| Titre | Impact melting on Venus: some considerations for the nature of the cratering record |
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| Auteur | Grieve, R A F; Cintala, M J |
| Source | Icarus vol. 114, no. 1, 1995 p. 68-79, https://doi.org/10.1006/icar.1995.1044 |
| Année | 1995 |
| Séries alt. | Commission géologique du Canada, Contributions aux publications extérieures 23694 |
| Éditeur | Elsevier BV |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1006/icar.1995.1044 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Région | Venus |
| Sujets | cratères météoriques; interpretations structurelles; géologie extraterrestre |
| Illustrations | images satellitaires |
| Diffusé | 1995 03 01 |
| Résumé | (disponible en anglais seulement)
Modeling the volume of impact melt and its variation with the size of the impact event indicates that, for similar-sized final craters, venusian impacts create
about 25% more impact melt than terrestrial impacts. More significantly, venusian impacts result in approximately a factor of three more impact melt than lunar events producing equivalent-sized craters. This difference is due to the higher average
impact velocity and higher ambient temperatures on Venus, which enhance impact-melt production, combined with higher planetary gravity, which inhibits crater growth for a given impact event. The initial, higher intrinsic temperature of incorporated
clastic debris also contributes to impact melts with higher initial temperatures, lower viscosities, and longer cooling times on Venus with respect to lunar impact melts. The enhanced production of relatively hot, low-viscosity impact melts under
venusian impact conditions may account for the long exterior runout flows and also for the radar-smooth interior floors of some venusian craters. We also argue that the anomalously deep character of Cleopatra may be attributed to drainage of its
interior impact-melt pool to form the smooth deposits in the adjacent Fortuna Tessera. Increasing depth of melting with increasing cavity size, resulting in the progressive weakening of transient-cavity floor material, is offered as a possible
explanation for the replacement of uplifted central peaks by rings with increasing crater diameter. A consequence of this process is that interior rings will increase in diameter relative to the diameter of the final crater's rim crest with
increasing crater size, a trend observed on Venus and other terrestrial planets. This weakening of the target due to relatively enhanced impact-melt production in the venusian environment makes it unlikely that Orientale-style impact basins ever
formed on Venus. |
| GEOSCAN ID | 203542 |
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