Pre‐ and post‐folding magnetizations from the early Devonian Snowy River Volcanics and Buchan Caves Limestone, Victoria

P. W. Schmidt*, B. J.J. Embleton, H. C. Palmer

*Corresponding author for this work

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Abstract

Multicomponent magnetizations of the Snowy River Volcanics have been resolved into pre‐folding (dec. = 340.1°, inc. =−59.2°) and post‐folding (dec. = 10.5°, inc. =−72.3°) elements. The former is attributed to initial cooling of the volcanics while the latter is probably related to the waning stages of the deformational episode which was presumably accompanied by cooling. We argue that the pole position from the pre‐folding magnetizations (lat. = 74.3°S, long. = 222.7°E) represents the Australian palaeopole for the early Devonian. A reassessment of other Australian pole positions determined from rocks of about this age suggests that remagnetization during the Carboniferous may be common. Interpretation of the pole path prior to the Devonian is equivocal and awaits further study. The post‐folding magnetizations from the volcanics are similar in stability and direction to those from the Buchan Caves Limestone (dec. = 27.8°, inc. =−75.6°), which appears to be completely remagnetized. The age of this remagnetizing event appears to be mid‐Carboniferous if our interpretation of the pole path for this time is correct. It is noted that a much unappreciated attribute of the fold test lies with identifying not just the relative age of magnetization, but also the palaeohorizontal. Only when the palaeohorizontal is established can the calculation of a palaeopole be justified.

Original languageEnglish
Pages (from-to)155-170
Number of pages16
JournalGeophysical Journal of the Royal Astronomical Society
Volume91
Issue number1
DOIs
Publication statusPublished - 1987

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Keywords

  • fold belts
  • overprints
  • palaeomagnetism
  • terranes

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