A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The deep structure of the Red Sea

1970 ◽  
Vol 267 (1181) ◽  
pp. 181-189 ◽  
Keyword(s):  
Red Sea ◽  
Seismic Velocity ◽  
Deep Structure ◽  
Gravity Data ◽  
Seismic Refraction ◽  
Seismic Survey ◽  
Gulf Of Aden ◽  
Sea Floor ◽  
Central Trough ◽  
Sea Floor Spreading

The results of an intensive seismic survey in the Red Sea are presented. Analysis of twenty seismic refraction lines leaves no doubt that much more than just the central trough of the Red Sea is underlain by material with a seismic velocity which is characteristic of oceans. In addition, up to 5 km of what we interpret as evaporites were regularly found. The suggestion that the Red Sea crust could be oceanic in character over the major part of its width is examined in conjunction with magnetic and gravity data. We conclude that there is no evidence against sea floor spreading on a substantial scale in the Miocene. The implications of this in terms of neighbouring features is briefly discussed.

Perim Island, a volcanic remnant in the southern entrance to the Red Sea

1990 ◽  
Vol 127 (4) ◽  
pp. 309-318 ◽  
Author(s):  
D. I. J. Mallick ◽  
I. G. Gass ◽  
K. G. Cox ◽  
B. V. W. De Vries ◽  
A. G. Tindle
Keyword(s):  
Trace Element ◽  
Red Sea ◽  
Fractional Crystallization ◽  
Late Miocene ◽  
Gulf Of Aden ◽  
Sea Floor ◽  
Element Abundances ◽  
Major Oxide ◽  
Propagating Rift ◽  
Sea Floor Spreading

AbstractPerim Island is an eroded fragment of the southwest flank of a late Miocene (10.5 ± 1.0 Ma) volcano whose centre lay on the southwesternmost tip of Arabia. The volcano is the westernmost of the E–W line of six central vent volcanoes (the Aden Line) that extends 200 km along the south coast of Arabia from Perim to Aden. Major oxide and trace element abundances are given for 35 Perim specimens and these show that the volcano has within-plate trace element characteristics and consists of a petrographically and geochemically simple suite of alumina-poor olivine basalts, andesites, and transitional andesite–trachyandesites. Six specimens, however, are markedly enriched in Al2O3 and CaO, and contain abundant (20–30 mode %) highly calcic (An77–83) plagioclase phenocrysts. Geochemical modelling suggests that the main Perim volcanic sequence was produced by the fractional crystallization (o1 + cpx + Ti-mt + plag) of a silica saturated (SiO2 c. 45%) basic melt. The high A1, high Ca, magmas appear to be mixing products of plagioclase-enriched basic magmas with more evolved melts. Perim is the oldest volcano of the Aden line, which becomes increasingly younger and alkalic eastward. It is suggested that the volcanism is related to an eastwards-propagating rift produced before the most recent stage of sea-floor spreading in the Gulf of Aden (4.5 Ma–present).

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Introductory remarks

1970 ◽  
Vol 267 (1181) ◽  
pp. 5-7 ◽  
Keyword(s):  
Red Sea ◽  
World Ocean ◽  
The Other ◽  
Rift System ◽  
Gulf Of Aden ◽  
Sea Floor ◽  
The Earth ◽  
The World ◽  
The Many ◽  
Sea Floor Spreading

The Red Sea Discussion Meeting originated in the desire of the other organizers to bring together as many as possible of the earth scientists who have been working recently in that area to examine the latest evidence and ideas on its structure and origin, to see how they accord with modern continental and sea-floor spreading concepts. The Red Sea, Gulf of Aden and Afar crustal depressions, now known to be continuous with the extension of the world ocean rift system, have been claimed as a manifestation of crustal separation, but some Earth scientists still consider that the evidence can be explained by less drastic crustal rifting. Definite solutions to the many outstanding problems were not expected but discussions would clearly assist further researches.

A Measurement of Seismic Anistropy in the Northeast Pacific

1971 ◽  
Vol 8 (9) ◽  
pp. 1056-1064 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Seismic Refraction ◽  
Maximum Velocity ◽  
Mean Value ◽  
Ocean Basin ◽  
P Wave ◽  
Sea Floor ◽  
P Wave Velocity ◽  
The Pacific ◽  
Magnetic Lineations ◽  
Sea Floor Spreading

A seismic refraction experiment was conducted in the Pacific Ocean basin, off the coast of British Columbia, Canada. The purpose of these measurements was to obtain an estimate of the anisotropy of the mantle P-wave velocity in the area and to relate this parameter to the direction of sea floor spreading. The results show that the crustal structure is similar to that measured elsewhere in the Pacific basin. Significant anisotropy of the mantle rocks is observed; the direction in which the maximum velocity occurs being 107° and the change of velocity, about 8% of the mean value, 8.07 km/s. The direction of maximum velocity does not coincide exactly with the direction of sea floor spreading, 090°, inferred from magnetic lineations.

