Resurfacing styles and rates on Venus: assessment of 18 venusian quadrangles

We have quantitatively assessed the resurfacing sources and styles in eighteen mapped venusian quadrangles, about 30% of the venusian surface. Each quadrangle was split into 0.5 degrees by 0.5 degrees boxes, which were then identified as corona materials, large volcano materials (> 100 km diameter), intermediate volcano materials (10-100 km), small edifice materials (< 10 km), flow materials from rifts or fractures, plains without an identifiable source, impact crater materials and highly deformed materials, or data gaps. We find that coronae resurface approximately 21%, small edifices 22% and large volcanoes about 6% of the surfaces analyzed. Plains with no identifiable source account for an average of 35% of the surface assessed. Small edifices resurface on a scale of 10-100 s of km(2); large edifices resurface areas of 10(4)-10(5) km(2). Coronae have greatly varying amounts of associated volcanism, with some coronae producing negligible flow deposits and others producing deposits of 10(4)-10(6) km(2). The areas identified as plains with no visible source occur on small scales (102 km(2)) to large scales (> 10(5) km(2)). Our results indicate that the majority of plains resurfacing by volcanism can be tied to an identifiable source, that fields of small edifices contribute more to resurfacing than we had anticipated, and that resurfacing styles do not appear to have evolved over the time period represented by the surface geology in the mapped quadrangles. All of the units that we quantified occur throughout the histories of the regions mapped. We favor plains resurfacing to have occurred over at least 100 myr, which implies terrestrially reasonable resurfacing rates. (c) 2004 Elsevier Inc. All rights reserved.