Chronostratigraphic Applications of Paleomagnetism and Rock Magnetic Cyclostratigraphy: Case Studies from the Ediacaran and Devonian Periods

Download or read book Chronostratigraphic Applications of Paleomagnetism and Rock Magnetic Cyclostratigraphy: Case Studies from the Ediacaran and Devonian Periods written by and published by . This book was released on 2015 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Paleomagnetic, rock magnetic, and carbon isotope stratigraphies of the Ediacaran aged Johnnie Formation (Death Valley, USA) and the Wonoka Formation (Flinders Ranges, Australia) provide a robust chronostratigraphic framework for the Shuram carbon isotope excursion (SE). Competing hypotheses suggest the SE is either a major global ocean oxidation event preceding the evolution of metazoan life, or the product of diagenetic alteration of globally distributed sediments. Magnetostratigraphy shows the nadir of the excursion to be synchronous between the Death Valley and Australia locations, and an astrochronology gives a duration of approximately 9 Myr for each expression of the excursion. The geochronologic consistency of the excursion between these two localities makes a diagenetic source unlikely. The duration of the 13C depleted strata can be used to obtain a more robust estimate of the necessary dissolved organic carbon pool and amount of oxidants in the Ediacaran ocean-atmosphere system necessary to explain the Shuram Excursion.