scholarly journals Petrographic characteristics in the central part of Kosovo

2021 ◽  
Vol 15 (4) ◽  
pp. 139-144
Author(s):  
Festim Kutllovci ◽  
Islam Fejza
Keyword(s):  
Magmatic Rock ◽  
Optical Microscope ◽  
Research Area ◽  
Field Trips ◽  
Geochemical Analysis ◽  
Thin Sections ◽  
Rock Types ◽  
Lithostratigraphic Units ◽  
Complete Identification ◽  
Exploration Area

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.

scholarly journals Characteristics of Ultramafic Igneous Rock Ofiolite Complex in Asera District, North Konawe Regency Southeast Sulawesi Province

2020 ◽  
Vol 5 (3) ◽  
pp. 121-126
Author(s):  
Hasria ◽  
Erzam S. Hasan ◽  
Deniyatno ◽  
L M Iradat Salihin ◽  
Asdiwan
Keyword(s):  
Major Element ◽  
Research Area ◽  
Ultramafic Rocks ◽  
Petrographic Analysis ◽  
Geochemical Analysis ◽  
Rock Formation ◽  
Rock Types ◽  
Original Rock ◽  
Rock Lithology

The research area is located in Asera District, North Konawe Regency, Southeast Sulawesi Province which has ultramafic rock lithology. The purpose of this study is to determine the characteristics of ultramafic igneous rocks using petrographic and geochemical analysis. Petrographic analysis aims to determine the types and abundance of minerals present so that rock types can be determined based on the classification of Travis (1955) and Streckeisen (1976). The geochemical analysis aims to determine the oxide/major element so that it can determine the type of magma based on the AFM classification according to Irvine and Baragar  (1971) and the origin of the magma / original rock formation environment based on Pearce (1977).  Petrographic analysis results showed that ultramafic rocks in the study area consisted of 2 types of rocks namely peridotite consisting of wherlit and lherzoite and serpentinite.  The results of geochemical analysis indicate that the type of magma in the study area is thoellitic series and the origin of the magma/rock formation environment comes from the expansion of the oceanic floor or mid oceanig ridge (MOR) which is ultramafic.

Some early history of replica techniques for electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1076-1077
Author(s):  
Robert M. Fisher
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Optical Microscope ◽  
Early History ◽  
Bulk Materials ◽  
Thin Sections ◽  
Transmission Electron ◽  
Reflected Light ◽  
History Of ◽  
Electron Microscopes

By 1940, a half dozen or so commercial or home-built transmission electron microscopes were in use for studies of the ultrastructure of matter. These operated at 30-60 kV and most pioneering microscopists were preoccupied with their search for electron transparent substrates to support dispersions of particulates or bacteria for TEM examination and did not contemplate studies of bulk materials. Metallurgist H. Mahl and other physical scientists, accustomed to examining etched, deformed or machined specimens by reflected light in the optical microscope, were also highly motivated to capitalize on the superior resolution of the electron microscope. Mahl originated several methods of preparing thin oxide or lacquer impressions of surfaces that were transparent in his 50 kV TEM. The utility of replication was recognized immediately and many variations on the theme, including two-step negative-positive replicas, soon appeared. Intense development of replica techniques slowed after 1955 but important advances still occur. The availability of 100 kV instruments, advent of thin film methods for metals and ceramics and microtoming of thin sections for biological specimens largely eliminated any need to resort to replicas.

Correlation of Pore Structure and Permeability by SEM-Image Analysis

1990 ◽  
Vol 48 (1) ◽  
pp. 428-429
Author(s):  
C. A. Callender ◽  
Wm. C. Dawson ◽  
J. J. Funk
Keyword(s):  
Image Analysis ◽  
Pore Structure ◽  
Imaging System ◽  
Pore Space ◽  
Simulation Models ◽  
Image Analyzer ◽  
Imaging Data ◽  
Sem Images ◽  
Thin Sections ◽  
Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

scholarly journals Petrology and mineralogy of the Viñales meteorite, the latest fall in Cuba

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110198
Author(s):  
Feng Yin ◽  
Deqiu Dai
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Optical Microscope ◽  
Chemical Compositions ◽  
Atmospheric Entry ◽  
Thin Sections ◽  
Homogeneous Chemical ◽  
Del Rio ◽  
The Masses ◽  
Metal Phases

