Generation of Mobile Components during Subduction of Oceanic Crust

Schmidt, M. W.

doi:10.1016/b0-08-043751-6/03034-6

Cited by 140 publications

(141 citation statements)

References 82 publications

Supporting

Mentioning

135

Contrasting

Unclassified

Order By: Relevance

“…The nitrogen abundance likely also is heterogeneously distributed with considerably greater nitrogen contents in subduction zone environments where abundances above 0.1% N 2 have been reported (Fisher et al 2002). This latter environment likely also is where most of the exchange of volatiles (including nitrogen) occurs between the solid Earth and the atmosphere (Schmidt and Poli, 2003;Bebout, 2007).…”

Section: Introductionmentioning

confidence: 99%

Mass transfer in the Earth’s interior: fluid-melt interaction in aluminosilicate–C–O–H–N systems at high pressure and temperature under oxidizing conditions

Mysen

2018

Prog Earth Planet Sci

View full text Add to dashboard Cite

Understanding what governs the speciation in the C-O-H-N system aids our knowledge of how volatiles affect mass transfer processes in the Earth's interior. Experiments with aluminosilicate melt + C-O-H-N volatiles were, therefore, carried out with Raman and infrared spectroscopy to 800°C and near 700 MPa in situ in hydrothermal diamond anvil cells. The measurements were conducted in situ with the samples at the desired temperatures and pressures in order to avoid possible structural and compositional changes resulting from quenching to ambient conditions prior to analysis. Experiments were conducted without any reducing agent and with volatiles added as H 2 O, CO 2 , and N 2 because both carbon and nitrogen can occur in different oxidation states. Volatiles dissolved in melt comprise H 2 O, CO 3 2-, HCO 3 -, and molecular N 2 , whereas in the coexisting fluid, the species are H 2 O, CO 2 , CO 3 2-, and N 2 . The HCO 3 -/CO 3 2-equilibrium in melts shift toward CO 3 2-groups with increasing temperature with ΔH = 114 ± 22 kJ/mol. In fluids, the CO 2 abundance is essentially invariant with temperature and pressure. For fluid/melt partitioning, those of H 2 O and N 2 are greater than 1 with temperature-dependence that yields ΔH values of − 6.5 ± 1.5 and − 19.6 ± 3.7 kJ/mol, respectively. Carbonate groups, CO 3 2-are favored by melt over fluid. Where redox conditions in the Earth's interior exceed that near the QFM oxygen buffer (between NNO and MW buffers), N 2 is the stable nitrogen species and as such acts as a diluent of both fluids and melts. For fluids, this lower silicate solubility, in turn, enhances alkalinity. This means that in such environments, the transport of components such as high field strength cations, will be enhanced. Effects of dissolved N 2 on melt structure are considerably less than on fluid structure.

show abstract

Section: Introductionmentioning

confidence: 99%

Mass transfer in the Earth’s interior: fluid-melt interaction in aluminosilicate–C–O–H–N systems at high pressure and temperature under oxidizing conditions

Mysen

2018

Prog Earth Planet Sci

View full text Add to dashboard Cite

show abstract

“…At great depths in subduction zones (15 to 100 km), fluids (aqueous fluids in shallower levels and possibly silicate melts in deeper levels; cf. Bebout 2007a, b) derived from subducting slabs can transport various components into the mantle wedge, causing hydration and metasomatism of the mantle (Maury et al 1992;Ryan et al 1996;Morris and Ryan 2003;Schmidt and Poli 2003;Rüpke et al 2004). It is generally believed that such fluid flow is essential to generate arc magmas with elevated concentrations of fluid-mobile components such as largeion lithophile elements (LILE; e.g., Ba, K, Rb, Cs), B, U, and Pb (Morris et al 1990;Hawkesworth et al 1993;Tatsumi and Eggins 1995;Davidson 1996;Elliott 2003).…”

Section: Introductionmentioning

confidence: 99%

Fluid-metapelite interaction in an ultramafic mélange: implications for mass transfer along the slab-mantle interface in subduction zones

