyrite framboids in siltstone layers. The subsequent diagenetic iron reduction promoted the formation of chamosite from siderite. The goethite precipitation occurred in an oxidic aqueous environment. The Cretaceous continental sediments of the Ilek and Kia Formations of the Chulym-Yenisei depression consist of fine- and medium-grained, cross-stratified, poorly sorted litho-feldspatho-quartzose sandstones of fluvial channel origin alternating with bluish-gray siltstones and ironstones of floodplain–lacustrine–bog origin. Thin layers of iron-bearing rocks within siltstones formed in meromictic waters. The changes in geochemical proxies demonstrate fluctuations of paleoenvironmental conditions within the Cretaceous sequence. Siltstones and sandstones formed under humid and arid conditions, respectively. The primary iron source for sediments of the Chulym-Yenisey depression was determined as volcanogenic and igneous rocks of the Altai-Sayan mountainous region.
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SHARMA, SHIKHA, MANEESH SHARMA, and INDRA BIR SINGH. "Facies characteristics and cyclicity of Lower Siwalik sediments, Jammu area: a new perspective." Geological Magazine 138, no. 4 (July 2001): 455–70. http://dx.doi.org/10.1017/s0016756801005659.
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The Lower Siwalik succession of the Jammu area has been distinguished into three major lithofacies associations: a sand-dominant association, a sandy-mud-dominant association, and a silty-heterolithic association. The sand-dominant association is made up of three lithofacies: cross-bedded sandstone, rippled silty sandstone and bioturbated sandy siltstone, which are organized in multi-storeyed sandbodies representing deposition in major river channels. The sandy-mud-dominant association is made up of two lithofacies, mottled clayey siltstone and interbedded sandstone, siltstone and mudstone, representing deposition in overbank areas of flood-plain and natural levee-crevasse splays. The sand-dominant association and sandy-mud-dominant association are grouped together as a channel-related succession and are products of processes in the river channel. The silty-heterolithic association consists of four lithofacies: mottled siltstone, mottled silty sandstone, bedded calcrete and mottled mudstone. They are considered to be deposits of Doab (upland interfluve) areas operating independently of present-day major river channels. These deposits have been formed in minor channels, sloping surfaces, and lakes and ponds of the interfluve regions. The cyclicity of both successions (channel-related and Doab-related) has been determined using a partial-independence statistical model.
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Adib, Mazen E. "Slope Failure in Weathered Claystone and Siltstone." Journal of Geotechnical and Geoenvironmental Engineering 126, no. 9 (September 2000): 787–97. http://dx.doi.org/10.1061/(asce)1090-0241(2000)126:9(787).
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Pratap, Yogendra, Himanshu Tanvar, Débora Moreira, and Nikhil Dhawan. "Processing of Glauconitic Siltstone for Potash Recovery." Mining, Metallurgy & Exploration 37, no. 4 (May 4, 2020): 1231–39. http://dx.doi.org/10.1007/s42461-020-00218-5.
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Wang, Mei Yan, Xin Xin Lin, Zhao Jun Mo, and Lu Lu Pan. "Experimental Analysis on Thermal Conductivity of Rock." Applied Mechanics and Materials 438-439 (October 2013): 318–20. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.318.
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This paper carried out the experimental study on the thermal conductivity of rock in different depth by transient hot-strip method and the analysis on the reliability of the data. The results show that thermal conductivity of pelitic siltstone has been less affected by the varying versus depth of the rock stratum than tuff, but the thermal conductivity of tuff slightly higher than pelitic siltstone.
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Burrow, Carole J., John A. Long, and Kate Trinajstic. "Disarticulated acanthodian and chondrichthyan remains from the upper Middle Devonian Aztec Siltstone, southern Victoria Land, Antarctica." Antarctic Science 21, no. 1 (September 4, 2008): 71–88. http://dx.doi.org/10.1017/s0954102008001521.
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AbstractWell-preserved vertebrate microremains are abundant in the residues from a calcareous grey siltstone in the karawaka biozone (?late Givetian) of the Aztec Siltstone at Mount Crean, Lashly Mountains, Antarctica. Acanthodians are represented by scales of acritolepid Pechoralepis juozasi sp. nov., climatiid Nostolepis sp. cf. N. gaujensis Valiukevičius, diplacanthid Milesacanthus antarctica Young & Burrow, and an undetermined acanthodiform. The acanthodian assemblage resembles those from early Frasnian carbonates of central Iran. Chondrichthyan elements in the fauna include rare teeth of Aztecodus harmsenae Long & Young and Antarctilamna prisca Young, ctenacanthoid-type scales and branchial denticles which are possibly from Antarctilamna, and scales of an indeterminate chondrichthyan. An isolated set of acanthodid acanthodiform jaws from the uppermost ‘phyllolepid’ biozone of the Aztec Siltstone at Mount Ritchie, Warren Range, Antarctica is also described.
