The Four‐Stage Evolution of Martian Mantle Inferred From Numerical Simulation of the Magmatism‐Mantle Upwelling Feedback

Ogawa, Masaki

doi:10.1029/2021je006997

Cited by 4 publications

(2 citation statements)

References 97 publications

(215 reference statements)

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“…The melts can also decrease MIC viscosity by an order of magnitude or higher. However, a recent planetary evolution model with the magma migration and extraction showed that the incorporation of melting did not change the global‐scale upwelling structures (e.g., Ogawa, 2021). Our current study focuses on solid‐state convection and is aimed at understanding the first‐order behavior of the MIC layer after cumulate mantle overturn.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Pressure‐Dependent Viscosity on the Dynamics of the Post‐Overturn Lunar Mantle

Zhang,

Liang

et al. 2023

JGR Planets

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Mare‐basalt volcanism is concentrated on the lunar nearside. A plausible explanation for this asymmetric distribution is long‐wavelength (spherical harmonic degree‐1) mantle convection driven by upwellings of the overturned ilmenite‐bearing magma ocean cumulates (IBCs). The pattern of lunar mantle convection depends in part on the rheological properties of ilmenite. This study explores the effect of pressure‐dependent ilmenite viscosity on the instability of an overturned IBC layer initially at the core‐mantle boundary and the pattern of lunar mantle convection through three‐dimensional numerical simulations. We show that the convective patterns are sensitive to the activation volume for viscous flow. An effective activation volume of 10 cm3/mol would reduce the internal convection in the overturned IBC layer and promote the hemispherical upwelling. However, when the activation volume is too small, vigorous convection in the overturned IBC layer would inhibit heat from concentrating on one hemisphere. When the activation volume is too large, the size of the upwelling plumes is restricted, preventing a stable long‐wavelength structure in the upper mantle. Decompression melting during asymmetric upwelling would produce the localization of mare basalts on the lunar surface.

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Section: Discussionmentioning

confidence: 99%

The Effect of Pressure‐Dependent Viscosity on the Dynamics of the Post‐Overturn Lunar Mantle

Zhang,

Liang

et al. 2023

JGR Planets

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“…However, many of these models agree that mantle evolution was most dramatic in the pre‐Noachian and Noachian. For example, Ogawa ( 2021 ) proposed a four‐stage evolution of the Martian mantle, with a phase of water‐rich plume magmatism subsiding into the final stage of thermally driven mantle convection by ∼3.5 Ga. Modest magma generation and extraction since the Noachian suggests that H 2 O/Th may have remained relatively stable over the past 3.5 Ga.…”

Section: Constraints On Primary H 2 Omentioning

confidence: 99%

The History of Water in Martian Magmas From Thorium Maps

Black

Manga

Ojha

et al. 2022

Geophysical Research Letters

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Water inventories in Martian magmas are poorly constrained. Meteorite‐based estimates range widely, from 102 to >104 ppm H2O, and are likely variably influenced by degassing. Orbital measurements of H primarily reflect water cycled and stored in the regolith. Like water, Th behaves incompatibly during mantle melting, but unlike water Th is not prone to degassing and is relatively immobile during aqueous alteration at low temperature. We employ Th as a proxy for original, mantle‐derived H2O in Martian magmas. We use regional maps of Th from Mars Odyssey to assess variations in magmatic water across major volcanic provinces and through time. We infer that Hesperian and Amazonian magmas had ∼100–3,000 ppm H2O, in the lower range of previous estimates. The implied cumulative outgassing since the Hesperian, equivalent to a global H2O layer ∼1–40 m deep, agrees with Mars’ present‐day surface and near‐surface water inventory and estimates of sequestration and loss rates.

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