Hydrogen in nominally anhydrous upper-mantle minerals concentration levels and implications
Jannick Ingrin,Henrik Skogby +1 more
TLDR
In this article, it was shown that hydrogen saturation in the upper mantle is highly unprobable and that the maximum average amount of hydrogen stored in the nominally anhydrous minerals of the upper manifold is around 600 ppm H 2 O.Abstract:
Several of the supposedly anhydrous major minerals of the upper mantle have been shown to regularly contain small amounts of hydrogen. The concentrations measured in the most important minerals obtained from mantle xenoliths are, expressed in ppm H 2 O, 100-1300 for clinopyroxene, 60-650 for orthopyroxene, 0- 140 for olivine and 1-200 for garnet. Hydrogen is normally structurally incorporated as hydroxyl ions, and in many cases the hydrogen ions seem to act as charge compensators associated with point defects, such as metal vacancies or substitution by mono- or trivalent cations. The determination of the exact amount of hydrogen stored in these nominally anhydrous upper mantle minerals is a key-step toward quantification of the water content of the mantle, as well as understanding of its internal water cycle. For instance, a concentration of 100 ppm H 2 O homogeneously distributed within the upper mantle above 410 km depth is approximately equivalent to a 100 m water layer at the Earth9s surface. However, the relatively fast kinetics of dehydrogenation with concomitant oxidation of iron within these minerals, implies that hydrogen as well as Fe 3+ concentrations in equilibrium with mantle conditions might be different from those measured from recovered xenolith samples. High-pressure experimental measurements of hydrogen solubility as a function of PH 2 O show a trend similar to the hydrogen contents of natural samples, with hydrogen saturation levels that decrease following the mineral series: diopside > enstatite > olivine > pyrope. Except pyrope, these minerals may incorporate more than 1000 ppm H 2 O. Based on recent data of water solubility, stability and partitioning, we suggest that an entire upper mantle saturated in hydrogen is highly unprobable and that the maximum average amount of hydrogen stored in the nominally anhydrous minerals of the upper mantle is around 600 ppm H 2 O. Despite the important progress achieved during the last years, our knowledge of the concentration of hydrogen stored as point defects in the mantle above 410 km is still too poorly constrained. The importance of nominally anhydrous minerals for the water budget of the upper mantle is now well established but still awaits complete quantification.read more
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Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie–Sulu orogen in China: implications for geodynamics and fluid regime
TL;DR: In this article, a fried ice cream model was proposed to explain the rapid processes of both plate subduction and exhumation, with a short residence time of the UHP slab at mantle depths.
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Melting and dissolution of subducting crust at high pressures: the key role of white mica
TL;DR: In this article, the phase rule and heterogeneous equilibrium were shown to hold for all three bulk compositions of the mid-ocean ridge basalt (MORB), a greywacke, and a pelite with excess H2O of 0.4-1.4 wt.
Book
Deformation of Earth Materials: An Introduction to the Rheology of Solid Earth
TL;DR: In this article, a comprehensive, unified treatment of the materials science of deformation as applied to solid Earth geophysics and geology is presented in a systematic way covering elastic, anelastic and viscous deformation.
Journal ArticleDOI
Storage capacity of H2O in nominally anhydrous minerals in the upper mantle
TL;DR: The storage capacity of the upper mantle is considerably greater than generally appreciated, as recent studies show that H2O uptake in olivine is ∼3 times that originally inferred by Kohlstedt et al. as mentioned in this paper.
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The Dabie–Sulu continental collision zone: A comprehensive review
TL;DR: The Dabie-Sulu Triassic orogen in central-eastern China was created by northward subduction of the Yangtze cratonal plate beneath the Sino-Korean craton.
References
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Journal ArticleDOI
Geochim. cosmochim. acta: Rubin A.E. and Wasson J. T. (1987) Chondrules, matrix and coarsegrained chondrule rims in the Allende meteorite: Origin, interrelationships and possible precursor components 51, 1923–1937
Alan E. Rubin,John T. Wasson +1 more
Journal ArticleDOI
Serpentine Stability to Mantle Depths and Subduction-Related Magmatism
Peter Ulmer,V. Trommsdorff +1 more
TL;DR: Results of high-pressure experiments on samples of hydrated mantle rocks show that the serpentine mineral antigorite is stable to ∼720�C at 2 gigapascals, to ∼690 �C at 3 gigapascalals, and to ∼620�C to 5 gigapASCals.
Journal ArticleDOI
Water in Earth's Mantle: The Role of Nominally Anhydrous Minerals
David R. Bell,George R. Rossman +1 more
TL;DR: Nominally anhydrous minerals constitute a significant reservoir for mantle hydrogen, possibly accommodating all water in the depleted mantle and providing a possible mechanism to recycle water from Earth's surface into the deep mantle.
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Solubility of water in the α, β and γ phases of (Mg,Fe)2SiO4
TL;DR: In this paper, the solubility of hydroxyl in the α, β and γ phases of (Mg,Fe)2SiO4 was investigated by hydrothermally annealing single crystals of San Carlos olivine.
Journal ArticleDOI
Correlation of O-H Stretching Frequencies and O-H O Hydrogen Bond Lengths in Minerals
TL;DR: In this article, a correlation of O-H stretching frequencies (from infrared spectroscopy) with O…O and H…O bond lengths (from structural data) of minerals was established.
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