Search

This article discusses the prospects for using large-format ceramic stones in the construction of contemporary homes, as well as an overview of raw materials and technologies for production. The most promising technology is stiff extrusion with the ability to load the raw products on firing trolleys and accelerate the processes of firing and drying. Characteristics of Eastern Donbass waste heaps processing screenings are given, which are coal mining by-products and are considered to be main raw material for the production of large-sized ceramic stone. It is shown that as a result of introduction of waste heaps into the production of ceramic stones with the lowest prime cost, the density of the resulting products will be less than 800 kg/m3, the thermal conductivity will be less than 0.20 m·°C/W, and the strength grade will be M150 and higher. Thus, the use of ceramic stones in total volume of wall products for residential construction will reach the level of 80% and will increase the competitiveness of the material, especially when compared with gas silicate products, as used in Western Europe. High economic feasibility of the production of such materials based on by-products of waste heap processing is shown as well.

The main objective of this research is to propose scheme to solve creep hazards caused by mining. Rock is the main body of underground coal mining, and among them stratified siltstone is very common. Creep of underground stratified siltstone is one of the main inducing factors of ground fissures and ground surface settlement. In this study, the VCM of stratified siltstone was built and theoretically analyzed. Creep tests under multi stress were conducted, also, numerical simulation was carried out with 3DEC. Numerical simulation results under high, medium and low stress were consistent with the creep test results, it made up for the deficiency of traditional creep models in predicting plastic deformation at low stress level. Numerical simulation results showed that under different boundary conditions, the proposed model had advantage to more accurately simulate creep behavior of stratified siltstone compared to traditional models. Also, the numerical simulation results reveled creep characteristics of underground roadway surrounding rock, based on which a supporting scheme was put forward. In the stress adjustment stage, the strain rate dropped significantly from 14.6 mm/day to 10.3 mm/day. Then, it entered the deceleration creep stage. Creep of roadway surrounding rock and ground surface settlement stopped. The creep hazards were solved to a great extent. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper 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.)

In order to reveal the damage and deterioration law of siltstone in Ningming area of Guangxi under dry-wet cycle, the process of water loss and water absorption of rock was simulated by dry-wet cycle test. The variation rules of saturated water content and longitudinal wave velocity of siltstone under dry-wet cycle were analyzed. The degradation characteristics of mechanical parameters and microstructure of siltstone after dry-wet cycles were studied. The damage of siltstone after dry-wet cycle was defined, and the damage of siltstone after loading was defined based on Weibull distribution. The damage evolution equation of siltstone under dry-wet cycle was obtained. The results show that with the dry-wet cycle times increase, the saturated water content of siltstone increases nonlinearly, the longitudinal wave velocity, uniaxial compressive strength and elastic modulus decrease nonlinearly. The exponential function can be used to fit the water content of siltstone, and the trend of change is three stages. The degradation degree of uniaxial compressive strength is more significant than that of uniaxial compressive strength. The stage degradation decreases with the increase of dry-wet cycles, and the total degradation increases with the increase of dry-wet cycles. The peak strain increases gradually, the plasticity of rock samples has developed significantly, and the failure mode changes from brittle failure to plastic failure. [ABSTRACT FROM AUTHOR]

Copyright of Revue Française de Géotechnique is the property of EDP Sciences 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.)

Dinosaur footprints occur in the Upper Cretaceous strata known as the Nubian Sandstone Formation in the south Eastern Desert, Egypt. The Nubian Sandstone unit is subdivided into three informal members: A lower member is marked by reddish‐brown, trough cross‐bedded, coarse‐ to medium‐grained sandstone interbedded with thin beds of varicolored mudstone, reflecting deposition in a braided fluvial system, a middle member is characterized by reddish‐white to yellow, planar cross‐bedded, medium‐grained sandstone with ferruginous siltstone intercalations, interpreted as meandering fluvial deposits, and an upper member consists of repeated coarsening‐upward cycles of rippled siltstone to fine‐ to medium‐grained sandstone and planar cross‐bedded, yellowish‐white sandstone, containing many vertebrate footprints and invertebrate trace fossils, reflecting deposition in a coastal to deltaic environment. Sixteen dinosaur footprints are recorded at the base of the upper member of the Nubian Sandstone, on inclined surfaces of rippled, fine‐grained sandstones. Twelve are overlapping each other and belong to distinct individuals of dinosaurs, the other four are distributed on a younger bedding surface. Twelve footprints are from more than one sauropod dinosaur, while three of the isolated footprints belong to a theropod dinosaur. The footprints described are semiplantigrade and digitigrade. This discovery is the second record of tetrapod footprints in Egypt and the first record of tetrapod footprints in the Eastern Desert. [ABSTRACT FROM AUTHOR]

Shield tunnelling has become the development direction of tunnel construction due to its safety, economy, and speed. The complex formation has complicated geological changes, including soft rock, hard rock, and soft and hard inhomogeneous formation. It is particularly difficult to select and control the tunnelling parameters in shield tunnelling, while the reasonable selection and control of the tunnelling parameters play an important role in the excavation efficiency, tool wear, and surface settlement. Based on the tunnel project between the Dinggong Road North Station and the People's Park Station online 4 of Nanchang Metro during shield tunnelling construction, this paper collects thrust, torque, and revolution speed of the cutterhead during shield tunnelling in the complex strata with differentiated argillaceous siltstone and gravel and analyzes these parameters by means of mathematical statistics analysis, in order to explore the interrelationship between shield tunnelling parameters under different stratigraphic conditions and put forward optimization suggestions for tunnelling parameters, which can provide a reference for control of tunnelling parameters of earth pressure shield in composite strata. [ABSTRACT FROM AUTHOR]

In order to study the creep mechanical properties of surrounding rock under long-term stress, the triaxial creep test of siltstone was carried out by using zyss2000 creep instrument of high temperature and high pressure of rock of Anhui University of Science and Technology. The creep mechanical properties and model applicability of siltstone were analyzed with Burgers model. The results show that: (1) under confining pressure, rock creep undergoes three stages: (a) decay creep stage, rock shows transient elasticity and then tends to be stable; (b) constant creep stage, rock microstructure continuously reorganizes to reach a dynamic balance; (c) acceleration creep stage, rock weakens and yield failure. (2) Based on the analysis of the viscoelastic plastic strain characteristics of triaxial test, the creep deformation of rock increases with the increase of stress level. (3) Combined with the Burgers model and the test results, the fitting effect is good. The model can better explain the creep characteristics of the roadway under the long-term action, which has a good reference value for the analysis of the long-term stability of the roadway. [ABSTRACT FROM AUTHOR]

