scholarly journals The results of the research of sandstones closed porosity

2019 ◽  
Vol 27 (3) ◽  
pp. 414-421
Author(s):  
V. A. Baranov ◽  
Y. V. Antipovich
Keyword(s):  
Homogenization Temperature ◽  
Optical Microscope ◽  
Donets Basin ◽  
Closed Porosity ◽  
Thin Sections ◽  
Distinctive Features ◽  
Genetic Types ◽  
Total Magnification ◽  
Homogenization Temperatures ◽  
Quartz Grains

The article presents the results of the study of gas inclusions in quartz grains of Donets Basin sandstones. It describes the main genetic types of inclusions, their conditions of formation, shape, size, as well as features of the transformation under the conditions of catagenesis of rocks.The presence and distinctive features of the primary and secondary inclusions were established by studying of their homogenization temperatures. Thanks to these studies, it was found that the homogenization temperature of the primary inclusions is 1.5–2 higher than for secondary ones. Also, characteristic of the primary inclusions is that they are mainly gas-liquid. In size, primary inclusions are 1.5–2 times larger than secondary ones, and on average they are 2–3 µm. Secondary inclusionsessentially consist of gas. A characteristic feature of secondary inclusions in quartz grains of the sandstones of the Donetsk Basin is that they decorate the microdeformations of these grains, thereby forming numerous Boehm stripes. The gas inclusions of Boehm strips are indicators of paleotemperature, and the Boehm strips themselves carry information about paleopressure. To calculate the volume of gas inclusions, a methodwas proposed.This method is easy to use and does not require significant financial expenses. For its implementation, standard petrographic thin sections are used, which are examined using an optical microscope with a total magnification of 1000-1200 times. Using the proposed method, the volumes of gas inclusions in quartz grains of sandstones of different substages of catagenesis were established. Considering that gas inclusions are part of closed porosity, it is proposed to conditionally subdivide closed porosityinto cement closed porosity (volume of closed pores in the cementing substance of the rock) and grain closed porosity (volume of closed pores in detrital grains of the rock). It is established that the indicator of grain closed porosity is 2-3 times higher than the indicator of cement closed porosity. The largest volumes of gas inclusions are established for the middle substage of catagenesis. Considering that rock and gas outbursts occur only at the middle substage of catagenesis, this confirms the theory about the additional effect of gas inclusions on the progress of gas-dynamic phenomena in mine opening.Also, duringthe determination of absolute porosity of rocks in laboratory conditions, it is very important to grind the rock to micron-sized fraction. This will allow opening a part of inclusions in the clastic grains of rocks, which will substantially complement the indexes of absolute porosity.

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.

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 Analysis of the charging process of the lacustrine tight oil reservoir in the Triassic Chang 6 Member in the southwest Ordos Basin, China

2017 ◽  
Vol 54 (12) ◽  
pp. 1228-1247
Author(s):  
Zhengjian Xu ◽  
Luofu Liu ◽  
Tieguan Wang ◽  
Kangjun Wu ◽  
Wenchao Dou ◽  
...  
Keyword(s):  
Ordos Basin ◽  
Source Rocks ◽  
Driving Mechanism ◽  
Tight Oil ◽  
Geological Time ◽  
Tight Sandstone ◽  
Main Production ◽  
The Ordos Basin ◽  
Homogenization Temperatures ◽  
Quartz Grains

With the success of Bakken tight oil (tight sandstone oil and shale oil) and Eagle Ford tight oil in North America, tight oil has become a research focus in petroleum geology. In China, tight oil reservoirs are predominantly distributed in lacustrine basins. The Triassic Chang 6 Member is the main production layer of tight oil in the Ordos Basin, in which the episodes, timing, and drive of tight oil charging have been analyzed through the petrography, fluorescence microspectrometry, microthermometry, and trapping pressure simulations of fluid inclusions in the reservoir beds. Several conclusions have been reached in this paper. First, aqueous inclusions with five peaks of homogenization temperatures and oil inclusions with three peaks of homogenization temperatures occurred in the Chang 6 reservoir beds. The oil inclusions are mostly distributed in fractures that cut across and occur within the quartz grains, in the quartz overgrowth and calcite cements, and the fractures that occur within the feldspar grains, with blue–green, green, and yellow–green fluorescence colours. Second, the peak wavelength, Q650/500, and QF535 of the fluorescence microspectrometry indicate three charging episodes of tight oil with different oil maturities. The charging timings (141–136, 126–118, and 112–103 Ma) have been ascertained by projecting the homogenization temperatures of aqueous inclusions onto the geological time axis. Third, excess-pressure differences up to 10 MPa between the Chang 7 source rocks and the Chang 6 reservoir beds were the main driving mechanism supporting the process of nonbuoyancy migration.

scholarly journals Genesis of the Zhijiadi Ag-Pb-Zn Deposit, Central North China Craton: Constraints from Fluid Inclusions and Stable Isotope Data

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-23 ◽  
Author(s):  
Tao Liu ◽  
Suo-Fei Xiong ◽  
Shao-Yong Jiang ◽  
Hua-Liang Li ◽  
Qi-Zhi Chen ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
North China Craton ◽  
North China ◽  
Early Stage ◽  
Homogenization Temperature ◽  
Main Stage ◽  
Magmatic System ◽  
Hydrothermal Deposit ◽  
Homogenization Temperatures ◽  
Late Stages

The Zhijiadi Ag-Pb-Zn deposit is located in the central North China Craton. Fluid inclusions (FIs) studies indicate three types of FIs, including aqueous, aqueous-carbonic, and daughter mineral-bearing multiphase inclusions. The daughter minerals in FIs are mainly composed of marcasite, chalcopyrite, calcite, and dolomite. Microthermometric data show that the homogenization temperature and salinity of FIs decrease gradually from early to late stages. Homogenization temperatures from early to main to late stages span from 244 to 334°C, from 164 to 298°C, and from 111 to 174°C, respectively, while their salinities are 4.0–9.9 wt.% NaCl equiv., 0.5–12.7 wt.% NaCl equiv., and 0.2–8.8 wt.% NaCl equiv., respectively. Trapping pressures drop from 203–299 MPa (the early stage) to 32–158 MPa (the main stage). The dropping of pressure and temperature and mixing and/or dilution of ore-forming fluids result in the formation of ore deposit. Combined with C-O-S-Pb isotopic compositions, the initial ore-forming fluids and materials were likely derived from a magmatic system. As a whole, we proposed that this deposit belongs to medium-low temperature hydrothermal deposit related to volcanic and subvolcanic magmatism strictly controlled by the fault zones.

Effect of Homogenization on Recrystallization of Twin Roll Cast AA3003 Alloy

2013 ◽  
Vol 404 ◽  
pp. 122-126
Author(s):  
Yi You Tu ◽  
De Zhong Zhang
Keyword(s):  
Annealing Temperature ◽  
Volume Fraction ◽  
Resistivity Measurement ◽  
Optical Microscope ◽  
Intermetallic Particles ◽  
Temperature Homogenization ◽  
Homogenization Temperatures ◽  
Twin Roll Cast ◽  
Twin Roll ◽  
Electric Resistivity Measurement

The effect of homogenizations on the recrystallization microstructure of as-rolled twin roll cast AA3003 alloy were investigated using optical microscope, scanning electron microscopy and electric resistivity measurement. The results indicate that high temperature homogenization significantly decrease the supersaturation of Mn in the alloy, and both the volume fraction and the diameter of intermetallic particles increase as the homogenization temperatures. The shape of the recrystallized grains changes from pancake-like to equiaxed, as the annealing temperature increases above 520°C.

Balneaves: Soil Thin Sections

1992 ◽  
Vol 58 (S2) ◽  
pp. 23-25
Author(s):  
Donald Davidson
Keyword(s):  
Iron Oxides ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
Random Pattern ◽  
Medium Sand ◽  
Thin Sections ◽  
Amorphous Iron ◽  
Channel Pattern ◽  
Mineral Components ◽  
Quartz Grains

1. Structure: partially accommodated channels (0.16 to 0.80mm in width) above the pan; no aggregates; fewer channels below the pan; channel pattern - straight to curved; vughs (spherical to elongate, not normally connected) 0.4 to 0.8mm in diameter and are not orientated and have random pattern: above pan channels and vughs partially connected; pellicular grain microstructure - weakly developed.2. Mineral components: coarse fraction: quartz grains range in size from silt to fine/medium sand (<lmm). One large quartz (200mm). Dominance of single and compound quartz grains; instances of biotite and plagioclase; quartz grains -angular/subangular and smooth. Fine fraction: brown, optically amorphous iron oxides, isotropic.

Isotope-Geochemical Features of Apoultrabasic Metasomatites of the Sayan–Baikal Folded Area

2021 ◽  
Vol 62 (9) ◽  
pp. 1021-1035
Author(s):  
M.V. Rampilova ◽  
G.S. Ripp ◽  
M.O. Rampilov ◽  
B.B. Damdinov ◽  
L.B. Damdinova ◽  
...  
Keyword(s):  
Low Temperature ◽  
Isotopic Composition ◽  
Fluid Inclusions ◽  
Siberian Craton ◽  
Carbonate Rocks ◽  
Fluid Phase ◽  
Homogenization Temperature ◽  
Crustal Component ◽  
Geochemical Study ◽  
Homogenization Temperatures

