Limestone Fragments Research Articles

New Design Criteria for Long, Large-Diameter Bored Piles in Near-Shore Interbedded Geomaterials: Insights from Static and Dynamic Test Analysis

This paper presents an analysis of long, large-diameter bored piles’ behavior under static and dynamic load tests for a megaproject located in El Alamein, on the northern shoreline of Egypt. Site investigations depict an abundance of limestone fragments and weak argillaceous limestone interlaid with gravelly, silty sands and silty, gravelly clay layers. These layers are classified as intermediate geomaterials, IGMs, and soil layers. The project consists of high-rise buildings founded on long bored piles of 1200 mm and 800 mm in diameter. Forty-four (44) static and dynamic compression load tests were performed in this study. During the pile testing, it was recognized that the pile load–settlement behavior is very conservative. Settlement did not exceed 1.6% of the pile diameter at twice the design load. This indicates that the available design manual does not provide reasonable parameters for IGM layers. The study was performed to investigate the efficiency of different approaches for determining the design load of bored piles in IGMs. These approaches are statistical, predictions from static pile load tests, numerical, and dynamic wave analysis via a case pile wave analysis program, CAPWAP, a method that calculates friction stresses along the pile shaft. The predicted ultimate capacities range from 5.5 to 10.0 times the pile design capacity. Settlement analysis indicates that the large-diameter pile behaves as a friction pile. The dynamic pile load test results were calibrated relative to the static pile load test. The dynamic load test could be used to validate the pile capacity. Settlement from the dynamic load test has been shown to be about 25% higher than that from the static load test. This can be attributed to the possible development of high pore water pressure in cohesive IGMs. The case study analysis and the parametric study indicate that AASHTO LRFD is conservative in estimating skin friction, tip, and load test resistance factors in IGMs. A new load–settlement response equation for 600 mm to 2000 mm diameter piles and new recommendations for resistance factors φqp, φqs, and φload were proposed to be 0.65, 0.70, and 0.80, respectively.

Age and origin of closed depressions in the Paris Basin: A majority of marl pits dug since the Neolithic period?

Marling (limestone alkaline amendment) agrarian practices have a plurimillennial influence on soil pH and on soil-associated ecosystems. Although the earliest written records in Europe date back to antiquity, the origin of this agrarian practice is not well known. In order to trace the evolution of this practice in the early agrarian societies of Western Europe, we searched for topographic anomalies of ancient limestone quarries that may have been used for marling. Four hundred circular closed topographic depressions (CDs) were identified under two areas of ancient forest in northern France with Lidar digital elevation models (DEMs). Soils, morphology and archaeological context were studied and filling sediments were dated in several dozen CDs.The gaps in the carbonate rocks, soils with calcaric properties (scattered limestone fragments), unstratified fills, the absence of buried paleosols, and dates (OSL, C-14) later than the first local agricultural societies made it possible to recognise the CDs that may have served as limestone quarries. This was the case for most of the 30 CDs studied, leaving a minority of natural origin (suffosion, depressions of thermokarstic origins). Amongst the quarries identified, the preferential excavation of soft (friable) limestone and the location of these quarries in fossil agrarian plots led us to hypothesize that they were used for alkaline amendments of the cultivated fields. The quarries were filled from the Middle Neolithic to Late Antiquity, shortly before the period of afforestation of these former agrarian territories.

Impact-induced fragmentation of coral reef limestone based on fractal theory

Impact-induced fragmentation of coral reef limestone based on fractal theory

Application of Air Deck Method to Reduce the Impact of Ground Vibration and Optimization of Limestone Fragment Size in Blasting Activities at PT Semen Baturaja (Persero), Tbk.

