1,721,146 research outputs found
Holdsworth, R S, 401953
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/392865Surname: HOLDSWORTH. Given Name(s) or Initials: R S. Military Service Number or Last Known Location: 401953. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 53186.211961
Item: [2016.0049.25158] "Holdsworth, R S, 401953
Fault zone weakening processes along low-angle normal faults: insights from the Zuccale Fault, Isle of Elba, Italy
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Intraplate strike-slip deformation belts: an introduction. In: Intraplate strike-slip deformation belts. F. Storti, R. Holdsworth & F. Salvini Editeurs
No full textIntraplate strike-slip deformation belts are typically steeply-dipping structures that develop in both oceanic and continental lithosphere where they form some of the largest and most spectacular discontinuities found on Earth. In both modern and ancient continental settings, intraplate strike slip deformation belts are of major importance in accomodating horizontal displacements where they additionally form very persistent zones of weakness that substantially influence the rheological behavior of the lithosphere over very long time periods (up to 1 Ga or more). These deformation zones provide a fundamental geometric, kinematic and dynamic link between the more rigid plate-dominated tectonics of the oceans and the non-rigid, complex behaviour of the continents. During convergence, they help to transfer major displacements deep into the plate interiors. During divergence, they act as transfer zones that segment rifts, passive continental margins and, ultimately, oceanic spreading ridges. Such belts are also of great economic importance, controlling the location of many destructive earthquakes, offshore and onshore hydrocarbon deposits and metalliferous ore deposits. In the oceans, intraplate strike-slip movements are relatively minor along transform-related fracture zones, but there are an increasing number of documented examples that may reflect spatial and temporal variations in spreading rate along individual active ridge segments
The nature and regional significance of structures in the Gala Group of the Southrn Uplands Terrane, Berwickshire coast, southeastern Scotland
Get PDFStructures deforming Llandovery turbidites of the Gala Group in the Southern Uplands terrane are spectacularly exposed in the Berwickshire coastal section, southeastern Scotland. The upward-facing, upright to NW-vergent folds and associated structures appear to record a single regional phase of subhorizontal NW–SE contractional deformation, with a steeply dipping direction of bulk finite extension. These structures are markedly different from those developed in rocks corre- lated with the Upper Llandovery Hawick Group exposed some 5km to the south in the Eyemouth–Burnmouth coastal section. Here a highly domainal system of sinistral transpressional strain occurs, with zones of steeply plunging curvilinear folds, clockwise cleavage transection and bedding-parallel sinistral detachment faults. The markedly different bulk strain patterns in the Berwickshire coastal sections are thought to reflect the regionally diachronous nature of transpres- sional deformation in the Southern Uplands terrane. There are striking similarities in the structures recognized in the Berwickshire coastal sections and those developed in stratigraphically equivalent units along strike in southwestern Scotland and Northern Ireland. This confirms the lateral structural continuity and correlation of tracts and tract boundaries along the entire length of the Southern Uplands terrane. The regional structure suggests that a phase of top-to-the-NW backthrusting and backfolding associated with the southern margin of the Gala Group outcrop marks the transition from orthogonal contraction to sinistral transpression in the Southern Upland thrust wedge during late Llandovery times
The Moine Supergroup of NW Scotland: insights into the analysis of polyorogenic supracrustal sequences
No full textInteractions between low-angle normal faults and plutonismin the upper crust: Insights from the Island of Elba, Italy
No full textFault zone weakening and character of slip along low-angle normal faults: Insights from the Zuccale fault, Elba, Italy
No full textA seismically active low-angle normal fault is recognized at depth in the Northern Apennines, Italy, where recent exhumation has also exposed ancient examples at the surface, notably the Zuccale fault on Elba. Field-based and microstructural studies of the Zuccale fault reveal that an initial phase of pervasive cataclasis increased fault zone permeability, promoting influx of CO2-rich hydrous fluids. This triggered low-grade alteration and the onset of stress-induced dissolution–precipitation processes (e.g. pressure solution) as the dominant grain-scale deformation process in the pre-existing cataclasites leading to shear localization and the formation of a narrow foliated fault core dominated by fine-grained hydrous mineral phases. These rocks exhibit ductile deformation textures very similar to those formed during pressure-solution-accommodated ‘frictional–viscous’ creep in experimental fault rock analogues. The presence of multiple hydrofracture sets also points to the local attainment of fluid overpressures following development of the foliated fault core, which significantly enhanced the sealing capacity of the fault zone. A slip model for low-angle normal faults in the Apennines is proposed in which aseismic frictional–viscous creep occurs on a weak, slow-moving (slip rate <1 mm a–1) fault, interspersed with small seismic ruptures caused by cyclic hydrofracturing events. Our findings are potentially applicable to other examples of low-angle normal faults in many tectonic settings
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