| 2006 Philadelphia Annual Meeting (22–25 October 2006) | |
| Paper No. 230-12 | |
| Presentation Time: 1:30 PM-5:30 PM | ||
INTEGRATED PALEONTOLOGIC, SEDIMENTOLOGIC, AND STABLE ISOTOPIC DATA ACROSS THE IREVIKEN AND LUNDGRENI EXTINCTION EVENTS IN THE CAPE PHILLIPS FORMATION, NUNAVUT, CANADA | ||
|
NOBLE, Paula J., Geological Sciences and Engineering, University of Nevada, MS 172, Reno, NV 89557-0138, noblepj@unr.edu, LENZ, Alfred C., Dept. Earth Sciences, Univ Western Ontario, London, ON, N6A 5B7, Canada, HOLMDEN, Chris, Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK S7N 5E2, Canada, MASIAK, Monika, Institute of Geological Sciences, Polish Academy of Sciences, Warsaw, 00-818, Poland, POULSON, Simon R., Geological Sciences, Univ of Nevada, Reno, Geological Sciences, MS-172, Reno, NV 89557, ZIMMERMAN, Matthew K., Geological Sciences, Univ of Nevada, MS 172, Reno, NV 89557-0138, and KOZLOWSKA, Anna, Institute of Paleobiology, Polish Academy of Sciences, Warsaw, 00-818, Poland
Stratigraphic sections of the basinal Cape Phillips Formation, Nunavut, Canada, have been sampled across the Llandovery-Wenlock, and lower-upper Homerian (upper Wenlock) boundary intervals for the integration of paleontologic (graptolite, radiolarian, palynomorph), sedimentologic, and geochemical (13C) data for two well-known extinction events, the Ireviken and lundgreni Extinction (LEE) events. Graptolites are abundant and well-preserved, and provide a solid biostratigraphic base for other data. Graptolites were globally severely affected by both extinction events: about 80% reduction for the Ireviken, and 90-95% for the LEE. Recovery from the LEE was slow and diversity low through the late Homerian. Radiolarians, which are diverse, abundant, and beautifully preserved in the lower Homerian, are sharply reduced slightly below the LEE boundary. Upper Homerian data are more scattered, but diversity appears low with few radiolarian taxa surviving the LEE. Palynological studies are only preliminary, but it appears that chitinozoans were impacted by the LEE, briefly disappearing across the lower-upper Homerian boundary. Other rare palynomorphs, including prasinophytes and sphaeromorphs of varying preservation were recovered, but data are presently insufficient to determine the local impact of the LEE on these palynomorphs. Stable isotope geochemistry shows well-marked, positive excursions in the d13Corganic fraction associated with the Ireviken event and LEE. The Ireviken excursion (C1) curve has a sharp base, reaches a peak at about the Llandovery-Wenlock boundary, and tapers to the top of the centrifugus Zone. The LEE excursion (C4) peaks at, or slightly below, the lower-upper Homerian boundary. Both positive excursions appear to be close to, or coincident with regressions, particularly so across the LEE interval. The C4 excursion has a greater magnitude in the inshore sections relative to the offshore section, and is interpreted to be a result of accelerated weathering of carbonates exposed during a lowstand.
| ||
|
2006 Philadelphia Annual Meeting (22–25 October 2006)
General Information for this Meeting | ||
| Session No. 230 Paleontology/Paleobotany (Posters) II: Fossils in Time, Space, and Morphospace Pennsylvania Convention Center: Exhibit Hall C 1:30 PM-5:30 PM, Wednesday, 25 October 2006 Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 552 | ||
© Copyright 2006 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. | ||