The field experiment of applying the air deck method to the limestone blasting activities of PT Semen Baturaja (Persero), aims to reduce the impact of ground vibration considering that mining activities are approaching residential areas. In addition, the size of the fragmentation of the blasting results is very important for the effectiveness of the crushing plant. To determine the effectiveness of the application of the air deck method in limestone mining (quarry), blasting planning activities are carried out by dividing the two blasting locations, namely blasting with the air deck method and without using an air deck. By using a zig-zag blasting pattern and the number of holes of 50 Lb, the depth of the drill holes is 9 meters (without air deck) and 13 meters and the type of explosive used is Nonel. From the results of the analysis of limestone blasting with data processing using the split desktop 2.0 demo application, the ground vibration value (micromater system) was obtained. The average value of ground vibration (pVS) shows a smaller value using the air deck method of 0.68 mm/sec while without air deck of 0.74 mm/sec. The results of limestone fragmentation analysis with the air deck method obtained size <75cm reached 91.93%, while for without air deck it was 80.27%. These results show that the air deck method can be applied as a method to assist the Company in reducing ground vibration and limestone fragmentation effectively and efficiently by considering natural factors including geographical factors.

ARCHAEOLOGY OF THE 16th CENTURY CHURCH IN THE ST. NICHOLAS IN UGRESHA MONASTERY (works in 2004)

The article publishes materials from excavations of one of the stone churches lost in the 1930s–1940s in the monastery of St. Nicholas “in Ugresha” in the Moscow vicinity. In 2004, the remains of its basement masonry were cleared, which contained a large amount of spolia from an earlier church of the 15th – first half of the 16th century. A part of the monastery cemetery of the 14th–15th centuries was investigated, the site stratigraphy was established. The paper presents a complete plan and cross-sections of the structure, as well as all the limestone fragments found there. The article accompanies the research of A.L. Batalov, which focuses on the history of the church after written and visual sources, published in the same issue.

Development of a methodology for the characterisation and assessment of biodeteriogens on archaeological surfaces by use of a portable LED-induced fluorescence instrument

The present study focuses on the development of a fast, non-invasive methodology, appropriate for the detection and characterization of biodeterioration present on the surface of archaeological/historical stone objects and monuments, by exploiting the characteristic fluorescence emission of biological deposits. Fluorescence spectra were collected by use of a portable LED (Light Emitting Diode)-Induced Fluorescence (LED-IF) instrument. Three limestone fragments and one mortar fragment, from different monuments in Greece, presenting various types of biodeterioration on their surface, have been investigated in the laboratory. First, fluorescence emission spectra were acquired with a benchtop laboratory spectrofluorometer in order to select the optimum excitation wavelengths for the fluorophores present in the biological crust. An evaluation of the portable LED-IF instrument was conducted by assessing the performance of its optical components and different LED excitation sources, while an investigation of several experimental parameters on the fluorescence signal was also performed. Furthermore, issues related to the efficiency of detection and identification of biological growth have been studied, such as the effect of sample surface wetting on the fluorescence signal. The results of the present study demonstrate that the LED-IF instrument can be used for a fast and reliable assessment of the presence of biodeterioration on monuments.

The Flims rock avalanche: structure and consequences

The Flims rock avalanche has a gliding surface that cuts down section in a limestone sequence and does not follow a weak horizon. The gliding surface is parallel to bedding and/or to the penetrative Alpine foliation in the limestone that is characterized by a shape-preferred orientation of calcite grains. Predisposition was governed by structural weaknesses in form of sub-vertical fault zones within solid limestone. Faults controlled the orientation of lateral scarps of the rock avalanche. The main body of the rock avalanche behaved as semi-coherent mass, which preserved the original overall structure. The internal deformation occurred by dynamic fragmentation, which was distributed rather heterogeneously. Fragmentation starts by the formation of veins consisting of comminuted limestone. In a later stage crosscutting veins coalesce to form a texture with entirely comminuted limestone (“rock flour”) containing angular shattered fragments of limestone of variable sizes. The involvment of the post-glacial water-saturated substrate contributed to the long-runout of the Flims rock avalanche. The substrate was plowed bulldozer-wise at the front of the rock avalanche and escaped upward through the moving rock avalanche as clastic dikes and blow-out pipes. Bulldozing raised the valley floor in front of the rock avalanche by more than 100 m and, on the margins, entrained pieces of the valley flank and the neighboring, older Tamins rock avalanche deposit. The liquefied substrate breached the Tamins rock avalanche at Reichenau and entrained fragments thereof down the valley. The fragments now form the famous tumas of Domat/Ems, Felsberg and Chur. Lake Ilanz, dammed the by Flims rock avalanche, experienced a first major outburst shortly after its formation.

