Search Results

Search Constraints

Start Over
Filtering by: Keyword Moderately volatile elements Remove constraint Keyword: Moderately volatile elements

Search Results

  • Data of the paper "Cooling history and Evolution Dynamics of Green Glass Beads during Lunar Fire-Fountain Eruptions: Insights from Na, K and Cu Distributions"

    work
    Creator:
    Su, Xue, Zhang, Youxue, Liu, Yang, and Holder, Robert M.
    Description:
    Volcanic glass beads on the Moon have traditionally been thought to only record volatile loss during pyroclastic eruptions. However, recent discoveries have shown that lunar orange glass beads, representing primitive high-Ti basalts, experienced both outgassing and in-gassing of volatile elements such as Na, K, Cu, and S. In this work, we examine lunar green glass beads from sample 15421 and 15366, representing primitive very-low-Ti basalts, for the distribution of Na, K and Cu using EMP analyses and LA-ICP-MS mapping. It is found that all studied lunar green beads show increased Na, K and Cu concentrations near bead surfaces, indicative of in-gassing. A quantitative model is developed to simulate the concentration evolution of Na and Cu in individual green glass beads during eruption and cooling. The presence of similar in-gassing diffusion profiles of volatile elements in beads from different eruptions indicates a common behavior of lunar volcanic gas. In addition to volatile in-gassing, LA-ICP-MS mapping of Na and K in one green bead from sample 15366 shows features suggesting collision of melt droplets during the fire-fountain eruption, revealing more details in the dynamic aspects of lunar fire-fountain eruptions. Compared to orange glass beads, the varying boundary conditions of green glass beads during formation may suggest that their eruption plume evolved and dissipated more rapidly, potentially linked to changes in the global lunar atmosphere.
    Keyword:
    Moon, Lunar green glass beads, Diffusion, Outgassing and in-gassing, Moderately volatile elements, Cooling time scales, and Lunar pyroclastic beads
    Discipline:
    Science

  • Data of the paper "Outgassing and In-gassing of Na and Cu in Lunar 74220 Orange Glass Beads"

    work
    Creator:
    Su, Xue, Zhang, Youxue, Liu, Yang, and Holder, Robert M.
    Description:
    It is commonly thought that volcanic glass only records volatile loss during the eruptions in the Moon. However, our recent work shows that Na, K and Cu (moderately volatile elements) in lunar 74220 orange glass beads are enriched near the bead surfaces and depleted in the bead interiors, forming an overall “U-shaped” profile. The “U-shaped” profile means that rather than being “lost” into space, Na, K and Cu were “gained” into the volcanic glass during the eruption, which is contrary to the “volatile loss” story. Three different instruments (EMP, SIMS and LA-ICP-MS) were used to verify the discovery. We propose that such U-shaped Na, K and Cu profiles were formed by initial outgassing and subsequent in-gassing of Na, K and Cu when the beads were flying from the vent onto the surface through the cooling volcanic gas plume. Hence, in-gassing and the formation of surface coatings are two processes that are genetically linked during the pyroclastic eruption and evolution of the gas cloud. To quantify the processes that formed the U-shaped profiles, we developed a diffusion and surface-equilibrium model using available literature data on Na and Cu diffusivity in basaltic melts. The model reproduced U-shaped Na and Cu concentration profiles with outgassing at high temperature and subsequent in-gassing as beads cooled. By fitting the measured Na and Cu profiles, we found that the cooling time scales of individual orange glass beads range from 48 to 179 s. This is the first time that both outgassing and in-gassing were modeled and the cooling time scales of individual 74220 volcanic orange glass beads were estimated. The discovery of the U-shaped profiles of moderately volatile elements inside volcanic beads provides significant constraints on partial pressures of relevant volcanic gas species in the eruption plume.
    Keyword:
    Moon, Volcanic orange glass beads, Moderately volatile elements, Outgassing and in-gassing, and Cooling time scales
    Citation to related publication:
    Su, X., Zhang, Y., Liu, Y. and Holder, R.M. (2023) Outgassing and in-gassing of Na, K and Cu in lunar 74220 orange glass beads. Earth and Planetary Science Letters 602.  https://doi.org/10.1016/j.epsl.2022.117924
    Discipline:
    Science