Geologic/geomorphic map of the Galindo Quadrangle (V-40), Venus

The Galindo quadrangle (V-40; centered at lat 12.5 degrees S., long 255 degrees) was geologically mapped at 1:5,000,000 scale under the Venus Data Analysis and Venus Geologic Mapping Programs as part of a project focused on the study of venusian geologic terrains containing assemblages of coronae, arachnoids, and novae; these are enigmatic circular features perhaps related to hot-spot volcanism. Mapping of the quadrangle indicates most coronae are related to extension zones, and some aligned coronae and corona-like features show systematic variations in age. Standard photogeologic techniques were used to map the geology on the synthetic aperture radar (SAR) backscatter mosaic of V-40, which was generated by the radar image data base gathered by the Magellan spacecraft, launched May 4, 1989. Ninety percent of the coverage of the Galindo quadrangle consists of left-looking radar images generated during mission cycle 1 (cycle 2 images cover a narrow swath across the bottom of the quadrangle). The incidence angles of the cycle 1 data within the map area vary from 35.5 degrees (at lat 25 degrees S.) to 44.9 degrees (at lat 0 degrees; Plaut, 1993). Geologic mapping of the quadrangle was assisted by the altimetry, root mean square (rms) slope, emissivity, and reflectivity datasets (fig. 1). The topography of coronae and other features was determined by stereoscope examination of synthetic parallax stereo images (Batson and others, 1978). Understanding of the morphology and history of deformation was enhanced by examination of three-dimensional perspective views of geologically significant features (Soderblom and others, 1993; Chapman and others, 1994).