Loss of trace elements from serpentinites during fluid-assisted transformation of chrysotile to antigorite — An example from Guatemala

Kodolányi, János; Pettke, Thomas

doi:10.1016/j.chemgeo.2011.03.016

Cited by 79 publications

(32 citation statements)

References 39 publications

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“…It has been proposed that the breakdown of antigorite produces a high-pressure olivine-orthopyroxene-chlorite assemblage and fluids with a low salinity of 0.4-2 wt% NaCl eq (Scambelluri et al, 2004). Additional constraints can be derived from bulk rock measurements that consistently show antigorite serpentinites containing 100-300 ppm of Cl (Scambelluri et al, 2004;John et al, 2011;Kodolanyi and Pettke, 2011). If all chlorine is released into the 6.5 wt% H 2 O that forms during the breakdown of antigorite to form chlorite-orthopyroxene-olivine rocks, then the resulting salinity will be 0.25-0.75 wt% NaCl eq , which is at the lower end of the proposed salinity for this high-pressure fluid (Scambelluri et al, 2004).…”

Section: Implications For CL Recycling In Subduction Zonesmentioning

confidence: 98%

“…For example, Kodolanyi and Pettke (2011) studied a chrysotile-antigorite serpentinite sample from the Deep Sea Drilling Project Leg 84 (Site 566) in the Guatemala forearc, and reported 0.3-0.6 wt% Cl in low grade serpentinites. However, about 90% of the Cl, hosted originally by chrysotile was lost during fluid-assisted chrysotile-to-antigorite transformation along with partial dehydration, which can occur in the shallow ($30 km) region of the subduction zone (Kodolanyi and Pettke, 2011). It was proposed that a saline fluid with 4-8 wt% NaCl eq forms during early partial dehydration of serpentinites releasing 1-2 wt% H 2 O at 1.5 GPa, 500°C (Scambelluri et al, 2004).…”

Section: Implications For CL Recycling In Subduction Zonesmentioning

confidence: 99%

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Apatite as an indicator of fluid salinity: An experimental study of chlorine and fluorine partitioning in subducted sediments

Hermann

2015

Geochimica et Cosmochimica Acta

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Section: Implications For CL Recycling In Subduction Zonesmentioning

confidence: 98%

Section: Implications For CL Recycling In Subduction Zonesmentioning

confidence: 99%

Apatite as an indicator of fluid salinity: An experimental study of chlorine and fluorine partitioning in subducted sediments

Hermann

2015

Geochimica et Cosmochimica Acta

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“…For this reason we propose that Cl was a high-pressure fluid component, as pointed out by the significant Cl concentrations measured in olivine-hosted inclusions from garnet peridotite MG160-C1 (Table 1). Serpentinite dehydration is known to release chlorine-bearing fluids, es- pecially during the chrysotile and the antigorite + brucite breakdown reactions (1) and (2) (Scambelluri et al, 2004a;Kodolanyi and Pettke, 2011). Scambelluri et al (2004aScambelluri et al ( , 2004b) estimated a bulk loss of 2 wt% H 2 O during this reaction.…”

Section: Fluid Inclusion Compositionsmentioning

confidence: 99%

“…(3) Reaction (1) takes place during early subduction (200-300 • C) beneath accretionary wedges and liberates trace-element charged fluids (Kodolanyi and Pettke, 2011). Reaction (2) occurred in eclogitefacies Alpine serpentinites, showing rock-and vein-forming antigorite + olivine-bearing parageneses.…”

Section: Introductionmentioning

confidence: 99%

Fluid-related inclusions in Alpine high-pressure peridotite reveal trace element recycling during subduction-zone dehydration of serpentinized mantle (Cima di Gagnone, Swiss Alps)

