Bunce
Elizabeth T.
Bunce
Elizabeth T.
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Technical ReportStructure of the western Somali Basin(Woods Hole Oceanographic Institution, 1967-07) Bunce, Elizabeth T. ; Langseth, Marcus G. ; Chase, R. L. ; Ewing, W. MauriceThe 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.
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Technical ReportNarrative of CHAIN cruise #36 : Woods Hole to the Outer Ridge north of Puerto Rico and the Barracuda Fault east of the Lesser Antilles, and back, 4 June - 10 July, 1963(Woods Hole Oceanographic Institution, 1964-06) Bunce, Elizabeth T.This narrative report of CHAIN Cruise 36 includes the chief scientist's journal, a summary track chart, and a log of stations occupied. The cruise was made in two parts : the first, to the Outer Ridge north of Puerto Rico for seismic reflection and refraction work with ATLANTIS II, and the second from the Outer Ridge to the area of the Barracuda Fault east of the Lesser Antilles for bathymetric and gravity surveys and a detailed geophysical study of the area between 16° and 17 °N and 57 ° and 59 °W. The scientific program included echo sounding, continuous seismic reflection profiling, seismic refraction profiles , gravity measurements, dredging, bottom photography, and heat flow measurements.