scholarly journals SEAFLOOR MAPPING OF THE ATLANTIC OCEAN BY GMT: VISUALIZING MID ATLANTIC RIDGE SPREADING, SEDIMENT DISTRIBUTION AND TECTONIC DEVELOPMENT

2020 ◽  
Vol 6 (3) ◽  
pp. 145-157
Author(s):  
Polina Lemenkova ◽  
Keyword(s):  
Atlantic Ocean ◽  
Sediment Distribution ◽  
Seafloor Mapping ◽  
Mid Atlantic Ridge ◽  
Tectonic Development

Surveying the flanks of the Mid-Atlantic Ridge: the Atlantis Basin, North Atlantic Ocean (36°N)

2004 ◽  
Vol 209 (1-4) ◽  
pp. 199-222 ◽  
Author(s):  
T.M. Alves ◽  
T. Cunha ◽  
S. Bouriak ◽  
A. Volkonskaya ◽  
J.H. Monteiro ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Mid Atlantic Ridge

scholarly journals Living organisms pseudomorphs in modern volcanites of the Mid-Atlantic Ridge

2020 ◽  
Vol 12 ◽  
pp. 26-31
Author(s):  
I. G. Dobretsova ◽  
Keyword(s):  
Atlantic Ocean ◽  
Volcanic Rocks ◽  
Sulfide Ores ◽  
Geological Processes ◽  
Deposit Feeders ◽  
Geological Past ◽  
Mid Atlantic Ridge ◽  
Living Organisms

The study of samples of volcanic rocks, sulfide ores, and near-ore metasomatites from the bottom of the Atlantic Ocean resulted in the discovery of vital forms of organisms: foraminiferal shells, mineral pseudomorphs after the bodies of polychaetes, deposit feeders, and other fauna. This allows us to understand not only modern geological processes in the depths of the oceans, but also to reconstruct events of the distant geological past based on the principle of actualism.

scholarly journals THE ORIGIN AND STRUCTURE OF THE LOWER CRUST OF OCEANS AND BACK-ARC SEAS: EVIDENCE FROM THE MARKOV DEEP (MID-ATLANTIC RIDGE) AND THE VOIKAR OPHIOLITE ASSOCIATION (POLAR URALS)

2019 ◽  
Vol 10 (1) ◽  
pp. 101-121
Author(s):  
E. V. Sharkov
Keyword(s):  
Lithospheric Mantle ◽  
Lower Crust ◽  
Structural Element ◽  
Polar Urals ◽  
Magma Sources ◽  
Mid Atlantic Ridge ◽  
Tectonic Development ◽  
Slow Spreading ◽  
Back Arc ◽  
Markov Deep

The Markov Deep (the axial part of the slow-spreading Mid-Atlantic Ridge, 6°N, Sierra Leone oceanic core complex) and the Paleozoic Voikar ophiolite association (Polar Urals) formed in the back-arc sea conditions. In both cases, the lower crust of a close structure was formed on the basements composed ofdepleted peridotites of the ancient lithospheric mantle. The available data show that the composition of the lower crust of the oceans and back-arc seas is dominated by layeredmafic-ultramafic intrusions originating from the MORB melts, and suggest a similar asthenospheric source of magmas. Sills and dykes formed from other magma sources represent the second structural element of the lower oceanic crust: in case of the ocean, mainly ferrogabbroids originating from specific melts with the OIB involvement, and, in case of the back-sea sea, gabbro-norites of the supra-subduction calc-alkaline series. In both cases, the upper crust originates frombasaltic flows that occurred later and are associated with new episodes in the tectonic development. According to [Sharkov,2012], the development of slow-spreading ridges takes place in discrete impulses and non-simultaneously along their entire length. Furthermore, oceanic core complexes (OCC) in their axial parts are the ridge segments, where spreading is resumed. At the OCC stage, newly formed basalt melts move upwards from the magma generation zone into fractures (dykes) through the lithospheric mantle, and the thickness of the lower crust is built up by sills. As spreading develops in this area, the crust becomes thicker from below due to underplating in form of large layered intrusions. The newly formed restites, in their turn, cause an increase in the lithospheric mantle thickness from below. Apparently, the lower crust formed in the back-arc seas according to a similar scenario, although complicated by the processes taking place in the subduction zone.

The Mid-Atlantic Ridge Near 45 °N. XXII. Sedimentary Deposition and Lithogenesis on Mid-Atlantic Ridge Mountain Tops

1974 ◽  
Vol 11 (8) ◽  
pp. 1157-1167 ◽  
Author(s):  
Charles T. Schafer
Keyword(s):  
Surface Sediments ◽  
Bottom Current ◽  
Current Direction ◽  
Sediment Distribution ◽  
Rock Types ◽  
Rock Cores ◽  
Rapid Changes ◽  
Unconsolidated Sediment ◽  
Mid Atlantic Ridge ◽  
Coralline Limestone

Bottom photographs and drilled rock cores collected on several mountain tops along the crest of the Mid-Atlantic Ridge near 45°N describe the sediment distribution, sediment dynamics and shallow stratigraphy of these sites. Lag pebble deposits and pebble waves indicate rapid changes in bottom current direction and velocities that may approach 100 cm/s (>2 knots) one meter above the bottom so that surface sediments are often not indicative of sediment and rock types sampled using shallow drilling techniques. Absolute dates (14C) of coralline limestone, which underlies coarse unconsolidated sediment at most drilling sites, suggest deposition and initial lithification of these deposits during a middle Wisconsin interstadial period.

scholarly journals Occurrence of Omura’s whale, Balaenoptera omurai (Cetacea: Balaenopteridae), in the Equatorial Atlantic Ocean based on Passive Acoustic Monitoring

2020 ◽  
Author(s):  
Sergio C Moreira ◽  
Marcelo Weksler ◽  
Renata S Sousa-Lima ◽  
Marcia Maia ◽  
Alexey Sukhovich ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Northeastern Brazil ◽  
Equatorial Atlantic ◽  
Equatorial Atlantic Ocean ◽  
Mid Atlantic Ridge ◽  
Vocal Activity ◽  
Passive Acoustic ◽  
Warm Temperate ◽  
The Western Pacific ◽  
Indian And Atlantic Oceans

Abstract The current known distribution of Omura’s whale includes the tropical and warm temperate waters of the western Pacific, Indian, and Atlantic Oceans. Evidence of their presence in the Atlantic Ocean is based on beach cast specimens found on the coasts of Mauritania (North Atlantic) and Northeastern Brazil (South Atlantic). The present study characterizes the occurrence of this species in the São Pedro and São Paulo Archipelago (SPSPA), on the mid-Atlantic ridge between South America and Africa, based on autonomous recording systems. Acoustic signals were similar, but not identical, to B. omurai vocalizations recorded off the coast of Madagascar. Although these signals were recorded for only 11 months, there are peaks in vocal activity between May and June in the vicinities of SPSPA, suggesting either a shift in distribution within the Atlantic equatorial waters or seasonality in the species’ vocal behavior in this region. The first acoustic records of Omura’s whales in the Equatorial Atlantic suggest that these animals may also use deep-water habitats, in addition to the shallow-water habitat use observed in other regions.

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