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McLoughlin, S., and J. A. Long. "New records of Devonian plants from southern Victoria Land, Antarctica." Geological Magazine 131, no. 1 (January 1994): 81–90. http://dx.doi.org/10.1017/s0016756800010517.
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AbstractAn assemblage of fossil plants is here recorded from the Middle Devonian Beacon Heights Orthoquartzite and overlying Aztec Siltstone (Taylor Group), of the Cook Mountains and Skelton Névé regions, southern Victoria Land, Antarctica. The Beacon Heights Orthoquartzite exposed in the southern Cook Mountains yielded specimens of the lycopods Haplostigma lineare, Malanzania sp., and Archaeosigillaria sp. cf. A. caespitosa. The Aztec Siltstone flora contains Praeramunculus alternatiramus and H. lineare.
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Warrington, Geoffrey, and John E. Pollard. "On the records of the brachiopod ‘Lingula’ and associated fossils in Mid-Triassic deposits in England." Proceedings of the Yorkshire Geological Society 63, no. 4 (May 5, 2021): pygs2020–015. http://dx.doi.org/10.1144/pygs2020-015.
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Brachiopods were reported, as ‘Lingula’, from Anisian (early Mid-Triassic) deposits of the Tarporley Siltstone Formation (Mercia Mudstone Group) in Nottinghamshire in 1955, and from the Helsby Sandstone Formation (Sherwood Sandstone Group) in a borehole in Oxfordshire in 1975. Burrows (Lingulichnus) attributed to this organism were reported from the Tarporley Siltstone in Cheshire in 1981. These records are evidence of marine influence in the depositional environments of those formations.
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Perera, Mandadige, Kadinappuli Sampath, Pathegama Ranjith, and Tharaka Rathnaweera. "Effects of Pore Fluid Chemistry and Saturation Degree on the Fracability of Australian Warwick Siltstone." Energies 11, no. 10 (October 17, 2018): 2795. http://dx.doi.org/10.3390/en11102795.
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Fracability of unconventional gas reservoirs is an important parameter that governs the effectiveness of subsequent gas extraction. Since reservoirs are saturated with various pore fluids, it is essential to evaluate the alteration of fracability of varyingly saturated rocks. In this study, varyingly saturated (dry, water, and brine with 10%, 20% and 30% NaCl by weight) siltstone samples were subjected to uniaxial compressive loading to evaluate their fracability variation. Acoustic emission (AE) and ARAMIS photogrammetry analyses were incorporated to interpret the crack propagation. SEM analysis was carried out to visualize the micro-structural alterations. Results show that siltstone strength and brittleness index (BI) are reduced by 31.7% and 46.7% after water saturation, due to water-induced softening effect. High NaCl concentrations do not reduce the siltstone strength or brittleness significantly but may contribute to a slight re-gain of both values (about 3–4%). This may be due to NaCl crystallization in rock pore spaces, as confirmed by SEM analysis. AE analysis infers that dry siltstone exhibits a gradual fracture propagation, whereas water and brine saturated specimens exhibit a hindered fracturing ability. ARAMIS analysis illustrates that high NaCl concentrations causes rock mass failure to be converted to shear failure from splitting failure, which is in favour of fracability.
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Brasil, Eliana Paula Fernandes, Wilson Mozena Leandro, Welldy Gonçalves Teixeira, Marcos Antônio Vieira, José Patrício Nunes de Souza, and Henrique Victor Vieira. "Chemical Extractors to Assess Potassium Availability in Glauconitic Siltstone." Journal of Agricultural Science 12, no. 9 (August 15, 2020): 166. http://dx.doi.org/10.5539/jas.v12n9p166.
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This paper aimed to evaluate the efficiency of chemical extractors to measure the availability of potassium (K) in glauconitic siltstone. An experiment with successive crops of beans and maize was installed under field conditions in Quirinópolis, Goiás State, Brazil, in a typical ortic Neossolo Quartzarênico. For both crops, the experimental design was a randomized block with four replications, resulting in a total of 24 experimental plots. Two sources and four doses of K2O were used, in addition to a control treatment with any K fertilization. The sources used were glauconitic siltstone and potassium chloride (KCl), and the doses applied through glauconitic siltstone corresponded to 1, 2, 4 and 8 times the dose of K2O applied via KCl as a reference. The following extractors were used: neutral ammonium citrate (NAC), citric acid 2% (CA), CA + ammonium fluoride 0.5% (NH4F), tartaric acid 5% (TA) + sodium fluoride 0.5% (NaF) (1:100), TA + NaF 0.5% (1:500), hydrochloric acid (HCl), and the method for extracting potassium from silicatic materials (MAPA-8.2.4.2). Among the tested extractors, the best one regarding productivity was the MAPA-8.2.4.2. The NAC and CA extractors showed the lowest correlations and should not be used henceforth to quantify soluble K from glauconitic siltstone.
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Chen, Lei, Jian Zhao, and Zhiyang Zheng. "Acoustic Emission Characteristics of Compressive Deformation and Failure of Siltstone under Different Water Contents." Advances in Materials Science and Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/4035487.
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The uniaxial compression and acoustic emission (AE) monitoring of siltstone specimens in the Gongchangling open-pit iron mine in Liaoning Province was conducted by evaluating the effects of three water saturation levels: dry, natural, and water-saturated. The siltstone AE characteristics were analyzed according to water content; the relationship between the AE characteristics and the growth and expansion of siltstone cracks was subsequently discussed. Research results indicated the following: siltstone specimens had distinctly different mechanical properties and AE characteristics according to water content; as the water content increased the compressive strength and elasticity modulus of specimens decreased. In the compacting phase of specimens under compression, the AE count rate of the water-saturated specimen was relatively small and the events were relatively stable. In the linear-elastic deformation phase, the AE count rate of the dry specimen increased sharply, reaching approximately 400 times/s. In the plastic yield deformation phase, the peak value of the AE count rate of the dry specimen ranged between 955 and 1,068 times/s, whereas that of the water-saturated specimen only attained a range of 635 to 782 times/s. In the failure phase, the time to reach the peak stress value of the dry specimen was increased as compared to that of the AE count rate.
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Al-Wosabi, Mohammed A., and Sa’ad Z. Al-Mashaikie. "Investigation of Facies Types and Associations of Kuhlan Red Bed Formation in NW Yemen: A New Hypothesis for Origin and Depositional Environment." Sultan Qaboos University Journal for Science [SQUJS] 11 (June 1, 2006): 11. http://dx.doi.org/10.24200/squjs.vol11iss0pp11-38.
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Varieties of thirteen facies types were recognized in the Kuhlan Formation represented by red bed siliciclastic sequences of argillaceous sediments. Examination of the Kuhlan stratigraphic column included sequence relationships, lithology, sedimentary characters, structures and petrography of the dominant rock types. These facies types are grouped in three distinct associations of facies. The lower unit A comprises association of facies (Distal turbidites) represented by alternates of turbidity sequences including sandstone, siltstone and thick shale beds. These facies types confirm a regressive depositional environment in deep marine shelf conditions. There are three facies types which are identified as massive sandstone, cross-bedded sandstone and pebbly sandstone facies. The middle unit B association of facies (Proximal turbedites) represents glaciomarine sequences displaying high lateral and vertical facies changes of glacioturbidite sediment alternates with diamictites and tillite beds. The sequences are affected by eustatic and eustatism of the glacial advance and retreat. This unit B includes eight types of facies. These are identified as; tillite, massive diamictites, stratified diamictites, laminated siltstone/shale, deformed siltstone/mudstone, graded rhythmic siltstone, massive conglomerate and cross-stratified sandy conglomerate facies. The upper unit C association of facies is represented by shallow marine shelf sequences displaying very thick massive and locally cross-bedded sand bar sandstone overlying the laminated siltstone/shale interbeds. The upward gradual changes in mineralogical composition and color confirms the start of marine transgression and later deposited platform Amran Group. Mineralogical composition of Kuhlan sandstone displays impure dirty rocks consisting of more than 30% of argillaceous matrix, 50% of cristobalite and quartz grains, more than 10% of ferruginous cement and 10% of detrital iron oxide grains, potash feldspar, igneous rock fragments and carbonate cement. It is classified as quartz greywacke type in the lower and middle parts and as quartz arenite with subarkoses in the upper part.
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Turner, S., and G. C. Young. "Thelodont scales from the Middle-Late Devonian Aztec Siltstone, southern Victoria Land, Antarctica." Antarctic Science 4, no. 1 (March 1992): 89–105. http://dx.doi.org/10.1017/s0954102092000142.
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A new fossil agnathan, Turinia antarctica sp. nov., based on numerous isolated scales, comes from the lower fish-bearing beds of the Aztec Siltstone. Scales from moraine at Mount Suess, originally described as selachian or psammosteid heterostracan, are referred to the new species which shows close affinity with T. gondwana from Bolivia and T. cf. hutkensis from Iran. Reassessment of the biostratigraphy of Middle Devonian turiniid scales suggests that the lower part of the Aztec Siltstone may be of Eifelian age.
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McCabe, Bryan A., Éanna P. McKeon, Rasa J. Virbukiene, Patrick J. Mannion, and Aidan M. O’Connell. "Pyritiferous mudstone–siltstone: expansion rate measurement and prediction." Quarterly Journal of Engineering Geology and Hydrogeology 48, no. 1 (February 2015): 41–54. http://dx.doi.org/10.1144/qjegh2013-067.
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Gratz, Andrew J., and John M. Christie. "Recrystallization at grain contacts in a sandy siltstone." Journal of Structural Geology 15, no. 9-10 (September 1993): 1139–44. http://dx.doi.org/10.1016/0191-8141(93)90160-c.
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Hamza, O., and R. Stace. "Creep properties of intact and fractured muddy siltstone." International Journal of Rock Mechanics and Mining Sciences 106 (June 2018): 109–16. http://dx.doi.org/10.1016/j.ijrmms.2018.03.006.
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Goraj, Weronika, Anna Szafranek-Nakonieczna, Jarosław Grządziel, Cezary Polakowski, Mirosław Słowakiewicz, Yanhong Zheng, Anna Gałązka, Zofia Stępniewska, and Anna Pytlak. "Microbial Involvement in Carbon Transformation via CH4 and CO2 in Saline Sedimentary Pool." Biology 10, no. 8 (August 17, 2021): 792. http://dx.doi.org/10.3390/biology10080792.
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Methane and carbon dioxide are one of the most important greenhouse gases and significant components of the carbon cycle. Biogeochemical methane transformation may occur even in the extreme conditions of deep subsurface ecosystems. This study presents methane-related biological processes in saline sediments of the Miocene Wieliczka Formation, Poland. Rock samples (W2, W3, and W4) differed in lithology (clayey salt with veins of fibrous salt and lenses of gypsum and anhydrite; siltstone and sandstone; siltstone with veins of fibrous salt and lenses of anhydrite) and the accompanying salt type (spiza salts or green salt). Microbial communities present in the Miocene strata were studied using activity measurements and high throughput sequencing. Biological activity (i.e., carbon dioxide and methane production or methane oxidation) occurred in all of the studied clayey salt and siltstone samples but mainly under water-saturated conditions. Microcosm studies performed at elevated moisture created more convenient conditions for the activity of both methanogenic and methanotrophic microorganisms than the intact sediments. This points to the fact that water activity is an important factor regulating microbial activity in saline subsurface sediments. Generally, respiration was higher in anaerobic conditions and ranged from 36 ± 2 (W2200%t.w.c) to 48 ± 4 (W3200%t.w.c) nmol CO2 gdw−1 day−1. Methanogenic activity was the highest in siltstone and sandstone (W3, 0.025 ± 0.018 nmol CH4 gdw−1 day−1), while aerobic methanotrophic activity was the highest in siltstone with salt and anhydrite (W4, 220 ± 66 nmol CH4 gdw−1 day−1). The relative abundance of CH4-utilizing microorganisms (Methylomicrobium, Methylomonas, Methylocystis) constituted 0.7–3.6% of all taxa. Methanogens were represented by Methanobacterium (0.01–0.5%). The methane-related microbes were accompanied by a significant number of unclassified microorganisms (3–64%) and those of the Bacillus genus (4.5–91%). The stable isotope composition of the CO2 and CH4 trapped in the sediments suggests that methane oxidation could have influenced δ13CCH4, especially in W3 and W4.
