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  • Data of the paper "Sulfur Outgassing and In-gassing in Lunar Orange Glass Beads and Implications for 33S “Anomaly” in the Moon "

    work
    Creator:
    Su, Xue, Zhang, Youxue, and Liu, Yang
    Description:
    Our recent investigations have discovered inward diffusion (in-gassing) of moderately volatile elements (MVEs; e.g., Na, K and Cu) from volcanic gas into volcanic beads/droplets. In this work, we examine the distribution of sulfur in lunar orange glass beads. Our analyses reveal that sulfur exhibits a non-uniform distribution across the beads, forming "U" or "W" shaped profiles typical of in-gassing. A model developed to assess sulfur contributions from different sources (original magmatic sulfur versus atmospheric in-gassed sulfur) in the orange beads indicates that atmospheric sulfur in-gassed during eruption contributes approximately 9–24% to the total sulfur content of an orange bead, averaging around 16%. This in-gassed sulfur is derived from the eruption plume, where atmospheric sulfur could undergo photochemical reactions induced by UV light, leading to mass independent fractionation and a distinct sulfur isotope signature. Interestingly, a recent study discovered a small mass independent isotope fractionation of sulfur in lunar orange glass beads in drive tube 74002/1 and a lack of such mass independent isotope fractionation in black glass beads in the same lunar sample. This finding contrasts with sulfur in lunar basalts, which typically exhibit mass dependent fractionation. With our work, the observed mass independent fractionation signal in sulfur isotopes of orange beads can be attributed to the in-gassing of photolytic sulfur in the optically thin part of the eruption plume where UV light can penetrate. Using the sulfur isotope data of lunar orange beads, we estimate that the Δ33S value of atmospheric sulfur is approximately −0.18‰. Our study provides new insights into the complex dynamics of volatile elements in lunar volcanic processes, highlighting the role of in-gassing in shaping sulfur isotope signatures in volcanic glass beads.
    Keyword:
    Moon, Lunar orange glass beads, Sulfur, Sulfur isotope, Diffusion, Outgassing and in-gassing, Mass independent fractionation, and Eruption plume
    Citation to related publication:
    Su, X., Zhang, Y., Liu, Y. (2024) Sulfur Outgassing and In-gassing in Lunar Orange Glass Beads and Implications for 33S “Anomaly” in the Moon. (under review)
    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