Publication Date:
2022-05-26
Description:
Originally issued as Reference No. 67-38, series later renamed WHOI-. Reprint from Journal of Geophysical Research, vol. 72, no. 10, May 1967.
Description:
The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits
of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern
parts to be very different. The northern sections is a deep basin filled with thick uniformly
stratified sediments. It is enclosed by the continental margin to the west and north,
Chain ridge to the east, and shallow basement structure to the south. A change in depth
of basement occurs along an approximately east-west line at latitude 3°30'N very near the
southern end of Chain ridge. In the southern portion of the basin the basement is shallow,
and, immediately south of latitude 3°30'N, it has high relief. Stratified flat-lying sediments
fill the basement depressions, and isolated hills formed of basement material rise above the
abyssal plain deposits. Farther to the south the abyssal plain becomes very narrow. Gabbro
dredged from the southeast slope of Chain ridge has been dated by the potassium-argon
method as 89.6 ± 4.5 m.y., which should be considered a minimum age. The evidence suggests
that the entire sediment sequence of the northern basin was deposited subsequent to
the formation of the ridge. The thin sediment cover of the southern portion of the basin is
probably no older than Tertiary.
Description:
Office of Naval Research under contract
Nonr-4029(00) NR 260-101.
Keywords:
International Indian Ocean Expedition (1960-1965)
;
Chain (Ship : 1958-) Cruise CH43
;
Marine geophysics
;
Seismic reflection method
Repository Name:
Woods Hole Open Access Server
Type:
Technical Report
Format:
application/pdf
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