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Glushkova, Tatyana, Aleksei Kachkin, Ivan Nejmyshev, Aleksandr Talalaj, and Irina Shinkaryuk. "Study of the geochemical processes of radionuclides of oil and gas fields." E3S Web of Conferences 177 (2020): 02002. http://dx.doi.org/10.1051/e3sconf/202017702002.
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The objects of study of the geochemical processes of radionuclides are deposits of the West Siberian Plate, the distribution of radioactive elements in the areas of the Tyumen oil and gas region. In the process of work, the chemical composition of sedimentary rocks was investigated, and the mass fractions of uranium, radium, thorium, potassium, and other chemical elements were determined. Data on the distribution of radionuclides in individual wells and areas were considered, correlation diagrams of geochemical specificity were constructed. To determine the mass fractions of uranium, radium, thorium, potassium, and other chemical elements, gamma spectrometric, neutron activation, X-ray spectral, and laser-luminescent measurements were used. In order to control the measurement results, the determination of uranium in the samples was duplicated using the delayed neutron method in a specialized facility. The accuracy of uranium determination, estimated from independent measurements, was ~ 6.4% (rel.). The radioactive equilibrium is shifted towards uranium, which indicates an increase in the mass fractions of naturally radioactive elements in the raw of sandstones -sandstone-siltstone open pits - siltstones. The increase of the level of natural radioactivity in the direction from sandstones to siltstones is explained by the difference in brittleness between quartz and grains of active accessories, which indicates a stable ratio between radium and uranium in the sandstones-siltstones in relation to the considered areas of the Tyumen region.
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Junussov, Medet, Ferenc Mádai, and Bánhidi Olivér. "Sequential extraction of carbonaceous siltstone rock for multi-element analysis by ICP OES." Contemporary Trends in Geoscience 7, no. 2 (December 1, 2018): 145–52. http://dx.doi.org/10.2478/ctg-2018-0010.
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Abstract The carbonaceous siltstone rock material is a disseminated sulfide-rich sedimentary rock from a sediment-hosted gold deposit of Bakyrchik. The Bakyrchik deposit is located in Eastern Kazakhstan, which includes in Qalba gold province. The main purpose of this paper is a demonstration on chemical extraction of heavy metals from the carbonaceous siltstone rock and detection of its elemental concentrations. In the work was used a rock sample from the deposit which is a sericizited carbonaceous-siltstone rock. In sequential extraction method was selected four stages such as water soluble fraction (reaction with deionized water) for extraction of water soluble metals, reducible metal fraction (reaction with hydroxyl ammonium chloride) for extracting all reducible metals, organics and sulfides (reaction with hydrogen peroxide) for dissolution of organics and copper sulfide, and extraction of metal oxides and residual fraction (reaction with aqua regia) for extracting of all remaining metals. The paper comprises analytical methods for research outlooks. They are X-Ray Diffraction (determination of mineralogical composition), X-Ray Fluorescence (determination of chemical composition) and Inductively Coupled Plasma – Optical Emission Spectrometry (determination of heavy metal concentrations).
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Wang, Yu, Hua Feng Deng, Tao Lu, and Zong Yong Zhao. "Research on Shear Creep Property of Soft Rock in Dam Foundation." Advanced Materials Research 243-249 (May 2011): 2744–47. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.2744.
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Creep characteristic is one of the most important mechanical characteristics of rock. It controls the stability of rock engineering. Under step load conditon, the shear creep test of argillaceous siltstone which was collected in dam foundation is performed by using the RMT150c rock and soil mechanics testing machine. The shear creep curves under different normal stresses show that the argillaceous siltstone is very significant in creep, which should be considered in the stability analysis of dam foundation. According to the analysis of experimental results, the long-term shear strength parameters are determined to provide reference for engineering survey and design.
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Wang, Yu, and Jian Lin Li. "Investigation on Shear Creep Mechanical Properties of Soft Rock." Advanced Materials Research 261-263 (May 2011): 1024–28. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.1024.
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The construction of slope or underground engineering often encounters soft rocks, which control the stability of rock engineering, with obvious characteristics of rheology. Under step load conditon, the shear creep test of argillaceous siltstone is performed by using the RMT150c rock and soil mechanics testing machine. Testing results show that the amount of creep deformation for argillaceous siltstone is big enough, which should be taken into consideration for analysis of stability or design of slope or underground engineering. Based on testing results, the long-term shear strength parameters are determined to provide theory basis for engineering survey and design.
