Preparation Of Thin Sections Research Articles

Geology and characteristics of petrographic rocks in the region of Trepça, Kosovo

Purpose. The purpose of this paper is to accomplish a thorough identification of rock types occurring within the Mitrovica region by describing in detail all encountered varieties. The authors aim to determine the discontinuity or continuity of all inter-formational boundaries, crucial for accurate delineation on the ground and complete reflection on a 1:25000 scale map. Additionally, the objective is to identify the nature of contact between rock types and provide a detailed their description. Methods. Field exploration in the Mitrovica region was conducted for several months. Rock identification involved detailed sampling and petrographic analysis, including thin section preparation of magmatic rocks. The method included sample preparation, polarized light source interactions with minerals and observation of optical properties. Key properties observed are birefringence, interference colors, extinction angles, identification and analysis. Findings. Based on the study of stratigraphic units and geological descriptions of mineral outcrop areas, various types of rocks through petrographic microscope preparation, as well as chemical and geochemical analyses, have been differentiated. The Mitrovica area encompasses the following lithostratigraphic units: harzburgite, gabbro, diabase, metasandstone, sandstone, quartzite and grainstone with calcium (Aeolisaccus sp.; Bioclastic grainstone with dacycladal algae and small milliolides; Salpin-goporella sp.). Originality. The originality of the research lies in employing an optical microscope for the precise identification of rocks. Through the re-search carried out in the study area, we obtained a comprehensive petrographic description of mineral composition, texture, and mineralization, facilitating the assessment of the area exploitation potential. Practical implications. The petrographic exploration yielded the conclusion that the Pb-Zn mineralization is present in the study area, which is a sig-nificant finding for the advancement of the mining sector and the local community, provided that environmental preservation measures are upheld and responsible methods of area exploitation are implemented.

An innovative sample preparation strategy to visualize the crystalline structure of fiber reinforced thermoplastic composites by polarized optical microscopy

AbstractThis study aims at an innovative sample preparation strategy for fiber reinforced thermoplastic (FRTP) composites analyzed via polarized optical microscopy to visualize the crystalline structure of the matrix resin. Investigating the structure is relevant for understanding the relationship with the mechanical properties. In general, polarized optical microscopy is a powerful technique for visualizing polymer crystalline structures at samples sliced into thin sections below 30 μm. However, analyzing FRTPs remains challenging in absence of suitable methods for the preparation of thin sections owing to the embedded fibers. Herein, the preparation of appropriately thin sections in a novel sequence of steps is shown that may generically be applied to FRTPs. Four different types of FRTPs with major matrix resins (GF/PBT, CF/PA6, CF/PEEK and GF/PP) were successfully processed to thickness of 5 μm or below without fiber loss, resin breakage or delamination between fiber and resin demonstrating the utility of the developed method, which is the significant outcome of the study. To the best of our knowledge, the subsequently obtained polarized optical microscopic images for the first time visualized the crystalline structure of the matrix resin revealing nucleation of crystals from the fiber surface and effects of mold flow on the crystallization behavior.Highlights Thinning of fiber reinforced thermoplastics to thickness of 5 μm or below. Thinning achieved despite fiber volume at industrial applications level. Sample preparation ensures ideal conditions for polarized optical microscopy. Visualization of crystalline structure of the matrix resin for the first time. Potential advancement for spectroscopic and electron microscopic analyses.

Particle size analysis: A comparison of laboratory-based techniques and their application to geoscience