2014

View full text Add to dashboard Cite

The slab-mantle interface in subduction zones is a site of tectonic mixing of crustal and mantle rocks. It is the interface for fluid flow of slab-derived components into the mantle wedge. To assess the fluid-rock interaction along the slab-mantle interface, we studied the bleaching of pelitic schist in an ultramafic mélange. The Nishisonogi metamorphic rocks in Kyushu, Japan, comprise ultramafic mélanges intercalated with epidote-blueschist facies schists. The ultramafic mélange consists of tectonic blocks of various lithologies and a matrix of chlorite-actinolite schist and serpentinite. Along the contact with the mélange matrix, pelitic schist blocks are bleached mainly due to the modal increase of albite and the consumption of carbonaceous material. The bleaching is probably attributed to infiltration of Na-rich external fluid from the mélange matrix. Mass balance analysis indicates losses of C, Rb, K 2 O, Ba, Pb, and SiO 2 from the bleached pelitic schist, although Al 2 O 3 , TiO 2 , Sc, Y, Zr, Nb, La, Ce, and Nd remain immobile. This suggests fractionation of large-ion lithophile elements (LILE) and Pb from the high-field-strength elements and rare earth elements during the bleaching. If this ultramafic mélange is analogous to the slab-mantle interface, similar infiltration metasomatism will promote liberation of C, Si, LILE, and Pb from subducting metapelites and enhance metasomatism of the mantle wedge.

show abstract

“…Peacock, 1996;Hacker et al, 2003;Guillot et al, 2009) with concomitant metasomatism induced by the circulating fluid phase (e.g. Scambelluri and Philippot, 2001;Schmidt and Poli, 2003;Bebout, 2007) (Fig. 2b).…”

Section: The Geodynamic Settingsmentioning

confidence: 99%

“…serpentines and amphiboles) (e.g. Trommsdorff and Evans, 1974;Evans, 1977;Schmidt and Poli, 2003;Bebout, 2007;Bellot, 2008). The continuous feedback between dynamic recrystallization, strain localization, and fluid channelling implies deep changes into the structural permeability of the rock volume (e.g.…”

Section: Fluid-rock Interactionmentioning

confidence: 99%

Linking rock fabric to fibrous mineralisation: a basic tool for the asbestos hazard

Vignaroli

Rossetti

Belardi

et al. 2011

Nat. Hazards Earth Syst. Sci.

View full text Add to dashboard Cite

Abstract. In recent years, many studies have addressed the effect on human health caused by asbestos exposures. As asbestos is a group of fibrous minerals that mainly occurs in mafic and ultramafic rocks (ophiolitic sequences), a close relationship between asbestos occurrence and the geological history of host rocks should be expected. By reviewing the existing literature and presenting characteristic examples, it is proposed a direct correspondence exists between the presence of fibrous minerals in ophiolites and the rock fabric systematics due to the combined activity of deformation, metamorphism/metasomatism, and rock/fluid interaction. Understanding the geological factors that may be at the origin of the nucleation/growth of fibrous minerals constitutes a necessary requirement for developing a methodological and analytical procedure to evaluate asbestos hazard (A H ) in the natural prototype (ophiolitic rocks). A parameterisation of the A H in function of the main geological processes that produce the rock fabric systematics in different tectonic/geodynamic settings is discussed. A geological multidisciplinary approach (based on geological-structural field evidence combined with textural, mineralogical, petrological, and geochemical investigations) is proposed as the prerequisite for the evaluation of A H in natural environments. This approach, in particular, can provide a robust basis to formulate a procedural protocol finalised to the mitigation of asbestos effects in environments where these effects are still a real threat.

show abstract

Generation of Mobile Components during Subduction of Oceanic Crust

Cited by 140 publications

References 82 publications

Mass transfer in the Earth’s interior: fluid-melt interaction in aluminosilicate–C–O–H–N systems at high pressure and temperature under oxidizing conditions

Mass transfer in the Earth’s interior: fluid-melt interaction in aluminosilicate–C–O–H–N systems at high pressure and temperature under oxidizing conditions

Fluid-metapelite interaction in an ultramafic mélange: implications for mass transfer along the slab-mantle interface in subduction zones

Linking rock fabric to fibrous mineralisation: a basic tool for the asbestos hazard

Contact Info

Product

Resources

About