Two Stage Red Sea Floor Spreading

Nature ◽  
1974 ◽  
Vol 247 (5435) ◽  
pp. 7-11 ◽  
Author(s):  
R. W. GIRDLER ◽  
P. STYLES
Keyword(s):  
Red Sea ◽  
Two Stage ◽  
Sea Floor ◽  
Sea Floor Spreading

Cenozoic deformation and Mesozoic abandoned spreading centre in the Tagus Abyssal Plain (west of Portugal): results of a multichannel seismic survey

1989 ◽  
Vol 26 (6) ◽  
pp. 1101-1123 ◽  
Author(s):  
A. Mauffret ◽  
D. Mougenot ◽  
P. R. Miles ◽  
J. A. Malod
Keyword(s):  
Spreading Rate ◽  
Abyssal Plain ◽  
Seismic Survey ◽  
Ocean Drilling Program ◽  
Sea Floor ◽  
Slow Spreading ◽  
Sea Floor Spreading ◽  
Multichannel Seismic Data ◽  
Ocean Boundary ◽  
Lusitanian Basin

The seismic stratigraphy of the sedimentary section that fills in the Tagus Abyssal Plain is specified by means of new multichannel seismic data. Six sedimentary sequence units are identified. These, ranging from Late Jurassic to Recent, have been dated by extrapolation of Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) drilling results and from sampling by dredging and submersible surveys. Based on this stratigraphic calibration and other geophysical data, a geodynamic evolution can be established for the Tagus Abyssal Plain. Faulting and folding in these sedimentary units clearly indicate that both the Portuguese Margin and the adjacent oceanic crust were deformed by a Miocene compressive event. An Oxfordian–Kimmeridgian rifting in the Lusitanian Basin and on the Portuguese Margin may herald a sea-floor spreading in the Tagus Abyssal Plain. The continent–ocean boundary is marked by landward-dipping reflectors similar to those observed along the Canadian margin. The oceanic structure of the Tagus Abyssal Plain is compared with those of the small oceans and (or) slow-spreading-rate centres. The eastern Tagus Abyssal Plain could be underlain by a Latest Jurassic (M-21)–Earliest Cretaceous (M16) spreading centre that was abandoned in Earliest Cretaceous (142 Ma), whereas the western Tagus Abyssal Plain could be underlain by a younger crust (from M10 to J) formed after a ridge jump. This younger oceanic domain may have a western complement in the Newfoundland Basin.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The seismicity of the Red Sea, Gulf of Aden and Afar triangle

1970 ◽  
Vol 267 (1181) ◽  
pp. 49-74 ◽  
Keyword(s):  
Red Sea ◽  
Body Wave ◽  
Western Boundary ◽  
Earthquake Activity ◽  
Gulf Of Aden ◽  
Transform Faults ◽  
Fault Plane Solutions ◽  
Afar Depression ◽  
Sea Floor Spreading ◽  
Afar Triangle

The seismicity of the Red Sea, Gulf of Aden and Afar triangle has been studied for the period January 1953 through December 1968. Epicentres have been relocated using the method of joint Epicentral Deter­mination (Douglas 1967) and some fault plane solutions have been attempted. Magnitude-frequency studies indicate that with the present distribution of teleseismic stations, earthquakes with body wave magnitude m b ≽ 4.8 are well determined in this region. The study confirms that there is surprisingly little major earthquake activity in the northern part of the Red Sea. Between 19.5 and 21.0° N, there is a concentration of epicentres and some of these might be associated with an active NNE transform fault. In the southern part of the Red Sea, most of the epicentres are associated with the deep, axial trough, although some are associated with the western mar­gin, especially in the neighbourhood of the Gulf of Zula (15° N). Earthquake activity is confined to the centre of the Gulf of Aden with concentrations of epicentres occurring on or near to NNE transform faults. The seismically active zone continues westwards through the Gulf of Tadjoura and across the Afar depression to the western boundary scarp. There are no teleseismically recorded epicentres between latitudes 12.2 and 14.2° N. In general, most of the seismic activity occurs along the centres of the Red Sea and Gulf of Aden and this supports a sea-floor spreading mechanism for their origin. The number of plates involved is discussed.

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