A discussion concerning the floor of the northwest Indian Ocean - The Gulf of Aden

1966 ◽  
Vol 259 (1099) ◽  
pp. 150-171 ◽  
Keyword(s):  
Indian Ocean ◽  
Heat Flow ◽  
Gravity Field ◽  
Oceanic Crust ◽  
Seismic Refraction ◽  
Gulf Of Aden ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Made In

The details of topography outlined in a new contour chart of the sea floor are related to the geophysical studies made in the Gulf of Aden during the last decade. These studies include magnetic and gravity field, seismic refraction, heat flow and earthquake epicentre measurements. The Gulf is interpreted as a tensional feature involving the separation of the continental blocks of Arabia and Africa and the formation of new oceanic crust in between. The central rough zone is compared with mid-ocean ridges. The matching of pre-Miocene continental geology on either side is discussed in the light of this theory.

Heat flow from the Mid-Ocean Ridges and sea-floor spreading

1969 ◽  
Vol 8 (4-6) ◽  
pp. 319-344 ◽  
Author(s):  
X. Lepichon ◽  
M.G. Langseth
Keyword(s):  
Heat Flow ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Sea Floor Spreading

scholarly journals Positive geothermal anomalies in oceanic crust of Cretaceous age offshore Kamchatka

2011 ◽  
Vol 3 (1) ◽  
pp. 453-476
Author(s):  
G. Delisle
Keyword(s):  
Heat Flow ◽  
Oceanic Crust ◽  
High Heat ◽  
Great Depth ◽  
Alternative Interpretation ◽  
High Heat Flow ◽  
Flow Measurements ◽  
Sea Floor ◽  
Erosion Rates ◽  
Bathymetric Data

Abstract. Heat flow measurements were carried out in 2009 offshore Kamchatka during the German-Russian joint-expedition KALMAR. An area with elevated heat flow in oceanic crust of Cretaceous age – detected ~30 years ago in the course of several Russian heat flow surveys – was revisited. One previous interpretation postulated anomalous lithospheric conditions or a connection between a postulated mantle plume at great depth (> 200 km) as the source for the observed high heat flow. However, the positive heat flow anomaly – as our bathymetric data show – is closely associated with the fragmentation of the western flank of the Meiji Seamount into a horst and graben structure, initiated during descend of the oceanic crust into the subduction zone offshore Kamchatka. This paper offers an alternative interpretation, which connects high heat flow primarily with natural convection of fluids in the fragmented rock mass and, as a potential additional factor, high rates of erosion, for which evidence is available from our collected bathymetric image. Given high erosion rates, warm rock material at depth rises to nearer the sea floor, where it cools and causes temporary elevated heat flow.

The structure of the oceanic lithosphere

1971 ◽  
Vol 268 (1192) ◽  
pp. 619-619
Keyword(s):  
Oceanic Crust ◽  
Upper Mantle ◽  
Oceanic Lithosphere ◽  
Ocean Floor ◽  
Mass Motion ◽  
Sea Floor ◽  
Ocean Ridges ◽  
Velocity Gradients ◽  
The Earth ◽  
Sea Floor Spreading

Sea-floor spreading requires that new ocean floor be generated at mid-ocean ridges and that along with the underlying oceanic crust it move laterally away from its site of generation. In so far as it is unlikely that the 5 km thick oceanic crust moves independently of the underlying upper mantle, the horizontal mass motion associated with spreading extends at least some way into the mantle. The lithosphere is the crust and that part of the upper mantle to which it is mechanically coupled; together they form the brittle and relatively ‘strong’ outermost part of the Earth; velocity gradients within the lithosphere are negligible.

scholarly journals Positive geothermal anomalies in oceanic crust of Cretaceous age offshore Kamchatka

Solid Earth ◽  
2011 ◽  
Vol 2 (2) ◽  
pp. 191-198
Author(s):  
G. Delisle
Keyword(s):  
Heat Flow ◽  
Oceanic Crust ◽  
High Heat ◽  
Great Depth ◽  
Alternative Interpretation ◽  
High Heat Flow ◽  
Flow Measurements ◽  
Sea Floor ◽  
Erosion Rates ◽  
Bathymetric Data

Abstract. Heat flow measurements were carried out in 2009 offshore Kamchatka during the German-Russian joint-expedition KALMAR. An area with elevated heat flow in oceanic crust of Cretaceous age – detected ~30 yr ago in the course of several Russian heat flow surveys – was revisited. One previous interpretation postulated anomalous lithospheric conditions or a connection between a postulated mantle plume at great depth (>200 km) as the source for the observed high heat flow. However, the positive heat flow anomaly – as our bathymetric data show – is closely associated with the fragmentation of the western flank of the Meiji Seamount into a horst and graben structure initiated during descent of the oceanic crust into the subduction zone offshore Kamchatka. This paper offers an alternative interpretation, which connects high heat flow primarily with natural convection of fluids in the fragmented rock mass and, as a potential additional factor, high rates of erosion, for which evidence is available from our collected bathymetric image. Given high erosion rates, warm rock material at depth rises to nearer the sea floor, where it cools and causes temporary elevated heat flow.

