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Damage zone geometry around fault tips
GEOLOGYENVIRONMENTAL sheared metamorphic terrain of the Kazakhstan type. (from Author) 963019 Catalogue of world wide diamond and kimberlite oecarrences: a selective and annotative approach A. J. A. Janse & P. A. Sheahan, Journal of Geochemical Exploration, 53(1-3), 1995, pp 73-111. The paper discusses the cratonic areas of each continent and the occurrence of kimberlites and diamonds. (from Authors) 963020 Geoteetonic controls of primary diamond deposits: implications for area selection H. H. Helmstaedt & J. J. Gurney, Journal of Geochemical Exploration, 53(1-3), 1995, pp 125-144. Area selection in modern diamond exploration should be based on: 1) prediction of regions under which diamonds may have formed, 2) selection of those areas under which the diamonds may have survived until entrained by younger kimberlites or lamproites, and 3) identification of mantleroot-friendly structures which served as pathways for diamondiferous kimberlites or lamproites in the appropriate areas. (from Authors) 963021 Damage zone geometry around fault tips A. G. McGrath & I. Davison, Journal of Structural Geology, 17(7), 1995, pp 1011-1024. Damage zones are described around small scale normal, strike-slip, and reverse faults cutting horizontally-bedded carbonates, shales and siltstones in the Bristol Channel basin, UK. Two different types of brittle damage zone have been recognized: 1) fractures branching directly from the fault tip; and 2) fractures forming an en echelon array, which are disconnected from the fault tip, Similar damage zones are repeated at regular intervals along the faults and they are interpreted to represent paleo-tip lines or sticking points along fault planes. Strike-slip and thrust faults were observed to produce more variable damage zone geometries compared to those at normal fault tips. (from Authors)
Environmental
effects
963022 Weathering and weathering processes D. G. Price, Quarterly Journal of Engineering Geology, 28(3), 1995, pp 243-252. Definitions of weathering are examined and a definition of weathering for geotechnical purposes is proposed. Weathering is achieved by weathering processes, which depend upon the nature of the new environment to which the geological materials are introduced. Weathering processes are reviewed with particular reference to examples from engineering practice. The weathering product, the modified geological material and mass, is a consequence of the interaction of the weathering processes and the geological materials and mass on which the weathering processees act. Modes of weathering of particular rock types are reviewed. The paper concludes with a discussion of classification policy, recommending simplification. (Author) 963023 Engineering in weathered rock S. R. Hencher & D. P. McNicholl, Quarterly Journal of Engineering Geology, 28(3), 1995, pp 253-266. The potential problems to be faced when engineering in zones of weathered rock are reviewed. Di~~culties in formulating realistic geotechnical models by standard methods of site investigation and routine testing are emphasized and the consequences of being wrong are illustrated by examples. Alternative approaches for delineating weathered zones for design are presented. The constraining influence of particular characteristics of weathered zones on methods of construc-
EFFECTS
105A
tion are discussed with reference to brief case histories, (Authors) 963024 The survey and recording of historic monuments K. Emerick, Quarterly Journal of Engineering Geoiogy, 28(3), 1995, pp 201-205. Historic monuments are a valuable asset and provide information on man’s past activities. They also provide the engineering geologist with useful guidance on rates of weathering. Fountains Abbey, near Ripon in Yorkshire was founded in 1132 but has been without a roof or windows since the Dissolution of the Monasteries in 1539. Some remarkable contrasts in weathering are apparent. The severe weathering is probably related to winds coming in through the large open east window; conversely the render and limewash is still in very good conditions after over 400 years of exposure, albeit in a less exposed location. The records of such a building provide documentation on rates of weathering in engineering time, and also provide insights into the effect of various processes on a range of different materials. (from Author) 963025 Stones in monuments: natural and antbropogenic deterioration of marble artifacts l~&Fr;~tini, European Journal of Mineralogy, 7(4), 1995, pp . Two decay scenarios are described in relation to marble monuments. ‘Cooked marble’ decay is caused by temperature and pressure variations, or by soluble salts crystallizing inside the marble. These causes may act separately or jointly. The genesis of Ca-oxalate patinas is thought to be due to the natural decay of organic material spread onto monuments for finishing or conservation purposes. Environmental pollution, especially the formation of inorganic acids, causes rapid removal of the Ca-oxalate patinas. It is suggested that the formation of Ca-oxalate patina plays a protective role so their disappearance is to be regarded as a decay process. (from Author) 963026 Role de la cristallisation du natron dans la desagregation sableuse d’un monument granitique en Bretagane (Role of natron crystallization on granular disintegration of a granitic monument in Brittany) (French with abridged Englisb) E. Bernabe, P. Bromblet & M. Robert, Comptes Rendus Academic des Sciences, Serie II: Sciences de la Terre et des Planetes, 320(7), 1995, pp 571-578. The Saint Nonna church of Pemnarc’h, near the Brittany coast, shows an intense granular disintegration of granitic stones associated with soluble