D/H ratios of the inner Solar System

Hallis, L. J.

doi:10.1098/rsta.2015.0390

Cited by 47 publications

(23 citation statements)

References 129 publications

(189 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition to the one ocean (≅1.5 × 10 21 kg) of water on Earth's surface, another several oceans' worth of hydrogen as OH and H 2 O are believed to reside in Earth's mantle including the transition zone (Bercovici & Karato, ; Genda, ; Hirschmann, ; Mottl et al, ). The average D/H ratio of this water is approximately 150 × 10 −6 (or − 37‰ in δD notation; Hallis, ). (Here following common usage, D refers to 2 H and H to 1 H; H 2 is of unspecified isotopic composition.…”

Section: Introductionmentioning

confidence: 99%

Origin of Earth's Water: Chondritic Inheritance Plus Nebular Ingassing and Storage of Hydrogen in the Core

Desch

Schaefer

et al. 2018

JGR Planets

View full text Add to dashboard Cite

Recent developments in planet formation theory and measurements of low D/H in deep mantle material support a solar nebula source for some of Earth's hydrogen. Here we present a new model for the origin of Earth's water that considers both chondritic water and nebular ingassing of hydrogen. The largest embryo that formed Earth likely had a magma ocean while the solar nebula persisted and could have ingassed nebular gases. The model considers iron hydrogenation reactions during Earth's core formation as a mechanism for both sequestering hydrogen in the core and simultaneously fractionating hydrogen isotopes. By parameterizing the isotopic fractionation factor and initial bulk D/H ratio of Earth's chondritic material, we explore the combined effects of elemental dissolution and isotopic fractionation of hydrogen in iron. By fitting to the two key constraints (three oceans' worth of water in Earth's mantle and on its surface; and D/H in the bulk silicate Earth close to 150 × 10−6), the model searches for best solutions among ~10,000 different combinations of chondritic and nebular contributions. We find that ingassing of a small amount, typically >0–0.5 oceans of nebular hydrogen, is generally demanded, supplementing seven to eight oceans from chondritic contributions. About 60% of the total hydrogen enters the core, and attendant isotopic fractionation plausibly lowers the core's D/H to ~130 × 10−6. Crystallized magma ocean material may have D/H ≈ 110 × 10−6. These modeling results readily explain the low D/H in core‐mantle boundary material and account for Earth's inventory of solar neon and helium.

show abstract

Section: Introductionmentioning

confidence: 99%

Origin of Earth's Water: Chondritic Inheritance Plus Nebular Ingassing and Storage of Hydrogen in the Core

Desch

Schaefer

et al. 2018

JGR Planets

View full text Add to dashboard Cite

show abstract

“…The second is thought to represent the primordial martian mantle with a D/H ratio of 1.99 ± 0.02 × 10 −4 , which is enriched relative to VSMOW by a factor of 1.3 6 . Analyses of hydrous phases in martian meteorites and in-situ analyses of materials on the martian surface yield a wide range of D/H values that largely sit between these two endmembers 7 , 8 , so many previous studies have implicated mixing of these reservoirs and/or terrestrial contamination to explain the observed variations in D/H ratios. However, Mars lacks unambiguous evidence of once having Earth-style plate tectonics, and in the absence of plate tectonics, the crust acts as a physicochemical barrier between the atmosphere and mantle, hence it is a critical part of constraining any mixing model between the atmosphere and mantle reservoirs.…”

mentioning

confidence: 99%

Multiple early-formed water reservoirs in the interior of Mars

et al. 2020

View full text Add to dashboard Cite

The abundance and distribution of water within Mars through time plays a fundamental role in constraining its geological evolution and habitability. The isotopic composition of martian hydrogen provides insights into the interplay between different water reservoirs on Mars. However, D/H (deuterium/hydrogen) ratios of martian rocks and of the martian atmosphere span a wide range of values. This has complicated identification of distinct water reservoirs in and on Mars within the confines of existing models that assume an isotopically homogenous mantle. Here we present D/H data collected by secondary ion mass spectrometry for two martian meteorites. These data indicate that the martian crust has been characterized by a constant D/H ratio over the last 3.9 billion years. The crust represents a reservoir with a D/H ratio that is intermediate between at least two isotopically distinct primordial water reservoirs within the martian mantle, sampled by partial melts from geochemically depleted and enriched mantle sources. From mixing calculations, we find that a subset of depleted martian basalts are consistent with isotopically light hydrogen (low D/H) in their mantle source, whereas enriched shergottites sampled a mantle source containing heavy hydrogen (high D/H). We propose that the martian mantle is chemically heterogeneous with multiple water reservoirs, indicating poor mixing within the mantle after accretion, differentiation, and its subsequent thermochemical evolution.

show abstract

“…However, exceptions occur with the recent discovery of the regolith breccia, NWA 7034 [3,4]. Martian meteorites are not only crucial for constraining the petrology of Mars but also for studying the paleoclimate history [5], Martian chronology [6], the origin of Martian water, and the habitability of Mars [7,8]. Such records are however challenging to constrain based on the convolution of information retained in meteoritic phases from the limited suite of Mars laboratory samples we have on Earth.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Isotopic Variations in the Shergottites

Wang

2020

Geosciences

View full text Add to dashboard Cite

Hydrogen isotopes in the shergottite Martian meteorites are among the most varied in Mars laboratory samples. By collating results of previous studies on major hydroxyl, deuterium, and H2O bearing phases, we provide a compendium of recent measurements in order to elucidate crustal-rock versus mantle-rock processes on Mars. We summarize recent works on volatile and δD measurements in a range of shergottite phases: from melt inclusions, apatite, merrillite, maskelynite, impact melt glass, groundmass glass, and nominal anhydrous minerals. We interpret these observations using an evidence-based approach, considering two particular scenarios: (1) water-rock crustal interactions versus (2) magmatic-based processes. We consider the implications of these measurements and the scope they have for future studies, paying particular attention to future works on H, S, and Cl isotopes in situ, shedding light on the nature of volatiles in the hydrosphere and lithosphere of Mars.

show abstract

D/H ratios of the inner Solar System

Cited by 47 publications

References 129 publications

Origin of Earth's Water: Chondritic Inheritance Plus Nebular Ingassing and Storage of Hydrogen in the Core

Origin of Earth's Water: Chondritic Inheritance Plus Nebular Ingassing and Storage of Hydrogen in the Core

Multiple early-formed water reservoirs in the interior of Mars

Hydrogen Isotopic Variations in the Shergottites

Contact Info

Product

Resources

About