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.

scholarly journals Porosity of very young oceanic crust from sea floor gravity measurements

1998 ◽  
Vol 25 (11) ◽  
pp. 1959-1962 ◽  
Author(s):  
Matthew J. Pruis ◽  
H. Paul Johnson
Keyword(s):  
Oceanic Crust ◽  
Sea Floor ◽  
Gravity Measurements

Convection tectonics: some possible effects upon the Earth's surface of flow from the deep mantle

1988 ◽  
Vol 25 (8) ◽  
pp. 1199-1208 ◽  
Author(s):  
J. Tuzo Wilson
Keyword(s):  
Land Surface ◽  
Angle Of Incidence ◽  
Gulf Of Aden ◽  
Upward Flow ◽  
New Techniques ◽  
Ocean Ridges ◽  
The Earth ◽  
Mid Ocean Ridge ◽  
The Subject ◽  
Ocean Ridge

Until a little more than a century ago the land surface not only was the only part of the Earth accessible to humans but also was the only part for which geophysical and geochemical methods could then provide any details. Since then scientists have developed ways to study the ocean floors and some details of the interior of the Earth to ever greater depths. These discoveries have followed one another more and more rapidly, and now results have been obtained from all depths of the Earth.New methods have not contradicted or greatly disturbed either old methods or old results. Hence, it has been easy to overlook the great importance of these recent findings.Within about the last 5 years the new techniques have mapped the pattern of convection currents in the mantle and shown that these rise from great depths to the surface. Even though the results are still incomplete and are the subject of debate, enough is known to show that the convection currents take two quite different modes. One of these breaks the strong lithosphere; the other moves surface fragments and plates about.It is pointed out that if expanding mid-ocean ridges move continents and plates, geometrical considerations demand that the expanding ridges must themselves migrate. Hence, collisions between ridges and plates are likely to have occurred often during geological time.Twenty years ago it was shown that the effect of a "mid-ocean ridge in the mouth of the Gulf of Aden" was to enter and rift the continent. This paper points out some of the conditions under which such collisions occur and in particular shows that the angle of incidence between a ridge and a coastline has important consequences upon the result. Several past and present cases are used to illustrate that collisions at right angles tend to produce rifting; collisions at oblique angles appear to terminate in the lithosphere in coastal shears, creating displaced terrane, but in the mantle the upward flow may continue to uplift the lithosphere far inland and produce important surface effects; collisions between coasts and mid-ocean ridges parallel to them produce hot uplifts moving inland. For a time these upwellings push thrusts and folds ahead of them, but they appear to die down before reaching cratons.

Thermal regime of the lithosphere in the Canadian ShieldThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (4) ◽  
pp. 389-408 ◽  
Author(s):  
Claire Perry ◽  
Carmen Rosieanu ◽  
Jean-Claude Mareschal ◽  
Claude Jaupart
Keyword(s):  
Heat Flow ◽  
Heat Generation ◽  
Seismic Refraction ◽  
Surface Heat ◽  
Canadian Shield ◽  
P Wave ◽  
Seismic Velocities ◽  
Flow Measurements ◽  
Surface Heat Flow ◽  
Mantle Heat Flow

Geothermal studies were conducted within the framework of Lithoprobe to systematically document variations of heat flow and surface heat production in the major geological provinces of the Canadian Shield. One of the main conclusions is that in the Shield the variations in surface heat flow are dominated by the crustal heat generation. Horizontal variations in mantle heat flow are too small to be resolved by heat flow measurements. Different methods constrain the mantle heat flow to be in the range of 12–18 mW·m–2. Most of the heat flow anomalies (high and low) are due to variations in crustal composition and structure. The vertical distribution of radioelements is characterized by a differentiation index (DI) that measures the ratio of the surface to the average crustal heat generation in a province. Determination of mantle temperatures requires the knowledge of both the surface heat flow and DI. Mantle temperatures increase with an increase in surface heat flow but decrease with an increase in DI. Stabilization of the crust is achieved by crustal differentiation that results in decreasing temperatures in the lower crust. Present mantle temperatures inferred from xenolith studies and variations in mantle seismic P-wave velocity (Pn) from seismic refraction surveys are consistent with geotherms calculated from heat flow. These results emphasize that deep lithospheric temperatures do not always increase with an increase in the surface heat flow. The dense data coverage that has been achieved in the Canadian Shield allows some discrimination between temperature and composition effects on seismic velocities in the lithospheric mantle.

Heat-flow and hydrothermal circulation at the ocean–continent transition of the eastern gulf of Aden

2010 ◽  
Vol 295 (3-4) ◽  
pp. 554-570 ◽  
Author(s):  
Francis Lucazeau ◽  
Sylvie Leroy ◽  
Frédérique Rolandone ◽  
Elia d'Acremont ◽  
Louise Watremez ◽  
...  
Keyword(s):  
Heat Flow ◽  
Gulf Of Aden ◽  
Hydrothermal Circulation
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