Paired chemostratigraphic and biostratigraphic data suggest that the Devonian–Carboniferous boundary and the Hangen‐ berg extinction event are recorded in the Coffee Pot Member of the Dyer Formation of the White River uplift region of northwestern Colorado. The Hangenberg isotopic excursion interval occurs in biostratigraphically depauperate shallow plat‐ form micritic dolostone and limestone representing the aculeatus–?ultimus–kockeli? Zone. The Hangenberg interval strata have δ13Ccarb values up to 7.69‰, and locally contain ooids, stromatolites, and other microbial structures. In three sections, there is a short-lived > 4‰ “pre-Hangenberg” positive excursion that is associated with the presence of detrital dolomite siltstone. The main Hangenberg isotopic signature exists in overlying strata, and is replicated in four different sections of the Dyer Formation across an area ~300 km². In each section, the excursion interval is preceded by, and in one location is inter‐ rupted by, evidence of meteoric diagenesis and/or emergence characterized by macroscopic dissolution features and pro‐ nounced negative δ13Ccarb values (to ca. -6‰). Conodont 87Sr/86Sr ratios through the Dyer Formation dip to nearly 0.708 during the onset of the Hangenberg Event, consistent with the brachiopod based 87Sr/86Sr nadir from the same interval in Missouri, France, and Germany. The least-radiogenic trendline through the Dyer 87Sr/86Sr record matches the global mini‐ mum 87Sr/86Sr trendline through the Famennian–Tournaisian transition and infills several gaps in the global record. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) static modelling techniques are applied to the characterization of the Qishn Formation (Fm.) in the Sharyoof oil field locating within the Masila basin, southeastern Yemen. The present study was initiated by the seismic structural interpretation, followed by building a 3D structural framework, in addition to analysing well log data and from these, 3D facies and petrophysical models are constructed. In the Sharyoof oil field, the Qishn Fm. exhibits depth values within the range of 400–780 m below sea level, with a general increase towards the SSE. A set of high dip angle normal faults with a general ENE–WSW trend dissect the rocks. The strata are also folded as a main anticline with an axis that is parallel to the fault trend, formed as a result of basement uplift. According to the facies models, the Qishn Fm. comprises 43.83% limestone, 21.53% shale, 21.26% sandstone, 13.21% siltstone and 0.17% dolomite. The Qishn Carbonates Member has low porosity values making it a potential seal for the underlying reservoirs whereas the Upper Qishn Clastics S1A and C have good reservoir quality and S1B has fair reservoir quality. The Upper Qishn Clastics S2 and S3 also have fair reservoir quality, while the Lower Qishn Clastics zone has good reservoir quality. The water saturation decreases towards the west and east and increases towards north and south. The total original oil in‐place (OOIP) of the Upper Qishn clastics is 106 million STB within the S1A, S1C and S2 zones. Drilling of development wells is recommended in the eastern study area, where good trapping configuration is exhibited in addition to the presence of a potential seal (Upper Qishn Carbonates Member) and reservoir (Qishn Clastics Member) with high porosity and low water saturation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum 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.)

The Coniacian–Santonian Matulla Formation is one of the important reservoirs in the July oilfield, Gulf of Suez Basin. However, this formation is characterized by uncertainty due to the complexity of reservoir architecture, various lithologies, lateral facies variations and heterogeneous reservoir quality. These reservoir challenges, in turn, affect the effectiveness of further exploitation of this reservoir along the Gulf of Suez Basin. In this work, we conduct an integrated study using multidisciplinary datasets and techniques to determine the precise structural, petrophysical, and facies characteristics of the Matulla Formation and predict their complex geometry in 3D space. To complete this study, 30 2D seismic sections, five digital well logs, and core samples of 75 ft (ft = 0.3048 m) length were used to build 3D models for the Matulla reservoir. The 3D structural model shows strong lateral variation in thickness of the Matulla Formation with NW–SE, NE–SW and N–S fault directions. According to the 3D facies model, shale beds dominate the Matulla Formation, followed by sandstone, carbonate, and siltstone beds. The petrophysical model demonstrates the Matulla reservoir's ability to store and produce oil; its upper and lower zones have good quality reservoir, whereas its middle zone is a poor quality reservoir. The most promising areas for hydrocarbon accumulation and production via the Matulla reservoir are located in the central, southeast, and southwest sectors of the oilfield. In this approach, we combined multiple datasets and used the most likely parameters calibrated by core measurements to improve the reservoir modeling of the complex Matulla reservoir. In addition, we reduced many of the common uncertainties associated with the static modeling process, which can be applied elsewhere to gain better understanding of a complex reservoir. [ABSTRACT FROM AUTHOR]

Rock dusts in association with organic sources have been used in agriculture to improve soil chemical characteristics and food composition. In this context, this study aimed to evaluate the effect of the rock dusts siltstone, tephrite, and olivine melilitite pure or combined and associated or not with cattle manure on the chemical composition of soybean seeds of the cultivar BRS 232 grown on a Cambisol and Nitisol subjected to these treatments and conventional fertilization. For this, an experiment was carried out with pots in a greenhouse using a Cambisol and Nitisol to cultivate the soybean from January to May 2019 until seed production. The seeds were harvested, ground, and sieved through a 1 mm mesh sieve to determine the nutrient, phytate, and crude protein contents. The effects of the rock dusts on the chemical composition of seeds were directly related to the chemical characteristics of the evaluated soils. The tested rock dusts had a more pronounced response in the Cambisol (poorer soil) than in the Nitisol (more fertile). The contents and accumulation of nutrients in the seeds, as well as the total dry matter production in both soils subjected to the treatments with the rock dusts olivine melilitite and siltstone + olivine melilitite, pure and combined with manure, were similar and, in some cases, higher than the treatments subjected to conventional fertilization. The combination of manure and rock dusts provided an increase in the concentration of nutrients in both soils, resulting in their higher availability for plants and directly reflecting on the chemical composition of seeds. [ABSTRACT FROM AUTHOR]

