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GSA Annual Meeting, November 5-8, 2001

Paper No. 0
Presentation Time: 3:30 PM

OLIGOCENE TO PLIOCENE SEQUENCE STRATIGRAPHY, BENTHIC FORAMINIFERA, AND STRONTIUM ISOTOPES FROM THE CONTINENTAL MARGIN OF NORTHWEST ARCTIC CANADA


MCNEIL, David H.1, DIXON, Jim1, DIETRICH, Jim R.1 and MILLER, Kenneth G.2, (1)Geol Survey of Canada, 3303 33rd St. N.W, Calgary, AB T2L 2A7, Canada, (2)Dept. of Geological Sci, Rutgers Univ, 610 Taylor Rd, Piscataway, NJ 08854-8066, dmcneil@nrcan.gc.ca

The Oligocene to Pliocene stratigraphic record on the continental margin of northwestern Arctic Canada consists of four major depositional sequences: the Kugmallit, Mackenzie Bay, Akpak, and Iperk. The sequences have been mapped regionally on seismic reflection profiles and were dated primarily from benthic foraminiferal distributions and strontium isotope correlations.

The lower part of the Oligocene Kugmallit Sequence consists of a prominent and widespread submarine fan deposit. The upper part of the sequence is dominated by thick deltaic deposits that prograded basinward during the mid to late Oligocene. A foraminiferal break at about the middle of the Oligocene can be recognized within the Kugmallit, but there is no major sequence boundary associated with it. The top of the Kugmallit Sequence occurs within the latest Oligocene, and the Oligocene-Miocene boundary apparently occurs within the overlying Mackenzie Bay Sequence.

The latest Oligocene to middle Miocene Mackenzie Bay and the late Miocene Akpak sequences contain no obvious submarine fan deposits or deltaic sediments and are characterized by thinner shelf and slope deposits. A regional denudation surface occurs at the top of the Akpak Sequence and affects progressively older strata southward towards the basin margin. Remarkably, the denudation surface can be correlated from the cratonic mainland (Richardson Mountains) to the base of the continental slope. The minimum age for strata below the unconformity is Messinian.

Offshore, under the current continental shelf and slope, the post-Miocene unconformity is overlain by conspicuous lowstand submarine fan deposits and thick prograding deltaic deposits of the Pliocene to early Pleistocene Iperk Sequence. Strontium isotope age estimates from the lowermost Iperk Sequence indicate a younger age (ca. 2 Ma) than that determined by foraminiferal and regional data including paleomagnetic records (ca. 3.5 Ma). Strontium age estimates for the Oligocene and Miocene deposits are consistent with foraminiferal age estimates.

Session No. 39

T19. New Perspectives on the Character and Origin of Late Cretaceous-Cenozoic Sequences on the U.S. Atlantic Margin
Monday, 5 November 2001: 1:30 PM-5:30 PM
Geological Society of America Abstracts with Programs. Vol. 33, No. 6, October 2001, p.590
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