HR: 08:00h
AN: T11E-01 INVITED    [Abstracts]
TI: Jurassic to Present Evolution of the Arctic Ocean Region: Questions for IPY
AU: * Lawver, L L
EM: lawver@ig.utexas.edu
AF: Jackson School of Geosciences, Institute for Geophysics, Univ. of Texas, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road (R2200), Austin, TX 78758-4445, United States
AU: Gahagan, L M
EM: lisa@ig.utexas.edu
AF: Jackson School of Geosciences, Institute for Geophysics, Univ. of Texas, J.J. Pickle Research Campus, Bldg. 196; 10100 Burnet Road (R2200), Austin, TX 78758-4445, United States
AU: Childers, V A
EM: vicki@qur.nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Avenue Southwest, Washington, DC 20375, United States
AU: Brozena, J M
EM: john.brozena@nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Avenue Southwest, Washington, DC 20375, United States
AU: Grantz, A
EM: agrantz@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd, Menlo Park, CA 94025, United States
AB: In 1955, Carey first suggested a rotational opening of the Arctic Ocean based on his theories concerning oroclinal bending. It was only with the plate tectonic revolution in the next decade that there were a number of seminal abstracts and papers concerning the tectonic evolution of the Canada Basin. Grantz in 1966, Hamilton in 1967 and Tailleur in 1969 formulated the idea that the Canada Basin may have opened about a pivot point in the Mackenzie Delta. In 1968, Karasik first published his revolutionary idea that aeromagnetic anomalies collected over the Gakkel Ridge in the Eurasian Basin suggested that seafloor spreading during the Tertiary accounted for most of the oceanic crust between the Lomonosov Ridge and the Barents and Kara shelves. From the results of the 1979 Lomonosov Ridge experiment by Forsyth and Mair, it was established that the deep crustal velocities of the Lomonosov Ridge are remarkably similar to those of the Kara Sea shelf at 82°N, making it a continental sliver that rifted off the Barents and Kara Sea shelves. Consequently, the Arctic Ocean can be divided into a mostly Tertiary to present Eurasian Basin, and the older Mesozoic Amerasian Basin. Even with additional data from the Amerasian Basin including extensive airborne, ship-based, and satellite magnetics and gravity, the tectonic evolution of the Canada and Makarov components of the Amerasian Basin are still controversial. While the final phase of opening of the Amerasian Basin may have been rotational about a pivot point near or south of the Mackenzie Delta, the earlier phases and even the directions of the initial basin formation are still in doubt. Vogt and others first suggested a possible hotspot origin for the Alpha and Mendeleev Ridges and related them to the Iceland hotspot. Age versus depth and heat flow versus depth give a tentative age for the Amerasian Basin of latest Jurassic to early Cretaceous with seafloor spreading ending prior to the beginning of the Cretaceous Normal Superchron around 120 Ma. A brief review of the tectonic history of Arctic Ocean will be used to formulate a list of unknowns that IPY and subsequent work might investigate. We see a three or more stage opening of the Amerasian Basin. First stage is rifting between the Arctic Alaska/Chukokta block from the Canadian Arctic Islands with rotation of the Chukchi Borderland/Northwind Ridge out of the North Chukchi Basin similar to present motion in the Afar region and rotation of the Danakil block. This first stage was followed by a reorganization and the final stage is a rotational opening about a pole east of Fairbanks, AK. The Northwind Ridge was originally along the Sverdrup Basin margin of Canada. Timing of the stages is inexact due to a lack of correlatable magnetics but the final stage had to end prior to the start of the Cretaceous Normal Superchron because the gravity anomaly that marks the abandoned spreading center is flanked by magnetic anomalies.
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8157 Plate motions: past (3040)
DE: 8158 Plate motions: present and recent (3040)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting