Catastrophic resurfacing and episodic subduction on Venus

There is clear evidence that a catastrophic resurfacing event occurred on Venus in the relatively recent past. A primary data source for this resurfacing event is the spatial distribution of impact craters. In this paper, we apply the pair-correlation technique to the observed crater distribution and find that the result is identical to that for a random distribution. In order to test the sensitivity of the technique, we also apply it to the spatial distribution of coronae on Venus. For the coronae, we find substantial deviations from a random distribution. One explanation for the catastrophic resurfacing is the episodic subduction hypothesis. We model episodic subduction using a thermal boundary-layer stability analysis. We find that episodic subduction events with intervals of 500 to 700 Myr can transport only 15-25% of the radiogenic heat produced within the planet. We suggest that the remainder of the heat must be lost to the surface during a period of vigorous tectonic activity, following the subduction event but prior to the subsequent stabilization of a global lithosphere. (C) 1999 Academic Press.