The Mid-Atlantic Ridge near 45 °N, XVII: Al, As, Hg, and Mn in Ferruginous Sediments from the Median Valley

1972 ◽  
Vol 9 (3) ◽  
pp. 319-323 ◽  
Author(s):  
D. S. Cronan
Keyword(s):  
Hydrothermal Activity ◽  
Ocean Floor ◽  
Ridge Crest ◽  
Mid Atlantic Ridge ◽  
Submarine Hydrothermal Activity

Iron-rich sediments similar to those forming on other active mid-oceanic ridges have been found in the Median Valley of the Mid-Atlantic Ridge near 45 °N. The sediments are enriched in arsenic and mercury, and are thought to have formed largely as a result of submarine hydrothermal activity associated with the generation of new ocean floor at the ridge crest.

The oldest seafloor massive sulfide deposits at the Mid-Atlantic Ridge: 230Th/U chronology and composition

2015 ◽  
Vol 42 (1) ◽  
Author(s):  
Vladislav Kuznetsov ◽  
Eriks Tabuns ◽  
Kathrine Kuksa ◽  
Georgy Cherkashov ◽  
Fedor Maksimov ◽  
...  
Keyword(s):  
Massive Sulfide ◽  
Hydrothermal Activity ◽  
Ocean Floor ◽  
Hydrothermal Field ◽  
Sulfide Deposits ◽  
Massive Sulfides ◽  
Geochemical Properties ◽  
Geochemical Study ◽  
Mid Atlantic Ridge ◽  
Seafloor Massive Sulfide

Abstract A geochronological and geochemical study on 10 samples of seafloor massive sulfides (SMS) from the inactive Peterburgskoye hydrothermal field at the Mid-Atlantic Ridge (MAR) was carried out. The 230Th/U ages of the SMS are the oldest for the Quaternary hydrothermal ores ever found at the ocean floor. According to them the hydrothermal activity at Peterburgskoye field started at least 170 ka and continued down to 63 ka. The oldest hydrothermal ores from this field consist mainly of pyrite and chalcopyrite and have geochemical properties typical for SMS associated with basalts.

Tectonic fabric and hydrothermal activity of Mid-Atlantic Ridge crest (lat 26°N)

1976 ◽  
Vol 87 (5) ◽  
pp. 661 ◽  
Author(s):  
PETER A. RONA ◽  
REGINALD N. HARBISON ◽  
BOBBY G. BASSINGER ◽  
ROBERT B. SCOTT ◽  
ANDREW J. NALWALK
Keyword(s):  
Hydrothermal Activity ◽  
Ridge Crest ◽  
Mid Atlantic Ridge

Hydrothermal activity at the Trans-Atlantic Geotraverse Hydrothermal Field, Mid-Atlantic Ridge crest at 26°N

1984 ◽  
Vol 89 (B13) ◽  
pp. 11365-11377 ◽  
Author(s):  
P. A. Rona ◽  
G. Thompson ◽  
M. J. Mottl ◽  
J. A. Karson ◽  
W. J. Jenkins ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Hydrothermal Field ◽  
Ridge Crest ◽  
Mid Atlantic Ridge

Diking, young volcanism and diffuse hydrothermal activity on the southern Mid-Atlantic Ridge: The Lilliput field at 9°33′S

2009 ◽  
Vol 266 (1-4) ◽  
pp. 52-64 ◽  
Author(s):  
K.M. Haase ◽  
A. Koschinsky ◽  
S. Petersen ◽  
C.W. Devey ◽  
C. German ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Mid Atlantic Ridge

Serpentinization at the Rainbow and Saldanha sites, Mid-Atlantic Ridge: Mineralogical, geochemical, and isotopic features

2019 ◽  
Vol 57 (5) ◽  
pp. 677-706
Author(s):  
Isabel Ribeiro da Costa ◽  
Frederick Joseph Wicks ◽  
Fernando J.A.S. Barriga
Keyword(s):  
Upper Mantle ◽  
Hydrothermal Activity ◽  
Isotopic Data ◽  
Geochemical Characterization ◽  
Textural Evolution ◽  
Mantle Peridotites ◽  
Carbonate Deposition ◽  
Mid Atlantic Ridge ◽  
Ree Patterns

Abstract The Rainbow hydrothermal field (36°14′N) and the Saldanha seamount (36°34′N), in the Mid-Atlantic Ridge (MAR), are tectonic exposures of serpentinized upper mantle peridotites, both associated with significant hydrothermal activity. On the basis of detailed mineralogical and geochemical characterization of serpentinites from both sites, several serpentinization-related issues are discussed in the present work. As expected in oceanic environments, most of the sampled rocks are lizardite-chrysotile serpentinites exhibiting a variety of pseudomorphic through non-pseudomorphic textures, such textural evolution probably being related to changing water/rock ratios during this retrograde process. Oxygen isotope temperatures indicate that the serpentinization took place at 300–200 °C; on the other hand, isotopic data suggest that replacement of early pseudomorphic lizardite by lizardite ± chrysotile non-pseudomorphic textures requires that temperatures and/or water/rock ratios are high enough to promote the necessary dissolution–recrystallization processes. Mass-balance calculations for olivine-serpentine and orthopyroxene-serpentine pairs provided a basis for establishing serpentinization reactions likely to have produced the present rocks. Moreover, these calculations also showed that, notwithstanding some noticeable loss of MgO from olivine and of SiO2 from orthopyroxene, serpentinization of both minerals implies volume increases on the order of 26–27%, therefore potentially promoting the overall expansion of the rock. The geochemical and isotopic features of the studied rocks indicate that unmodified seawater was responsible for the serpentinization of the MAR peridotites. However, the mineralogy and REE patterns of some of these serpentinites indicate occasional subsequent interaction of the serpentinized rocks with seawater at much lower temperatures (seafloor alteration, characterized by carbonate deposition and negative Ce anomalies), or with high-temperature ore-forming hydrothermal fluids (ore-forming alteration, characterized by sulfide precipitation and steep positive Eu anomalies).

Sedimentation on young ocean floor at the Mid-Atlantic Ridge, 29 °N

1998 ◽  
Vol 148 (1-2) ◽  
pp. 1-8 ◽  
Author(s):  
Neil C. Mitchell ◽  
Simon Allerton ◽  
Javier Escartín
Keyword(s):  
Ocean Floor ◽  
Mid Atlantic Ridge
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