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Assessing the Plausibility of Past Cryovolcanism on Umbriel Using the Wunda Impact Crater.

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Title: Assessing the Plausibility of Past Cryovolcanism on Umbriel Using the Wunda Impact Crater.
Authors: Denton, C. A.1 (AUTHOR) adeene.denton@contractor.swri.org, Scully, J. E. C.2 (AUTHOR), Castillo‐Rogez, J. C.2 (AUTHOR), Sori, M. M.3 (AUTHOR), Elder, C. M.2 (AUTHOR), Leonard, E. J.2 (AUTHOR), Cartwright, R.4 (AUTHOR), Nordheim, T. A.4 (AUTHOR), Beddingfield, C.4 (AUTHOR)
Source: Journal of Geophysical Research. Planets. Feb2026, Vol. 131 Issue 2, p1-10. 10p.
Subject Terms: *Ocean, Cryosphere, Impact craters, Natural satellites, Thermal engineering, Volcanism
Abstract: The imaged portion of Umbriel's surface is dark and cratered, suggesting limited geologic activity. However, bright deposits occupying the Wunda impact crater may be of endogenic origin, similar to proposed cryovolcanic sources for fresh bright material occupying Occator crater on Ceres. Here, we model the formation of Wunda using iSALE‐2D. Our goal is to determine whether Wunda's inferred morphology is consistent with the interior structure predicted for Umbriel and whether Wunda's interior might originate from impact‐induced cryovolcanism and/or was sourced from a subsurface ocean. We find that, if Wunda is indeed a complex crater, as coarsely resolved imagery suggests, Umbriel's ice shell may have been much thinner (≤ ${\le} $50 km) and/or warmer (≥ ${\ge} $240 K) than predicted at present or subject to significant structural/compositional differences, such as abundant volatiles. These results help assess the thermal evolution of the Uranian satellites as potential ocean worlds. Plain Language Summary: Umbriel, a moon of Uranus, appears to have an ancient and geologically inactive surface. However, its crater Wunda possesses unusual bright deposits whose origins remain unknown. If the material comes from within Umbriel, it may have originated from eruptions of either melt generated by the impact, or a subsurface ocean uplifted underneath the crater floor. Here, we try to understand whether Umbriel's predicted interior structure can facilitate the potential eruptions associated with Wunda. We find that Wunda's formation may not be compatible with the thick, cold ice shell that Umbriel likely possesses today, and that Umbriel may have possessed a potentially warmer, thinner ice shell, and thus a larger potential ocean, earlier in its history. Assessing Umbriel's potential as an ocean world places important constraints on the formation, evolution, and habitability of all the Uranian satellites. Key Points: We performed numerical simulations of the formation of Umbriel's Wunda impact crater to explore the origin of its bright depositsWunda's morphology is most compatible with a thinner and/or weaker ice shell than currently predicted, which may imply higher past heat flowWunda's formation could facilitate cryovolcanism, directly from a shallow subsurface ocean or indirectly through eruption of impact melt [ABSTRACT FROM AUTHOR]
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Abstract:The imaged portion of Umbriel's surface is dark and cratered, suggesting limited geologic activity. However, bright deposits occupying the Wunda impact crater may be of endogenic origin, similar to proposed cryovolcanic sources for fresh bright material occupying Occator crater on Ceres. Here, we model the formation of Wunda using iSALE‐2D. Our goal is to determine whether Wunda's inferred morphology is consistent with the interior structure predicted for Umbriel and whether Wunda's interior might originate from impact‐induced cryovolcanism and/or was sourced from a subsurface ocean. We find that, if Wunda is indeed a complex crater, as coarsely resolved imagery suggests, Umbriel's ice shell may have been much thinner (≤ ${\le} $50 km) and/or warmer (≥ ${\ge} $240 K) than predicted at present or subject to significant structural/compositional differences, such as abundant volatiles. These results help assess the thermal evolution of the Uranian satellites as potential ocean worlds. Plain Language Summary: Umbriel, a moon of Uranus, appears to have an ancient and geologically inactive surface. However, its crater Wunda possesses unusual bright deposits whose origins remain unknown. If the material comes from within Umbriel, it may have originated from eruptions of either melt generated by the impact, or a subsurface ocean uplifted underneath the crater floor. Here, we try to understand whether Umbriel's predicted interior structure can facilitate the potential eruptions associated with Wunda. We find that Wunda's formation may not be compatible with the thick, cold ice shell that Umbriel likely possesses today, and that Umbriel may have possessed a potentially warmer, thinner ice shell, and thus a larger potential ocean, earlier in its history. Assessing Umbriel's potential as an ocean world places important constraints on the formation, evolution, and habitability of all the Uranian satellites. Key Points: We performed numerical simulations of the formation of Umbriel's Wunda impact crater to explore the origin of its bright depositsWunda's morphology is most compatible with a thinner and/or weaker ice shell than currently predicted, which may imply higher past heat flowWunda's formation could facilitate cryovolcanism, directly from a shallow subsurface ocean or indirectly through eruption of impact melt [ABSTRACT FROM AUTHOR]
ISSN:21699097
DOI:10.1029/2025JE009282