salt crystallizations in its interior walls. Alkaline solutions, pH about 10, dissolve silicated minerals and crystallization pressure of natron are the main origin of decay. Possible origins of alkaline solutions and sodium are discussed. (from English summary) 963027 Organic and inorganic compounds in limestone weathering crusts from cathedrals in Soutbem and Western Europe B. 0. Fobe & 7 others, Environmental Science & Technology, 29(6), 1995, pp 1691-1701. In the different types of limestone, the deterioration is largely influenced by the petrographic characteristics of the stone. Gypsum crusts from Mechelen and Sevilla show variable textures, even on the same stone types. Sulfatation of calcite provides Ca for the gypsum crusts. Except for a part of the Sr and Fe fractions in the crust, all other elements may be of external origin. Concentrations of the various elements are more or less comparable in crusts from Mechelen and Sevilla. (from Authors)
Environmental
effects
963022 Weathering and weathering processes D. G. Price, Quarterly Journal of Engineering Geology, 28(3), 1995, pp 243-252. Definitions of weathering are examined and a definition of weathering for geotechnical purposes is proposed. Weathering is achieved by weathering processes, which depend upon the nature of the new environment to which the geological materials are introduced. Weathering processes are reviewed with particular reference to examples from engineering practice. The weathering product, the modified geological material and mass, is a consequence of the interaction of the weathering processes and the geological materials and mass on which the weathering processees act. Modes of weathering of particular rock types are reviewed. The paper concludes with a discussion of classification policy, recommending simplification. (Author) 963023 Engineering in weathered rock S. R. Hencher & D. P. McNicholl, Quarterly Journal of Engineering Geology, 28(3), 1995, pp 253-266. The potential problems to be faced when engineering in zones of weathered rock are reviewed. Di~~culties in formulating realistic geotechnical models by standard methods of site investigation and routine testing are emphasized and the consequences of being wrong are illustrated by examples. Alternative approaches for delineating weathered zones for design are presented. The constraining influence of particular characteristics of weathered zones on methods of construc-
EFFECTS
105A
tion are discussed with reference to brief case histories, (Authors) 963024 The survey and recording of historic monuments K. Emerick, Quarterly Journal of Engineering Geoiogy, 28(3), 1995, pp 201-205. Historic monuments are a valuable asset and provide information on man’s past activities. They also provide the engineering geologist with useful guidance on rates of weathering. Fountains Abbey, near Ripon in Yorkshire was founded in 1132 but has been without a roof or windows since the Dissolution of the Monasteries in 1539. Some remarkable contrasts in weathering are apparent. The severe weathering is probably related to winds coming in through the large open east window; conversely the render and limewash is still in very good conditions after over 400 years of exposure, albeit in a less exposed location. The records of such a building provide documentation on rates of weathering in engineering time, and also provide insights into the effect of various processes on a range of different materials. (from Author) 963025 Stones in monuments: natural and antbropogenic deterioration of marble artifacts l~&Fr;~tini, European Journal of Mineralogy, 7(4), 1995, pp . Two decay scenarios are described in relation to marble monuments. ‘Cooked marble’ decay is caused by temperature and pressure variations, or by soluble salts crystallizing inside the marble. These causes may act separately or jointly. The genesis of Ca-oxalate patinas is thought to be due to the natural decay of organic material spread onto monuments for finishing or conservation purposes. Environmental pollution, especially the formation of inorganic acids, causes rapid removal of the Ca-oxalate patinas. It is suggested that the formation of Ca-oxalate patina plays a protective role so their disappearance is to be regarded as a decay process. (from Author) 963026 Role de la cristallisation du natron dans la desagregation sableuse d’un monument granitique en Bretagane (Role of natron crystallization on granular disintegration of a granitic monument in Brittany) (French with abridged Englisb) E. Bernabe, P. Bromblet & M. Robert, Comptes Rendus Academic des Sciences, Serie II: Sciences de la Terre et des Planetes, 320(7), 1995, pp 571-578. The Saint Nonna church of Pemnarc’h, near the Brittany coast, shows an intense granular disintegration of granitic stones associated with soluble salt crystallizations in its interior walls. Alkaline solutions, pH about 10, dissolve silicated minerals and crystallization pressure of natron are the main origin of decay. Possible origins of alkaline solutions and sodium are discussed. (from English summary) 963027 Organic and inorganic compounds in limestone weathering crusts from cathedrals in Soutbem and Western Europe B. 0. Fobe & 7 others, Environmental Science & Technology, 29(6), 1995, pp 1691-1701. In the different types of limestone, the deterioration is largely influenced by the petrographic characteristics of the stone. Gypsum crusts from Mechelen and Sevilla show variable textures, even on the same stone types. Sulfatation of calcite provides Ca for the gypsum crusts. Except for a part of the Sr and Fe fractions in the crust, all other elements may be of external origin. Concentrations of the various elements are more or less comparable in crusts from Mechelen and Sevilla. (from Authors)