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Wood, J. M. "Crushed-Rock Vs. Full-Diameter Core Samples for Water-Saturation Determination in a Tight-Gas Siltstone Play." SPE Reservoir Evaluation & Engineering 18, no. 03 (July 20, 2015): 407–16. http://dx.doi.org/10.2118/174548-pa.
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Summary The efficacy of crushed-rock samples vs. small plugs or full-diameter core samples for measurement of porosity, permeability, and fluid saturation is an important consideration in the evaluation of tight-gas reservoirs and shale-gas reservoirs. Crushed-rock core analysis methods originally developed for shale reservoirs are now, in some cases, being extended to low-quality tight-gas reservoirs. In this study, crushed-rock and full-diameter core measurements from two wells drilled with oil-based mud are compared to evaluate which of the two core-analysis methods is more reliable for water-saturation assessment of a major North American tight-gas siltstone play (Montney Formation, western Canada). Measurements from the studied full-diameter core samples have wide ranges of water saturation (10 to 45%) and bulk volume water (BVW) (0.5 to 2.6%). In contrast, measurements from crushed-rock samples have much narrower ranges of water saturation (10 to 20%) and BVW (0.2 to 0.7%). The lower values and limited range of water-content measurements from crushed-rock samples suggest a significant degree of artificial water loss during sample handling in the laboratory. This conclusion is supported by comparing core-measured BVW with deep-resistivity values from openhole well logs. Full-diameter BVW measurements correlate well with log resistivity, indicating they are generally representative of in-situ reservoir conditions. Crushed-rock BVW values, on the other hand, show no correlation with log resistivity. The results of this study suggest caution is warranted in the use of crushed-rock samples for water-saturation measurements of siltstones or silty shales. Failure to recognize artificial water loss from crushed-rock siltstone samples could lead to an erroneous interpretation of irreducible water saturation at in-situ reservoir conditions with potentially serious implications for resource evaluation and exploitation.
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Stokes, T. R., M. Zentilli, and N. Culshaw. "Structural and lithological controls of gold-bearing quartz-breccia zones in Archean metaturbidites, Gordon Lake, Northwest Territories, Canada." Canadian Journal of Earth Sciences 27, no. 12 (December 1, 1990): 1577–89. http://dx.doi.org/10.1139/e90-169.
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Gold lode deposits, hosted within shear zones of Archean metavolcanic belts, have produced some of the world's largest gold mines. Consequently, exploration has focussed on regional lineaments within these belts. However, commonly associated metaturbidite terrains may also become good exploration targets once previously unrecognized structural and lithological ore controls are determined and their genesis better understood. Mapping of lower-greenschist-grade metaturbidites of the Burwash Formation at Gordon Lake (62°54′N, 113°15′W) has identified gold-bearing, quartz-breccia zones that are confined to the central area of a south-closing regional refold of earlier, vertically plunging isoclinal (F1) folds. The refold is partly transected by a "regional" cleavage (S3) and has a crenulation cleavage (S4) restricted to its hinge region. Of five breccia types recognized, the strata-bound, gold-bearing, and sulphide-rich breccias found at Knight Bay are economically the most important. These breccias are restricted to the crenulated domains within the central part of the refold and are hosted preferentially in the black, carbon-rich siltstones. Our data are compatible with a model whereby metamorphic fluids, carrying gold extracted from the metaturbidite pile, were focussed into fractures within the central domain of the refold during (anticlockwise) rotation of the refold's east limb. The limb rotation induced dextral bedding-parallel slip in the central domain of the refold and resulted in the formation of a crenulation cleavage and hydraulic fracturing within overpressured siltstone beds. Decompression during the episodic hydraulic fracturing led to precipitation of grey quartz, gold, sulphides, and minor carbonates. The organic matter within the black siltstone host may have physically enhanced bedding-parallel slip and, if the mineralizing solutions were oxidizing, led to chemical reduction at the site of ore concentration.
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Safatle, Frederico Amorim, Kátia Dionísio de Oliveira, and Cícero Naves de Ávila Neto. "Potassium recovery from Brazilian glauconitic siltstone by hydrothermal treatments." REM - International Engineering Journal 73, no. 2 (June 2020): 213–24. http://dx.doi.org/10.1590/0370-44672019730047.
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Kralj, Polona. "Dacite – siltstone peperite from Trlično at Rogatec, Eastern Slovenia." Geologija 49, no. 1 (June 30, 2006): 85–90. http://dx.doi.org/10.5474/geologija.2006.006.
