Palaeomagnetic Results from the Gordon Subgroup of Tasmania: Further Evidence for a Late Cretaceous Magnetic Overprint in Southeastern Australia

• Main Authors: Sharples, C, Klootwijk, CT
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society of Tasmania 1981
• Subjects: Environmental Sciences; Environmental Science and Management; Environmental Management; Ida; Ida Bay; South Pole; South pole
• Online Access: http://www.rst.org.au/publications.html; http://ecite.utas.edu.au/71416

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 59.85 1 41.1E, 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 Au stral ia ,which is attributed to r ift forming processes preceding the opening of t he Tasman Sea.Conodont colour indicates that the limestones studied have not been subjected to temperatures in e xcess of l00c . This suggests a possible widespread occurrence of this magnetic overprint.