Study on the dense structure and properties of cement-stabilized coral aggregates

The performance of cement stabilized coral aggregates semi-rigid base of pavement with coral reef limestone fragments and biological debris as the main materials is essential in the current reef engineering constructions. The performance of inorganic mixtures such as cement-stabilized coral aggregates mainly depends on the packing state of aggregates and the interfacial bonding among each component. Via digital image analysis theory, a simulation model of the dense packing of particles method was established, considering the influence of arbitrary particles shape distribution, upper limit of particles size, and aggregates gradation. The influencing mechanism of different factors on the packing state was revealed. It was found that the dense packing of coral aggregates is a strong suspension dense structure which did not form the skeleton structure. The strengthening mechanism of the coral particle-coated cement slurry was studied through the experimental analysis of the pore structure of coral rocks and debris particles and the crushing strength of particle-coated cement slurry, combined with the microhardness test of the cement- coral particle interface and the analysis of hydration products. The physicochemical excitation mechanism of hydration products densification，“physical interlocking” and “micro pump” effect at the interface of the cement-coral particle was revealed. Furthermore, based on the macroscopic mechanical properties of cement stabilized coral aggregates, the optimal design ratio of coral aggregates with upper limit particle size of 53mm, fine aggregates content of 45% and cement content of 8% was proposed. The findings of this study can provide a reference for the design and application of cement stabilized coral aggregates semi-rigid pavement base.

РОЛЬ ДРЕВНЕГО КАРСТА В ФОРМИРОВАНИИ МЕСТОРОЖДЕНИЯ УРАНА (ГОРНАЯ ШОРИЯ)

Marmorized limestones of the Upper Proterozoic are widely viewed as host rocks of the Labysh deposit. The formation of uranium ores in carbonate rocks does not correspond to existing сoncepts of the uranium ore process geochemistry. A detailed study of lode ores of the deposit showed that karst cavities were originally filled with limestone fragments of different sizes and finely-dispersed kaolinite. Further, an input of thermal alkaline solutions led to the leaching of earth silicon of metamorphogenic limestone silicates and formation of “silicinate–tar” veins. In fact, the rocks hosting mineralization are morphologically veined sedimentary wellpermeable rocks with geochemical properties approximating to hydrothermally altered rocks of intermediate composition.

Autochthonous nutrient recycling driven by soil microbiota could be sustaining high coconut productivity in Lakshadweep Islands sans external fertilizer application

The soils of Lakshadweep Islands are formed as a result of the fragmentation of coral limestone, that iscarbonate-rich, with neutral pH, but poor in plant nutrients. Coconut palm (Cocos nucifera L.) isthe main crop cultivated, supporting the life and livelihood of the islanders. No external fertilizer application or major plant protection measures are adopted for their cultivation as the Islands were declared to go organic decades back. Yet, Lakshadweep has one of the highest productivity of coconut compared with other coconut growing areas in India. Therefore, a question arises: how is such a high coconut productivity sustained? We try to answer by estimating in three main islands (i) thenutrients added to the soil via the litter generated by coconutpalms and (ii) the role of soil microbiota, including arbuscular mycorrhizae, for the high productivity. Our results indicatedthat, besides adding a substantial quantum of organic carbon,twice the needed amount of nitrogen, extra 20% phosphorus to the already P-rich soils, 43-45% of potassium required by palms could be easilymet by the total coconut biomass residues returned to the soil.Principal Component Analysis showed thatsoil organic carbon %, potassium, and organic carbon added via the palm litter and AM spore load scored >± 0.95 in PC1, whereas, available K in the soil, bacteria, actinomycetes, phosphate solubilizers and fluorescent pseudomonads scored above >± 0.95 in PC2. Based on our analysis, we suggest that the autochthonous nutrients added via the coconut biomass residues, recycled by the soil microbial communities, could be one of the main reasons for sustaining a high productivity of the coconut palms in Lakshadweep Islands, in the absence of any external fertilizer application, mimicking a semi-closed-loop forest ecosystem.