The new Cuban chondrite, Viñales, fell on February first, 2019 at Pinar del Rio, northwest of Cuba (22°37′10″N, 83°44′34″W). A total of about 50–100 kg of the meteorite were collected and the masses of individual samples are in a range 2–1100 g. Two polished thin sections were studied by optical microscope, Raman spectroscopy and electron microprobe analysis in this study. The meteorite mainly consists of olivine (Fa24.6), low-Ca pyroxene (Fs20.5), and troilite and Fe-Ni metal, with minor amounts of feldspar (Ab82.4-84.7). Three poorly metamorphosed porphyritic olivine-pyroxene and barred olivine chondrules are observed. The homogeneous chemical compositions and petrographic textures indicate that Viñales is a L6 chondrite. The Viñales has fresh black fusion crust with layered structure, indicating it experienced a high temperature of ∼1650°C during atmospheric entry. Black shock melt veins with width of 100–600 μm are pervasive in the Viñales and olivine, bronzite, and metal phases are dominate minerals of the shock melt vein. The shock features of major silicate minerals suggest a shock stage S3, partly S4, and the shock pressure could be >10 GPa.

scholarly journals Lithostratigraphy and microfacies analysis of Avanah Formation (Middle Eocene) in Gomaspan section northeast Erbil City, Kurdistan region, Iraq

2021 ◽  
Author(s):  
Irfan Sh. Asaad ◽  
Keyword(s):  
Middle Eocene ◽  
Planktonic Foraminifera ◽  
Middle Part ◽  
Petrographic Analysis ◽  
Microfacies Analysis ◽  
Dolomitic Limestone ◽  
Kurdistan Region ◽  
Thin Sections ◽  
Lithostratigraphic Units ◽  
Lagoon Environment

Lithostratigraphy and microfacies analysis of the Avanah Formation (Middle Eocene) were studied in the Gomaspan section in the Bina Bawi anticline, northeast of Erbil city, Kurdistan Region, Iraq. The field observations refer that the formation attains 56 m of medium to thick bedded yellow limestone, grey dolomitic limestone and blue marly dolomitic limestone interbedded with thin beds of blue marl and dark grey shale with an interval of sandy limestone in the middle part and thin to medium bedded limestone interbedded with red mudstone. The petrographic study of 29 thin sections of Avanah carbonates revealed that the majority of the matrix is carbonate mud (micrite) with few microspar. The skeletal grains include benthic foraminifera, dasycladacean green algae, ostracods, calcispheres, pelecypods, rare planktonic foraminifera and bryozoa in addition to bioclasts. Non-skeletal grains encompass peloids, oncoids, intraclasts and extraclasts with common monocrystalline quartz. Based on the field observation and petrographic analysis, three different lithostratigraphic units were identified. They are in ascending order: A-Thick bedded dolomitic marly limestone interbedded with shale. B- Bedded dolomitic limestone interbedded with shale and marl. C- Thin to medium bedded limestone interbedded with red mudstone. Depending on detailed microfacies analysis of carbonate rocks, three main microfacies and 12 submicrofacies are recognized. From the sum of all petrographic, facies, textural analyses, it is concluded that Avanah Formation in Gomaspan section, was deposited in shallow marine environment, semi restricted lagoon, in lower and upper parts and open lagoon environment in the middle part interval.

scholarly journals Multi-scale virtual field experience, Grand Ledge, Michigan, USA

2021 ◽  
Author(s):  
Madeline S. Marshall ◽  
Melinda C. Higley
Keyword(s):  
Student Learning ◽  
Liberal Arts ◽  
Field Experience ◽  
Field Experiences ◽  
3D Models ◽  
Field Trips ◽  
Stratigraphic Correlation ◽  
Thin Sections ◽  
Learning Platform ◽  
Virtual Field

