Palaeomagnetic results from the Gordon Subgroup of Tasmania: Further evidence for a late Cretaceous magnetic overprint in Southeastern Australia

• Published in: Papers and Proceedings of The Royal Society of Tasmania
• Main Authors: Sharples, C, Klootwijk, CT
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1981
• Subjects: South Pole; Ida; Ida Bay; South pole
• Online Access: https://eprints.utas.edu.au/11756/; https://eprints.utas.edu.au/11756/3/Sharples%26Klootwijk1981_GordonLimestoneCretace.pdf

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 = l. 3o, N = 92 South pole position 59.8°5 1 41.1°E, dp = 2.4°, dm = 2.5°) during Late Cretaceous or less likely Early Tertiary time . This finding further supports a recently recognized Late Cretaceous remagnetization event in southeastern Australia , which is attributed to rift forming processes preceding the opening of t he Tasman Sea. Conodont colour indicates that the limestones studied have not been subjected to temperatures in excess of l00°c . This suggests a possible widespread occurrence of this magnetic overprint.