ARCHAEOLOGICAL EXPLORATION OF THE FORTIFICATION OF ANNALISTIC VOLODYMYR IN 2018

For the first time in the history of archeological research in Volodymyr the cross-section of the ramparts of «Valy» hill-fort were made. According to external morphological features the hill-fort belongs to the «Volyn type», and most researchers consider it to be remains of the citadel of annalistic city. There is no direct evidence of the latter but the available written sources directly indicate the location of the brick castle of Casimir the Great in the 14th century and the later wooden-earthen headman’s castle. Just the main task of the work was to ascertain the conformity of the ramparts to these objects.
 The internal structure of the rampart was explored by laying a stepped trench measuring 2 × 11 m at the end of the rampart at the place of its gap (entrance to the territory of hill-fort). The cross-section made it possible to record the stratigraphic column of layers and backfills for more than 6 m long and to ascertain the general picture of the rampart construction.
 It was learned that the embankment of the rampart was carried out above the level of the cultural layer which occured on a yellow homogeneous loess-like loam (possibly the virgin soil). The generalization of the layers traced above for 5.96 m allows us to identify three of their main groups which probably reflect the sequence of erecting of the rampart at this area.
 The first large-scale backfill, which formed the basis of the embankment, was traced in the square 5. It consisted mainly of yellow loess-like loam with inclusions of limestone fragments.
 The middle part of the embankment was explored in squares 2—4, where the complex stratigraphic sequence of various layers and strata have been traced, which, in addition to loess-like yellow loam with limestone fragments, included the larger backfills of dark gray sand with inclusions of yellow loam and the same soil with inclusions of debris.
 Finally, the upper part of the embankment, explored in the square 1, consisted of dark gray humused sand with inclusions of clay and charcoal. Since this layer contained a lot of pottery of the Late Middle Ages, it is possible that this is a filling of the late medieval building inserted into the embankment.
 The research revealed material from different times, dating from the Bronze Age to nowadays. The dating of the embankment of rampart is indicated by the findings of late medieval pottery in its middle part. They confirm the written reports about the construction of a wooden-earthen headman’s castle in the 15th century.
 Some structural features of the rampart are in good agreement with historical data. In particular, the first backfill at the base of the embankment of yellow loess-like loam had significant inclusions of fragments of limestone, which may be the remains of the masonry of the walls of Casimir the Great castle, dismantled in 1370.
 Dating the construction of rampart to the 15th century indicates that the explored hill-fort was not the citadel of Old Volodymyr. On the other hand, it allows us to re-date at least the part of hill-forts of «Volyn type», which are traditionally attributed to the 10th—11th centuries.

KINEMATIC ANALYSIS OF BALANTAK FAULT USING FAULT-SLIP DATA IN BALANTAK AREA, BANGGAI REGENCY, CENTRAL SULAWESI

Balantak is one of the sub-districts in Banggai Regency, Central Sulawesi Province. The research area is along the Balantak Strike-Slip Fault. This study presents geological mapping with focus on the deformation style that occurred within the area. The study provides an analogue of strike-slip structural trap types in convergent setting to support oil and gas field development. This research method was conducted using field observation and kinematic analysis of fault-slip data. Lithology in the study area that is part of the Banggai-Sula microplate has the characteristics of sedimentary rocks that are grainstone intercalating calcareous sandstone and rudstone consisting of limestone fragments. While part of the Sulawesi East Arm has crystalline rocks in the form of ultramafic-mafic rocks such as Peridotite, Serpentinite, Gabbro and Basalt. Structural analysis along the strike-slip fault indicates the collision of Banggai-Sula with Sulawesi East Arm on the side part of the micro-plate generates thrust fold belt along with well-developed uniform tearing faults present. The orientation and shape of the strain ellipsoid is pure shear transpression with the Balantak Fault as its plane of movement. The characteristic of the structure pattern complying with the model shows that the type of structures is en echelon thrusts and folds while the tearing faults are Riedel synthetics of the Balantak dextral Strike-Slip Fault that developed offset on the fold structures.