This study aimed at writing a suitable permeability model from well logs, and also comparing to select the best empirical permeability model for the Enyenra field. Four (4) empirical permeability models (Tixier, Timur, Coates and Dumanoir, and Wylie and Rose), poro-perm transforms and statistical means of predicting permeability values were applied to eight (8) well log data sets to ascertain the best model for the field. Petrophysical interpretation and Multilinear Regression (MLR) analysis were carried out with the data provided. Results obtained showed that the transform realised from the MLR equation provided the most suitable model for the field that could reduce cost in reservoir characterization. Also, the porosity- permeability cross-plots transforms were suitable for the cored wells while the Timur model was selected as the best predictive method among the empirical models compared. Furthermore, the five (5) lithofacies predicted across all wells from the Self Organizing Maps (SOM) were sandstone (argillaceous), siltstone, mudstone and claystone. Generally, the Turonian reservoirs of the Enyenra Field had good reservoir quality while lithofacies recorded values of permeability ranges of 50-100 mD. [ABSTRACT FROM AUTHOR]

The mechanical properties and post-peak behaviour of rocks are typically determined using axial and circumferential strain control load methods. However, the effects of the load control mode on the mechanical properties and post-peak behaviour of rocks have not been investigated comprehensively. In this study, the mechanical properties and post-peak behaviour of siltstone are investigated using both the axial and circumferential strain control modes. Rock specimens are tested under uniaxial and triaxial compression. Laboratory test results indicate that the compressive strength, residual strength, and fracture angle are smaller when loading is performed via the circumferential strain control mode; however, the elastic modulus is higher. The stress–strain curves obtained from the axial strain control test are those of class I. However, the stress–strain curves obtained from the circumferential strain control test transited from that of class II to class I as the confining pressure increases. The occurrence mechanism of the class II curve and the transition of the stress–strain curve from class II to class I are clarified. The brittleness estimated from the rock specimens under the two load control modes indicate greater brittleness under circumferential strain control loading. [ABSTRACT FROM AUTHOR]

Subway tunnels in Nanchang, China, may pass through one or several weathered argillaceous siltstones in the construction process. To reveal the influence of weathered argillaceous siltstone on the long-term settlement of subway tunnels, dynamic triaxial tests of intensely and moderately weathered argillaceous siltstone were carried out. Based on these tests results, the evolution law of cumulative plastic dynamic strain was analyzed and a prediction model of cumulative plastic strain was established. Finally, an actual subway tunnel with weathered argillaceous siltstone was selected for long-term settlement prediction analysis. The results of settlement prediction indicate that the sedimentation value of this tunnel is approximately 20.87 mm under 100 years of operation (service life). Research results show that the dynamic strain of weathered argillaceous siltstone under cyclic vibration load is mainly affected by dynamic stress and static deviatoric stress. When the static deviatoric stress increased from 0 to 200 kPa, the dynamic strain of intensely and moderately weathered argillaceous siltstone increased by 8.53 and 5.97 times, respectively. Therefore, the intensely weathered argillaceous siltstone (IWAS) is more susceptible to static deviatoric stress than moderately weathered argillaceous siltstone (MWAS). In addition, increasing the confining pressure will accelerate the expansion of fissures in intensely weathered argillaceous siltstone, while the fissures in moderately weathered argillaceous siltstone will be inhibited, and the effect is completely opposite. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience 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.)

Groundwater pumped from the terrigenous Middle Devonian (D2) aquifer system is naturally rich in iron (Fe), making it a challenge to fulfil the requirements for drinking water quality. The total iron (Fetot) concentrations are above the limit value set for drinking water (0.2 mg/L) in 81% of the analysed water samples. The highest Fetot values reach up to 26 mg/L in some locations of southern Estonia. Due to the reducing conditions in the aquifer system, most of the Fetotconcentrations are caused by a high Fe2+ content. Infiltrated aerobic water becomes anaerobic and Fe3+ reducing along a deep flow path, leading to the downgradient increase in dissolved Fe concentrations. In order to study the natural sources of Fe in the Middle Devonian aquifer system, rock samples from the Narva, Aruküla, Burtnieki and Gauja stages were used for chemical analyses and leaching experiments. The whole-rock chemical analyses showed large variation in the Fe2O3 content (1.20â9.91%), whereas the values were higher in aquifer-forming siltstones than in sandstones. The amount of the leached Fe in groundwater is partly controlled by the granulometric composition of terrigenous rocks. The highest leached Fetot (up to 1.7 mg/L) concentrations were detected in the rocks where the share of the sand fraction is over 70%. As a rule, water is abstracted from sandstones having large pores and good groundwater yield, therefore water quality problems could only be solved by installing Fe removal facilities in southern Estonia.

. Rock dusts in association with organic sources have been used in agriculture to improve soil chemical characteristics and food composition. In this context, this study aimed to evaluate the effect of the rock dusts siltstone, tephrite, and olivine melilitite pure or combined and associated or not with cattle manure on the chemical composition of soybean seeds of the cultivar BRS 232 grown on a Cambisol and Nitisol subjected to these treatments and conventional fertilization. For this, an experiment was carried out with pots in a greenhouse using a Cambisol and Nitisol to cultivate the soybean from January to May 2019 until seed production. The seeds were harvested, ground, and sieved through a 1 mm mesh sieve to determine the nutrient, phytate, and crude protein contents. The effects of the rock dusts on the chemical composition of seeds were directly related to the chemical characteristics of the evaluated soils. The tested rock dusts had a more pronounced response in the Cambisol (poorer soil) than in the Nitisol (more fertile). The contents and accumulation of nutrients in the seeds, as well as the total dry matter production in both soils subjected to the treatments with the rock dusts olivine melilitite and siltstone + olivine melilitite, pure and combined with manure, were similar and, in some cases, higher than the treatments subjected to conventional fertilization. The combination of manure and rock dusts provided an increase in the concentration of nutrients in both soils, resulting in their higher availability for plants and directly reflecting on the chemical composition of seeds.

