1 results for Alsop, GI

  • Slump folds as estimators of palaeoslope: a case study fromthe Fisherstreet Slump of County Clare, Ireland

    Strachan, Lorna; Alsop, GI (2006)

    Journal article
    The University of Auckland Library

    Folds and faults preserved within slump horizons are thought to be the only sedimentary structures that primarily re??ect palaeoslope direction. By evaluating methods for the analysis of slump folds, the robustness of many palaeoslope and palaeogeographical reconstructions can be tested. Five methods for estimating palaeoslope direction from slump fold orientation data are tested with reference to the Upper Carboniferous Fisherstreet Slump horizon of County Clare, Ireland.These methods are the Mean AxisMethod, the Separation ArcMethod, theDownslope Average axisMethod, the Axial^ planar IntersectionMethod and the FoldHinge Azimuth and Interlimb AngleMethod.Transport determination techniques have mixed success when applied to this example and reveal a mean downslope transport direction of 0671.This result re??ects the varied boundary conditions that are possible during slumping, resulting fromvariations in initial fold geometries, progressive fold formation, spatial and temporal changes in velocity,material properties, pore ??uid pressures and the local slope.Without a comprehensive analysis of slump data ^ using all available techniques ^ large errors in interpreted transport direction can exist and may invalidate palaeogeographic reconstructions. It is essential to use as many transport determination techniques as possible to determine slip direction accurately.With this in mind, a general procedure for determining palaeoslope directions is suggested and used to examine existing palaeogeographic models for the Clare Basin.

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