Textural evolution during high-pressure dehydration of serpentinite to peridotite and its relation to stress orientations and kinematics of subducting slabs: Insights from the Almirez ultramafic massif

Dilissen, Nicole; Hidas, Károly; Garrido, Carlos J.; Kahl, Wolf‐Achim; Sánchez‐Vizcaíno, Vicente López; Padrón‐Navarta, José Alberto

doi:10.1016/j.lithos.2018.09.033

Cited by 19 publications

(24 citation statements)

References 85 publications

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“…11a) in natural meta-peridotites (Clément et al, 2019;Nagaya et al, 2014), or by anisotropic growth with fast-growing axis parallel to the [001] ol in the jackstraw-textured veins (Clément et al, 2019). The (010)[h0l] olivine CPO has been suggested to form by topotactic growth of [010] ol //[001] atg (Clément et al, 2019 (Dilissen et al, 2018). Padrón-Navarta et al (2015) reported that the topotactic growth of [100] ol,opx //[001] atg induced a strong concentration of the [100] ol normal to the former foliation and a girdle distribution of the other two olivine crystallographic axes along the former foliation plane in both natural samples (Figure 11b) and the dehydration experiments on foliated antigorite (Figure 11c).…”

Section: Comparison With Previous Experimental Results and Natural Samplesmentioning

confidence: 99%

Hydrostatic Dehydration Fabrics of Antigorite at High Pressure and High Temperature: Implications for Trench Parallel Seismic Anisotropy at Convergent Plate Boundaries

Liu

Zhang

et al. 2021

JGR Solid Earth

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Antigorite dehydration is well known as a key process at convergent boundaries for the genesis of mantle wedge partial melting and intermediate‐depth earthquakes. However, the crystallographic preferred orientations (CPOs) of prograde minerals from antigorite dehydration and their effects on the seismic anisotropy of subducting slabs remain ambiguous and controversial. Here we report antigorite dehydration experiments on a foliated serpentinized peridotite at pressures of 0.3–6 GPa and temperatures of 700–900°C. Our results show that olivine CPO evolves from a fiber‐[100] type in fine grains to a type‐C like in coarse grains. We propose that the fiber‐[100] olivine CPO is developed by topotactic growth during incipient hydrostatic dehydration, while the orthorhombic type‐C like olivine CPO is developed by anisotropic growth resulting from an anisotropic fluid flow during later dehydration. The type‐C like olivine CPO in the antigorite‐rich layers after antigorite dehydration could contribute to the trench parallel fast shear wave seismic anisotropy at convergent plate boundaries.

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Section: Comparison With Previous Experimental Results and Natural Samplesmentioning

confidence: 99%

Hydrostatic Dehydration Fabrics of Antigorite at High Pressure and High Temperature: Implications for Trench Parallel Seismic Anisotropy at Convergent Plate Boundaries

Liu

Zhang

et al. 2021

JGR Solid Earth

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“…Granofels Chl-harzburgites are made up of coarse anhedral olivine, chlorite flakes, and prismatic orthopyroxene, with an interlocked texture, whereas spinifextextured Chl-harzburgites are characterized by a criss-cross arrangement of olivine single crystals (up to 12 cm in length), and by centimetre-scale radial aggregates of orthopyroxene with variable grain size and orientation. Granofels and spinifex Chl-harzburgites occur in interspersed lenses that are thought to record, respectively, sequences of slow and fast fluid draining events during serpentinite dehydration (Padrón-Navarta et al, 2011;Dilissen et al, 2018). Both textural types of Chl-harzburgite are locally recrystallized along grain size reduction zones (Padron-Navarta et al, 2010a).…”

Section: Geological Settingmentioning

confidence: 99%

Iron and zinc stable isotope evidence for open-system high-pressure dehydration of antigorite serpentinite in subduction zones

Debret

Garrido

Pons

et al. 2021

Geochimica et Cosmochimica Acta

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…(b) Geological map of the NFC in the central part of the Betic Cordillera (South Spain), with location of the two studied ultramafic massifs Almirez and Milagrosa; modified from Martínez‐Martínez, Torres‐Ruiz, Pesquera, and Gil‐Crespo (). (c) Conceptual sketch of subduction and exhumation of the NFC (after Dilissen et al., ; modified from Behr & Platt, )…”

Section: The Nevado‐filábride Complexmentioning

confidence: 99%

“…). (c) Conceptual sketch of subduction and exhumation of the NFC (afterDilissen et al, 2018; modified from Behr & Platt, 2012) …”

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confidence: 99%

Subduction metamorphism of serpentinite‐hosted carbonates beyond antigorite‐serpentinite dehydration (Nevado‐Filábride Complex, Spain)

Menzel

Garrido

Sánchez‐Vizcaíno

et al. 2019

Journal Metamorphic Geology

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At sub‐arc depths, the release of carbon from subducting slab lithologies is mostly controlled by fluid released by devolatilization reactions such as dehydration of antigorite (Atg‐) serpentinite to prograde peridotite. Here we investigate carbonate–silicate rocks hosted in Atg‐serpentinite and prograde chlorite (Chl‐) harzburgite in the Milagrosa and Almirez ultramafic massifs of the palaeo‐subducted Nevado‐Filábride Complex (NFC, Betic Cordillera, S. Spain). These massifs provide a unique opportunity to study the stability of carbonate during subduction metamorphism at P–T conditions before and after the dehydration of Atg‐serpentinite in a warm subduction setting. In the Milagrosa massif, carbonate–silicate rocks occur as lenses of Ti‐clinohumite–diopside–calcite marbles, diopside–dolomite marbles and antigorite–diopside–dolomite rocks hosted in clinopyroxene‐bearing Atg‐serpentinite. In Almirez, carbonate–silicate rocks are hosted in Chl‐harzburgite and show a high‐grade assemblage composed of olivine, Ti‐clinohumite, diopside, chlorite, dolomite, calcite, Cr‐bearing magnetite, pentlandite and rare aragonite inclusions. These NFC carbonate–silicate rocks have variable CaO and CO2 contents at nearly constant Mg/Si ratio and high Ni and Cr contents, indicating that their protoliths were variable mixtures of serpentine and Ca‐carbonate (i.e., ophicarbonates). Thermodynamic modelling shows that the carbonate–silicate rocks attained peak metamorphic conditions similar to those of their host serpentinite (Milagrosa massif; 550–600°C and 1.0–1.4 GPa) and Chl‐harzburgite (Almirez massif; 1.7–1.9 GPa and 680°C). Microstructures, mineral chemistry and phase relations indicate that the hybrid carbonate–silicate bulk rock compositions formed before prograde metamorphism, likely during seawater hydrothermal alteration, and subsequently underwent subduction metamorphism. In the CaO–MgO–SiO2 ternary, these processes resulted in a compositional variability of NFC serpentinite‐hosted carbonate–silicate rocks along the serpentine‐calcite mixing trend, similar to that observed in serpentinite‐hosted carbonate‐rocks in other palaeo‐subducted metamorphic terranes. Thermodynamic modelling using classical models of binary H2O–CO2 fluids shows that the compositional variability along this binary determines the temperature of the main devolatilization reactions, the fluid composition and the mineral assemblages of reaction products during prograde subduction metamorphism. Thermodynamic modelling considering electrolytic fluids reveals that H2O and molecular CO2 are the main fluid species and charged carbon‐bearing species occur only in minor amounts in equilibrium with carbonate–silicate rocks in warm subduction settings. Consequently, accounting for electrolytic fluids at these conditions slightly increases the solubility of carbon in the fluids compared with predictions by classical binary H2O–CO2 fluids, but does not affect the topology of phase relations in serpentinite‐hosted carbonate‐rocks. Phase relations, mineral c...

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Textural evolution during high-pressure dehydration of serpentinite to peridotite and its relation to stress orientations and kinematics of subducting slabs: Insights from the Almirez ultramafic massif

Cited by 19 publications

References 85 publications

Hydrostatic Dehydration Fabrics of Antigorite at High Pressure and High Temperature: Implications for Trench Parallel Seismic Anisotropy at Convergent Plate Boundaries

Hydrostatic Dehydration Fabrics of Antigorite at High Pressure and High Temperature: Implications for Trench Parallel Seismic Anisotropy at Convergent Plate Boundaries

Iron and zinc stable isotope evidence for open-system high-pressure dehydration of antigorite serpentinite in subduction zones

Subduction metamorphism of serpentinite‐hosted carbonates beyond antigorite‐serpentinite dehydration (Nevado‐Filábride Complex, Spain)

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