HR: 0800h
AN: PP41D-0776    [Abstracts]
TI: A Siliceous Microfossil View of Middle Eocene Arctic Paleoenvironments
AU: * Stickley, C E
EM: catherine.stickley@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, N-9296, Norway
AU: Koc, N
EM: nalan@npolar.no
AF: Norwegian Polar Institute, Polar Environmental Centre, Tromso, N-9296, Norway
AU: Koc, N
EM: nalan@npolar.no
AF: Department of Geology, University of Tromso, Tromso, N-9037, Norway
AU: Brumsack, H
EM: brumsack@icbm.de
AF: Institute for Chemistry and Biology of the Marine Environment (ICBM), Oldenburg University, P.O. Box 2503, Oldenburg, D-26111, Germany
AU: Jordan, R W
EM: sh081@kdw.kj.yamagata-u.ac.jp
AF: Department of Earth and Environmental Sciences, Yamagata University, Kojirakawa-machi 1-4-12, Yamagata, 990-8560, Japan
AU: Suto, I
EM: sutoitsu@geobio.eps.nagoya-u.ac.jp
AF: Department of Earth and Planetary Sciences, Nagoya University, Chikusa, Nagoya, 464- 8601, Japan
AB: Integrated Ocean Drilling Program Expedition 302, "The Arctic Coring Expedition" (ACEX) made arguably the most significant discovery of Paleogene siliceous microfossils in nearly 2 decades. 100 m of mm to sub-mm laminated biosiliceous sediments of Middle Eocene age are rich in marine and freshwater siliceous microfossils allowing intriguing insights into central Arctic paleoenvironments during the start of Cenozoic cooling to icehouse conditions. Largely endemic assemblages of marine diatoms and ebridians are preserved along with very high abundances of chrysophyte cysts, the endogenously formed resting stage of freshwater algae. These siliceous microfossil groups imply an overall brackish environment, but variations in group dominance suggest episodic variations in salinity, stratification and trophic status. We synthesize the overall characteristics of the biosiliceous sediments by reporting on broad scale variations in siliceous microfossils and give some exciting insights into the composition of the laminae which may help explain the formation of these sediments. Our results indicate basin-wide paleo-environmental fluctuations on long- and possibly seasonal timescales.
DE: 3030 Micropaleontology (0459, 4944)
DE: 4855 Phytoplankton
DE: 4944 Micropaleontology (0459, 3030)
DE: 9606 Paleogene
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting