HR: 08:45h
AN: T51E-04    [Abstracts]
TI: Constraints on the Origin and Development of the Amerasian Basin of the Arctic Ocean from the Morphology and Structure of the Lomonosov Ridge
AU: * Cochran, J R
EM: jrc@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Columbia University, Pslisades, NY 10964 United States
AU: Edwards, M H
EM: margo@soest.hawaii.edu
AF: School of Earth Science and Technology, University of Hawaii, Honolulu, HI 96822 United States
AU: Coakley, B J
EM: bernard.coakley@gi.alaska.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, Fairbanks, AK 99775 United States
AB: The Lomonosov Ridge is a continuous band of continental crust extending across the Arctic Ocean from just north of Greenland to the Siberian continental margin. It separates the Mesozoic Amerasian Basin from the Cenozoic Eurasian Basin and forms a continental margin to both ocean basins. From about 87°N north of Greenland across the Pole to about 86°N, the Lomonosov Ridge is a single high-standing blocky ridge with minimum depths of ~950-1400 m. South of 86°N on the Siberian side, the Lomonosov Ridge breaks up into a series of ridges spread over a width of about 200 km. In this region, a blocky ridge with depths of 500-1400 m bounds the Eurasian Basin and is continuous with the single ridge on the North American side. This ridge is the former outer continental shelf of Eurasia bounding the Amerasian Basin. The Eurasian side of the Lomonosov Ridge consists of a series of rotated fault blocks stepping down to the basin that result from nearly orthogonal rifting of the former outer shelf off of Eurasia to form the Eurasian Basin. Seaward of the former Eurasian shelf in the Amerasian Basin, Marvin Spur, a linear basement ridge separated from the Lomonosov Ridge by a deep sedimentary basin, parallels the Lomonosov Ridge from near the North American margin to 89°N, 180°W. At the bend in the Lomonosov Ridge near the Pole, Marvin Spur continues across the Makarov Basin and joins the Lomonosov Ridge near 86°N. South of 86°N to the Siberian margin, the Lomonosov Ridge is a complex of ridges and basins oriented subparallel to the former margin. A consistent feature of this region is a continuous outer ridge marking the seaward edge of the Lomonosov complex that extends south to at least 82°30'N and, based on gravity data, perhaps to the Siberian margin. The outer ridge and Marvin Spur very closely follow a small circle about a pole located on the Mackenzie delta. The observed structure of the Lomonosov Ridge on the Amerasian side of the former Eurasian shelf is analogous to that observed at well-studied transform continental margins and supports rotational models for the development of the Amerasian Basin.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 8105 Continental margins: divergent (1212, 8124)
DE: 8106 Continental margins: transform
DE: 9315 Arctic region (0718, 4207)
SC: Tectonophysics [T]
MN: Fall Meeting 2005