HR: 1340h
AN: GP33A-0107    [Abstracts]
TI: A new paleomagnetic Paleocene-Eocene apparent polar wandering path derived from magnetostratigraphies: correlations for faunal and floral development at high latitude.
AU: * moreau, m
EM: moreau@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Besse, J
EM: besse@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AU: Fluteau, F
EM: fluteau@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, 4 Place Jussieu, Paris, 75252 France
AB: The development of endemic warm-climate flora and fauna at high latitudes in both hemispheres attests to the global warming that affected the Earth at the end of the Paleocene and the beginning of the Eocene. Nonetheless, the presence of these species at very high latitudes is also conditional on insolation, and the presence of tropical flora and fauna at very high paleomagnetic paleolatitudes, well north of the Arctic Circle, remains intriguing. We thus reappraise paleomagnetic data in a new way, defining an apparent geomagnetic polar wander path (APWP) from the beginning of the Paleocene to the middle of the mid-Eocene (65-42Ma) using a selection of magnetostratigraphies published over the last 25 years. Six series of VGPs are sufficiently long and of high enough quality to be retained; they originate from Gubbio (Italy) and from leg 74 for the African plate; from the Aix en Provence (France) and Basque (Spain) basins for Europe; from leg 171B for North America, and from leg 121 for Australia. For each site, a VGP (virtual geomagnetic pole) is defined for each magnetic anomaly and then transferred using classical kinematic parameters onto Africa selected as the single reference frame. The successive mean geomagnetic poles for each anomaly (hence perfectly synchronous) are then calculated in order to define the APWP. This shows a loop with two cusps at anomalies 26-25 (61-56 Ma) and 24-23 (56-51 Ma); the corresponding mean poles differ according to McFadden and McElhinny (1990), whereas the end poles relating to anomalies 29-27 (65.5-61 Ma) and 22-19 (51-42.5 Ma) are identical. The plate movements inferred from this loop, possibly related to an episode of true polar wander, are shown to be in agreement with the climatic and paleoenvironmental data and suggests a migration of flora and fauna which is synchronous with migration of the pole, rather than an adaptation of these species to the polar obscurity.
DE: 1620 Climate dynamics (0429, 3309)
DE: 3344 Paleoclimatology (0473, 4900)
DE: 8157 Plate motions: past (3040)
DE: 9604 Cenozoic
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005