What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Widera, Marek

doi:10.2478/logos-2014-0001

Cited by 16 publications

(11 citation statements)

References 19 publications

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“…The face cleat is characterized by an elongated shape and firm, continuous line that has a regular orientation direction, unlike the butt cleat, which has a form of short lines, always abutting with face cleat. Some authors mention that the angle of intersection between the butt cleats and face cleats is 90 ∘ [30]. However, in this study the separation angle is within the range of 81 ∘ -87 ∘ .…”

Section: Resultscontrasting

confidence: 55%

X-Ray Computed Tomography Analysis of Sajau Coal, Berau Basin, Indonesia: 3D Imaging of Cleat and Microcleat Characteristics

Hamdani

2015

International Journal of Geophysics

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The Pliocene Sajau coals of the Berau Basin area have a moderately to highly developed cleat system. Mostly the cleat fractures are well developed in both bright and dull bands, and these cleats are generally inclined or perpendicular to the bedding planes of the seam. The presence of cleat networks/fractures in coal seam is the important point in coalbed methane prospect. The 3D X-ray computed tomography (CT) technique was performed to identify cleats characteristics in the Sajau coal seams, such as the direction of coal cleats, geometry of cleat, and cleats mineralization. By CT scan imaging technique two different types of natural fractures observed in Sajau coals have been identified, that is, face cleats and butt cleats. This technique also identified the direction of face cleats and butt cleats as shown in the resulting 3D images. Based on the images, face cleats show a NNE-SSW direction while butt cleats have a NW-SE direction. The crosscutting relationship indicated that NNE-SSW cleats were formed earlier than NW-SE cleats. The procedure also identified the types of minerals that filled the cleats apertures. Based on their density, the minerals are categorized as follows: very high density minerals (pyrite), high density minerals (anastase), and low density minerals (kaolinite, calcite) were identified filling the cleats aperture.

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Section: Resultscontrasting

confidence: 55%

X-Ray Computed Tomography Analysis of Sajau Coal, Berau Basin, Indonesia: 3D Imaging of Cleat and Microcleat Characteristics

Hamdani

2015

International Journal of Geophysics

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“…Some incipient microcleats have developed perpendicular to the bedding almost exclusively in the telovitrinite bands (Fig. 4b), which is expected with gelification by this coal rank (Smith 1981;Widera 2014). The organic macerals can be seen faintly, indicating that they have slightly different average densities.…”

Section: Variation In Pore-scale Morphology With Coal Rankmentioning

confidence: 76%

Nano-mechanical Properties and Pore-Scale Characterization of Different Rank Coals

et al. 2019

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Characterization of coal micro-structure and the associated rock mechanical properties are of key importance for coal seam exploration, coal bed methane development, enhanced coal bed methane production and CO 2 storage in deep coal seams. Considerable knowledge exists about coal chemical properties, but less is known about the nanoscale to the microscale structure of coals and how they change with coal strength across coal ranks. Thus, in this study, 3D X-ray micro-computed tomography (with a voxel size of 3.43 lm) and nanoindentation tests were conducted on coal samples of different ranks from peat to anthracite. The micro-structure of peats showed a well-developed pore system with meso-and micropores. The meso-pores essentially disappear with increasing rank, whereas the micro-pores persist and then increase past the bituminous rank. The micro-fracture system develops past the peat stage and by sub-bituminous ranks and changes into larger and mature fracture systems at higher ranks. The nano-indentation modulus showed the increasing trend from low-to high-rank coal with a perfect linear relationship with vitrinite reflectance and is highly correlated with carbon content as expected.

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“…3,4). Xylitic lignites are occasionally found within Polish lignite seams, that is, forming up to 10% of seam thickness (Widera, 2014a(Widera, , 2014b. This is due to the fact that the dry forest swamp is characterised by environmental conditions that are favourable for the decomposition of plant remains rather than their accumulation (Brzyski, 1981).…”

Section: Discussionmentioning

confidence: 99%

“…toWagner (1996); 2 -this paper; 3 -acc. toWidera (2012Widera ( , 2014aWidera ( , 2014b); 4 -acc. to Nowak (2012).…”

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confidence: 99%

An overview of lithotype associations of Miocene lignite seams exploited in Poland

Widera

2016

Geologos

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Currently, three stratigraphically distinct lignite seams of Early to Middle Miocene age are exploited in Poland, namely the third Ścinawa lignite seam (ŚLS-3), the second Lusatian lignite seam (LLS-2) and the first Mid-Polish lignite seam (MPLS-1). All of these are composed of numerous macroscopically distinguishable layers defined as lignite lithotypes. In the present paper, the lithotypes of Polish lignites are grouped into seven major lithotype associations that originated in various types of mire. Therefore, an approximate reconstruction of mire type can be based on lignite lithotypes. Within the Polish lignite seams examined, the commonest in order of importance are: xylodetritic (XDL), detroxylitic (DXL), detritic (DL) and xylitic (XL) lithotype associations, mostly with a massive (m) or horizontal (h) structure. They are particularly dominant in lignite opencasts belonging to the Konin and Adamów mines. However, in the lowermost seams at the Turów and Bełchatów mines, a substantial part of the seams comprises the bitumen-rich (BL) lithotype association. These seams also lignite lithotypes that in large quantities have a gelified (g) and/or nodular (n) structure. In contrast, lignites from the Sieniawa mine are characterised by an admixture of the best-developed lithotype associations of both fusitic (FL) and weathered (WL) lignites. Moreover, the vast majority of these lignites have a folded (fo) and/or faulted (fa) structure, because they were completely deformed by glaciotectonics.

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What are cleats? Preliminary studies from the Konin lignite mine, Miocene of central Poland

Cited by 16 publications

References 19 publications

X-Ray Computed Tomography Analysis of Sajau Coal, Berau Basin, Indonesia: 3D Imaging of Cleat and Microcleat Characteristics

X-Ray Computed Tomography Analysis of Sajau Coal, Berau Basin, Indonesia: 3D Imaging of Cleat and Microcleat Characteristics

Nano-mechanical Properties and Pore-Scale Characterization of Different Rank Coals

An overview of lithotype associations of Miocene lignite seams exploited in Poland

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