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High-Resolution Geologic Mapping of Urvara Crater, Ceres Discussed at LPSC

sizemore lpsc 23 crater talk

Excerpt of new geologic map of Urvara Crater on Ceres based on high-resolution image data (5-20 meters/pixel) from Dawn’s second extended mission shows nine distinct geologic units in the crater’s interior. The oldest unit, terrace material (trm, shown in teal), has a LDM(Lunar derived model) crater retention age of 180 +/- 7 million years. The youngest unit, Urvara smooth floor material (Usfm, mauve), is distinctly younger at 100 +/- 4 million years. This age difference, along with the morphological characteristics of Usfm (e.g., lobate margins), indicates that Urvara crater may be a third region of geologically recent extrusive cryovolcanic activity on CeresCredit: H.G. Sizemore, D.A. Crown, D.P. O’Brien.


PSI scientist Hanna Sizemore’s presentation at the 54th Lunar and Planetary Science Conference in The Woodlands, Texas shows new high resolution geologic mapping of Urvara crater on dwarf planet Ceres that indicates portions of the crater floor were resurfaced, likely via cryovolcanic extrusion, in the geologically recent past. The Dawn mission previously revealed two regions of recent cryovolcanic activity on Ceres, in Occator crater and at Ahuna Mons. Early mapping of Urvara crater based on Low Altitude Mapping Orbit (LAMO) Framing Camera (FC) data (35 meters/pixel) indicated that the older, more degraded Urvara region might be a third site of cryovolcanism. Co-authors on this study included David Crown, Daniel Berman, and David O’Brien of PSI, as well as Jennifer Scully (JPL), Debra Buczkowski (APL), and Alicia Neesemann (Freie Universität Berlin).

Occator and Urvara craters were imaged at resolutions as low as 5 meters/pixel at the end of Dawn’s second extended mission. High-resolution geologic mapping of Occator crater solidified the evidence of cryovolcanic activity there. High-resolution analysis of Urvara was more challenging, due to its greater age. The project team is developing a USGS Scientific Investigation Series map to test the cryovolcanic hypothesis at Urvara. The team presented the preliminary unit mapping, crater retention ages, and interpretation at LPSC. The team derived a Lunar Derived Model crater formation age of 180 +/- 6 million years and identified nine geologic units in the crater interior. The youngest of these units, Urvara floor smooth material (Ufsm), occupies most of the crater’s southern floor and was either emplaced or uniformly resurfaced 100 +/-4 million years ago. This unit is most easily interpreted as a volatile-rich deposit extruded onto the surface, effectively a “mud mare” by analogy with the Moon. Other units in the crater’s interior also exhibit smooth surfaces, indicating a long history of landscape modification by multiple processes. Some of these processes operate on long time scales and short depth scales (e.g., ice sublimation and impact gardening); some operate on short time scales and large depth scales (e.g., impact melt deposition, landslides). Because Urvara provides a third study region for cryovolcanic activity on Ceres, understanding the interplay between landscape-smoothing processes is important for delineating the history of Urvara itself, and for building a global understanding of how impacts and cryovolcanism are linked on Ceres. 

This work was supported by the NASA Discovery Data Analysis Program, grant 80NSSC20K1150.

sizemore lpsc 23 crater talk 

Above, Full Urvara crater map region showing the Dawn extended mission mosaic (XM2, >5 meter/pixel) overlaid on the earlier Low Altitude Mapping Orbit mosaic (LAMO, 35 meter/pixel). Credit: H.G. Sizemore, D.A. Crown, D.P. O’Brien.









May 7, 2023
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