The Regional Connector Transit Corridor (RCTC) project consists of an 89-m long, 17.7-m wide, and 11-m high span crossover cavern constructed beneath critical infrastructure using the sequential excavation method (SEM) at relatively shallow depth (15 m below ground surface) in downtown Los Angeles. The cavern construction involved a complex three-drift, two-sidewall configuration and was excavated in the Fernando formation, a weak clayey siltstone. This paper presents a comprehensive case study of the cavern excavation and initial support construction. The performance of the urban SEM was assessed and complex ground behavior was examined once per excavation step during the construction process. The overall average surface settlement was 20 mm and the largest single-stage incremental movements occurred in the center bench and invert excavation, accounting for 30%–40% of the total deformation. The subsurface experienced less differential settlement during the side drift excavations due to the ovate excavation profile and the restriction from surrounding infrastructure. The measured center crown vertical displacement varied between 5 and 10 mm and the center invert initial support was recorded to heave 8–12 mm. A systematic procedure was developed to apply a deliberate observational method. The lessons learned support that appropriate real-time analysis improves the quality of regular data review, continuously updating the knowledge of risk and enabling prompt adaptions and optimizations of the design and construction along the SEM tunneling process. [ABSTRACT FROM AUTHOR]

The Upper Paleozoic in the eastern Ordos Basin are rich in oil and gas resources, showing great po tential. In recent years, the effectiveness of cap plays a key role in gas accumulation with the deepening research in this area. Based on logging, core data, a logging model for the breakout pressure of the Upper Paleozoic cap rock in the eastern Ordos Basin was built. By applying this model, the spatial distribution and breakthrough pres sure distribution of the Upper Paleozoic cap in the eastern Ordos Basin were studied, which reveals the control ling factors of cap rock sealing ability. By integrating production data, the comprehensive evaluation of rock seal ing ability was discussed. The results show that there are three sets of mudstone caps in the Upper Paleozoic in the eastern Ordos Basin: The Shiqianfeng Formation, the Shangshihezi Formation and the Shanxi Formation. The cap in Shiqianfeng Formation is the thickest with wide distribution, and is in the middle diagenetic A stage. The mudstone has high plasticity and good toughness, showing the relatively high breakthrough pressure and good sealing performance, which is regional cap. The Shangshihezi Formation cap is between the middle diage netic A stage and B stage. However, the pure mudstone is relatively thin due to the frequent interbedded of ar gillaceous siltstone and fine sandstone. Therefore the breakthrough pressure is the lowest, leading to the worst seal ability. The cap at the top of the Shanxi Formation is the thinnest, however, it is in the middle diagenetic B Stage due to the deepest burial depth, and the mudstone plasticity is enhanced, therefore the breakthrough pres sure is the highest and the capping ability is the best. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office 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.)

Reliable ages of proximal conglomerates in the Cordilleran foreland basin that are associated with emplacement and erosion of major thrust sheets are essential for reconstructing the kinematic history of the Sevier fold-thrust belt. Although these conglomerates have been dated by palynology, their absolute ages have been difficult to determine because of their coarse-grained texture and a lack of marine interbeds and tuffaceous deposits. We collected sets of oriented samples from outcrops in northeastern Utah, USA, to construct an overall magnetic polarity stratigraphy that can be correlated to the geomagnetic polarity time scale (GPTS). We sampled fine-grained, hematitic interbeds in the Upper Cretaceous Echo Canyon Conglomerate and Weber Canyon Conglomerate. Common paleomagnetic and rock magnetic analyses were conducted, and several rock magnetic results indicated that the dominant magnetic carriers in these weakly magnetized rocks are hematite and very subordinate magnetite/titanomagnetite/maghemite and goethite. Demagnetization results show that hematitic, fine-grained sandstone to siltstone intervals carry a geologically stable magnetization with directions and polarity consistent with the Late Cretaceous geomagnetic field. A small percentage of samples carry a low laboratory unblocking temperature secondary overprint residing primarily in goethite. Magnetic polarity results indicate that the Echo Canyon Conglomerate is exclusively of normal polarity and that the younger Weber Canyon Conglomerate is of normal polarity in its lowermost part, reverse polarity in the middle, and normal polarity in the upper part of the sequence. The new data indicate that these coarse-grained strata were most likely deposited over the time span of the magnetic polarity Chron (C) 34n to C33r interval and the younger C33r to C33n interval; the former interval includes the Santonian-Campanian stage boundary (ca. 83.4 Ma/83.1 Ma). Palynological data suggest that these rocks span Coniacian-Santonian time (ca. 89--84 Ma); thus, the most parsimonious correlation of the normal polarity magnetozone of the Echo Canyon Conglomerate is with the youngest part of C34n Superchron, which is of ca. 30 Ma duration (ca. 115 Ma to 83.4 Ma/83.1 Ma). The normal polarity magnetozone of the lower part of the younger Weber Canyon Conglomerate likely correlates to the youngest part of C34n, whereas the reverse and normal magnetozone from the middle and upper parts of the Weber Canyon Conglomerate likely correlate to C33r and C33n, respectively. We infer that the Santonian-Campanian boundary resides in the lower Weber Canyon Conglomerate, which implies that deposition of the unit started prior to the C34n/C33r boundary age (ca. 83.4 Ma/83.1 Ma) and continued through the C33r and C33n chrons. Sediment provenance data and growth structures tie the Echo Canyon and Weber Canyon Conglomerates to emplacement of the Crawford thrust sheet. Based on the magnetic polarity data, as constrained by the biostratigraphic age estimates from these synorogenic deposits, we hypothesize that the principal displacement along the Crawford thrust started during the Coniacian (>C34n/C33r boundary age) and continued into the middle Campanian (

In view of the variation law of water level in water injection drill between double- system layers of hard rock strata in Datong mining zone, the failure process and mechanism of boreholes during propulsion are analyzed by the numerical simulation and the test measurement in this paper. After the coal seam is fully mined, it can be divided into the advanced deformation zone, the bending deformation zone and the compaction stable zone. Borehole damage intensifies from top to bottom. The junction of siltstone and sandy mudstone is a high-risk position. The results are verified by the water level measurement and the borehole peeping. [ABSTRACT FROM AUTHOR]