In sedimentary geoscience, the particle size distribution (PSD) of a sediment has a fundamental effect on a sediment's ability to be entrained, eroded, and deposited. Therefore, it is crucial to accurately measure the PSD of sediments. Several laboratory-based methods of particle size analysis are commonly employed in geoscience; however, each method is based on different principles and the comparison of data from one technique to another is challenging. In this study, we have compared the output of four commonly-used laboratory-based techniques: Laser Particle Size Analysis (LPSA), optical point counting, 2D automated image analysis, and X-ray Computed Tomography (XCT). Each technique has been used to measure eight samples of spherical silica particles, all prepared with known particle size ranges. Spherical particles have been used to minimise the effects of variable sorting and particle shape on data output. Here we have compared the differences between the measured PSD and descriptors of each PSD, showing that, at small particle diameters (<150 μm), all techniques agree. However, at particle diameters >150 μm, LPSA overestimates the size of particles, due to limitations in the way that particle diameter is calculated by this technique. In contrast, 2D automated image analysis and optical point counting underestimate the diameters of particles, due to stereology (e.g., the effect of slicing particles during thin section preparation). Results from XCT analyses have the lowest values of sorting (range of measured particle diameters) and are therefore the most tightly constrained. In addition, XCT is the only 3D analysis method, allowing particle shape, orientation, and intraparticle porosity to be measured for a volume of material. We therefore conclude that XCT is the most accurate way to determine a grain size distribution in sediments.

Features of the morphogenesis of oxalate and urate urinary stones in urolithiasis patients from heavely industrialized region.

Aim: Determining the characteristics of urinary stone composition in inhabitants of an industrially advanced region afflicted with oxalate and urate urolithiasis. Materials and Methods: A comparative analysis of the morphology of 246 kidney stones from residents of one of heavily industrialized region of Ukraine, was conducted. Petrographic examination of the calculi was performed through microscopic analysis. The qualitative composition of the calculi was investigated using X-ray structural analysis of fragments and dust remnants of the stones, which were formed during the preparation of thin sections. Results: A distinctive characteristic of all mineral components is their varying microblock structure and the presence of organic material inclusions. The inclusion of an organic component reduces the strength of the crystalline layers. Urolith resembles a brittle-hollow environment, which in certain cases allows for the selection of the most effective methods of their destruction (lithotripsy). Conclusions: A common feature among all mineral components is their diverse microblock structure and the presence of organic inclusions, which diversify the strength characteristics of uroliths. The prior determination of these characteristics allows for the selection of the most ef f ective method for destructive treatment (lithotripsy). The combination of data on the ontogenesis of uroliths, their mineral composition, and the state of the electrolyte balance in the body of a patient with urolithiasis will allow choosing an individually effective method of metaphylaxis of the disease.

Petrographic and Structural Study of Stalactites and Stalagmites of Mfamosing Camp II Cave in Cross River State, South Eastern Nigeria

This study investigated the petrographic and structural features of Mfamosing camp II cave stalactites and stalagmites. The cave is in the karst region of Udukpani in Cross River State, Southeast Nigeria. The objective of the study was to gain insights into the mineral composition, texture and structure of the stalactites and stalagmites of the cave through petrographic analysis. The study employed a methodology that involved field study, collection of representative samples, preparation of thin sections, and examination under a petrographic microscope. Field observations revealed that the stalactite and stalagmites were leucocratic in color. The rocks exhibited similar texture which was fine grained. The cave contained large number of stalactites and stalagmites of varrying lengths (icicle and cone dome shapes) with stromalitic features on the wall. The petrographic analysis revealed the predominance of carbonates (calcite) as the primary mineral. The average estimated minerals composition present were 54.5% of Calcite, 5.3% of Quartz, and 2% of feldspar for stalactites. 51% of Calcite, 5% of Quartz, and 2.67% of feldspar for stalagmites. The results shows that the major mineral composition of the speleothems the cave are CaO.

Preparation of thin histological sections from archaeological bone and tooth samples

Histological analysis of osteological remains from archaeological excavations provides data and information that can be difficult or impossible to obtain from macroscopic description and examination. Furthermore, the microscopic perspective provides important evidence for taxonomically indeterminate samples lacking morphologically diagnostic marks, e.g. determination of human/non-human bone origin, and can provide further information about analysed individual, e.g. studying of developmental stress in dental enamel. Microscopy of bone and tooth samples requires preparation of good quality thin histological sections for transmitted and polarized light microscopy examination and analysis. This paper presents detailed methodology description in several main steps which were modified to fit our laboratory. Finally, we suggest an easily repeatable protocol and know-how fitting in similar or identical laboratory conditions, including equipment, consumables, and other items

Good Practices for Histological Analysis of the Annual Killifish Nothobranchius furzeri (Nothobranchiidae).

Paraffin histology is one of the most important and commonly used laboratory techniques enabling the study of the microscopic structure of animal and plant tissues. This technique uses paraffin wax, which in liquid form impregnates fixed and dehydrated tissues and allows the preparation of thin sections when solidified in blocks. This protocol on good practices in paraffin histology of Nothobranchius furzeri (Nothobranchiidae) summarizes the authors' current experience in terms of technique, evaluation, and interpretation of sectioned tissues. The steps that precede paraffin block preparation are also presented as they play a key role in maximizing the quality of examined sections. The paraffin technique as described only requires basic laboratory conditions to produce good-quality results. The description of staining methods is limited to Mayer's hematoxylin and eosin (H&E), the routinely used histological dye staining cell nuclei in blue-black (hematein) and cell cytoplasm and connective tissue fibers in shades of pink-red (eosin). Killifish specialists are encouraged to engage in the study of histology and histopathology, taking advantage of interdisciplinary cooperation.

PETROGRAPHY AND HYDROTHERMAL ALTERATION OF ULTRAMAFIC BED-ROCKS OF SOUTH SIPILOU: IMPLICATION IN THE LATERITIC NICKEL MINERALIZATION (DEPARTMENT OF SIPILOU, WESTERN IVORY COAST)

South Sipilou is an area containing lateritic nickel mineralization that developed on ultramafic rocks in the department of Sipilou-Biankouma in western Ivory Coast. The objective of this study was to characterize the petrography and hydrothermal alterations affecting these ultramafic bed-rocks and to understand their involvement in lateritic nickel mineralization. Then to compare them to the ultramafic rocks already characterized in the department of Sipilou-Biankouma. Thus, the macroscopic characterization of these rocks was carried out in the field. Then, microscopic observations on the petrography and the hydrothermal alterations were made on these rocks after the preparation of thin sections in the laboratory.The results indicated that the lithologies of the ultramafic bed-rocks of South Sipilou consist of strongly serpentinized dunites, more or less harzburgitic lherzolites and olivine orthopyroxenites. Their petrographic characteristics showed a similarity with the ultramafic bed-rocks of the nickel-bearing lateritic mineralization of North Biankouma, North Sipilou and differences with those of Samapleu, Yepleu, in the department of Sipilou-Biankouma. Also, the main hydrothermal alterations of the ultramafic rocks of South Sipilou are composed of silicification, carbonation and serpentinization. Only serpentinizationcontributed to the concentration of nickel in the bed-rock and within the lateritic profile.

Polarization-fluorescence Microscopy in the Study of Aggregates and Concrete

Concrete structures may develop deleterious damage, which significantly reduces service life, structural integrity, and safety, posing serious issues in large or otherwise critical infrastructure. Routine petrographic assessments, including microstructure, texture, and fabric, of concrete and its (gravel and sand) aggregate and binder constituents in thin section using polarization-fluorescence microscopy (PFM) enables the unequivocal identification of features that would otherwise remain hidden in conventional petrography. Rigorous preparation procedures preserve original microstructural details, make preparation artefacts recognizable, and ensure that the fluorescent emission can be quantified. This contribution outlines the preparation of fluorescence-impregnated thin sections and elaborates on the application of PFM to damaged concrete, with further examples from selected rock types commonly used for concrete aggregate.

Integrating histology in the analysis of multispecies cremations: A case study from early medieval England

AbstractMethodological options for differentiating commingled human from nonhuman calcined remains are limited. A zooarchaeological analysis of human cremations from three early medieval sites in the Avon Valley (Warwickshire, England) identified commingled animal remains in burials from the site of Bidford‐on‐Avon, but not at the contemporary sites of Wasperton and Alveston Manor. A histological study was conducted to further investigate whether additional fragments of nonhuman bone could be identified and to quantify potential differences in preservation or cremation intensity between the sites. Bone fragments (n = 92) were selected from 44 cremation burials across the three sites for thin section preparation. Histological cross sections were observed to record the presence of fibrolamellar plexiform bone and secondary osteon banding, as well as to categorize the histological preservation and cremation intensity. The analysis did not identify any nonhuman remains from Wasperton or Alveston Manor, but nonhuman bone fragments were identified in the Bidford‐on‐Avon histology sample. These data supplement and support the findings of the macroscopic analysis that multispecies commingled cremations were only prevalent at Bidford‐on‐Avon. No statistically significant differences were identified in histological preservation or cremation intensity between the cemeteries. Variability in animal use in funerary rites between cemetery sites, rather than preservation bias, is therefore the likely explanation for the differential recovery of commingled nonhuman bone from excavated cremation burials. These results confirm that histomorphology is a useful tool to incorporate in the analysis of multispecies commingled cremations.

Protocol matters: A need for standardized procedure in cementochronology

Cementochronology has long been associated in the literature with a high correlation between chronological and estimated age, and low differences between the two ages. The excessive accuracy was rather suspicious, and the method did not even appear in common forensic practice. An important step towards more widespread use of the method is the need to standardize work procedures, including indexes for recording the quality of cementum, preparation of thin sections and the age calculation. In our study, we used the standardized protocol for the preparation of thin sections in a set of Czech modern teeth of known age and sex. In the initial phase, 11.5% of the teeth were discarded due to severe caries in the medial part of the root. In a set of single extractions (55 teeth from 55 individuals), we focused on the detailed results of the age estimation, using precision and accuracy indicators. We also used different dental development data to calculate age, given inconsistencies in the use of eruption / mineralization. In a set of multiple extractions (68 teeth from 22 individuals), intra-individual variability was examined. The result of the application of the standardized protocol is an estimate of age with an absolute inaccuracy of −1.7 years and a relative inaccuracy of 5.4%. Calculation of precision and accuracy in the set of single extractions, however, showed the method’s limitations: the imprecision measuring the variability of cementum increments counts increased with chronological age, as did the inaccuracy. The use of different dental development data did not significantly increase the accuracy of the age estimation results. Intra-individual variability remains poorly understood – in the set of multiple extractions the differences within one individual ranged between 0.9 and 10.8 years.

Petrographic and geochemical characteristics of rocks in the Drenas region, Kosovo

Purpose. The paper purpose is to provide complete identification of rock types and the geochemical characteristics in the Drenas region. The authors seek to determine the discontinuity or continuity of all inter-formational boundaries to accurately delineate them in the field and fully reflect on a 1:25000 scale map. In addition, they reveal the nature of the contact between rock types, giving its detailed description and geochemical characteristics. Methods. Geological study is focused on the following facts: complete identification of all rock types on the basis of studying their samples, preparation of thin sections for petrographic study, chemical and geochemical analysis. The methods applied for geochemical analysis use the MinPet software. This software, used for mineral chemistry, is programmed to process and recalculate the results of major-element analysis according to the most common normative calculation schemes. This software is used in scientific works for constructing diagrams of rock calcification and geochemical interpretations according to the components of Na2O + K2O/SiO2, as well as rare earth elements according to the component SiO2/Zr/TiO2. The exploration field trips have been conducted to identify and describe areas of mineral outcrop. Findings. Based on the study of geochemical analysis and the petrographic description of mineral outcrops, as well as examination under a microscope, different types of rocks have been identified. Based on these types, the origin, age and spread of these rocks in this region have been determined. Originality. The originality of the study is in the use of the analysis results obtained in the AcmelLabs Laboratory, Vancouver, Canada, for major elements, rare earth elements and trace elements, which are shown in the diagrams presented in this paper. Practical implications. The geochemical analysis leads to the conclusion that the studied area has Ni-mineralization, which is important for the development of mining sector, as well as for the community while preserving the environment and applying an adequate method of exploiting the area.

