- Email: [email protected]
Geology of Boston, Massachusetts, United States of America
GEOMECHANICS ABSTRACTS
924004 Analysis of spatial relationships among geomorphic, petrographic and structural characteristics of the Dartmoor tors Ehlen, J Earth Surf Process Land 1/17, NI, Feb 1992, P53-67
Geology Tectonic processes and structural geology See also: 924235, 924342, 924509
924O01 Geology of Boston, Massachusetts, United States of America Woodhouse, D; Barosh, P J; Johnson, E G; Kaye, C A; Russel, H A; Pitt, W E; AIsup, S A; Franz, K E Bull Assoc Engng Geol V28, N4, Nov 1991, P375-512 A comprehensive description is presented of the geology of the area around Boston. Regional geologic setting is outlined and bedrock and surficial geology described. The geotechnical and engineering characteristics of these materials and customary practices for their investigation are then considered. Geological constraints on development and seismicity are next examined. Environmental concerns for Boston are discussed and examples of major developments, in particular tunnelling projects, are described. 294 refs.
924002 Regional fractures h a mechanism for the formation of regional fractures at depth in fiat-lying reservoirs Lorenz, J C; Teufel, L W; Warpinski, N R Bull Am Assoc Petrol Geol V75, Nil, Nov 1991, P1714-1737 Regional fractures have been observed at depth in unfolded strata. A mechanism for their formation is proposed which requires tectonic compression in combination with high pore pressure (low effective confining stress) of a brittle material. Fractures initiate at locally induced tensile stresses caused by flaws in the rock and propagate in the plane of maximum and intermediate principal stresses. The differential stress required for this mechanism is much lower than that for shear failure.
924003 Conditions for hydrofracture and the fluid permeability of accretionary wedges Behrmann, J H Earth Planet Sci Left 1/107. N3/4. Dec 1991. P550-558 Accretion of sediments at convergent plate margins requires deformation and reduction in porosity, which in turn requires efficient dewatering. In low permeability sedments, build up of material leads to high fluid pressures, which can ultimately cause hydraulic fractures, with permeability enhancement as fluids escape along fault-defined conduits. Conditions for the simultaneous shear and hydrofracture are examined for thrust, normal and wrench faulting.
The granite tots of Dartmoor were classified according to 21 geomorphic, petrographic, and structural variables using data derived from topographic maps, field measurements, and laboratory analysis of field samples. The map based details (GIS, ARC/INFO) were used to identify and compare spatial patterns. Three types of tors - summit, valleyside, and spur - were qualitatively distinguished on the basis of relative relief, joint spacing and joint type, rock texture, grain size, and composition.
924005 London's Docklands: engineering geology Howland, A F lnst Civ Engrs Proe V90, Ptl, Dec 1991, P1153-1178 The London Docklands area lies on part of the flood plain of the river Thames within the geological province of the London Basin. Information gathered during the regeneration program has been collected and some revisions made to prior published data. The Greenwich Fault is not present in the area and the dominant feature is the northwards plunging Greenwich Syncline. Geotechnical parameters of the principal formations are described. Human influence on surficial deposits is evident. Local hydrology is complex, the confined deep aquifer of Central London being unconfined in this area, and overlying Thames Gravel acting as a shallow aquifer.
924006 Single layer buckle folding in non-linear materials - I. Experimental study of fold development from an isolated initial perturbation Abbassi, M R; Mancktelow, N S J Struct Geoi VI4, N1, 1992, P85-104 The influence of a pre-existing isolated perturbation in an otherwise planar layer on the location and shape of folds developed during pure shear compression has been examined. Laboratory model tests with a single layer embedded in a weaker matrix are described. Different grades of paraffin wax were used to represent rocks with power law theology. Viscosity ratios of 30:1 and 8:1 were used. Bell-shaped perturbations were introduced into the layer. The fold packet develops at the site of the perturbation and spreads along the layer with increasing shortening. Effects of shape of initial perturbation on fold geometry and of nature of the interlayer boundary (welded or sliding) were investigated.
