Publication Date:
2022-05-26
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology October 1979
Description:
An investigation was carried out to observe the geologic effects of
steady bottom currents on sediments of East Katla Ridge on the southern
insular rise of Iceland. Near-bottom southwest to west-flowing currents
exceeded 20 cm sec-1 for two weeks over a 25-kilometer wide section of
the ridge flank between approximately 1400 and 1800 meters water depth;
maximum density and minimum temperature were observed at 1800 meters.
Total transport of Iceland-Scotland Overflow Water was calculated to be
5.0 x 106 m3 sec-1; suspended sediment transport is approximately
0.4 x 106 grams sec-1, with a net deposition of 10 to 15 cm/1000
years estimated from the flux difference in and out of the station array.
Sediment distribution patterns indicate that the current axis, where
flow exceeds approximately 15 cm sec-1, is a site of erosion and winnowing
(sand layer formation) while the current margin is a site of rapid
accumulation (from observed Holocene rates of 25 to 35 cm per 1000 yr to
estimated rates of greater than 100 cm/1000 yr based on 3.5 kHz echo-sounder
records). Holocene silty turbidites are locally thick in a sub-marine
channel; sandy turbidites and current-winnowed 'sandy contourites'
are present in the axis of the major submarine canyon.
‘ Sandy contourite' deposits beneath the axis of the Iceland-Scotland
Overflow Current are very poorly sorted muddy sands lacking primary sedimentary
structures. Bioturbation is inferred to cause the unique characteristics
of these deposits, as well as the absence of fine silt laminae
in 'muddy contourites' at the current margin.
Description:
Financial support for shipboard operations and most of the post-cruise
data analysis was provided by NSF Grant OCE76-Sl49l to Dr. Charles Hollister.
Sediment trap and hydrocast operations received partial support
under ONR Contract N00014-74-C-0262.
Keywords:
Marine sediments
;
Sedimentation and deposition
;
Ocean currents
;
Submarine geology
;
Ocean circulation
;
Atlantis II (Ship : 1963-) Cruise AII94-1
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
application/pdf
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