Geology topics

N. Schmedemann

Publications and source records attributed to N. Schmedemann.

3 recordsLinked to original sources

USGS2023

The lunar cratering chronology

This chapter provides an introduction to crater-size frequency distribution (CSFD) measurements and presents a review of the work performed on dating lunar geological units using CSFDs since the last New Views of the Moon volume (2006), including various volcanic and tectonic features, as well as individual impact craters. At the end of the chapter, implications for the new CSFD age determinations for the geologic history and evolution of the Moon are discussed.

Reviews in Mineralogy and Geochemistry↗

USGS2016

Cryovolcanism on Ceres

Volcanic edifices are abundant on rocky bodies of the inner solar system. In the cold outer solar system, volcanism can occur on solid bodies with a water-ice shell, but derived cryovolcanic constructs have proved elusive. We report the discovery using Dawn Framing Camera images of a landform on dwarf planet Ceres, which we argue represents a viscous cryovolcanic dome. Parent material of the cryomagma is a mixture of secondary minerals, including salts and water ice. Absolute model ages from impact craters reveal that extrusion of the dome has occurred recently. Ceres’ evolution must have been able to sustain recent interior activity and associated surface expressions. We propose salts with low eutectic temperatures and thermal conductivities as key drivers for Ceres’ long-term internal evolution.

Science↗

USGS2016

Cratering on Ceres: Implications for its crust and evolution

Thermochemical models have predicted that Ceres, is to some extent, differentiated and should have an icy crust with few or no impact craters. We present observations by the Dawn spacecraft that reveal a heavily cratered surface, a heterogeneous crater distribution, and an apparent absence of large craters. The morphology of some impact craters is consistent with ice in the subsurface, which might have favored relaxation, yet large unrelaxed craters are also present. Numerous craters exhibit polygonal shapes, terraces, flowlike features, slumping, smooth deposits, and bright spots. Crater morphology and simple-to-complex crater transition diameters indicate that the crust of Ceres is neither purely icy nor rocky. By dating a smooth region associated with the Kerwan crater, we determined absolute model ages (AMAs) of 550 million and 720 million years, depending on the applied chronology model.

Science↗