The Serra da Saudade Formation, Ediacaran/Cambrian Bambuí Group, cropping out along the ridge of the same name in Central-Western Minas Gerais, Brazil, contains important deposits of glauconitic siltstones associated with phosphatic rhythmite as well as other siliciclastic, volcaniclastic and carbonate lithofacies. Lithofacies indicate deposition by proximal and distal storm waves on a continental marine shelf. The basal gray siltstone and part of the green siltstone represent a transgressive systems tract. The glauconitic siltstone indicates sea level rise, with the maximum flooding surface located approximately at the interval of highest K2O content. Biogenic carbonate and an upward increase in sandstone beds are interpreted as a highstand systems tract. Gradual lateral facies changes reflect the transition from foredeep (to the west) to forebulge (to the east) deposition in a foreland basin as the final stage of a shallowing-upward second-order sequence. Black organic-rich limestone has d13C values between -8.78 and 9.79‰, negative d18O values from -11.50 to -9.35‰, and 87Sr/86Sr around 0.7075. This isotopic signature, similar to that of other Bambuí carbonates, indicates a probably-restricted depositional environment with organic sedimentation, methanogenesis and high evaporation rates from the Ediacaran through the early Cambrian period. [ABSTRACT FROM AUTHOR]

About 100-1 50 m thick intercalation of dark micaceous siltstone to black clayey shale can be distinguished in the middle part of the Letná Formation (Upper Ordovician, Lower Sandbian) at several localities in the NW and NE parts of the Prague Basin. Sandstone and greywacke, dominant elsewhere in this formation, form only a subordinate part of the sequence. In the NW belt of the Letná Formation, N of the Prague Fault (see Fig. 1C), this thick intercalation has been previously known from Bulovka -Bílá Skála Rock and from Rudolfova Štola Gallery (Rohlich 1956, 1960; Mikuláš 1994). A comparable, slightly thinner, and locally discontinuous intercalation of dark siltstone and black clayey shale was described also in the middle belt of the Letná Formation, S. of the Prague Fault (see Fig. 1C) by Rohlich (1956, 1960); such lithology is known from the Praha - Žižkov, Kyje and Malešice areas. An equivalent of this interlayer was documented by Budil (1996) in the middle part of the Letná Formation from the Černý Most area. No such interlayer of dark, fine-grained sediments has been reported from the southern belt of the Letná Formation (Fig. 1C), most probably because of its much poorer exploration. New borehole documentation at Praha - Střešovice extends our knowledge on the above - discussed dark siltstone and claystone intercalation in the NW belt of the Letná Formation. In two boreholes (HJ 11 and HJ 16), more than 60 m thick sequence of dark, fine-grained sediments has been documented in the middle part of the Letná Formation. The presence of these sediments was confirmed also by the study of archive data - previous geotechnical documentation of this area. The archive data documented the presence of a second, thinner and rather lenslike body of dark, fine-grained sediments which can be traced in the lower third of the Letná Formation in the Střešovice area. It is suggested that the sedimentation of relatively thick sequences of dark siltstones and shales reflects short-time periods of decrease in the input of clastic material. Alternatively, it could correspond to a partial, synsedimentary tectonic-related deepening of respective parts of the sedimentary basin. Locally bioturbated black siltstone and shale sequence is barren of benthos and contains only rare remains of indeterminable linguliformean brachiopods. It is supposed that such association corresponds to the Paterula Community of Havlíček (1982), so far only poorly documented from the Letná Formation (Van Roy et al. 2021). [ABSTRACT FROM AUTHOR]

Ordovician conodonts representing 28 genera and 28 named and three unnamed species were identified from 740 chert and siliceous siltstone spot samples (>3 000 thin sections) from deep-water turbiditic sequences of the Lachlan Orogen in central and southern New South Wales, Australia. Based on these faunas, a new conodont biozonal scheme has been established to divide the Ordovician turbiditic successions of the Lachlan Orogen into 12 superbiozones and biozones. They are (in ascending order) the Paracordylodus gracilis Superbiozone (including the Prioniodus oepiki Biozone), Periodon flabellum Superbiozone (including the Oepikodus evae Biozone in the lower part), Periodon hankensis Biozone, Periodon aculeatus Superbiozone (including the Histiodella labiosa, Histiodella holodentata, Histiodella kristinae, Pygodus serra and Pygodus anserinus biozones) and the Periodon grandis Biozone. The Pygodus anserinus Biozone is divided further into the lower and upper subbiozones. This new conodont biozonation scheme spanning the upper Tremadocian to middle Katian interval permits precise age-dating and correlation of deep-water siliciclastic rocks that characterize the Ordovician Deep-Sea Realm regionally and internationally. [ABSTRACT FROM AUTHOR]

New fossil discoveries are reported from the Grammajukku Formation at Luobákte south of Lake Torneträsk in northern Swedish Lapland, including a fauna of Small Shelly Fossils (SSF) from a limestone bed in the uppermost part of the formation and new occurrences of brachiopods and trilobites in siltstones of the lower part of the formation. The moderately diverse SSF fauna is the first of its kind reported from the Swedish Caledonides and includes the first record of the tommotiid Lapworthella schodackensis and the bradoriid spine Mongolitubulus spinosus from Baltica, together with fragmentary specimens of Bradoria sp. and remains of one additional bradoriid arthropod, a protoconodont and a helcionelloid mollusc. In addition, the limestone bed yields abundant specimens of the brachiopods Botsfordia cf. caelata and Eoobolus cf. priscus and an unidentified ellipsocephalid trilobite. Lower down in the Grammajukku Formation, specimens of both brachiopod taxa, orthothecid hyoliths, the trilobite Ellipsocephalus cf. gripi and an unidentified holmiid trilobite were found at several levels in a siltstone, previously regarded as unfossiliferous. These discoveries markedly increase the known diversity of the palaeobiota from the Grammajukku Formation in northern Lapland and provide new insights into the biostratigraphy and palaeoenvironment of the lower Cambrian in Scandinavia and the palaeobiogeography of Cambrian faunas in general. [ABSTRACT FROM AUTHOR]

