Magnetic fabric in mid-Cambrian rocks of the Central Flinders Zone and implications for the regional tectonic history

Zheng-Xiang Li, C.MCA. Powell

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    Abstract

    Magnetic fabric in the mid-Cambrian sedimentary rocks in the Central Flinders Zone, South Australia, varies from a bedding-parallel foliation to a well-developed lineation. No cleavage is visible in sampled outcrops but an incipient disjunctive cleavage is developed elsewhere. Comparison of magnetic-fabric data from different positions on a soft-sediment fold suggests that the magnetic lineation is not of depositional origin. Rather, it is interpreted as the result of two interfering generations of magnetic fabric: one is a compactional bedding-parallel magnetic foliation, and the other is a magnetic foliation of tectonic origin, defined by the girdle distribution of the site-mean lineation directions. This interpretation suggests that after bedding rotation during formation of the regional NNW-trending folds in the Central Flinders Zone, there was a phase of NNW-SSE-directed tectonic shortening during the Delamerian Orogeny. A model involving a southward-progressing orogeny could possibly account for the two phases of tectonic shortening, as well as for the development of the Nackara Arc in the Adelaide Fold Belt.
    Original languageEnglish
    Pages (from-to)165-176
    JournalTectonophysics
    Volume223
    DOIs
    Publication statusPublished - 1993

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