Rock magnetism and geophysical interpretation of the Black Hill Norite South Australia

Shanti Rajagopalan, Phillip Schmidt, David Clark

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)

    Abstract

    The Black Hill Norite is a mafic intrusion which formed around 487 Ma ago. It intruded sediments of the Kanmantoo Group and Adelaide Supergroup which were deformed and metamorphosed during the Delamerian Orogeny. The Norite gives rise to an unusual magnetic anomaly, a major negative to the north-east with a similar positive to the south-west, which is atypical of the present magnetic inclination of ?65° and declination of +8°. Measurements of natural remanent magnetization on oriented samples revealed a high magnetic susceptibility (2000 to 5000*10−5 SI units) and a very stable remanent magnetization with the following properties: declination 221.2°, inclination 7.6° (α95 = 4°) and a Koenigsberger ratio of approximately 2. The Black Hill Norite is inferred to have formed at equatorial latitudes. Surface measurements are probably representative of the rock at depth since forward modelling incorporating remanent magnetization gave a good match between observed and modelled magnetic anomalies.

    Original languageEnglish
    Pages (from-to)209-212
    Number of pages4
    JournalExploration Geophysics
    Volume24
    Issue number2
    DOIs
    Publication statusPublished - 1993

    Keywords

    • Black Hill Norite
    • Delamerian Orogeny
    • Magnetic anomaly
    • Natural remanent magnetization

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