Abstract. Field experiences are a critical component of undergraduate geoscience education; however, traditional onsite field experiences are not always practical due to accessibility, and the popularity of alternative modes of learning in higher education is increasing. One way to support student access to field experiences is through virtual field trips, implemented either independently or in conjunction with in-person field trips. We created a virtual field trip (VFT) to Grand Ledge, a regionally important suite of sedimentary outcrops in central lower Michigan, USA. This VFT undertakes all stages of a field project, from question development and detailed observation through data collection to interpretation. The VFT was implemented in undergraduate Sedimentation and Stratigraphy courses at two different liberal arts institutions, with one version of the VFT conducted in-person and the other online. The VFT was presented from a locally hosted website and distributed through an online learning platform. Students completed a series of activities using field data in the form of outcrop photos, virtual 3D models of outcrops and hand samples, and photos of thin sections. Student products included annotated field notes, a stratigraphic column, a collaborative stratigraphic correlation, and a final written reflection. VFT assessment demonstrated that students successfully achieved the inquiry-oriented student learning outcomes and student reflection responses provide anecdotal evidence that the field experience was comparable to field geology onsite. This VFT is an example of successful student learning in an upper-level Sedimentation and Stratigraphy course via virtual field experience with an emphasis on local geology.

scholarly journals TAPHONOMIC ASPECTS OF VERTEBRATE FOSSILS FROM BAURU GROUP, UPPER CRETACEOUS, BRAZIL

2013 ◽  
Vol 69 ◽  
Author(s):  
Karine Lohmann Azevedo ◽  
Cristina Silveira Vega ◽  
Luiz Alberto Fernandes
Keyword(s):  
Upper Cretaceous ◽  
Bone Structure ◽  
Minas Gerais ◽  
Sao Paulo ◽  
Field Trips ◽  
São Paulo ◽  
Class Iii ◽  
Mato Grosso ◽  
Thin Sections ◽  
Osseous Structure

The Bauru Basin covers an area of about 370.000 km2, occurring in São Paulo, Paraná, Mato Grosso, Mato Grosso do Sul, Minas Gerais and Goiás states in Brazil, and also in the northeast of Paraguay. These upper Cretaceous sequence correspond to a semi-arid to arid climate and is divided in two groups, Bauru and Caiuá. The first one has the major record of fossils, being the focus of the taphonomic study. Field trips to Marília and Monte Alto municipalities (São Paulo State) and also to Uberaba city (Minas Gerais State) were made to check the depositional context and collect fossiliferous material. Vertebrate collections were visited, as the Museu de Paleontologia from Marília and Monte Alto (SP), Museu de Paleontologia da Universidade de São Paulo, as well as Museu dos Dinossauros, Centro de Pesquisas Paleontológicas Llewellyn Ivor Price from Peirópolis (MG). Four biostratinomic classes related to articulated/disarticulated fossils were identified in Vale do Rio Peixe, Uberaba, Marília, São José do Rio Preto and Presidente Prudente formations. Class I represents articulated and almost complete specimens, corresponding mainly to turtles and crocodiles. Class II comprises partially articulated specimens of skull and jaw fossils, or sequences of vertebrae. Classes I and II were recorded in Vale do Rio do Peixe, Marília (Serra da Galga Member) and Presidente Prudente formations. Class III is represented by isolated bones, and Class IV by fragmented bones. These two last classes appear in all units of the basin. For diagenetic analysis, 19 thin sections were made showing that, in general, the bone structure is well preserved, with spatic calcite filling the bone and the presence of the original phosphatic material. Marília Formation, on Echaporã Member, is the most different unit of the basin, being more carbonatic. The study of thin sections, considering the osseous structure and the biostratinomic analysis, match with the paleoenvironmental contextualization.

scholarly journals Characteristics and dolomitization of the Lower Qiulitage Group reservoir in Bachu Uplift, Tarim Basin, China

2019 ◽  
Vol 23 (3) ◽  
pp. 199-208 ◽  
Author(s):  
Bin Li ◽  
Qingsong Xia ◽  
Jun Peng ◽  
Suju Yang ◽  
Qingqi Xu ◽  
...  
Keyword(s):  
Hydrothermal Fluids ◽  
Low Permeability ◽  
Positive Anomaly ◽  
Geochemical Analysis ◽  
Acid Dissolution ◽  
Bottom Part ◽  
Thin Sections ◽  
Crystalline Dolomite ◽  
Bachu Uplift ◽  
Intercrystalline Pores