Scambelluri

Pettke

Cannaò

2015

Earth and Planetary Science Letters

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108

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Available online xxxx Editor: T.A. Mather Keywords: serpentinized mantle garnet peridotite chlorite harzburgite polyphase inclusions subduction fluids fluid-mobile elementsSerpentinites release at sub-arc depths volatiles and several fluid-mobile trace elements found in arc magmas. Constraining element uptake in these rocks and defining the trace element composition of fluids released upon serpentinite dehydration can improve our understanding of mass transfer across subduction zones and to volcanic arcs. The eclogite-facies garnet metaperidotite and chlorite harzburgite bodies embedded in paragneiss of the subduction melange from Cima di Gagnone derive from serpentinized peridotite protoliths and are unique examples of ultramafic rocks that experienced subduction metasomatism and devolatilization. In these rocks, metamorphic olivine and garnet trap polyphase inclusions representing the fluid released during high-pressure breakdown of antigorite and chlorite. Combining major element mapping and laser-ablation ICP-MS bulk inclusion analysis, we characterize the mineral content of polyphase inclusions and quantify the fluid composition. Silicates, Cl-bearing phases, sulphides, carbonates, and oxides document post-entrapment mineral growth in the inclusions starting immediately after fluid entrapment. Compositional data reveal the presence of two different fluid types. The first (type A) records a fluid prominently enriched in fluid-mobile elements, with Cl, Cs, Pb, As, Sb concentrations up to 10 3 PM (primitive mantle), ∼10 2 PM Tl, Ba, while Rb, B, Sr, Li, U concentrations are of the order of 10 1 PM, and alkalis are ∼2 PM. The second fluid (type B) has considerably lower fluid-mobile element enrichments, but its enrichment patterns are comparable to type A fluid. Our data reveal multistage fluid uptake in these peridotite bodies, including selective element enrichment during seafloor alteration, followed by fluid-rock interaction along with subduction metamorphism in the plate interface melange. Here, infiltration of sediment-equilibrated fluid produced significant enrichment of the serpentinites in As, Sb, B, Pb, an enriched trace element pattern that was then transferred to the fluid released at greater depth upon serpentine dehydration (type A fluid). The type B fluid hosted by garnet may record the composition of the chlorite breakdown fluid released at even greater depth. The Gagnone study-case demonstrates that serpentinized peridotites acquire water and fluid-mobile elements during ocean floor hydration and through exchange with sediment-equilibrated fluids in the early subduction stages. Subsequent antigorite devolatilization at subarc depths delivers aqueous fluids to the mantle wedge that can be prominently enriched in sediment-derived components, potentially triggering arc magmatism without the need of concomitant dehydration/melting of metasediments or altered oceanic crust.

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“…Table 2). This relationship between the texture and the composition of serpentine minerals shows some similarity to the Guatemala forearc serpentinites (Kodolanyi and Pettke, 2011). The examined bastite shares in the same Al and Cr values with primary orthopyroxene in Oeyama harzburgites (Arai, 1975(Arai, , 1980Kurokawa, 1985) (Fig.…”

Section: Whole-rock Chemistrymentioning

confidence: 87%

Petrology and geochemistry of chromian spinel-bearing serpentinites in the Hida Marginal Belt (Ise area, Japan): characteristics of their protoliths

Khedr¹,

Arai²

2011

Journal of Mineralogical and Petrological Sciences

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The Ise area is located in the western part of the Hida Marginal Belt (central Japan), which includes several sporadic exposures of ultramafic rocks, sometimes forming a serpentinite mélange of the Paleozoic age. Ultramafic rocks in the Ise area, enveloped by Paleozoic -Mesozoic sedimentary rocks, are completely serpentinized; however, the abundance of bastite after orthopyroxene suggests harzburgite protoliths. ) atomic ratio, <0.03]}, similar to chromian spinel in Kotaki and Oeyama ultramafic masses. It is also similar in chemistry to spinels in forearc and abyssal peridotites, suggesting two possibilities for the derivation of the Ise serpentinite's protoliths. The degree of melting using Cr# versus TiO 2 of chromian spinel is ~ 20 -25%, which is in accordance with the harzburgite protoliths obtained by whole -rock chemistry models. We found that Cr, Al, Ni and Ca, preserved in bastite and meshtextured serpentine, are conservative during serpentinization, confirmed from the similarity in the whole -rock A1 and Ca of the Ise serpentinites to Horoman harzburgites. The occurrence of dolomite can stabilize the Ca and limited its mobility to escape outside the serpentinites. The harzburgite protoliths were possibly serpentinized by slab -derived fluids at a shallow depth relative to the Happo -O'ne serpentinites during the exhumation process.

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Loss of trace elements from serpentinites during fluid-assisted transformation of chrysotile to antigorite — An example from Guatemala

Cited by 79 publications

References 39 publications

Apatite as an indicator of fluid salinity: An experimental study of chlorine and fluorine partitioning in subducted sediments

Apatite as an indicator of fluid salinity: An experimental study of chlorine and fluorine partitioning in subducted sediments

Fluid-related inclusions in Alpine high-pressure peridotite reveal trace element recycling during subduction-zone dehydration of serpentinized mantle (Cima di Gagnone, Swiss Alps)

Petrology and geochemistry of chromian spinel-bearing serpentinites in the Hida Marginal Belt (Ise area, Japan): characteristics of their protoliths

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