• Strength and fatigue properties of argillaceous siltstone under different upper limit loads investigated. • Weakening and strengthening mechanism of argillaceous siltstone under different upper limit loads was revealed. • Increased uniformity of crack size and increased effective bearing surface contribute to rock strengthening. • Crack development tends to become localized and an increase in fracture scale leads to rock weakening. To examine the strength and fatigue characteristics of argillaceous siltstone under varying upper limit loads, cyclic-to-monotonic loads and fatigue failure tests were carried out with the upper limit load in different characteristic stress ranges. At upper limit loads between crack initiation stress and damage stress, the anti-deformation capacity and peak strength of argillaceous siltstone improved considerably after cyclic loading. Rock fatigue failure occurred when cyclic loads surpassed the stress causing damage, and the strain at the control point on the uniaxial compression (UC) curve served as a benchmark for identifying rock fatigue failure. The fatigue strength of the argillaceous siltstone was around 80–89% of the UC strength. The logarithm of fatigue life showed a negative linear correlation with upper limit load. In addition, deformation characteristics and modulus of elasticity also confirmed the weakening and strengthening phenomenon of argillaceous siltstone at various upper limit loads. On the basis of the macroscopic mechanical behaviour and microscopic fracture features of argillaceous quartz sandstone, the weakening and strengthening mechanism of argillaceous siltstone at a range of upper limit loads was revealed. The results indicate that increased uniformity of crack size, reduced degree of fragmentation and increased effective bearing surface contribute to rock strengthening, while crack development tends to become localized and an increase in fracture scale leads to rock weakening. [ABSTRACT FROM AUTHOR]

The siltstone reservoir with many small layers of pay zones is usually produced by slant holes. However, severe sand blockages take place when the siltstone reservoir is developed by slant holes. Currently, the sand blocking mechanisms and the effect of sand blocking on productivity of slant well are still challenges for engineers and scholars. In this paper, based on the existing productivity model of inclined slant wells, the mechanical skin factor, which describes the effect of sand blocking on productivity, is proposed. Meanwhile, many experimental works have been done to investigate the sand blocking mechanisms in siltstone reservoirs. From the experimental work, it is concluded that with the increase of displacement PV number and displacement flow rate, the permeability of sand control system decreases by 40%. When solid particles enter the casing and block the gravel and sand control screen in the annulus, the skin factor increases sharply and the productivity decreases by more than 80%. Through the productivity calculation of multilayer sand control wells, it is considered that larger gravel packing radius can keep particles away from the well bore, which is helpful to ensure oil well productivity. Furthermore, the influence of differential filling radius on the fluid production capacity of each layer of sand control well is analyzed. It is proved that optimizing the filling radius of each layer can improve the production effect of mediate- and low-permeability layers. This method has been applied in Kendong #12 block. The daily oil production rate is increased by 9.61 t/day, and the oil recovery of this block is increased by 2.12%. [ABSTRACT FROM AUTHOR]

Axial compressive capacity estimations determined from pile load tests (PLTs) are compared with theoretical methods for 13 rock-socketed cast-in-situ concrete piles constructed for different projects in Pakistan. Rock strata encountered at the project sites were mostly shale, siltstone, and sandstone. Rock quality designation (RQD) values fall within 20% to 50%, indicating that the rock mass is in fair to good condition, whereas the rock mass rating system yields a classification of poor to fair. The unconfined compressive strength of the rock cores ranges from 1.5 to 18 MPa. The PLT results show the axial compressive capacities are within 2 and 6 MPa. Axial compressive capacities were also calculated using theoretical methods. An equation is presented to determine the relationship between ultimate capacity and RQD using multiple linear regression analyses. The findings provide useful guidelines for selecting suitable and economical methods for the axial compressive capacities of rock-socketed cast-in-situ concrete piles. [ABSTRACT FROM AUTHOR]

The roof of coal seams are mostly soft rock with weak cementation. To further study the mechanical characteristics and deformation control scheme of the roadway with weakly cemented siltstone as roof, this paper took Linchang coal mine as the research background and adopted field investigation methods, laboratory experiments, and theoretical analysis. Using a scanning electron microscope, it is found that the weakly cemented siltstone is composed of coarse-grained minerals with a high degree of pore development. According to the analysis, the instability factors of weakly cemented siltstone roadway include the late diagenetic age of rock, the low mechanical strength of rock, and the change of surrounding rock properties by pouring water. The selection of grouting reinforcement materials was studied in detail. The test results show that cement-bonded specimens' strength is lower than that of Marithan polyurethane cement specimens in general. The combined support scheme based on grouting reinforcement is put forward. Field monitoring data show that the designed support scheme can effectively control the surrounding rock deformation of weakly cemented siltstone roadway. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of geological, structural geological, hydrogeological and geotechnical features of the host rock are essential for the design and performance evaluation of surface and underground excavations. The Hungarian National Radioactive Waste Repository (NRWR) at Bátaapáti is constructed in a fractured granitic formation, and Telfer Gold Mine in Australia is excavated in stratified siltstones, sandstones and quartzites. This study highlights relationships between GSI chart ratings and calculated GSI values based on RMR rock mass classification data. The paper presents linear equations for estimating GSI from measured RMR89 values. Correlations between a and b constants were analyzed for different rock types, at surface and subsurface settings. [ABSTRACT FROM AUTHOR]

In this work, the potential of a novel and highly efficient composite of Eleocharis dulcis biochar with magnetite nanoparticles and siltstone was explored for removing chromium from water. Characterization of the prepared biochar composite was carried out using thermal gravimetric analysis (TGA), X-ray photon spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy, point of zero charge and BET. XRD confirmed magnetite and quartz to be the main phases in biochar composite. TGA results showed higher thermal stability of the composite after the addition of siltstone. Batch adsorption mode was employed for studying the adsorption capacity of sample for the decontamination of chromium as a function of concentrations, time, temperatures and pHs. Kinetic modelling confirmed pseudo second order to fit best to the kinetic data for chromium adsorption on the composite biochar. An increase of adsorption was observed with the rise in temperature from 303 to 318 K showing the endothermic nature of the process whereas pH study showed higher removal efficiency of chromium in the acidic pH range. Langmuir model was applicable to the data with higher value of correlation. The thermodynamic parameter ΔH° (40.46 kJ mol−1) and negative but higher values of (ΔG°) shows the endothermic and spontaneous nature of the adsorption process respectively. Higher value of activation energy (15.08 kJ mol−1) confirmed the chemical nature of the process. Post adsorption FTIR and XPS confirmed the adsorption of chromium on the surface of the composite. The adsorption capacity obtained in the present study was found to be higher as compared to many other reported adsorbents used for chromium removal. [ABSTRACT FROM AUTHOR]

