Catastrophic resurfacing and episodic subduction on Venus

There is clear evidence that a catastrophic resurfacing event occurred on V enus in the relatively recent past. A primary data source for this resurfac ing event is the spatial distribution of impact craters. In this paper, we apply the pair-correlation technique to the observed crater distribution an d find that the result is identical to that for a random distribution. In o rder to test the sensitivity of the technique, we also apply it to the spat ial 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 subdu ction using a thermal boundary-layer stability analysis. We find that episo dic subduction events with intervals of 500 to 700 Myr can transport only 1 5-25% of the radiogenic heat produced within the planet. We suggest that th e remainder of the heat must be lost to the surface during a period of vigo rous tectonic activity, following the subduction event but prior to the sub sequent stabilization of a global lithosphere. (C) 1999 Academic Press.