Geology topics

Jennifer E. C. Scully

Publications and source records attributed to Jennifer E. C. Scully.

3 recordsLinked to original sources

USGS2018

Floor-fractured craters on Ceres and implications for interior processes

Several of the impact craters on Ceres have sets of fractures on their floors. These fractures appear similar to those found within a class of lunar craters referred to as floor-fractured craters (FFCs). We have cataloged the Ceres FFCs according to the classification scheme designed for the Moon. An analysis of the depth to diameter ratio for Ceres craters shows that, like lunar FFCs, the Ceres FFCs are anomalously shallow. Large (>50 km) Ceres FFCs are most consistent with Class 1 lunar FFCs, while smaller craters on Ceres are more consistent with Class 4 lunar FFCs. This suggests that Ceres FFCs may similarly be undergoing fracturing due to the intrusion of a low-density material below the craters. While on the Moon (and Mars) the intrusive material is hypothesized to be silicate magma, cryomagmatic intrusions are more likely responsible for the formation of the Ceres FFCs. However, new models suggest that at least some of the FFC fractures may have formed due to the solid-state flow of a low-viscosity and low-density material into the crater wall.

Journal of Geophysical Research↗

USGS2017

Evidence for the interior evolution of Ceres from geologic analysis of fractures

Ceres is the largest asteroid belt object, and the Dawn spacecraft observed Ceres since 2015. Dawn observed two morphologically distinct linear features on Ceres's surface: secondary crater chains and pit chains. Pit chains provide unique insights into Ceres's interior evolution. We interpret pit chains called the Samhain Catenae as the surface expression of subsurface fractures. Using the pit chains' spacings, we estimate that the localized thickness of Ceres's fractured, outer layer is approximately ≥58 km, at least ~14 km greater than the global average. We hypothesize that extensional stresses, induced by a region of upwelling material arising from convection/diapirism, formed the Samhain Catenae. We derive characteristics for this upwelling material, which can be used as constraints in future interior modeling studies. For example, its predicted location coincides with Hanami Planum, a high-elevation region with a negative residual gravity anomaly, which may be surficial evidence for this proposed region of upwelling material.

Geophysical Research Letters↗

USGS2017

Geomorphological evidence for ground ice on dwarf planet Ceres

Five decades of observations of Ceres suggest that the dwarf planet has a composition similar to carbonaceous meteorites and may have an ice-rich outer shell protected by a silicate layer. NASA’s Dawn spacecraft has detected ubiquitous clays, carbonates and other products of aqueous alteration across the surface of Ceres, but surprisingly it has directly observed water ice in only a few areas. Here we use Dawn Framing Camera observations to analyse lobate morphologies on Ceres’ surface and we infer the presence of ice in the upper few kilometres of Ceres. We identify three distinct lobate morphologies that we interpret as surface flows: thick tongue-shaped, furrowed flows on steep slopes; thin, spatulate flows on shallow slopes; and cuspate sheeted flows that appear fluidized. The shapes and aspect ratios of these flows are different from those of dry landslides—including those on ice-poor Vesta—but are morphologically similar to ice-rich flows on other bodies, indicating the involvement of ice. Based on the geomorphology and poleward increase in prevalence of these flows, we suggest that the shallow subsurface of Ceres is comprised of mixtures of silicates and ice, and that ice is most abundant near the poles.

Nature Geoscience↗