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Petrographic composition and depositional environments of Cretaceous coals and coal measures in the Middle Benue Trough of Nigeria
212A
PROPERTIES:COMPOSITION,
STRUCTURE,
DENSITY
consistent with the fractured crustal structure around the strainer position. (from Authors)
relevance to analysis of sections of soils are discussed. (from Author)
PROPERTIES OF ROCKS AND SOILS
955089 Quantitative micro-mineralogy and micro-fabric of soils and sediments N. K. Tovey, D. L. Dent, D. H. Krinsley & W. M. Corbett, in: Soil micromorphology, ed A.J. Ringrose-Voase 8z G.S. Humphreys, (Elsevier Science; Developments in Soil Science, 22), 1994, pp 541-547.
General 955085 Laboratory drilling of field-orientated block samples W. H. Owens, Journal of Structural Geology, 16(12), 1994, pp 1719-1721. Correlations required to restore specimens to their field attitude are given, for specimens cored in the laboratory from a block arbitrarily oriented on the drill table. (Author)
Composition, structure, texture and density Mineralogy and geochemistry of Bobov Do1 coals, Bulgaria S. V. Vassilev, M. G. Yossifova & C. G. Vassileva, International Journal of Coal Geology, 26(3-4), 1994, pp 185-213. The mineralogy, elemental composition, and modes of occurrence of 49 elements in nine composite samples of Bobov Do1 high-ash coals were studied by optical microscopy, scanning and transmission electron microscopy, X-ray diffractometry and chemical analysis. The modes of occurrence and some genetic peculiarities of the mineral phases are described. The Bobov Do1 coals have undergone complex syngenetic, diagenetic and epigenetic mineralization processes associated with hydrothermal and volcanic activities. (from Authors) 955087 Petrographic composition and depositional environments of Cretaceous coals and coal measures in tbe Middle Benue Trough of Nigeria N. G. Obaje, B. Ligouis 8c S. I. Abaa, International Journal of Coal Geology, 26(3-4), 1994, pp 233-260. Cretaceous coals and coal measure sequences in the area around the Obi/Lafia part of the Middle Benue Trough of Nigeria were studied petrographically. Maceral analyses of 32 coal samples from this area allow subdivision of the coal beds into three different coal facies: the vitrinite-fusinite coal facies, the trimaceritic coal facies and the shaly coal facies. The vitrinite-fusinite coal facies was deposited in wet forest swamp subenvironments along and within lagoons. The trimaceritic facies was deposited in limno-@matic elastic marsh subenviromnents in lower delta plains. The shaly coal facies shows characteristics of various subenvironments but generally tends to be more marine than the other two facies. (Authors) 955888 Some principles to be observed in the quantitative analysis of sections of soil A. J. Ringrose-Voase, in: Soil micromorphology. ed A.J. Ringrose-Voase & G.S. Humphreys, (Elsevier Science; Developments, in Soil Science, 22), 1994, pp 483-493. Image analysis of sections can be used to derive quantitative information about the structure of opaque materials such as soil. Some basic stereological principles must be observed when measuring sections because the measurements are being made in less than three dimensions.
Five topics of particular
An integrated package of techniques is described to quantify both the micro-fabric and the micro-mineralogy of soils and sediments. The techniques are illustrated using the Bt and 2C horizons of the Worlington Series, an argillic brown sand or Luvic Arenosol. Quantitative evidence from the distribution of calcium carbonate in the matrix indicates that as this is leached there is a removal of clay from the matrix. (from Authors) 955090 Description of microcrack orientation in a clayey soil using image analysis V. Hallaire, in: Soil micromorphology, ed A.J. RingroseVoase & G.S. Humphreys, (Elsevier Science; Developments in Soil Science, 22), 1994, pp 549-557. An image analysis method is proposed to describe microcrack orientation in clayey soils. Undisturbed soil cores were taken from vertical pit faces and their in situ orientation noted. The results are presented as histograms showing the porosity of the cracks according to their orientation. An example of this method is given for a soil at decreasing water contents, which shows that the crack network is isotropic at first and becomes anisotropic with a preferential vertical orientation of the cracks. (from Author) 955091 Mineralogy, geochemistry and genesis of clay deposits in Belgaum, Dbarwad and Cbitradurga Districts, Karnataka T. C. Devaraju, A. Khoshroo & A. G. Ugarkar, Journal Geological Society of India, 44(2), 1994, pp 157-165. A dozen clay deposits occurring in the districts of Belgaum, Dharwad and Chitradurga of Kamataka State have been studied. In Dharwad district, while the clay deposits derived from greywackes/phyllites are dominated by kaolin& those derived from the acid metavolcanics contain illite as the sole clay mineral. In Belgaum and Chitradurga districts the deposits are kaolinitic, character&d by poor crystallinity and near absence of illite. Chemically, the clay deposits studied have relatively high silica and low titania. (from Authors) 955092 A study of soil particle characteristics and post-depositional processes in a Deagon (Queensland, Australia) clay profile J. W. Sibley, Engineering Geology, 38(1-2), 1994, pp 25-34. An experimental study was undertaken to investigate the distributions of particle sizes and types in samples taken from a highly overconsolidated coastal clay profile at Deagon, Queensland, Australia. Systematic depth-related trends in particle sizes and micro-aggregation levels were observed. Superimposed on these trends were sinusoid-like patterns of variability in micro-aggregation levels, which were indicative of stratification. It is postulated that the stratification was associated with seasonal cycles of drying shrinkage and flooding that took place during deposition of the clay profile. The study suggests the significance of drying shrinkage as a cause of microaggregation during the formation of alluvial clay deposits in semi-arid climates. (from Author)
PROPERTIES:COMPOSITION,
STRUCTURE,
DENSITY
consistent with the fractured crustal structure around the strainer position. (from Authors)
relevance to analysis of sections of soils are discussed. (from Author)
PROPERTIES OF ROCKS AND SOILS
955089 Quantitative micro-mineralogy and micro-fabric of soils and sediments N. K. Tovey, D. L. Dent, D. H. Krinsley & W. M. Corbett, in: Soil micromorphology, ed A.J. Ringrose-Voase 8z G.S. Humphreys, (Elsevier Science; Developments in Soil Science, 22), 1994, pp 541-547.
