Structural analyses of specific features in naturally deformed rock consist of geometric observations (e.g. shape), kinematic measurements (e.g. strain), and dynamic models (e.g. stress). Although analytical definitions clearly... more
Structural analyses of specific features in naturally deformed rock consist of geometric observations (e.g. shape), kinematic measurements (e.g. strain), and dynamic models (e.g. stress). Although analytical definitions clearly distinguish strain and stress, common usage of the terms tends to blur the conceptual difference. Strain and stress do not have a simple cause-and-effect relationship. The fundamental difference between strain and stress is that strain terms reflect descriptive interpretations of what movements produced a structure, while stress terms reflect genetic interpretations of why the structure formed. This descriptive vs genetic distinction has several implications. First, kinematic analysis is less speculative and more directly related to observations than dynamic analysis. Second, kinematic analysis is less computationally and analytically intensive than dynamic analysis. Third, kinematic analysis is amenable to more intuitive, but shallower, understanding than dynamic analysis. The most useful terminology communicates this conceptual framework through clear and accurate use of terms for strain, stress, and related concepts. A variety of examples illustrate the descriptive and genetic usage of strain and stress terminology.
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Strike-slip faults are commonly the final phase of contraction in orogenic belts, occurring when the folds have locked-up and the thrusts have become too steep for further displacement to occur. Where the maximum stress axis (sigma1) is... more
Strike-slip faults are commonly the final phase of contraction in orogenic belts, occurring when the folds have locked-up and the thrusts have become too steep for further displacement to occur. Where the maximum stress axis (sigma1) is perpendicular to the orogenic belt (i.e. pure shear), the strike-slip faults are conjugate and represent strike-perpendicular shortening and necessary strike-parallel extension. An example of such behaviour occurs in the steeply dipping Silurian sandstones and shales in Kirkcudbrightshire, in the Southern Uplands of Scotland. If sigma1 is at ~ 70°; to the strike of the orogenic belt, the conjugate strike-slip faults become asymmetric. One set of strike-slip faults occurs at a high angle to the strike of bedding, and the conjugate set has a ramp-flat trajectory across steeply dipping beds. An example of this behaviour occurs in the steeply dipping Silurian turbidites at Ardglass, in the Longford-Down terrane of Northern Ireland. If sigma1 is at a lower angle to the orogenic belt (i.e. transpression), one set of strike-slip faults tends to dominate. In some cases, the dominant strike-slip fault set is parallel to the strike of the orogenic belt, the Caledonian-age Great Glen Fault of Scotland being such an example. In other cases, block rotation occurs on the set of strike-slip faults that are at a high angle to the orogenic belt, as in the Variscan Orogenic Belt of SW England. An annulus model is presented to illustrate the variations in geometries of late-orogenic strike-slip faults from pure shear to transpression.
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Models developed to explain the deformation of Kilauea volcano largely rely on seismic and geodetic data that cover only a short period of activity. Kilauea's active South Flank contains two normal fault systems — the Koa'e and... more
Models developed to explain the deformation of Kilauea volcano largely rely on seismic and geodetic data that cover only a short period of activity. Kilauea's active South Flank contains two normal fault systems — the Koa'e and Hilina systems — that must reflect longer-term deformation of the edifice. The scale and origin of these faults is poorly understood. Both fault systems consist of en echelon fault segments that have significant interaction and linkage. The presence of relay ramps between fault segments, systematic stepping senses, and slip and displacement data all suggest that the fault systems link down to individual larger faults. The Hilina Fault System (HFS) is ≥42km long and ∼9km deep, while the Koa'e Fault System (KFS) is underlain by two to three smaller faults, the largest of which is at least 14km long and 4km deep (and possibly extends down to the basal thrust at 9km depth). We suggest that the HFS has developed as a result of ‘differential slip’ on the thrust at the base of the edifice and that footwall uplift on the HFS causes antithetic faulting in the South Flank, which provides a new explanation of the origin of the KFS.
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... The bridges between neighbouring veins are characterized by two symmetrically arranged zones of solution seams, and occasionally by one or ... 4 Ol 91-8141/97 $17.00 + 0.00 Nucleation and growth of strike-slip faults in limestones... more
... The bridges between neighbouring veins are characterized by two symmetrically arranged zones of solution seams, and occasionally by one or ... 4 Ol 91-8141/97 $17.00 + 0.00 Nucleation and growth of strike-slip faults in limestones from Somerset, UK EMANUEL JM WILLEMSE ...
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... S~me dtslortton,, t~cL'ur because td' irnperlecl hi <~I lhe photograph~ and hecau.,,e ttl htp~graphic var~allons These pr~blems were reduced at Gipsy Pt~int by using aerial ph~tographs as lemplales (the aerial pholographs... more
... S~me dtslortton,, t~cL'ur because td' irnperlecl hi <~I lhe photograph~ and hecau.,,e ttl htp~graphic var~allons These pr~blems were reduced at Gipsy Pt~int by using aerial ph~tographs as lemplales (the aerial pholographs were laken by J. Allen ,~1 SI Andrew.,+ LJnlw'rslty, U ...
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Abstract Oversteps and bends along cross-sections through small-scale (&lt; 2 m displacement) normal faults are described. Lithological variations, particularly the relative proportions of brittle to less brittle layers, have... more
Abstract Oversteps and bends along cross-sections through small-scale (&lt; 2 m displacement) normal faults are described. Lithological variations, particularly the relative proportions of brittle to less brittle layers, have important effects on fault initiation, ...
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Suckling mice have proved successful for the isolation of measles virus from the brain biopsy specimens of two clinical eases of subacute sclerosing panencephalitis (SSPE). A productive infection, with cell-free virus, has been obtained... more
Suckling mice have proved successful for the isolation of measles virus from the brain biopsy specimens of two clinical eases of subacute sclerosing panencephalitis (SSPE). A productive infection, with cell-free virus, has been obtained in mouse brain tissues with both isolates. Subsequent infection of Vero cell cultures was obtained with mouse brain homogenates but not with mouse brain derived cell-free virus, thereby mimicking the situation with SSPE in which cocultivation of brain and Vero cells is needed to infect the Vero cells. A non-productive infection, with cell-associated virus, has been obtained in Vero cells for a limited period with one isolate (LW) and for an indefinite period with the other isolate (MD). Infectivity experiments with MD isolate suggest that the cell-associated character of this SSPE measles virus is not an indication of genomic defectiveness.