Transport, survival and modification of xenoliths and xenocrysts from source to surface

Sasse, David; Jones, Thomas J.; Russell, James K.

doi:10.1016/j.epsl.2020.116499

Cited by 6 publications

(2 citation statements)

References 51 publications

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“…These processes can be ordered by depth within the volcanic system. During vigorous, rapid (>4 m s −1 ), flow attending subsurface transport, mantle-derived olivine crystals (and other minerals) are reshaped by chemical processes and are abraded by particle–particle interactions to form rounded, ellipsoidal shapes 49 , 50 , 52 – 55 (Fig. 4a ).…”

Section: Discussionmentioning

confidence: 99%

Melt stripping and agglutination of pyroclasts during the explosive eruption of low viscosity magmas

et al. 2022

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Volcanism on Earth and on other planets and satellites is dominated by the eruption of low viscosity magmas. During explosive eruption, high melt temperatures and the inherent low viscosity of the fluidal pyroclasts allow for substantial post-fragmentation modification during transport obscuring the record of primary, magmatic fragmentation processes. Here, we show these syn-eruption modifications, in the form of melt stripping and agglutination, to be advantageous for providing fundamental insights into lava fountain and jet dynamics, including eruption velocities, grain size distributions and melt physical properties. We show how enigmatic, complex pyroclasts termed pelletal lapilli form by a two-stage process operating above the magmatic fragmentation surface. Melt stripping from pyroclast surfaces creates a spray of fine melt droplets whilst sustained transport in the fountain allows for agglutination and droplet scavenging, thereby coarsening the grain size distribution. We conclude with a set of universal regime diagrams, applicable for all fluidal fountain products, that link fundamental physical processes to eruption conditions and melt physical properties.

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Section: Discussionmentioning

confidence: 99%

Melt stripping and agglutination of pyroclasts during the explosive eruption of low viscosity magmas

et al. 2022

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“…However Truong and Lunine (2021) suggested that mantle plume volcanism could bring phosphorus from the deep mantle, where it is predominantly present as phosphide, to the surface. It is well known that small fragments of material a few millimeters in diameter can be dredged from the lower mantle by volcanism and appear as xenoliths in surface rocks on Earth (Sasse et al, 2020). However this potential possibility for phosphide delivery confuses two mechanisms (Bains et al, 2022b).…”

Section: Introductionmentioning

confidence: 99%

Source of phosphine on Venus—An unsolved problem

Bains,

Seager,

Clements

et al. 2024

Front. Astron. Space Sci.

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The tentative detection of ppb levels of phosphine (PH3) in the clouds of Venus was extremely surprising, as this reduced gas was not expected to be a component of Venus’ oxidized atmosphere. Despite potential confirmation in legacy Pioneer Venus mass spectrometry data, the detection remains controversial. Here we review the potential production of phosphine by gas reactions, surface and sub-surface geochemistry, photochemistry, and other nonequilibrium processes. None of these potential phosphine production pathways is sufficient to explain the presence of phosphine in Venus atmosphere at near the observed abundance. The source of atmospheric PH3 could be unknown geo- or photochemistry, which would imply that the consensus on Venus’ chemistry is significantly incomplete. An even more extreme possibility is that a strictly aerial microbial biosphere produces PH3. The detection of phosphine adds to the complexity of chemical processes in the Venusian environment and motivates better quantitation of the gas phase chemistry of phosphorus species and in situ follow-up sampling missions to Venus.

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