Enigmatic wood and first evidence of tetrapods in the Yaguarí Formation (Middle-Late Permian), Uruguay

This article describes an intriguing fossil material recently found in the fine-grained sandstone levels from the upper section of the Yaguarí Formation of Uruguay. The nature of this specimen and its relationships were, initially, not easy to determine with confidence although it was subjected to several analyses, such as morphological and comparative examination complemented with preparation of thin sections and microanatomical and chemical studies under SEM. However, the anatomical structure shown in the performed transversal thin sections allowed solving the issue on the different animal or plant interpretations of the fossil specimen, which was finally discerned in favor of the latter. Therefore, after a detailed comparative study of the thin sections, we concluded that the specimen is a wood fragment related to the Dadoxylon-Araucarioxylon complex. Moreover, in order to provide a better biostratigraphic calibration for these deposits until now devoid of fossils, we include a preliminary description of recently found fossil footprints, which represent the first evidence of the presence of tetrapods in levels of the Yaguarí Formation (sensu Elizalde et al., 1970), below the conglomerates that have yielded the Colonia Orozco Fauna. The footprints were preliminary assigned to the ichnotaxa cf. Karoopes isp, cf. Capitosauroides isp., and cf. Pachypes isp., suggesting the presence of gorgonopsids and therocephalian therapsids and pareiasauromorphs, respectively. The Middle-Late Permian age recently suggested for the Yaguarí Formation based on paleomagnetic and radioisotopic studies is here supported by the described fossils, which thus constitute preliminary but nonetheless relevant discoveries for deposits whose fossiliferous potential has yet to be explored.

Indigenous carbon-rich matter associated with unusual aqueous alteration features in Nakhla: Complex formation and preservation history

While indigenous organic matter has been previously reported in the Mars meteorite Nakhla, little is known as to either its form or distribution. A notable feature of Nakhla is the prevalence of secondary phases associated with aqueous alteration. By analogy with the terrestrial environment, our objective was to determine whether Martian secondary minerals could also act to accumulate and preserve such organic matter. Through a multidisciplinary approach, we have characterized the nature of carbonaceous matter and spatially associated phases within the Martian meteorite Nakhla using a wide-ranging suite of analytical instrumentation including optical microscopy, laser Raman spectroscopy, focused ion beam microscopy, secondary ion mass spectrometry, and scanning and transmission electron microscopy. In freshly fractured chips of Nakhla, we found carbonaceous phases intimately associated with secondary aqueous alteration phases, both mineral and amorphous, interpreted to have formed through the low-temperature aqueous dissolution of the host basalt while on Mars. The carbonaceous matter is present both in condensed phases and in a dispersed state spatially associated with secondary alteration phases. In the former, we identified discrete refractory micron to submicron assemblages that appear macromolecular in nature and, in several cases, associated with fluorine and, in one case, significant nitrogen. Textural, chemical, mineralogical and isotopic considerations argue for a non-terrestrial origin of this carbonaceous matter. Additionally, we report the presence of the ferrous hydroxycarbonate mineral chukanovite (Fe2OH2CO3) within some of the secondary mineral aggregates studied. Neither the intimate association of carbonaceous matter with secondary phases nor the identification of chukanovite have been previously reported in any of the Martian meteorites. In this regard, we note such microscale features within alteration phases would most likely be lost in the preparation of conventional polished thin sections and thus explain why they have not been previously reported. In lieu of sample return, the sui generis nature provided by Mars meteorites provide insight to alteration processes on Mars currently denied to robotic exploration and remote sensing. Our results show a variety of habitability-related sample attributes, formed hundreds of millions of years ago near Mars’ surface, have persisted there until very recently and may be more widespread in the surface regolith than previously thought. This may have implications in sample selection criteria for Mars sample return.