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Motanated, Kannipa, and Michael M. Tice. "Siltstone Geochemical Compositions: Applications for Event Size and Correlation." International Journal of Geosciences 07, no. 02 (2016): 189–99. http://dx.doi.org/10.4236/ijg.2016.72015.
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Noh, Beyong-Seob, Jae-Moon Park, Seung-Bum Kim, and Woo-Hun Ryang. "Basaltic Andesite-Siltstone Peperite in the Gyehwari Formation (Cretaceous)." Journal of the Korean earth science society 30, no. 1 (February 28, 2009): 33–39. http://dx.doi.org/10.5467/jkess.2009.30.1.033.
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Violatti, Isabel Cristina Acciardi, Camila de Andrade Carvalho Gualberto, Luiz Henrique Silveira, Gustavo Alves Santos, Bárbara Campos Ferreira, Pedro Magno Mendes Machado, and Hamilton Seron Pereira. "Glauconitic siltstone as a multi-nutrient fertilizer for Urochloa brizantha cv. Marandú." August 2019, no. 13(08):2019 (August 20, 2019): 1280–87. http://dx.doi.org/10.21475/ajcs.19.13.08.p1609.
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Potassium (K) is one of the most absorbed nutrients by forage plants and it is found at low levels in tropical soils, requiring large amounts of fertilizers. The use of glauconitic siltstone as multi-nutrient fertilizers is an economic alternative to improve pasture-based production systems due to their low-cost production and long-term nutrient release. This study evaluated the effect of the glauconitic siltstone (GS) powder on three successive crops of Urochloa brizantha cv. Marandú (Syn. Brachiaria brizantha). Two experiments were carried out under greenhouse conditions, one using a Typic Dystrustox and the other a Typic Quartzipsamment. Both experiments were arranged in a completely randomized design with one factor, i.e., five glauconitic siltstone doses (0, 5, 20, 40, and 80 mg dm-3 of K2O) and four replications. In addition, three additional treatments were used, as potassium chloride, wollastonite and manganese sulfate at doses of 80 mg dm-3 of K2O, 270 mg dm-3 of silicon (Si) and 2 mg dm-3 of manganese (Mn), respectively. The sources were incubated for 60 days on the two soil types and, after the incubation period, Urochloa brizantha plants were grown. Three consecutive cuts were performed at 68, 104 and 168 days after sowing. The application of the GS in tropical soils promoted increases in plant dry matter, as well as K, Si and Mn levels in soil samples and accumulated in plants. In general, greater effects were obtained following the application of GS after consecutive cropping cycles due to its long-term release. Results described in this study provide an important understanding of the use of glauconitic siltstone as multi-nutrient fertilizers in tropical soils, being an efficient alternative to improve soil fertility and increase tropical pasture productivity.
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Young, Gavin C., and John A. Long. "New arthrodires (placoderm fishes) from the Aztec Siltstone (late Middle Devonian) of southern Victoria Land, Antarctica." Australian Journal of Zoology 62, no. 1 (2014): 44. http://dx.doi.org/10.1071/zo13070.
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A small collection of arthrodire remains is described from the Devonian Aztec Siltstone of southern Victoria Land, Antarctica. Barwickosteus antarcticus, gen. et sp. nov., is a small phlyctaeniid arthrodire probably closely related to Barrydalaspis from the Bokkeveld Group of South Africa. Grifftaylor antarcticus, gen. et sp. nov., is a generalised phlyctaeniid resembling Phlyctaenius and Neophlyctaenius. New specimens of Boomeraspis show that it had a high-spired trunk-armour with a median dorsal plate of similar proportions to Tiaraspis, Mithakaspis, Turrisaspis or Africanaspis. Other fragmentary median dorsal plates are provisionally referred to Turrisaspis and Mulgaspis. With these new taxa the vertebrate assemblage from the Aztec Siltstone comprises at least 37 genera and 50 species, making it one of the most diverse of Middle–Late Devonian age.
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Wanigarathna Jayasekara, Dinesha, and Ranjith Pathegama Gamage. "The effect of CO2 injection on caprock permeability in deep saline aquifers." E3S Web of Conferences 205 (2020): 02010. http://dx.doi.org/10.1051/e3sconf/202020502010.