Cretaceous uplift history of the Tibetan Plateau: Insights from the transition of marine to terrestrial facies in central Tibet

The uplift of the Tibetan Plateau has been widely associated with India-Asia continental collision during the Cenozoic. However, recent studies have proposed that a proto-Tibetan Plateau in central Tibet was elevated during the late Mesozoic. This paper improves that understanding by focusing on the Cretaceous terrestrial strata in the Gerze area of central Tibet. Our studies suggest that the Qushenla Formation in the Nare area contains alluvial fan conglomerate intercalated with rhyolitic ignimbrite and vesicular rhyolite. Zircon UPb dating of rhyolitic ignimbrite (103.9 ± 1.4 Ma) and two granitoid boulders of conglomerate (106.0 ± 1.6 and 106.1 ± 1.5) indicate that the Qushenla Formation was deposited during the late Albian. The compositions of the Qushenla Formation conglomerate were dominated by hypabyssal intrusions on the southern Qiangtang terrane, which recorded a rapid uplift and denudation process in the late Albian, accompanied by intense volcanic eruptions. The second set of terrestrial strata is the Upper Cretaceous Jingzhushan Formation alluvial fan-braided river deposits, which can be divided into a lower conglomerate member (Member 1) and a upper sandstone member (Member 2). The large amount of bioclastic limestone fragments in the Member 1 show that they come from the Upper Cretaceous Langshan Formation in the central and northern Lhasa subterranes. While in the Member 2, abundant limestone debris, detrital zircon yielding Jurassic–Cretaceous ages with εHf(t) values between −18.6 and + 8.4, and occurrence of volcanic and ancient zircon grains indicate a volcanic-sedimentary source located in the central and northern Lhasa subterranes, with some input from the Bangong-Nujiang suture zone. This suggests that the central and northern Lhasa subterranes experienced rapid crustal uplift in the Late Cretaceous, thus ending the marine sedimentary environment since the Jurassic. Based on the temporal and spatial sedimentary characteristics of the Qushenla and Jingzhushan formations as well as the regional data, our integrated study suggests that the central plateau (Lhasa and southern Qiangtang terranes) experienced a complex uplift history during the Aptian-Turonian, with southwards stepwise growth in time and space. Furthermore, the uplift mechanism of the central plateau is complex, which was controlled by the diachronous closure of the Bangong-Nujiang Tethyan Ocean from east to west during the Early Cretaceous, and by the far-field forces associated with northwards subduction of the Neo-Tethys Ocean during the Late Cretaceous.

Assessment of Bholari River Sand for its Geotechnical Characterization as Fine Aggregate

Present study is aimed at assessment of Bholari river sand for its geotechnical characterization and suitability as fine aggregate which is being quarried in Jamshoro district, Sindh, Pakistan. For this purpose, sand samples (n=11) were collected from quarry sites and main river channel. Physical properties reveal that Bholari sand is mainly coarse to fine in size (0.2 mm-5 mm). Average values of fineness modulus, specific gravity, bulk density and void content of collected samples are 2.58, 2.56, 1659.90 kg/m3 and 35.12% respectively which varied within the corresponding permissible ranges of ACI (American Concrete Institute). Carbonate content of about 57.59% is also in agreement with corresponding range for fine aggregate. Petrographic examination revealed that Bholari River sand mainly comprises of quartz and rock fragments with subordinate limestone fragments. As per classification of Dott (1964), Bholari sand is lithic arenite where quartz (50%) occurs as main mineral followed by rock fragments (30%), feldspars (15%) and other opaque minerals (5%). Texturally, the sediments are angular (77%) to sub-round (33%). All these physical properties lie within the range set by National Highway Authority (NHA) and American Standard of Testing Material (ASTM). It is concluded that Bholari River sand is suitable for use in concrete mixed with cement and asphalt.