© 1992 Pergamon Press Ltd. Reproduction not permitted 205A
924004 Analysis of spatial relationships among geomorphic, petrographic and structural characteristics of the Dartmoor tors Ehlen, J Earth Surf Process Land 1/17, NI, Feb 1992, P53-67
Geology Tectonic processes and structural geology See also: 924235, 924342, 924509
924O01 Geology of Boston, Massachusetts, United States of America Woodhouse, D; Barosh, P J; Johnson, E G; Kaye, C A; Russel, H A; Pitt, W E; AIsup, S A; Franz, K E Bull Assoc Engng Geol V28, N4, Nov 1991, P375-512 A comprehensive description is presented of the geology of the area around Boston. Regional geologic setting is outlined and bedrock and surficial geology described. The geotechnical and engineering characteristics of these materials and customary practices for their investigation are then considered. Geological constraints on development and seismicity are next examined. Environmental concerns for Boston are discussed and examples of major developments, in particular tunnelling projects, are described. 294 refs.
924002 Regional fractures h a mechanism for the formation of regional fractures at depth in fiat-lying reservoirs Lorenz, J C; Teufel, L W; Warpinski, N R Bull Am Assoc Petrol Geol V75, Nil, Nov 1991, P1714-1737 Regional fractures have been observed at depth in unfolded strata. A mechanism for their formation is proposed which requires tectonic compression in combination with high pore pressure (low effective confining stress) of a brittle material. Fractures initiate at locally induced tensile stresses caused by flaws in the rock and propagate in the plane of maximum and intermediate principal stresses. The differential stress required for this mechanism is much lower than that for shear failure.
924003 Conditions for hydrofracture and the fluid permeability of accretionary wedges Behrmann, J H Earth Planet Sci Left 1/107. N3/4. Dec 1991. P550-558 Accretion of sediments at convergent plate margins requires deformation and reduction in porosity, which in turn requires efficient dewatering. In low permeability sedments, build up of material leads to high fluid pressures, which can ultimately cause hydraulic fractures, with permeability enhancement as fluids escape along fault-defined conduits. Conditions for the simultaneous shear and hydrofracture are examined for thrust, normal and wrench faulting.
The granite tots of Dartmoor were classified according to 21 geomorphic, petrographic, and structural variables using data derived from topographic maps, field measurements, and laboratory analysis of field samples. The map based details (GIS, ARC/INFO) were used to identify and compare spatial patterns. Three types of tors - summit, valleyside, and spur - were qualitatively distinguished on the basis of relative relief, joint spacing and joint type, rock texture, grain size, and composition.
924005 London's Docklands: engineering geology Howland, A F lnst Civ Engrs Proe V90, Ptl, Dec 1991, P1153-1178 The London Docklands area lies on part of the flood plain of the river Thames within the geological province of the London Basin. Information gathered during the regeneration program has been collected and some revisions made to prior published data. The Greenwich Fault is not present in the area and the dominant feature is the northwards plunging Greenwich Syncline. Geotechnical parameters of the principal formations are described. Human influence on surficial deposits is evident. Local hydrology is complex, the confined deep aquifer of Central London being unconfined in this area, and overlying Thames Gravel acting as a shallow aquifer.
924006 Single layer buckle folding in non-linear materials - I. Experimental study of fold development from an isolated initial perturbation Abbassi, M R; Mancktelow, N S J Struct Geoi VI4, N1, 1992, P85-104 The influence of a pre-existing isolated perturbation in an otherwise planar layer on the location and shape of folds developed during pure shear compression has been examined. Laboratory model tests with a single layer embedded in a weaker matrix are described. Different grades of paraffin wax were used to represent rocks with power law theology. Viscosity ratios of 30:1 and 8:1 were used. Bell-shaped perturbations were introduced into the layer. The fold packet develops at the site of the perturbation and spreads along the layer with increasing shortening. Effects of shape of initial perturbation on fold geometry and of nature of the interlayer boundary (welded or sliding) were investigated.
© 1992 Pergamon Press Ltd. Reproduction not permitted 205A