A low diversity Sinuites-dominated gastropod community is described from the Floian, Arenig Series, of the Llangynog Inlier, southwest of Carmarthen, South Wales. The abundant material comes from shallow-water siltstone and mudstone beds of the Bolahaul Member of the Ogof Hên Formation. The locality has an exceptionally diverse mollusc-dominated fauna (63.5% of the fauna), with gastropods constituting 6% and tergomyans 1% and echinoderms, arthropods and other fauna making up the rest. Except for one rare tergomyan mollusc, identified as Carcassonnella cf. vizcainoi, other tergomyans are described elsewhere. Nearly half of all gastropod specimens are represented by Sinuites ramseyensis. Three of the five taxa described are new: Mimospira llangynogensis sp. nov., Catalanispira prima sp. nov., and Ceratopea? moridunensis sp. nov. The assemblage compares best with those of contemporaneous high-latitude peri-Gondwana areas. Early Ordovician species of Carcassonnella are typically found in France, Iberia, Czech Republic, and Morocco, while species of Mimospira are found in Germany and Czech Republic, but also in Baltica where the main radiation took place later. Two of the oldest occurrences of Mimospira are from Avalonian Wales (Carmarthenshire and Anglesey). Catalanispira occurs later in Baltica and Laurentia in the late Middle and early Late Ordovician, when taxa from these areas start to appear in Wales and vice versa. The presence of Ceratopea?, a genus typical of Laurentia, is at odds with the biogeographic distribution of faunas at this time. Part of the observed distribution pattern may be explained by different latitudinal position and facies depths of Avalonia compared to Armorica, Bohemia, and Morocco. The species described herein are amongst the first Floian taxa of these groups formally described from this area and add significantly to the global Floian record. [ABSTRACT FROM AUTHOR]

The Montney tight siltstone reservoir is a multi-stacked play, which covers a total area of 130,000 km2 along the Alberta–British Columbia border in Western Canada. Since the late 1990s, different fracturing methods and fluids have been tested in 4000-plus Montney wells to find the optimal fracturing method and fluid. The previous studies reviewing the performance of fracturing methods in Montney do not represent a holistic evaluation of these methods, owing to some limitations, including: (1) using a small sample size, (2) having a limited scope by focusing on a specific aspect of fracturing (method/fluid), (3) relying on data analytics approaches that offer limited subsurface insight, and (4) generating misleading results (e.g., on optimum fracturing method/fluid) through using disparate data that are unstructured and untrustworthy as a result of significant regional variations in true vertical depth (TVD), geological properties, fluid windows, completed lateral length, fracturing method/fluid/date, and drawdown rate management and choke size strategy. The present study eliminates these limitations by rigorously clustering 4000-plus Montney wells based on the TVD, fluid window, completed lateral length, fracturing method/fluid/date, and drawdown rate strategy to isolate the effect of each fracturing method by comparing each well's production to that of its offsets, which use different fracturing methods but possess similar geology, fluid window, and TVD. With similar TVD, fracturing fluid, and completion date, wells completed with pinpoint fracturing method outperform their offsets completed with ball-and-seat and plug-and-perforate (PnP) fracturing methods. However, wells completed with ball-and-seat and PnP methods that outperform their offset pinpoint wells have either: (1) been fractured one to four years earlier than the pinpoint wells and/or (2) used energized oil-based fluid, hybrid fluid, and energized slickwater versus slickwater used in the pinpoint offsets. This suggests that the water-phase trapping is more severe in these pinpoint wells attributable to the use of slickwater. Previous studies often favored one specific fracturing method or fluid without highlighting these complex interplays between the type of fracturing method, fracturing fluid, completion date (regional depletion or well vintage), and the reservoir properties and hydrodynamics. [ABSTRACT FROM AUTHOR]

However, the value of crack closure stress ( I i SB cc sb ) and crack initiation stress ( I i SB ci sb ) will be clearly changed by small fluctuations of Poisson's ratio. If the stress level is higher than the crack damage stress ( I i SB cd sb ) but lower than peak strength ( I i SB f sb ), cracks will propagate continuously and coalescence to reach macroscopic failure. 6 Curves of lateral strain difference for a siliceous siltstone and b limestone Moving Point Regression Method (MPR) Eberhardt et al. ([4]) proposed a new method to obtain the crack closure stress ( I i SB cc sb ) and the crack initiation stress ( I i SB ci sb ). If the stress level is higher than crack initiation stress ( I i SB ci sb ) but lower than crack damage stress ( I i SB cd sb ), cracks randomly initiated but they will cease at a certain length without coalescence. [Extracted from the article]

Six lithofacies were identified in the Lokoja Formation, Southern Bida Basin: fanglomerate/conglomerate lithofacies (Gmc), fine to coarse-grained ferruginized weakly cross-bedded, pebbly sandstone lithofacies (Scx), fine to coarsegrained sandstone lithofacies (Sfc), silty claystone lithofacies (Csm), siltstone lithofacies (Slt) and lateritic ironstone lithofacies (Ilt). These were grouped into three lithofacies associations viz: alluvial fan, braided river channel, floodplain lithofacies association. Nine lithofacies were identified in the Ahoko Formation. These are: black-dark grey carbonaceous shale lithofacies (Shc), bioturbated ripple-laminated siltstone lithofacies (Sbr), poorly cross-laminated claystone lithofacies (Cxl), concretionary/nodular ironstone lithofacies (Icn), medium to coarse-grained sandstone lithofacies (Smc) fine grained, well-sorted, friable bioturbated herringbone cross-bedded sandstone lithofacies (Sxf), massive brownish claystone lithofacies (Clm), massive claystone with lateritic ironstone lithofacies (Cli) and lateritic ironstones lithofacies (Ilt). These have been grouped into three lithofacies associations viz: shallow marine lithofacies association, tidal-intertidal flat lithofacies association and floodplain lithofacies association. Similarly, three lithofacies were identified in the Agbaja Formation and have been grouped into two lithofacies association. These are: fine to medium-grained sandstone ironstone interbedded lithofacies (Sti), oolitic-pisolitic ironstone lithofacies (Iop) and concretionary ironstone lithofacies (Icr). The lithofacies associations are: tidal-intertidal flat lithofacies association and shallow marine lithofacies association. Result of lithofacies analysis helped in interpreting the depositional environments. The Lokoja Formation is a product of a fluvial dominated alluvial system from debris/gravity flow in alluvial fan. This developed further into braided river channels and later meandering river during the closing stages. Sediments of the Ahoko Formation were deposited in tidal/intertidal flats and shallow marine environments while sediments of the Agbaja Formation were produced by a shallow marine system with a high tidal influence. [ABSTRACT FROM AUTHOR]

