The Kiaman its Beginning and End.

Thursday, 18 December 2014: 10:35 AM
Neil D Opdyke, Univesity of Florida, Dept. of Geology,, Gainesville, FL, United States
The Earth’s magnetic field appears to have two states:-times when it reverses polarity several times per million years and other times when reversal of the field do not occur at all for intervals as long as 30 to 40 my. Two intervals are well established, The Cretacious Quiet Zone and the Kiaman and others may exist. Irving and Parry named the Kiaman from exposures at Kiama point in Sew South Wales where Mercanton had first observed reversely magnetized lavas of Permian age. Irving’s naming this Superchron was a large leap of faith. Recently published studies on Cape Breton island places the beginning of the Kiaman in the Arnsbergian substage of Pennsylvanian time and younger rocks are all of reverse polarity within the Maritime Basin. Studies in western US show uniformly magnetized sediments with reverse polarity of Pennsylvanian and lower Permian age. The contact of the Kiaman reversed polarity interval with sediments of both polarities in the late Kiaman takes place at the base of the Kazanian. The presence of short normal polarity within the Kiaman have been postulated but are hard to confirm.