Measurements of bottom currents in fractures of the southern part of the Mid-Atlantic Ridge on cruises 39, 40, and 41 of the R/V Akademik Sergey Vavilov

Oceanology ◽  
2017 ◽  
Vol 57 (5) ◽  
pp. 753-755 ◽  
Author(s):  
R. Yu. Tarakanov ◽  
E. G. Morozov ◽  
N. I. Makarenko ◽  
D. I. Frey ◽  
T. A. Demidova
Keyword(s):  
Bottom Currents ◽  
Mid Atlantic Ridge

scholarly journals DISTRIBUTION OF THE SEDIMENTARY COVER IN THE EQUATORIAL SEGMENT OF THE ATLANTIC OCEAN

2021 ◽  
pp. 53-67
Author(s):  
S.Yu. Sokolov ◽  
◽  
K.O. Dobrolyubova ◽  
V.N. Efimov ◽  
A.V. Koltsova ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
High Amplitude ◽  
Bright Spot ◽  
Normal Faults ◽  
Small Contribution ◽  
Structural Barriers ◽  
Bottom Currents ◽  
Mid Atlantic Ridge ◽  
Continental Source ◽  
Spot Type

The thickness of the Atlantic Equatorial segment sedimentary cover decreases with the distance from the continental source of mass removal and increases slightly with the distance from the Mid-Atlantic Ridge (MAR). Background sedimentation makes a small contribution to the total sedimentary volume near the continents and the major contribution in basins with the formation of sedimentary bodies with a thickness of no more than 500 m. Sedimentary bodies with a thickness up to 1000 m near MAR are the results of unloading of bottom currents near structural barriers in topography and in fault troughs. The total thickness tends to increase from north to south on the western flank of the MAR. The multidirectional spatial migration of the basement depressions filled with sediments is revealed. To the west of the MAR, contrasting acoustic stratification and tectonic deformations of sediments were found. To the east of the MAR, deformations are rare and expressed by piercing structures and normal faults. Anomalies of the "bright spot" type associated with local manifestations of magmatism forming aligned high-amplitude reflectors are revealed. Normal faulting in the passive parts of the transforms zones indicates the presence of local stretching, which is part of the simple shear paragenesis. In the troughs, sediment deposition from the bottom currents, which forms channel drifts, is revealed.

Near-bottom Currents in the Mid-Atlantic Ridge Rift Valley

1975 ◽  
Vol 12 (4) ◽  
pp. 703-710 ◽  
Author(s):  
George H. Keller ◽  
Susan H. Anderson ◽  
J. William Lavelle
Keyword(s):  
Rift Valley ◽  
Tidal Currents ◽  
Bottom Current ◽  
Mean Flow ◽  
Bottom Currents ◽  
Unidirectional Flow ◽  
Local Topography ◽  
Mid Atlantic Ridge

Near-bottom current measurements during a 46 day period (October to December 1973) in the rift valley of the Mid-Atlantic Ridge just south of the Azores reveal a mean flow at two stations of 2.6 and 8.2 cm/s, predominantly trending parallel to the northeast orientation of the valley. Maximum velocities recorded at the sites were 14.4 and 24.2 cm/s. Semi-diurnal tidal currents appear to strongly influence the flow within the valley causing current reversals, except in areas where local topography and constrictions in the valley apparently result in a unidirectional flow to the northeast.

Acoustic Reverberation at Selected Sites in the Mid-Atlantic Ridge Region,

1993 ◽  
Author(s):  
Jerald W. Caruthers ◽  
J. R. Fricke ◽  
Ralph A. Stephen
Keyword(s):  
Mid Atlantic Ridge ◽  
Acoustic Reverberation

The age of magmatic and metamorphic events in the Mid-Atlantic Ridge: interpretation of K-Ar isotope dating data

2001 ◽  
Vol 2 (3) ◽  
pp. 269-278
Author(s):  
S. A. Silantiev ◽  
L. K. Levskiy ◽  
M. M. Arakelyants ◽  
V. A. Lebedev ◽  
A. Bugo ◽  
...  
Keyword(s):  
Mid Atlantic Ridge ◽  
Isotope Dating

PRELIMINARY FORESHOCK ANALYSIS OF SUBMARINE TRANSFORM FAULT EARTHQUAKES ALONG THE EQUATORIAL MID-ATLANTIC RIDGE

2016 ◽  
Author(s):  
Ross P. Meyer ◽  
◽  
Joe H. Haxel ◽  
Robert P. Dziak ◽  
Deborah K. Smith
Keyword(s):  
Transform Fault ◽  
Mid Atlantic Ridge

WEAK PLIOCENE BOTTOM CURRENTS IN THE JANE BASIN, NW WEDDELL SEA BASED ON MULTIVARIATE ANALYSIS OF GRAIN SIZE SPECTRA

2017 ◽  
Author(s):  
Melissa R. Luna ◽  
◽  
Suzanne O'Connell ◽  
Joseph D. Ortiz ◽  
Michael C. Wizevich
Keyword(s):  
Grain Size ◽  
Multivariate Analysis ◽  
Weddell Sea ◽  
Size Spectra ◽  
Bottom Currents

scholarly journals Geochemical Fractions of Heavy Metals in Bottom Sediments of the Pobeda Hydrothermal Field, Mid-Atlantic Ridge (17°07′–17°08′ N)

2021 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Liudmila Demina ◽  
Irina Gablina ◽  
Olga Dara ◽  
Dmitry Budko ◽  
Nina Gorkova ◽  
...  
Keyword(s):  
Total Content ◽  
Element Distribution ◽  
Hydrothermal Field ◽  
Residual Fraction ◽  
Carbonate Sediments ◽  
Metalliferous Sediments ◽  
Geochemical Fractions ◽  
Metalliferous Sediment ◽  
Fe And Mn ◽  
Mid Atlantic Ridge

We examined the distribution of Fe, Mn, Cu, Zn, and Pb in one core of metalliferous, and one core of non-mineralized (background) carbonate sediments (located 69 km northwards), from the Pobeda hydrothermal field. Mechanisms of metal accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including mobile (exchangeable complex, authigenic Fe-Mn hydroxides, and sulfides), and lithogenic (fixed in crystalline lattices) forms. Maps of element distribution in sediment components were obtained using a scanning electron microscope equipped with an energy-dispersive spectrometry detector. In metalliferous sediments, according to X-ray diffraction data, the main Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis). The contents of Fe and Mn reached 31.6 and 0.18%, respectively, whereas concentrations of Cu, Zn and Pb were 0.98, 0.36, and 0.059%. The coefficient of metal enrichment relative to background values varied from 16 to 125 times. The exception was Mn, for which no increased accumulation was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes. Among geochemically mobile fractions, 90–97% of total Fe was found in the form of authigenic oxyhydroxides. The same fraction was the predominant host for Mn in both metalliferous and background sediments (55–85%). A total of 40–96 % of Cd, Cu, Zn, and Pb were associated with these Fe and Mn fractions. The sulfide fraction amounted to roughly 10% of each metal. In metalliferous sediment core, the maximum concentrations of metals and their geochemically mobile fractions were recorded in deeper core intercepts, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that metals are mostly accumulated in carbonate sediments in their contact zone with the underlying serpentinized basalts.

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