Balıkkaya formation consists of olistostromal units with a burgundy coloured mudstone, siltstone and pelagic limestone matrix containing various sizes of UpperJurassic-Lower Cretaceous limestone (Bilecik Limestone) blocks and Triassic Karakaya Complex blocks, which crop out in the west, south and southwest of Biga Town in Biga Peninsula (NW Anatolia). The matrix of Balıkkaya formation, of which age and sedimentary environment are controversial, contains Late Cretaceous (Maastrichtian) Abathomphalus mayaroensis (Bolli), Abathomphalus sp., Rosita fornicata (Plummer), Globotruncanidae, early Paleocene (Danian) Morozovella pseudobulloides (Plummer), late Paleocene (Thanetian) Morozovella velascoensis (Bolli), early Eocene Acarinina pentacamarata (Subbotina), middle Eocene Turborotalia frontosa (Subbotina), Turborotalia cerroazulensis (Cole), Orbulinoides beckmanni (Saito), Hantkenina sp. pelagic foraminifera and Radiolariafossils representing the deep marine environment. These paleontological, lithological and sedimentological data obtained from Balıkkaya formation show that Balıkkaya formation developed in a deep marine environment under tectonic control starting from Late Cretaceous and ending in early-middle Eocene. This pelagic unit indicates the presence of a extensional tectonic regime on the Biga Peninsula and the fault activity along the southeastern edge of the Thrace Basin in the Late Cretaceous-Middle Eocene time interval. [ABSTRACT FROM AUTHOR]

The point load test is an indirect method to estimate the uniaxial compressive strength (UCS) of rock. In order to investigate the influence of the shape effect on the point load test strength of the siltstone in the Red Stratum, a series of point load tests were carried out on siltstone specimens with different shapes (cylinders, blocks, irregular specimens). The results show that the point load strength index of red-bed siltstone specimens with different shapes exhibits significant dispersion. As long as being corrected, the specimen shape has no significant effect on the point load strength index Is(50). The average value of Is(50) from formula correction is consistent with the value obtained by the graphical method with all different shape specimens in consideration. An empirical relation is proposed for the estimation of UCS by the point load strength IS(50). The red-bed siltstone specimens under the point load test are broken into two pieces or three pieces, but the former failure is dominant. [ABSTRACT FROM AUTHOR]

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias 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.)

Object . The zonal pyrite nodules and metacrystals from siliceous siltstones of ore-bearing horizon of the Second ore body from the Yubileynoe massive sulfide deposit are studied. Materials and methods . We used 9 samples and 15 polished sections of siliceous siltstones with pyrite mineralization. Analysis of chemical composition minerals was determined by Tescan Vega 3 with an energy dispersive microprobe Oxford Instruments X-act (Institute of Mineralogy UB RAS, Miass). Quantitave LA-ICP-MS analysis of pyrite for major and trace elements was carried out using New Wave Research UP-213 laser microprobe coupled to an Agilent 7500 quadrupole ICP-MS housed (University of Tasmania, Australia). Results. Microtopochemistry was established that the diagenetic core of the nodule is characterized by trace elements of typical poikilites of quartz (Si) and alumosilicates (Si, Al, Mg, V, Cr, K, Na, Ca), rutile and titanite (Ti), inclusions of chalcopyrite (Cu), sphalerite (Zn), galena (Pb, Sb, Bi), tetrahedrite-tennantite (As, Sb), native gold, petzite, hessite (Au, Ag, Te), tellurobismuthite, altaite, and coloradoite (Te, Bi, Pb). Cobalt and Ni substitute for Fe2+. The rim of subhedral pyrite is depleted in most trace elements except for Ni and As. Subhedral pyrite became rich in chalcophile (Au, Ag, Sb, Bi, Cu, Zn, Hg) and lithophile (Ca, K, Na, Cr) elements at the final stage of growth of the nodule. Similar mineralogical and geochemical zonation is typical of the pyrite metacrystals, where a micro-grained core concentrates Pb, Bi and Te, and a rim of subhedral pyrite is depleted in most trace elements. Similarly to the nodules, the outer rim of pyrite metacrystals is enriched in most trace elements (Pb, Au, Ag, Sb, Cu, As, Mo, Cr, etc.). The nodules and metacrystals were formed from diagenetic micronodule of poikilite pyrite. Conclusions. It is suggested that mineralogical and geochemical differences in pyrite metacrystals and nodules are caused by the greater degree of development of rims of subhedral pyrite.

The stratigraphic sequence exposed in Wandhaya area comprises of marine clastic sediments of Mesozoic, which includes M-III and M-IV of Jumara Formation, Lower Member of Jhuran Formation and Upper Member of Bhuj Formation. Lithofacies erected from the study area are Shale Facies (SF), Oolitic Limestone Facies (OLF), Intercalated Shale Siltstone Facies (ISSF) and Massive Sandstone Facies (MSF). SF is developed in M-III and M-IV of Jumara Formation suggesting its deposition in transition zone. Oolitic Limestone Facies (OLF) occurs only in M-IV of Jumara Formation indicates its depositional environment as offshore region. Intercalated Shale Siltstone Facies (ISSF) is deposited in lower shoreface to transitional and Massive Sandstone Facies (MSF) in foreshore environment, are exposed in Lower Member of Jhuran Formation and also in Upper Member of Bhuj Formation. The sediment characteristics and association of trace fossils in the rocks indicate distinction in sedimentation from foreshore to offshore environments. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience 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.)