History of Cenozoic Sedimentation in the Central Amundsen Basin: Implication from Seismic and Acex Drilling Data
Andrey Chernyh, Alexey Krylov, and Vladimir Glebovsky
VNIIOkeangeologia, Saint-Petersburg, Russia.
Since the IODP-302 ACEX results on the Lomonosov Ridge were published [Backman et al., 2006, 2008], many scientists were trying to use them for geological study of the Arctic Ocean and, particularly, of the Amundsen Basin [e.g. Verba, 2008; O’Regan et al., 2008; Langinen et al., 2008, etc.]. We present our point of view on geology of the Central Amundsen Basin implicated from seismic and ACEX data.
The seismic reflection data obtained by Polar Marine Geological Expedition during the drifting of Soviet ice station “NP-24” in 1980 [e.g. Pavlenkin et al., 2005] and along seismic line AWI-91090 from German RV Polarstern in 1991 [Jokat et al., 1992, 1995, 2004] were analyzed. Fragment of NP-24 line covers the Central Amundsen Basin from the Lomonosov Ridge to the Gakkel Ridge. AWI-91090 line crosses the Lomonosov Ridge in vicinity to the North Pole and goes 15 km apart from ACEX drill sites. The age of seismic units was inferred from the linear magnetic anomalies [Brozena et al., 2003; Glebovsky et al., 2006] and by analysis of the ACEX data.
Three (LR3-LR6) and four (ABSU1-ABSU4) prominent seismic units are distinguished within the Cenozoic sediments on the Lomonosov Ridge and in the Amundsen Basin respectively. Recognition of these units was based on detailed analysis of NP-24, AWI-91090 seismic data and results of the ACEX drilling. Seismostratigraphic correlation of units between considered structures was carried out. It was found that some lithological boundaries are traced from the Lomonosov Ridge to the Amundsen Basin. Several prominent Cenozoic tectonic events were imprinted into the sedimentary sequence of the Amundsen Basin and Lomonosov Ridge and are correlated with each other. During the 26 My hiatus in sedimentation established on the Lomonosov Ridge [Backman et al., 2008], thick sequence in the Amundsen Basin was accumulated. Based on our estimation, sedimentation rates in the Amundsen Basin during the period of the hiatus were considerably increased (up to ~40 m/My). We explain this phenomenon by regression at ~C13 time (about 33.5 Ma) and mass wasting of the terrigenous material to the basin. Regression took place on the adjacent shelves, and probably on the Lomonosov Ridge. It is revealed that the geological structure and evolution of the Amundsen Basin are in good accordance with geology of adjacent continental structures.
AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia