Water in orthopyroxene from abyssal spinel peridotites of the East Pacific Rise (ODP Leg 147: Hess Deep)

Hesse, K.; Gose, Jürgen; Stalder, Roland; Schmädicke, Esther

doi:10.1016/j.lithos.2015.06.011

Cited by 18 publications

(30 citation statements)

References 59 publications

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“…The calculated water contents in Opx vary from 24 to 262 ppm (Table ). In general, these values span the range of previously published water contents in Opx with similar compositions [ Gose et al ., ; Peslier , ; Schmädicke et al ., ; Warren and Hauri , ; Hesse et al ., ]. The water contents in Opx from 63.5°E peridotites are high and less variable (207–262 ppm), while the five samples from 53°E segment show variable water contents (24–246 ppm), with sample 21V‐D1‐1 extending to very low value (24 ± 8 ppm).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, on a segment (even dredge) scale, the water contents variation in the 53°E peridotites cannot be explained by partial melting alone. Likewise, at high Opx Cr# (∼19), sample 21V‐D1‐1 has low Opx water contents similar to one sample from MAR [ Schmädicke et al ., ] but significantly lower than samples from EPR [ Hesse et al ., ], further implying that mantle melting is not the only pathway for water content variation in the oceanic upper mantle.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, it was found that Opx in oceanic spinel peridotite from the Mid‐Atlantic Ridge (ODP Leg 153 at 23°N) contain 160–270 ppm H 2 O [ Gose et al ., ], while Opx in peridotites from SWIR amagmatic accretionary segments (9°E–25°E) could contain 145–198 ppm H 2 O [ Warren and Hauri , ]. In addition, abyssal peridotites from East Pacific Rise (ODP Leg 147) have Opx water contents ranging from 86 to 233 ppm [ Hesse et al ., ]. Hence, due to its volumic abundance, the Opx may constitute the main water reservoir in the upper mantle.…”

Section: Introductionmentioning

confidence: 98%

“…The character of the water distribution beneath other oceanic ridges is still not well understood. High water contents in Opx from abyssal peridotites are not consistent with mantle partial melting, but can be explained by postmelting rehydration [ Schmädicke et al ., ; Hesse et al ., ], which could stem from mantle metasomatism via water reequilibration between minerals and percolating melts. However, the origin of the percolating melts and their geochemical influence are still pending issues.…”

Section: Introductionmentioning

confidence: 98%

“…Most of the water concentration measurements in natural mantle minerals are limited to xenoliths from subcontinental and oceanic lithosphere, mantle wedge, and some peridotite massifs [ Peslier et al ., ; Peslier and Luhr , ; Grant et al ., ; Li et al ., ; Yang et al ., ; Bonadiman et al ., ; Peslier , ; Soustelle et al ., ; Xia et al ., ; Yu et al ., ; Doucet et al ., ; Bizimis and Peslier , ; Demouchy et al ., ; Peslier and Bizimis , ; Peslier et al ., ; Chin et al ., ; Demouchy and Bolfan‐Casanova , ]. The water budget of the uppermost oceanic lithospheric mantle is nevertheless poorly constrained as there was only five previous reports on water contents in abyssal peridotites [ Gose et al ., ; Peslier , ; Schmädicke et al ., ; Warren and Hauri , ; Hesse et al ., ]. The lack of water measurements in abyssal peridotite is mainly due to the intense high‐temperature serpentinization or low‐temperature seafloor weathering.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Origins of water content variations in the suboceanic upper mantle: Insight from Southwest Indian Ridge abyssal peridotites

Li¹,

Soustelle

Zhang

et al. 2017

Geochem Geophys Geosyst

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To investigate the origin of heterogeneous water distribution in the suboceanic lithospheric mantle, we performed a detailed petrological and geochemical analysis of abyssal peridotites collected from two localities (53°E and 63.5°E) on the Southwest Indian Ridge. These serpentinized peridotites display primary olivine‐orthopyroxene‐clinopyroxene‐spinel assemblage and record equilibrium temperature of 1150–1200°C and around 1000°C for the 53°E and 63.5°E locations, respectively. The rocks were thus equilibrated in the spinel stability field prior to their exhumation to the seafloor. Our FTIR analyses show variable water contents in orthopyroxene ranging from 24 to 262 wt ppm H2O. Orthopyroxene in the 63.5°E peridotites is characterized by homogeneous and high water content (>200 ppm), whereas orthopyroxene in the 53°E peridotites displays a wider range of water contents (24–246 ppm). We first demonstrate that differences in equilibrium conditions (i.e., pressure and temperature) and mineral chemistry and serpentinization cannot explain the water content variations. Melting modeling show that a fractional melting in both garnet and spinel stability fields is needed to explain the MREE and HREE concentrations in clinopyroxene. Enrichment in LREE, high water contents, and high H2O/Ce, however, require a postmelting rehydration event such as metasomatism. Based on petrographic evidence and investigation of chemical heterogeneities at segment/dredge scale, we suggest that this event involves a metasomatic agent enriched in water and incompatible elements. We infer that the small‐scale heterogeneities in water and trace elements may result either from successive infiltration of various amounts of melt/fluids as described in the formation of oceanic core complex or from spatial heterogeneities of melt infiltration as observed in peridotite massifs.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Origins of water content variations in the suboceanic upper mantle: Insight from Southwest Indian Ridge abyssal peridotites

Li¹,

Soustelle

Zhang

et al. 2017

Geochem Geophys Geosyst

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Composition and evolution of the lithospheric mantle beneath the interior of the South China Block: insights from trace elements and water contents of peridotite xenoliths

Zhang

Zheng

et al. 2018

Contrib Mineral Petrol

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Water contents of nominally anhydrous orthopyroxenes from oceanic peridotites determined by SIMS and FTIR

et al. 2021

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This study presents new secondary ion mass spectrometry (SIMS) reference materials (RMs) for measuring water contents in nominally anhydrous orthopyroxenes from upper mantle peridotites. The enstatitic reference orthopyroxenes from spinel peridotite xenoliths have Mg#s between 0.83 and 0.86, Al2O3 ranges between 4.02 and 5.56 wt%, and Cr2O3 ranges between 0.21 and 0.69 wt%. Based on Fourier-transform infrared spectroscopy (FTIR) characterizations, the water contents of the eleven reference orthopyroxenes vary from dry to 249 ± 6 µg/g H2O. Using these reference grains, a set of orthopyroxene samples obtained from variably altered abyssal spinel peridotites from the Atlantic and Arctic Ridges as well as from the Izu-Bonin-Mariana forearc region was analyzed by SIMS and FTIR regarding their incorporation of water. The major element composition of the sample orthopyroxenes is typical of spinel peridotites from the upper mantle, characterized by Mg#s between 0.90 and 0.92, Al2O3 between 1.66 and 5.34 wt%, and Cr2O3 between 0.62 and 0.96 wt%. Water contents as measured by SIMS range from 68 ± 7 to 261 ± 11 µg/g H2O and correlate well with Al2O3 contents (r = 0.80) and Cr#s (r. = -0.89). We also describe in detail an optimized strategy, employing both SIMS and FTIR, for quantifying structural water in highly altered samples such as abyssal peridotite. This approach first analyzes individual oriented grains by polarized FTIR, which provides an overview of alteration. Subsequently, the same grain along with others of the same sample is measured using SIMS, thereby gaining information about homogeneity at the hand sample scale, which is key for understanding the geological history of these rocks.

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Water in orthopyroxene from abyssal spinel peridotites of the East Pacific Rise (ODP Leg 147: Hess Deep)

Cited by 18 publications

References 59 publications

Origins of water content variations in the suboceanic upper mantle: Insight from Southwest Indian Ridge abyssal peridotites

Origins of water content variations in the suboceanic upper mantle: Insight from Southwest Indian Ridge abyssal peridotites

Composition and evolution of the lithospheric mantle beneath the interior of the South China Block: insights from trace elements and water contents of peridotite xenoliths

Water contents of nominally anhydrous orthopyroxenes from oceanic peridotites determined by SIMS and FTIR

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