2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 56-5
Presentation Time: 10:00 AM

MAGNETIC SUSCEPTIBILITY AND THE DEVONIAN-CARBONIFEROUS BOUNDARY IN THE EXSHAW FORMATION, ROCKY MOUNTAINS, ALBERTA CANADA


DANIELSEN, Erika1, KOHN, Jennifer L.2, OVER, D. Jeffrey3, SCHMITZ, Mark D.4, BUNDY, Kathleen5 and EKHOFF, Josh5, (1)Geological Sciences, SUNY-Geneseo, Geneseo, NY 14454, (2)Geosciences, Texas Tech University, Lubbock, TX 79409-1053, (3)Geological Sciences, SUNY-Geneseo, Geneseo, NY 14454-1401, (4)Department of Geosciences, Boise State University, 1910 University Drive, Boise, ID 83725-1535, (5)Geoscience, Boise State University, Boise, ID 83706

The Exshaw Formation at Jura Creek, the type section, and Mount Rundle, consisting predominately of black shale and silty carbonates, in the Front Ranges of the Rocky Mountains, overlies the Costigan Member of the Palliser Formation, known to be Famennian (latest Devonian) and is overlain by the early Mississippian Banff Formation. The Devonian-Carboniferous boundary in the Exshaw is placed within the lower black shale member, 3.28 m above the base at the type Exshaw, indicated by a shift to increased magnetic susceptibility. This is located 1.01 m above a tephra bed that yielded U/Pb dates from zircons of 359.96 +/- 0.09 Ma. At Mt. Rundle a similar shift was documented within the limited sample set collected above a tephra dated to 360.08 +/- 0.118 Ma, presumed to be the same tephra bed dated at Jura Creek. The magnetic susceptibility shows a meter-scale cyclicity which possibly represents the orbital precession cycle.

Session No. 56

Stratigraphy (Posters)
Sunday, 19 October 2014: 9:00 AM-5:00 PM
Exhibition Hall C (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.152
© Copyright 2014 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
Back to: Stratigraphy (Posters)
<< Previous Abstract | Next Abstract >>