The characteristics of the Lower Qiulitage Group in Bachu uplift, which originated in the Upper Cambrian period, are not clear. Based on four core observations, identification of 40 thin sections, and geochemical analysis of samples, this study concludes that crystal dolomite reservoirs developed in the Lower Qiulitage Group in Bachu uplift. Intercrystalline pores and dissolved pores formed the main reservoir space, while dissolution pores and fractures were developed in the middle and bottom part of the formation. The reservoir features low porosity and low permeability, and the fine-medium crystalline dolomite reservoir has the best pore structure. According to a petrochemical analysis, the Lower Qiulitage Group reservoir experienced intense dolomitization, with slightly higher content of trace elements Mn and Sr and negative oxygen isotropy. Tectonic hydrothermal dolomitization developed locally under the influence of base faults, and vug pores were filled with saddle dolomites and siliceous filling. The presence of rare earth elements Ce and Eu presented positive anomaly characteristics. It suggested that the CO2 acid dissolution caused by hydrothermal fluids may be a new mechanism for the increase in pores in deeply buried reservoirs, which is worth further study.

Induced‐polarization response of zeolitic conglomerate and carbonaceous siltstone

Geophysics ◽  
1982 ◽  
Vol 47 (1) ◽  
pp. 71-88 ◽  
Author(s):  
P. H. Nelson ◽  
W. H. Hansen ◽  
M. J. Sweeney
Keyword(s):  
Electrical Response ◽  
Induced Polarization ◽  
Phase Response ◽  
Electrical Measurements ◽  
Intimate Contact ◽  
Thin Sections ◽  
Field Surveys ◽  
Core Samples ◽  
Rock Types ◽  
Geologic Materials

Three case studies investigating induced‐polarization (IP) responses of a zeolite‐bearing conglomerate and of two carbonaceous siltstones are presented. The IP response of these noneconomic geologic materials can either mask or mimic the response from sulfide mineralization which is sought by electrical field surveys. The nonsulfide rock types which produced unusually high responses on IP field surveys were sampled by core drilling for chemical, mineralogical, and electrical laboratory study. The electrical response of core samples was measured in a four‐electrode sample holder over the 0.03–1000 Hz range. Geologic description of the core, petrographic examination of thin sections, mineral identification by x‐ray diffraction (XRD), and chemical analysis of samples supplemented the electrical measurements. A surface phase response of 20 mrad was obtained from field surveys over the Gila conglomerate at an Arizona location. Core samples of the Gila were examined in thin section, and clast surfaces were found to be coated with a thin layer of zeolites. These zeolites project into pore spaces in the conglomerate, and thus are in intimate contact with formation waters. A series of laboratory experiments suggests that zeolites cause most of the observed IP response. Phase responses as high as 100 mrad were measured with field surveys over siltstone and limestone sequences in western Nevada. Samples recovered from the Luning and Gabbs‐Sunrise formations include siltstones containing small amounts of amorphous carbon. These siltstones are very conductive electrically, and the high‐phase response is attributed to polarization of the carbon‐pore water interface. Low porosity in these carbonaceous siltstones enhances the phase response.

Formation of the hour-glass structure in augite

1969 ◽  
Vol 37 (288) ◽  
pp. 472-479 ◽  
Author(s):  
D. F. Strong
Keyword(s):  
Glass Structure ◽  
Coarse Grained ◽  
Crystal Face ◽  
Thin Sections ◽  
Rapid Crystallization ◽  
Fine Grained ◽  
Rock Types ◽  
The Common

SummaryA study of augite in over three hundred thin sections of mainly alkalic rocks permits the distinction of two main types of hour-glass structure. The common ‘swallow-tailed’, sometimes skeletal augite crystals are found in the fine-grained groundmass of many rock types, and it is suggested that rapid crystallization alone accounts for their formation. Hence, this type of hour-glass structure has been called ‘quench hour-glass’. The hour-glass structures of larger augite crystals of porphyritic and coarse-grained rocks are commonly described as hour-glass ‘zoning’, as they result primarily from compositional differences between the different sectors. These were formed under conditions of relatively slower cooling than the ‘quench hour-glass’, and thus cannot be explained in the same way. They are thought to have formed by a process involving adsorption of impurities on a particular crystal face so as to impede growth of these faces, producing an initial skeleton of hour-glass form, which is completed by later crystallization of augite richer in FeO, Na2O, TiO2, and Al2O3. This hypothesis also explains the patchy zoning of other augite crystals, casting doubt on some petrogenetic interpretations of such zones as core zones.

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