Effects of lateral resolution on the identification of volcanotectonic provinces on Earth and Venus

Abstract

Topographic data sets for the continental United States and the North Pacific have been degraded and displayed in the same manner as the Pioneer‐Venus altimeter data for Venus. Results for the U.S. data show that the Cordillera orogenic zone would be seen as a broad swell with a height of 2 km and a wavelength of about 2500 km. Individual structural elements within the Cordillera are reduced to mild (height about 700 m; wavelength about 500 km) swells that are superimposed on the broad Cordillera rise. For the Pacific data, the Hawaiian swell, the E‐W trending fractures in the Eastern Pacific, the increase in depth away from the East Pacific Rise, and most trenches, can still be discerned. The Venusian data do not show the integrated trench, transform, and ridge system evident in the degraded Pacific data. These features would be discernible in the degraded Pacific data even after correcting depths for: (a) the higher surface temperature on Venus, and (b) the lack of loading due to ocean water. Thus, a plate tectonic regime similar to Earth's does not appear to currently exist on Venus. Unfortunately, as shown by the degraded Cordillera data, the PV altimetry data are not of sufficient quality to discern whether or not the highlands of Venus preserve evidence for orogenic events related to an ancient epoch of plate tectonics.