Serpentinization of mantle peridotites along an uplifted lithospheric section, Mid Atlantic Ridge at 11° N

Boschi, Chiara; Bonatti, Enrico; Ligi, Marco; Brunelli, Daniele; Cipriani, Anna; Dallai, Luigi; D’Orazio, Massimo; Früh-Green, Gretchen L.; Tonarini, S.; Barnes, Jaime D.; Bedini, R. M.

doi:10.1016/j.lithos.2013.06.003

Cited by 64 publications

(43 citation statements)

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“…Oceanic serpentinites also inherit the REE compositions of their mantle protoliths. Figure 4 reports the trace-element compositions of numerous abyssal serpentinites from the large datasets by Deschamps et al (2013) and Peters et al (2017) normalized to the Primitive Mantle (PM, McDonough & Sun, 1995) (the dataset, in Table S1, includes analyses by Lagabrielle et al, 1992;Parkinson & Pearce, 1998;Viti & Mellini, 1998;Anselmi et al, 2000;Pearce et al, 2000;Guillot et al, 2001;Scambelluri et al, 2001b;Chalot-Prat et al, 2003;Garrido et al, 2005;Savov et al, 2005aSavov et al, , b, 2007Aldanmaz & Koprubasi, 2006;Marchesi et al, 2006Marchesi et al, , 2009Paulick et al, 2006;Hattori & Guillot, 2007;Delacour et al, 2008;Pereira et al, 2008;De Hoog et al, 2009;Deschamps et al, 2010Deschamps et al, , 2012Jöns et al, 2010;Saumur et al, 2010;Ulrich et al, 2010;Aziz et al, 2011;Blanco-Quintero et al, 2011;Augustin et al, 2012;Kodolányi et al, 2012;Boschi et al, 2013;Lafay et al, 2013;Andreani et al, 2014;Cannaò et al, 2015Cannaò et al, , 2016…”

Section: Oceanic Serpentinitementioning

confidence: 99%

“…Figure 5 shows the Br/Cl and I/Cl ratios of serpentinites from present-day mid-ocean ridges, passive margins and forearcs, along with non-subducted ophiolitic serpentinites (Northern Apennine and Alps; data after John et al, 2011; Kendrick et al, 2013). While abyssal and passive-margin serpentinites display I/Cl and Br/Cl ratios Boschi et al (2013). The bold red pattern represents the depleted mantle by Salters & Stracke (2004) and the bold black lines represent the refertilized plagioclase-rich oceanic peridotite from Lanzo (data by Guarnieri et al, 2012). close to seawater, forearc serpentinites progressively shift their I/Cl and Br/Cl towards sedimentary pore fluids (Fig.…”

Section: Oceanic Serpentinitementioning

confidence: 99%

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The water and fluid-mobile element cycles during serpentinite subduction. A review

Scambelluri

Cannaò

Gilio

2019

ejm

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The key role of serpentinites in the global cycles of volatiles, halogens and fluid-mobile elements in oceans and in subduction zones is now ascertained by many studies quantifying their element budgets and the composition of fluids they release during subduction. Geochemical tracers (e.g. B, As, Sb; stable B and radiogenic Sr and Pb isotopes) have also been employed to trace the provenance of serpentinites (slab or forearc mantle?) accreted to the plate interface of fossil subduction zones. In turn, this helps defining the tectonic processes, seismicity and mass transfer attending rock burial and exhumation within subduction zones. The results suggest that the sole use of geochemical data is insufficient to track the origin of subduction-zone serpentinites and the timing of serpentinization, whether oceanic or subduction-related. Integrated multidisciplinary studies of ophiolitic serpentinites show that pristine, oceanic, geochemical imprints (e.g. high 11 B, marine Sr isotopes, low As + Sb) become reset towards more radiogenic Sr, lower 11 B, and higher As + Sb via metasomatic exchange with crust-derived fluids during subduction accretion to the plate interface.The dehydration fluids released by serpentinite dehydration at various subduction stages and still preserved in these rocks as inclusions, carry significant amounts of halogens and fluid-mobile elements. The key compositional similarities of antigorite-breakdown fluids from different localities (Betic Cordillera, Spain; Central Alps, Switzerland) indicate that rocks record comparable subduction processes. We individuate the fluid-mediated exchange with sedimentary and/or crustal reservoirs during subduction as the key mechanism for geochemical hybridization of serpentinite. The antigorite dehydration fluids produced by hybrid serpentinites have high Cs, Rb, Ba, B, Pb, As, Sb and Li overlapping those of the arc lavas and representing the mixed serpentinite-sediment (crustal) component released to arcs. This helps discriminating the mass transfer processes responsible for supra-subduction mantle metasomatism and arc magmatism. The studied plate-interface hybrid serpentinites are also proxies of forearc mantle metasomatized by slab fluids. Based on the above observations, we propose that the mass transfer from slabs to plate interface and/or forearc mantle and the subsequent down-drag of this altered mantle to subarc depths potentially is a major process operating in subduction zones.The nominally anhydrous olivine, orhopyroxene, clinopyroxene and garnet produced by serpentinite dehydration host appreciable amounts of halogens and fluid-mobile elements that can be recycled in the deep mantle beyond arcs. Involvement of de-serpentinized residues in lower mantle metasomatism begins to be increasingly recognized by studies of ocean island basalts (OIB) and of B-bearing blue diamonds and by the isotopic serpentinite compositions presented here.

