Details

Autor(en) / Beteiligte

• Williams, D.A.
• Jaumann, R.
• McSween, H.Y.
• Marchi, S.
• Schmedemann, N.
• Raymond, C.A.
• Russell, C.T.

Titel

The chronostratigraphy of protoplanet Vesta

Ist Teil von

• Icarus (New York, N.Y. 1962), 2014-12, Vol.244, p.158-165

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2014

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• •We propose a chronostratigraphic scheme and geologic timescale for Vesta.•Vesta has four periods: Pre-Veneneian, Veneneian, Rheasilvian, and Marcian.•These periods are based on major impact events.•Our proposed vestan geologic timescale is comparable to those developed for other airless terrestrial planets.•Vesta’s youngest period is not based on rayed craters, due to different space weathering. In this paper we present a time-stratigraphic scheme and geologic time scale for the protoplanet Vesta, based on global geologic mapping and other analyses of NASA Dawn spacecraft data, complemented by insights gained from laboratory studies of howardite–eucrite–diogenite (HED) meteorites and geophysical modeling. On the basis of prominent impact structures and their associated deposits, we propose a time scale for Vesta that consists of four geologic time periods: Pre-Veneneian, Veneneian, Rheasilvian, and Marcian. The Pre-Veneneian Period covers the time from the formation of Vesta up to the Veneneia impact event, from 4.6Ga to >2.1Ga (using the asteroid flux-derived chronology system) or from 4.6Ga to 3.7Ga (under the lunar-derived chronology system). The Veneneian Period covers the time span between the Veneneia and Rheasilvia impact events, from >2.1 to 1Ga (asteroid flux-derived chronology) or from 3.7 to 3.5Ga (lunar-derived chronology), respectively. The Rheasilvian Period covers the time span between the Rheasilvia and Marcia impact events, and the Marcian Period covers the time between the Marcia impact event until the present. The age of the Marcia impact is still uncertain, but our current best estimates from crater counts of the ejecta blanket suggest an age between ∼120 and 390Ma, depending upon choice of chronology system used. Regardless, the Marcia impact represents the youngest major geologic event on Vesta. Our proposed four-period geologic time scale for Vesta is, to a first order, comparable to those developed for other airless terrestrial bodies.