Ultramafic-Mafic Plutonic Rock Suites Exposed Along the Mid-Atlantic Ridge (10°N-30°N). Symmetrical-Asymmetrical Distribution and Implications for Seafloor Spreading Processes.

Lagabrielle, Yves; Bideau, Daniel; Cannat, Mathilde; Karson, J. A.; Mével, Catherine

doi:10.1029/gm106p0153

Cited by 83 publications

(27 citation statements)

References 61 publications

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“…Most abyssal peridotites were collected by dredging or using submersibles (Karson, 1998;Lagabrielle et al, 1998;Tisseau and Tonnerre, 1995). Several peridotite samples were also collected in the frame of the international drilling programs Deep Sea Drilling Project -83) and Ocean Drilling Program (1985) (e.g., Karson et al, 1997;Kelemen et al, 2004;Mevel et al, 1996).…”

Section: The St Peter's and St Paul's Islands In The Atlanticmentioning

confidence: 99%

Orogenic, Ophiolitic, and Abyssal Peridotites

Bodinier

Godard

2014

Treatise on Geochemistry

194

148

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Section: The St Peter's and St Paul's Islands In The Atlanticmentioning

confidence: 99%

Orogenic, Ophiolitic, and Abyssal Peridotites

Bodinier

Godard

2014

Treatise on Geochemistry

194

148

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“…Tectonically exhumed peridotite was sampled during the Ocean Drilling Program (ODP) at various sites along the Mid-Atlantic Ridge (e.g., Karson & Lawrence, 1997;Lagabrielle et al, 1998;) were mantle rocks are exposed along fracture zones. The exhumation of mantle peridotite is ascribed to insufficient melt supply at slow-spreading midocean ridges leading to tectonic extension, crustal thinning, and incorporation of asthenospheric mantle into the oceanic lithosphere along low-angle normal faults (e.g., Cannat, 1993;Escart ın et al, 2003;Mac-Leod et al, 2002;Schroeder et al, 2007).…”

Section: Geological Context and Sample Characteristicsmentioning

confidence: 99%

“…Leg 209 is located between 148N and 168N were peridotite was sampled at several sites along a 100 km long traverse parallel to the rift valley (Lagabrielle et al, 1998;Shipboard Scientific Party, 2004). Again, harzburgite is the dominant peridotite type but the other ultramafic rock types are also present.…”

Section: Geological Context and Sample Characteristicsmentioning

confidence: 99%

Water in Abyssal Peridotite: Why Are Melt‐Depleted Rocks so Water Rich?

Schmädicke

Gose

Stalder

2018

Geochem Geophys Geosyst

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Evidence for the heterogeneity of the mantle's water content is generally acknowledged but it remains unclear if the variability of data is influenced by decompressional water loss. Here based on high water contents in peridotite, we explore if water gain may play a role. The study investigates water in abyssal peridotite by analyzing oriented orthopyroxene with polarized infrared radiation. Orthopyroxene from ODP‐Leg 153 (Mid‐Atlantic Ridge) contains 100 ppm more H2O (range: 220–323 ppm) than Leg 209 samples (range: 121–231 ppm). Possible explanations for high water concentrations are (1) water supply by gabbroic dykes, (2) reequilibration with ancient, H2O‐rich melts or melt‐derived fluid, (3) diffusional exchange between depleted peridotite and fertile rock volumes, or (4) high initial (premelting) water contents. Water in orthopyroxene is unrelated to the proximity of gabbroic dykes, and the inferred low H2O content of the latter renders possibility (1) unlikely. Possibilities (2) and (3) require that the rocks remained at mantle depth for an extended time span. This idea of a prolonged “mantle residence time” is corroborated by (i) literature data on isotopes and (ii) mantle equilibrium temperatures. Peridotite from Leg 153 reequilibrated at lower temperature (950–1,000°C) than Leg 209 peridotite (1,100–1,200°C) implying that more time elapsed between melt removal and exhumation—extending the time span for refertilization and explaining the its higher water content. The alternative that the measured concentrations are residual (4) requires high H2O amounts in original orthopyroxene (1,500 ppm) and peridotite (700 ppm)—values that are typical of an OIB‐source.

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“…In the oceanic lithosphere, serpentinization has been widely documented at slow-and ultraslow-spreading ridges where partially to fully serpentinized mantle peridotites represent up to 50% of the lithologies along some ridge segments (Cannat et al, 1995a;Escartin et al, 2008;Lagabrielle et al, 1998;Smith et al, 2006). Oceanic serpentinization is locally associated with active hydrothermal vents known to release significant amounts of abiotic H 2 , CH 4 , and possibly other complex carbon molecules (Charlou et al, 2002;Holm and Charlou, 2001;Lang et al, 2010;Proskurowski et al, 2008).…”

Section: Introductionmentioning

confidence: 99%