Beachrock as a Paleoshoreline Indicator: Example from Wadi Al-Hamd, South Al-Wajh, Saudi Arabia

The present study concerns the Holocene inland beachrocks that are exposed in the Red Sea coastal plain at the mouth of Wadi Al-Hamd, South Al-Wajh City, Saudi Arabia, and their utility as an indicator for Holocene climate and sea level changes. In addition, the framework composition, and carbon and oxygen isotopic data, are employed to interpret the origin of their cement. The beachrock consists mainly of gravel and coarse-grained terrigenous sediments dominated by lithic fragments of volcanic rocks, cherts and rare limestones along with quartz, feldspars and traces of amphiboles and heavy minerals. In addition, rare skeletal remains dominated by coralline algae, benthic foraminifera and mollusca remains are recognized. The allochems are cemented by high Mg-calcite (HMC) formed mainly in the intertidal zone under active marine phreatic conditions. The cement takes the form of isopachous to anisopachous rinds of bladed crystals, micritic rim non-selectively surrounding siliciclastic and skeletal remains, and pore-filling micrite. Pore-filling micrite cement occasionally displays a meniscus fabric, suggesting a vadose environment. The δ18O and δ13C values of carbonate cement range from −0.35‰ to 1‰ (mean 0.25‰) and −0.09‰ to 3.03‰ (mean 1.85‰), respectively, which are compatible with precipitation from marine waters. The slight depletion in δ18O and δ13C values in the proximal sample may suggest a slight meteoric contribution.

Late Carboniferous biota from the Ljubija iron mine area, Bosnia and Herzegovina

The Olistostrome member of the Sana-Una Paleozoic complex of the Ljubija ore mine in Bosnia and Herzegovina contains limestone fragments of pebble to block size that have been examined paleontologically. The recovered conodont fauna of the first sample is characterized by the species Declinognathodus lateralis, Idiognathoides sulcatus sulcatus and Idiognathodus sp. confirming its mid-Bashkirian age. This report is the first on the occurrence of these taxa in the area. The second sample with chaetetid demosponges yields an abundant diversified microbiota consisting of cyanobacteria, algae and foraminifera. Chlorophyts are marked by the common siphonoclad occurrence of Donezella lutugini and D. lunaensis, whereas rhodophyts include rare representatives of Stacheia, Stacheoides, Pseudoungdarella and Masloviporidium. The presence of Asphaltinella horowitzi and Aphralysia carbonaria of unclear taxonomic position is also documented. Pseudostaffellids, eostaffellids and other foraminifera, mostly endothyrids are present. The examined associations of fossils point to the Bashkirian age of the primary rock that originated in a very shallow habitat most probably linked to a high-energy reef environment.

Quantitative analysis of shapes and specific surface area of blasted fragments using image analysis and three-dimensional laser scanning

Blasted fragments, which are mainly characterised by the size, shape, and specific surface area (SSA), play a pivotal role in downstream mining processes. In this study, the shapes and SSAs of different types of blasted fragments at three quarries in China were investigated. Wide grading blasted fragments of limestone, tuff, and granite were randomly selected and classified into five categories according to their three-dimensional (3D) shapes. The sizes, shape parameters, and SSAs of the blasted fragments were determined using image analysis and 3D laser scanning, and their variation laws with respect to the lithology and fragment size were analysed. The results indicated that approximately 82%, 74%, and 79% of the fragments were hexahedron, pentahedron and tetrahedron in the limestone, tuff and granite muck piles, respectively, and these three types of fragments can be modelled as spheres. The limestone fragments were the most spherical, and the tuff and granite fragments were more angular. Under the same lithology, hexahedron, pentahedron, tetrahedron, and flat and elongated particles became more angular successively, while the surface texture remained almost same. The shape parameters of blasted fragments were related to the fragment size. Furthermore, the SSA reflected the combined effects of the size and shape of the blasted fragments. The SSAs of limestone, tuff and granite fragments decreased according to a power function at different rates as the size increased. The results can be helpful for improving the accuracy of the fragmentation size distribution obtained via image analysis and the calculation of fragmentation energy in blasting.