Petrographic characteristics in the central part of Kosovo

Purpose. This paper aims to provide complete identification of rock types in the Drenas region by detailed description of all types of the rocks found. The authors intended to determine interruption or continuity of all inter-formational boundaries to accurately delineate them on the ground and fully reflect on the 1: 25000 scale map, as well as to identify the nature of contact between rock types and give its detailed description. Methods. During August, September, October of 2019, the exploration field trips were carried out. Geological survey works focused on the following areas: complete identification of all rock types on the basis of studying their samples, preparation of thin sections for petrographic (only the magmatic rock), chemical and geochemical analysis. Systematic measurement of structural elements was conducted alongside with identification and description of mineral outcrops areas. Findings. Based on the study of stratigraphic units and geological description of mineral outcrop areas, we identified different types of rocks using petrography microscope preparation and chemical and geochemical analysis. The area of Drenas has the following lithostratigraphic units: gabbro diabase, harzburgite, metasandstone. Originality. The originality of the study consists in the use of optical microscope for precise identification of rocks. As a result of the research conducted in the exploration area, we have obtained a clear petrographic description of minerals composition, their texture and mineralization, which allows assessing the possibility of the area exploitation. The analyses were completed at the certified laboratory of Geology-Mining Faculty (Polytechnic University of Tirana) and Geosciences Institute. Practical implications. Petrographic study and chemical analysis led to the conclusion that the research area has Ni mineralization, which is important for the development of mining sector and the community given the environment is preserved and the adequate way of the area exploitation is applied.

LithoSpace: An Idea for an Automated System for in situ Petrographic Thin Section Preparation on Mars and Other Extraterrestrial Rocky Bodies

Optical microscopy analyses using thin sections is one of the most standard techniques in geology. It permits identification of most rock-forming minerals and it is essential for micropaleontology since observation in transmitted light is the only way to observe individual, or colonies of, microfossils in their mineralogical and textural context. Thin sections are also used for other techniques such as Raman spectroscopy. In the framework of exploration of the Martian surface and of the search for potential relics of microbial life, the possibility to observe petrographic thin sections in situ would be revolutionary. Nevertheless, although optical microscopes can be readily designed for space exploration, thin section preparation is not easy to do in situ on extraterrestrial rocky bodies due to the generally harsh environmental conditions and to the difficulty to automate a protocol that normally requires several human interventions. The aim of the LithoSpace project, supported by the French Space Agency (CNES) since 2014, is to work on the development of an automated system permitting preparation of petrographic thin sections on extraterrestrial bodies, such as Mars, the Moon or asteroids. In this paper, we describe the approaches used to study rocks in situ during space missions and compare them to those used on Earth. Then, the relevance of making thin sections during space exploration is highlighted from the description of the data that could be collected from the analysis of these specific samples, using new instruments and instruments already sent to Mars. The standard preparation protocol is described as well as previously envisioned or existing in situ sample preparation systems. We then propose a protocol for automation of the preparation. Particular attention is paid to demonstrating the feasibility of making thin sections in the absence of liquid water and with energy consumption compatible with automated space probes. Tests are then carried out to control the quality of the prepared samples. On the basis of the demonstrated feasibility, an automated system is proposed as a conceptual all-in-one system. Finally, a “proof-of-concept” model developed with the help of students at different educational levels is presented.

Micro-morphologies of SBS modifier at mortar transition zone in asphalt mixture with thin sections and fluorescence analysis

The microstructure control of modified asphalt, especially the micro-dispersion of the SBS modifier in the mortar transition zone, is a critical technology for the performance design of modified asphalt. To characterize the micro-dispersive morphology of SBS modifiers, thin-section preparation techniques that can be used to analyze the original microstructure of the asphalt mixture were proposed and introduced in this study. Flexible resin is filled into the mixture at vacuum conditions to ensure accepted sample conditions for preparing thin sections of asphalt mixture. The morphology parameters, including SBS area ratio, box dimension, SBS average particle area and its coefficient of variation, area-weighted average axis ratio, and coefficient of variation, were plotted from fluorescence images to characterize the micro-morphological distribution of the SBS modifier in detail. Results have shown that the area ratio increased with the increase in SBS content, while the box dimension was reduced and the distribution uniformity of the particles decreased. The superfluous SBS modifier in the binder at a too high adding ratio will decrease the value of the box dimension. Lower modification temperature worsened the SBS modifier in the mixture, resulting in a wide range of particle size, higher axis ratio, and higher area ratio. The micro-morphologies of SBS in the asphalt mixture phase varied a lot from the asphalt binder phase. The additional materials of mineral filler and fine aggregate, together with the other heating processes, will significantly influence the swelling state and particle size of the SBS modifier.

