Palaeomagnetic results from the Gordon Subgroup of Tasmania: further evidence for a Late Cretaceous magnetic overprint in southeastern Australia

A thermal demagnetization study of 48 limestone samples from the Ordovician Gordon Subgroup of Ida Bay (Tasmania), indicated complete remagnetization (D 9.4°, I -81.4°, k = 137.5, a95 = 1.30, N 92 South pole position 59.80 S 141.10E, dp = 2.4°, dm = 2.5°) during Late Cretaceous or less likely Early...

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Bibliographic Details
Main Authors: Sharples, C, Klootwijk, CT
Format: Article in Journal/Newspaper
Language:English
Published: 1981
Subjects:
Royal Society of Tasmania
RST
Van Diemens Land
natural history
science
ecology
taxonomy
botany
zoology
geology
geography
papers & proceedings
Australia
UTAS Library
South Pole
Ida
Ida Bay
South pole
Online Access:https://eprints.utas.edu.au/14138/
https://eprints.utas.edu.au/14138/1/1981__Sharples_palaeomagnetic.pdf
Description
Summary:A thermal demagnetization study of 48 limestone samples from the Ordovician Gordon Subgroup of Ida Bay (Tasmania), indicated complete remagnetization (D 9.4°, I -81.4°, k = 137.5, a95 = 1.30, N 92 South pole position 59.80 S 141.10E, dp = 2.4°, dm = 2.5°) during Late Cretaceous or less likely Early Tertiary time. This finding further supports a recently recognized Late Cretaceous renagnetization event in southeastern Australia, which is attributed to rift forming processes preceding the opening of the Tasman Sea. Conodont colour indicates that the limestones studied have not been subjected to temperatures in excess of 100°C. This suggests a possible widespread occurrence of this magnetic overprint.

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