General 955085 Laboratory drilling of field-orientated block samples W. H. Owens, Journal of Structural Geology, 16(12), 1994, pp 1719-1721. Correlations required to restore specimens to their field attitude are given, for specimens cored in the laboratory from a block arbitrarily oriented on the drill table. (Author)
Composition, structure, texture and density Mineralogy and geochemistry of Bobov Do1 coals, Bulgaria S. V. Vassilev, M. G. Yossifova & C. G. Vassileva, International Journal of Coal Geology, 26(3-4), 1994, pp 185-213. The mineralogy, elemental composition, and modes of occurrence of 49 elements in nine composite samples of Bobov Do1 high-ash coals were studied by optical microscopy, scanning and transmission electron microscopy, X-ray diffractometry and chemical analysis. The modes of occurrence and some genetic peculiarities of the mineral phases are described. The Bobov Do1 coals have undergone complex syngenetic, diagenetic and epigenetic mineralization processes associated with hydrothermal and volcanic activities. (from Authors) 955087 Petrographic composition and depositional environments of Cretaceous coals and coal measures in tbe Middle Benue Trough of Nigeria N. G. Obaje, B. Ligouis 8c S. I. Abaa, International Journal of Coal Geology, 26(3-4), 1994, pp 233-260. Cretaceous coals and coal measure sequences in the area around the Obi/Lafia part of the Middle Benue Trough of Nigeria were studied petrographically. Maceral analyses of 32 coal samples from this area allow subdivision of the coal beds into three different coal facies: the vitrinite-fusinite coal facies, the trimaceritic coal facies and the shaly coal facies. The vitrinite-fusinite coal facies was deposited in wet forest swamp subenvironments along and within lagoons. The trimaceritic facies was deposited in limno-@matic elastic marsh subenviromnents in lower delta plains. The shaly coal facies shows characteristics of various subenvironments but generally tends to be more marine than the other two facies. (Authors) 955888 Some principles to be observed in the quantitative analysis of sections of soil A. J. Ringrose-Voase, in: Soil micromorphology. ed A.J. Ringrose-Voase & G.S. Humphreys, (Elsevier Science; Developments, in Soil Science, 22), 1994, pp 483-493. Image analysis of sections can be used to derive quantitative information about the structure of opaque materials such as soil. Some basic stereological principles must be observed when measuring sections because the measurements are being made in less than three dimensions.
Five topics of particular
An integrated package of techniques is described to quantify both the micro-fabric and the micro-mineralogy of soils and sediments. The techniques are illustrated using the Bt and 2C horizons of the Worlington Series, an argillic brown sand or Luvic Arenosol. Quantitative evidence from the distribution of calcium carbonate in the matrix indicates that as this is leached there is a removal of clay from the matrix. (from Authors) 955090 Description of microcrack orientation in a clayey soil using image analysis V. Hallaire, in: Soil micromorphology, ed A.J. RingroseVoase & G.S. Humphreys, (Elsevier Science; Developments in Soil Science, 22), 1994, pp 549-557. An image analysis method is proposed to describe microcrack orientation in clayey soils. Undisturbed soil cores were taken from vertical pit faces and their in situ orientation noted. The results are presented as histograms showing the porosity of the cracks according to their orientation. An example of this method is given for a soil at decreasing water contents, which shows that the crack network is isotropic at first and becomes anisotropic with a preferential vertical orientation of the cracks. (from Author) 955091 Mineralogy, geochemistry and genesis of clay deposits in Belgaum, Dbarwad and Cbitradurga Districts, Karnataka T. C. Devaraju, A. Khoshroo & A. G. Ugarkar, Journal Geological Society of India, 44(2), 1994, pp 157-165. A dozen clay deposits occurring in the districts of Belgaum, Dharwad and Chitradurga of Kamataka State have been studied. In Dharwad district, while the clay deposits derived from greywackes/phyllites are dominated by kaolin& those derived from the acid metavolcanics contain illite as the sole clay mineral. In Belgaum and Chitradurga districts the deposits are kaolinitic, character&d by poor crystallinity and near absence of illite. Chemically, the clay deposits studied have relatively high silica and low titania. (from Authors) 955092 A study of soil particle characteristics and post-depositional processes in a Deagon (Queensland, Australia) clay profile J. W. Sibley, Engineering Geology, 38(1-2), 1994, pp 25-34. An experimental study was undertaken to investigate the distributions of particle sizes and types in samples taken from a highly overconsolidated coastal clay profile at Deagon, Queensland, Australia. Systematic depth-related trends in particle sizes and micro-aggregation levels were observed. Superimposed on these trends were sinusoid-like patterns of variability in micro-aggregation levels, which were indicative of stratification. It is postulated that the stratification was associated with seasonal cycles of drying shrinkage and flooding that took place during deposition of the clay profile. The study suggests the significance of drying shrinkage as a cause of microaggregation during the formation of alluvial clay deposits in semi-arid climates. (from Author)