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During CO2 injection into deep saline aquifers, the overlying caprock may be subjected to geochemical reactions which can alter the leakage pathways for injected CO2. Thus, it is crucial to identify the supercritical CO2 (scCO2) flow behaviour via fractures in caprock and its permeability to estimate the permanence of injected CO2. The objective of this study is to find the effect of scCO2 flow on fractured caprock permeability. A fractured siltstone sample was saturated in deionized water and conducted scCO2 permeability tests using a high-precision advanced core flooding apparatus under different injection pressures and confinements. Next, the siltstone sample was saturated in 10% w/w NaCl brine and conduced scCO2 permeability tests as described earlier. The results show that the brine-saturated sample has low permeability compared to water-saturated siltstone sample. The reason would be the deposition of evaporites during scCO2 flow through the fractured sample. This is known as CO2 dry-out phenomenon or absorbing moisture into the scCO2, making the remaining brine saturated with salts. Thus, the CO2 back-migration through the caprock discontinuities becomes minimized due to CO2 dry-out phenomenon, which is an advantage for the caprock integrity in deep saline aquifers. In addition, aquifers with high salinity contents show significant dry-out phenomenon because pore fluid easily becomes supersaturated with salts due to evaporation of moisture into the scCO2.
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Esperante, Raúl, and Orlando Poma. "Taphonomy and palaeopathology of two mysticete whales, upper Miocene Pisco Formation, Peru." Spanish Journal of Palaeontology 30, no. 1 (May 9, 2020): 1. http://dx.doi.org/10.7203/sjp.30.1.17198.
Full textAbstract:
Two mysticete fossil whales from the upper Miocene of the Pisco Formation in Peru are described that show healed bone-fractures in ribs. One specimen is preserved in a tuffaceous diatomaceous siltstone and the other specimen is preserved in siltstone. Both specimens are well preserved, mostly articulated and almost complete. Shark teeth were found associated with one of the skeletons, but both specimens lack any trace evidence for the activity macro-scavengers. We suggest that the cause of bone fracture may have been collision with rocky shores, other wales, or large predators. The fact that the rib fractures healed indicates that the whales did not die due the bone fractures. Sedimentologic and paleontological evidence indicate that they were rapidly buried in the marine platform with well-oxygenated water
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Sartakov, M. P., E. M. Osnitsky, K. Iu Kudrin, and N. S. Larina. "Mineral Composition of Sapropelles of Lakes of the Right Bank of the Ob River (Middle Ob Region)." Journal of Molecular Biology Research 9, no. 1 (October 17, 2019): 77. http://dx.doi.org/10.5539/jmbr.v9n1p77.
Full textAbstract:
The objective of this work is to study the mineral composition of bottom sediments of eight small lakes located on the right bank of the Ob River (Western Siberia) in the Surgut region of the Khanty-Mansiysk Autonomous Okrug - Yugra. The studies were carried out using wave dispersive X-ray fluorescence (WDFR) spectroscopy. The content of organic substances, ash, and oxides in the ash in the samples was determined. Based on these data, the studied bottom sediments were classified. The bottom sediments of Lake S-1 are siltstone sands, lakes Vach Lor and S-189 - weakly sapropelic siltstone sands, lakes S-5, S-6, S-3, S-89, and S-294 - typical sapropels. The article presents the content of the main elements in the ash of the studied samples.
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Vallejo, Luis E. "Fractal analysis of the slake durability test." Canadian Geotechnical Journal 31, no. 6 (December 1, 1994): 1003–8. http://dx.doi.org/10.1139/t94-114.
Full textAbstract:
Fragments of siltstone were subjected to the slake durability test. The profiles of the rock fragments experienced changes during the test as a result of saturation and abrasion-induced stresses. The profiles of the fragments were evaluated before and after the test using fractal analysis. Fractal analysis uses the concept of fractal dimension to calculate the roughness of profiles. Before the test, the profiles of the siltstone particles had an average fractal dimension equal to 1.1364. After the test, the average fractal dimension of the profiles became equal to 1.1187. The change in fractal dimension was a reflection of the smoothing action on the particle profiles by the combined effects of abrasion and wetting and drying action that take place during the slake durability test. Key words : durability, shape of rock fragments, fractal dimension.
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Chen, Yue-Gau, Wen-Shoung Wu, Cheng-Hong Chen, and Tsung-Kwei Liu. "A date for volcanic eruption inferred from a siltstone xenolith." Quaternary Science Reviews 20, no. 5-9 (December 2001): 869–73. http://dx.doi.org/10.1016/s0277-3791(00)00047-0.
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