GLOBAL DISTRIBUTION OF “UNDEFORMED” CHANNELS ON VENUS: POSSIBLE EVIDENCE FOR THEIR FORMATION THROUGH LONG-LIVED AND REPEATED PROCESSES

We have performed a global survey to identify potentially undeformed channels on Venus. 74 channels (or valles) were examined in JMars using Magellan left and right look images (~75 m/pxl) and altimetry data. Each channel was mapped to identify the source and terminus and to place it into a regional context. Longitudinal profiles were constructed for channels using Magellan altimetry data. Profiles were then examined for their overall trend to determine if they are undeformed, which is defined as one where the channel’s longitudinal profile qualitatively exhibits minimal to no long-wavelength deformation. 15 of the 74 analyzed channels (~20%) exhibit evidence of not being deformed, though this value could be an underestimate. Longitudinal profiles are predominantly convex and are mostly simple channels or sinuous rilles; multiple profiles appear to exhibit knickzones. Four channels are located along margins of highland regions; six channels are located in lowlands between Aphrodite Terra on the east and Beta, Phoebe, and Thetis on the west. Interestingly, two channels show evidence of channel migration. At 54.4° S, 170.4° E, Nahid Vallis diverges into two southeast-trending segments where the northern-most segment appears to be incised, but its longitudinal profile shows it traverses uphill; the second segment to the south is less defined than the first (possibly incised?) and appears to traverse uphill. At 55.6° S, 170.2° E the second segment breaks into a third that trends southwest; this segment is more subdued in radar images, appears to be constructional, and trends downhill. It is possible that deformation SE of Nahid Vallis occurred while the channel was active and caused the channel to migrate west. Bayara Vallis at 45.8° N, 16.3° E shows similar evidence for migration. If channels are volcanic in origin, the synchroneity of some channels with deformation suggests channels may be active for long time periods and may therefore not require high eruption rates or rapid formation. Although most channels appear to have distinct origins, some channels such as Bayara Vallis appear to have multiple sources. This suggests at least some channels may be fed at different times and/or different compositions or types of material could be involved. This work suggests channel formation is asynchronous and widespread in time.