Lithological characteristics and formation conditions of lower jurassic limestones occuring in the Patil mountain (south-western Crimea)

Background. In this article, we investigate an outcrop of the Lower Jurassic limestones of the Eskiorda suite located on the northern slope of the Bodrak River basin in the south-western Crimea.Aim. The outcrop under study is mentioned in the majority of monographs devoted to the geology of the Crimean Mountains. Although the palaeontology of this assemblage has been sufficiently studied, its lithological aspects require elucidation. We carried out a series of lithological studies to identify the composition, structure and formation conditions of this limestone assemblage.Materials and methods. A macroscopic study of the outcrop was conducted followed by a detailed lithological study of collected limestone samples using a polarising microscope.Results. The conducted microscopic analysis revealed three structural types: organogenic-detrital, detrital and oolitic-organogenic-detrital limestones. The dominant component in the composition was fragments of echinoderms, mainly crinoids. Among other components were — in descending order — brachiopods, gastropods, foraminifera, remains of green algae, sponges, ostracods, ammonites and radiolarians, whose total content did not exceed 10%. Cinoid fragments were round to a various degree. The limestone fragments (intraclasts) were characterised by organogenic-clastic and pelitomorphic structures with an organogenic sludge, occasionally containing fine-sandy and silty quartz admixtures. Oolitic-organogenic-detrital limestones were almost entirely composed of crinoid fragments, some of which represented oolith cores. A specific feature of the limestones under study is their significant hardness resulting from the cementation of the structural components predominantly with crustification cement of several generations.Conclusions. The obtained results allowed us to draw conclusions about the formation conditions of the studied rocks. The limestones were formed in shallow water under the action of waves on the sediment in zones of constant currents. The hydrodynamic action on the sediment led to the formation of intraclasts. The early lithification of the sediment contributed to the formation of a hard seabed, on which subsequent generations of echinoderms settled, lived and died, forming an accumulative carbonate body.

Experimental study on calcination and fragmentation characteristics of limestone in fluidized bed

The fragmentation degree of limestone affects seriously the particle size distribution of sorbent in the desulfurization process in fluidized bed combustion. In this paper, the variation of particle size and differences in microstructure of calcination and fragmentation were measured under different fluidizing medium in the same equipment. The effects of temperature, reaction rate, SO2 and CO2 atmosphere, firing exhaust gas atmosphere on the calcination and fragmentation of limestone with different properties in the fluidized bed were studied. It was found that the size evolution of larger limestone was more obvious than that of finer ones. Under the condition of fragmentation, the particle size evolution of limestone was more intense than that in calcination. The particle size was smaller under the condition of a higher reaction rate. Higher temperature can promote the calcination reaction and reduce the particle size to a certain extent. The coarser fragmentation products at high temperature may be related to the enhancement of agglomeration between particles. SO2 and CO2 can inhibit the fragmentation of limestone and lead to coarsening of products, which further confirms the main contribution of calcination reaction to limestone size evolution. The main chemical reaction in a given atmosphere is direct sulphation reaction and the primary fragmentation is restrained by the high concentration of CO2 in firing exhaust gas, which is more obvious in the oxygen-enriched exhaust gas.

Carboniferous fauna from erratics in the Hradyzk area (Poltava region, Ukraine): paleo-ice streams indicator of the Dnipro glacial maximum

ABSTRACT Several hundred fragments of limestone and cherts with debris of various macrofauna have been found in the glacial sediments among crystalline Precambrian erratics along the left bank of the Kremenchuk reservoir. The collection includes a variety of corals, chaetetids, brachiopods, orthoceratids, crinoids and other forms. In many cases, it was possible to identify species of the corals, chaetetids and brachiopods. The identified species showed its Carboniferous age. The stratigraphic distribution is limited to a rather narrow range spanning the time interval from the Upper Viséan to Serpukhovian. An overview of the outcrops where these rocks are now exposed indicates that the most likely source of the Carboniferous erratic pebbles and boulders is in the southern and western flanks of the Moscow Syneclise where fossil-rich Carboniferous rocks are exposed at the upper reaches of the Volga and Oka rivers. The configuration of the southern boundary of the Dnipro glacier indicates changes in its path from S to SW. This could have happened due to impingement of the glacier against the Central Russian Upland. The finding of a significant amount of Carboniferous erratics in glacial sediments of the southeastern part of the Dnipro lobe near the town of Hradyzk supports this conclusion.