Abstract —The paper is concerned with a geochemical study of apoultrabasic metasomatites of the Ospa–Kitoi, Parama, and Ust’-Kelyana ophiolite massifs located in the southern folded framing of the Siberian craton. The isotope (O, C, H, Sr, and Rb) systems of dunites, serpentinites, nephrites, listvenites, and talc–carbonate rocks are studied. The isotopic composition of oxygen in olivines from dunites is characterized by δ18O = 4.6–5.5‰. The δ18O values of serpentinites (4.67–7.35‰) point to the mantle genesis of fluids and might have been inherited from ultrabasic rocks. Nephrites are slightly enriched in heavy oxygen isotope (δ18O = 6.13–9.54‰). This indicates that their fluid phase was transported from serpentinites and captured a small portion of the crustal component. The widest variations in δ18O values, from 8.12 to 17.46‰, are observed in minerals from listvenites. Carbonates from these rocks show a highly heterogeneous isotopic composition of oxygen (δ18O = 12.9–18.8‰) and carbon δ13C = –2.8 to +2.8‰). These rocks formed with the contribution of metamorphogenic fluids. According to the isotopic composition of hydrogen, the examined serpentinites are divided into two groups: with δD values specific to “magmatic water” (δD = –73.50 to –85.00‰) and those typical of meteoric fluids (δD = –151.90 to –167.20‰). The listvenites are characterized by low Rb and high Sr contents. Their 87Sr/86Sr values (0.70702–0.70971) indicate the contribution of a crustal source. The study of fluid inclusions in minerals from listvenites has shown that the rocks formed under relatively low-temperature conditions. The homogenization temperatures of fluid inclusions in quartz and magnesite from listvenites of the Ospa–Kitoi massif are 184–290 ºC and 122–182 ºC, respectively. In the Parama massif, the homogenization temperature of fluid inclusions in quartz is 130–170 ºC. The solutions that formed listvenites of the Ospa–Kitoi massif were slightly saline (TDS = 2.9–8.4 wt.% NaCl eq.), with NaCl and Na2CO3 being the main salt components.

The Youngest Toba Tuff (74 ka) Crystals Characterization

2020 ◽  
Author(s):  
Gabriela Nogo Retnaningtyas Bunga Naen ◽  
Atsushi Toramaru ◽  
Tomoharu Miyamoto ◽  
Haryo Edi Wibowo
Keyword(s):  
Magma Chamber ◽  
Fractional Crystallization ◽  
Optical Microscope ◽  
Oscillatory Zoning ◽  
Geochemical Data ◽  
Thin Sections ◽  
Decompression Rate ◽  
Wide Range ◽  
Different Characteristics ◽  
Toba Caldera

&lt;p&gt;Toba Caldera Complex, Indonesia is well known as the largest Quaternary caldera (87x33 km) that formed by four major eruptions among which the biggest one is the eruption of the Youngest Toba Tuff (YTT) about 74,000 years ago. Textural study of the pumice clast from YTT has been done to estimate the decompression rate by using bubble number density data. The result shows that decompression rate of Toba Caldera forming eruption varies in two order magnitude ranging from 10&lt;sup&gt;6 &lt;/sup&gt;&amp;#8211; 10&lt;sup&gt;8&lt;/sup&gt; Pa/s. Southern pumices show the lower value than pumices from northern caldera. Similarly, new data about lithic distributions and mineral components of YTT from the northern and southern caldera showed several different characteristics. This fact suggests possibility of different processes which is distinguish production of southern and northern deposits. Therefore, understanding both conduit and chamber processes is needed to reveal the origin of differences in deposits. This study aims to elucidate magma chamber condition by characterizing the deposit especially crystals from YTT eruption.&lt;/p&gt;&lt;p&gt;Characterizations of Toba Tuffs have been made but not been enough to discuss YTT in detail. In this study, we focus on spatial differences in YTT deposits. Samples from four different locations were employed for the analyses. Component analysis was carried out on components larger than 2 mm. Whole-rock geochemical data were obtained by XRF. Petrography analysis for 37 thin sections was conducted using optical microscope. Textural analysis was carried out for 84 free crystals and 25 selected thin sections using microphotographs taken by SEM and further analyzed using image processing software. Chemical analysis for free crystal was carried out by SEM-EDS, while for pumices grain of 22 thin sections was conducted using EPMA.&lt;/p&gt;&lt;p&gt;Geochemical data showed that YTT magma is rhyodacitic to rhyolitic in whole-rock compositions with wide range of SiO&lt;sub&gt;2&lt;/sub&gt; (69.15&amp;#8211;76.83 wt.%). There are differences in abundance and type of pumices, free crystals, and lithic in each location&lt;strong&gt;.&lt;/strong&gt; Major minerals are plagioclase, biotite, sanidine, and quartz. Common characteristics of northern and southern part deposit is that most of crystals are fractured, some forming aggregates, has anhedral shape and wide variation in size (0.003 mm&lt;sup&gt;2&lt;/sup&gt;-13.113 mm&lt;sup&gt;2&lt;/sup&gt;). However, there are differences between northern and southern deposits: presence of amphibole with larger size, orange quartz, sieve texture, patchy zoning, oscillatory zoning, crystal clots, and wider range of anorthite (An&lt;sub&gt;25&lt;/sub&gt;&amp;#8211; An&lt;sub&gt;87&lt;/sub&gt;) is mostly found in northern deposits.&lt;/p&gt;&lt;p&gt;Plagioclase composition from northern part shows bimodal distribution suggesting that crystallization does not occur simultaneously by single process. Furthermore, plots of anorthite number versus size and of average anorthite number versus crystal content show random distribution, suggesting the complex crystallization of plagioclase: other processes than fractional crystallization in magma chamber. Moreover, presence of antecryst and disequilibrium textures in northern deposit indicates intervention from older rocks or even other systems. Different characteristics between northern and southern deposits suggest that YTT deposits are generated by multiple eruptions from independent, at least two magma chambers.&lt;/p&gt;&lt;p&gt;Keywords: Toba Caldera, the Youngest Toba Tuff (YTT), Crystal Characterization, Conduit Process, Chamber Process, Fractional Crystallization, Multiple eruptions&lt;/p&gt;