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Section: Oceanic Serpentinitementioning

confidence: 99%

Section: Oceanic Serpentinitementioning

confidence: 99%

The water and fluid-mobile element cycles during serpentinite subduction. A review

Scambelluri

Cannaò

Gilio

2019

ejm

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“…Older detachments are observed to be preserved off-axis during spreading [Smith et al, 2006[Smith et al, , 2008Reston and Ranero, 2011]. Detachment faults pervasively cut the lithosphere to depths of 7 km [Escart ın et al, 2008a;Reston and Ranero, 2011], providing pathways for seawater to infiltrate the lower crust and upper mantle and trigger pervasive hydrothermal alteration (serpentinization) [e.g., Schroeder et al, 2002;M evel, 2003;Bach et al, 2004Bach et al, , 2006Boschi et al, 2006aBoschi et al, , 2013Beard et al, 2009;Klein et al, 2009;Pl€ umper et al, 2012Pl€ umper et al, , 2014Andreani et al, 2014;Maffione et al, 2014]. As a result, detachments are associated with a relatively thick (up to 200 m) crystal-plastic (mylonitic) to cataclastic shear zone dominated by serpentine minerals and other phyllosilicates, including talc and chlorite [MacLeod et al, 2002;Escart ın et al, 2003;Schroeder and John, 2004;Boschi et al, 2006aBoschi et al, , 2006bKarson et al, 2006;Escart ın et al, 2008b;Andreani et al, 2014].…”

Section: Slow-spreading Ridges and Oceanic Detachment Faultsmentioning

confidence: 99%

Dynamics of intraoceanic subduction initiation: 1. Oceanic detachment fault inversion and the formation of supra‐subduction zone ophiolites

Maffione

Thieulot

Hinsbergen

et al. 2015

Geochem Geophys Geosyst

127

173

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Subduction initiation is a critical link in the plate tectonic cycle. Intraoceanic subduction zones can form along transform faults and fracture zones, but how subduction nucleates parallel to mid-ocean ridges, as in e.g., the Neotethys Ocean during the Jurassic, remains a matter of debate. In recent years, extensional detachment faults have been widely documented adjacent to slow-spreading and ultraslowspreading ridges where they cut across the oceanic lithosphere. These structures are extremely weak due to widespread occurrence of serpentine and talc resulting from hydrothermal alteration, and can therefore effectively localize deformation. Here, we show geochemical, tectonic, and paleomagnetic evidence from the Jurassic ophiolites of Albania and Greece for a subduction zone formed in the western Neotethys parallel to a spreading ridge along an oceanic detachment fault. With 2-D numerical modeling exploring the evolution of a detachment-ridge system experiencing compression, we show that serpentinized detachments are always weaker than spreading ridges. We conclude that, owing to their extreme weakness, oceanic detachments can effectively localize deformation under perpendicular far-field forcing, providing ideal conditions to nucleate new subduction zones parallel and close to (or at) spreading ridges. Direct implication of this, is that resumed magmatic activity in the forearc during subduction initiation can yield widespread accretion of suprasubduction zone ophiolites at or close to the paleoridge. Our new model casts the enigmatic origin of regionally extensive ophiolite belts in a novel geodynamic context, and calls for future research on three-dimensional modeling of subduction initiation and how upper plate extension is associated with that.

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“…In order to test if Mg is lost during reactions of seawater with MORP, we compared the chemical composition of primary unaltered MORP with that of hydrated MORP samples obtained at over 20 sites where mantle is exposed along the Vema Lithospheric Section in the central Atlantic3839. They represent mantle residual after extraction of basaltic melt at a single segment of the Mid Atlantic Ridge (MAR) throughout 26 million years of crustal accretion.…”

Section: Resultsmentioning

confidence: 99%

“…(d), Triangular Mg-Si-Fe diagram showing the bulk composition of hydrated mantle-derived peridotites (open symbols) and reconstructed primary compositions of the same rocks (filled symbols). Diamonds refer to SWIR peridotites34, circles to Vema Lithosperic Section peridotites3839. Both populations show Mg-loss in serpentinites compared to unaltered primary peridotites.…”

Section: Figurementioning

confidence: 99%

Post-Mesozoic Rapid Increase of Seawater Mg/Ca due to Enhanced Mantle-Seawater Interaction

Ligi

Bonatti

Cuffaro

et al. 2013

Sci Rep

Self Cite

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The seawater Mg/Ca ratio increased significantly from ~ 80 Ma to present, as suggested by studies of carbonate veins in oceanic basalts and of fluid inclusions in halite. We show here that reactions of mantle-derived peridotites with seawater along slow spreading mid-ocean ridges contributed to the post-Cretaceous Mg/Ca increase. These reactions can release to modern seawater up to 20% of the yearly Mg river input. However, no significant peridotite-seawater interaction and Mg-release to the ocean occur in fast spreading, East Pacific Rise-type ridges. The Mesozoic Pangean superocean implies a hot fast spreading ridge system. This prevented peridotite-seawater interaction and Mg release to the Mesozoic ocean, but favored hydrothermal Mg capture and Ca release by the basaltic crust, resulting in a low seawater Mg/Ca ratio. Continent dispersal and development of slow spreading ridges allowed Mg release to the ocean by peridotite-seawater reactions, contributing to the increase of the Mg/Ca ratio of post-Mesozoic seawater.

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Serpentinization of mantle peridotites along an uplifted lithospheric section, Mid Atlantic Ridge at 11° N

Cited by 64 publications

References 100 publications

The water and fluid-mobile element cycles during serpentinite subduction. A review

The water and fluid-mobile element cycles during serpentinite subduction. A review

Dynamics of intraoceanic subduction initiation: 1. Oceanic detachment fault inversion and the formation of supra‐subduction zone ophiolites

Post-Mesozoic Rapid Increase of Seawater Mg/Ca due to Enhanced Mantle-Seawater Interaction

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