Geological and Tectonic Setting of Andesitic Rock in Central Eastern Desert, Egypt

Objective. The current study aims to detect the geologic features, geochemical characteristics and tectonic setting of the investigated rock using field observations and geochemical analyses. Research methods. This work contains both field work (Collection samples and drawing of a new geological map) and laboratory work (preparation of thin sections for petrographic studies by polarizing microscope), X-ray Fluorescence analysis (XRF) in Institute of Biology, Southern Federal University and Mass-Spectrometer with Inductively Coupled Plasma (ICPMS) at the central Laboratory of Russian Geological Institute. Result. Investigated andesitic rock belongs to Dokhan volcanic that located in the Central Eastern Desert of Egypt a long Qena-Safaga Road. It is considered as one of the most important shear zones in Eastern Desert that includes distinctive rocks and economic mineral deposits. The investigated rock belongs to late to post tectonic magmatism of the East African Orogeny (EAO). Petrographically: Dokhan volcanic is represented by andesite according to petrographical studies. It consists of plagioclase, quartz, in addition to mafic minerals. Geochemically, the investigated andesite samples plotted in calk-alkaline nature. Conclusion. Tectonically, andesite samples fall in arc lava and continental fields. They are enriched in Ba, Sr, Rb, K, Nb and Ce with marked depletion in the most HFSEs like those of island arc calc-alkaline series.

Geological and geochemical studies on El-Missikat granites, Central Eastern Desert, Egypt

Objective. The present work deals with the detailed investigations of the geology, geochemistry, and tectonic setting of the studied granitic rocks. Research methods. This work involves both field work (Collection samples and drawing of a new geological map) and laboratory work (preparation of thin sections for petrographic studies by polarizing microscope), Atomic absorption, X-ray Fluorescence analysis (XRF) in the Central Laboratories of the Acme in Canada and Mass-Spectrometer with Inductively Coupled Plasma (ICPMS). Result. The study area restricted in the Central Eastern Desert of Egypt between the Red sea and the Nile Valley. ElMissikat pluton is covered by island arc related rock (as xenolith), older granites, and younger granites, in addition to different types of dikes and veins swarms. Petrographically older granites are classified into quartz diorite, tonalite and granodiorite, whereas the younger granites are divided into monzogranite, syenogranite and altered granites. The geochemical studies suggest the granitic rocks are calc-alkaline affinity. The quartz diorite, tonalite and granodiorite are related to volcanic arc granites, while the monzogranite and syenogranite are similar to the infinity of the within plate granites behavior. The quartz diorite, tonalite, granodiorite and monzogranite are belonging to I-type granite, otherwise the syenogranite has A-type granites. Conclusion. According to geological and petrographical studies the investigated granites are represented by quartz diorite, tonalite and granodiorite, whereas the younger granites are divided into monzogranite, syenogranite and altered granites that are traversed by different types of dikes and veins swarms . Generally, the older granites have low content of LILE, most probably due to the relatively low content of K-feldspars and HFSE. The younger granites exhibit a fractionated pattern from LREE to HREE with negative Eu anomaly.

Dehydration and stabilization of unconsolidated laminated lake sediments using gypsum for the preparation of thin sections

Abstract An improved Lamoureux method for subsampling of unconsolidated laminated sediment is described. Here, we describe a new methodological approach that changes the Lamoureux method in four steps of which the most important change concerns dehydration and stabilization. In this step, we adopted gypsum embedding of the subsample, which took about 1 h to harden and keeps the sediment partially moist. After drying of the gypsum, the subsamples are impregnated with Epoxy 2000 resin under room temperature. This method requires commonly available equipment and can be implemented cost-effectively within 3–4 days.