The optical determination of preferred orientation in clays and its application to the study of microstructure in consolidated kaolin. І

1967 ◽  
Vol 300 (1461) ◽  
pp. 218-234 ◽  
Keyword(s):  
Three Dimensional ◽  
Optical Microscope ◽  
Preferred Orientation ◽  
Distribution Functions ◽  
Thin Sections ◽  
Clay Particles ◽  
Degree Of Orientation ◽  
Dimensional Distribution ◽  
Optical Determination

Although single clay particles can seldom be seen with an optical microscope the preferred orientation of an aggregate of clay particles may be investigated by studying in thin section the birefringence of the aggregate. The techniques of preparing thin sections of clay with a minimum of disturbance of the structure and for measuring the birefringence under crossed nicols are described. It is shown that the birefringence of the aggregate arises solely from the birefringence of the constituent particles at least for the porosities of the clay used in this study. If a model distribution function for the spatial orientation of the particles be adopted the birefringent behaviour of the aggregate may be predicted and birefringence observations may be used to interpret the degree of orientation of an aggregate in terms of a model parameter. Two- and three-dimensional distribution functions are considered and the two-dimensional theory is judged to be preferable.

scholarly journals Formation of Diagenetic Minerals in the Carboniferous Rock Complex from the Fore-Sudetic Monocline (SW Poland): Fluid Inclusion, Isotopic and Raman Constraints

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 976
Author(s):  
Aleksandra Kozłowska ◽  
Katarzyna Jarmołowicz-Szulc ◽  
Marta Kuberska ◽  
Krystyna Wołkowicz
Keyword(s):  
Fluid Inclusion ◽  
Fluid Inclusions ◽  
Regional Metamorphism ◽  
Microscopic Analysis ◽  
Thin Sections ◽  
Mineralogical Characteristics ◽  
Low Degree ◽  
Isotopic Analyses ◽  
Homogenization Temperatures ◽  
Clastic Sedimentary

The paper presents the latest state of knowledge on clastic sedimentary rocks from the Carboniferous complex in the SW part of the Polish Lowlands, studied to help determine their potential prospectivity for the occurrence of oil and/or gas deposits. Rocks were analyzed with respect to the petrographic-mineralogical characteristics of the Carboniferous deposits, their diagenesis, determinations of pressure-temperature conditions of mineral formation and the hydrocarbon occurrence. Analyses were carried out on samples from four selected boreholes in the Fore-Sudetic Monocline. After microscopic analysis of rocks and minerals in thin sections, the following techniques were used: luminescence analysis (UV, blue light), microthermometric analysis of fluid inclusions in double-sided polished wafers, XRD analyses, stable isotopic analyses (carbon, oxygen) on calcite and dolomite-ankerite and Raman spectra of fluid inclusions. Orthochemical components, such as carbonates and authigenic quartz, that form cements or fill the veins cutting the sample material have been studied. Fluid inclusion data in quartz and carbonates result in homogenization temperatures of 74–233 °C. The Raman analysis gives temperature estimations for the organic matter of about 164 °C and 197 °C, depending on the borehole, which points to a low coalification degree. The post-sedimentary processes of compaction, cementation and diagenetic dissolution under eo- and meso-diagenetic conditions to temperatures of over 160 °C influenced the present character of the deposits. P-T conditions of brines and methane trapping have been estimated to be ~850–920 bars and 185–210 °C (vein calcite) and ~1140 bars and 220 °C (Fe-dolomite/ankerite). However, locally, temperatures might have been higher (>200 °C), which may be a symptom of local regional metamorphism of a very low degree.

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