Geologic Map of Aphrodite Map Area (AMA; I‐2476), Venus

Abstract

We present a 1:10-M-scale geologic map of the Aphrodite Map Area (AMA) of Venus (0°N-57°S/60-80°E). Geologic mapping employed NASA Magellan synthetic aperture radar and altimetry data. The AMA geologic map, with detailed structural elements and geologic units covering over one eighth of Venus' surface, affords an important and unique perspective to test models of global-scale geologic processes through time. Geologic relations record a history inconsistent with global catastrophic resurfacing. The AMA displays a regional coherence of preserved geologic patterns that record three sequential geologic eras: the ancient era, the Artemis superstructure era, and the youngest fracture zone era. The ancient era and Artemis superstructure, with a footprint covering more than 25% of the surface, are recorded in the Niobe Map Area to the north. The latter two eras likely overlap in time. The fracture zone domain, part of a globally extensive province, marks the most spatially focused tectonomagmatic domain within the AMA. Impact craters are both cut by and overprint fracture zone structures. Twelve percent of AMA impact craters that occur within the fracture zone domain predate or formed during fracture zone development. This observation indicates the relative youth of the fracture zone era and is consistent with the possibility that this domain remains geologically active. The AMA records a rich geologic history of large tract of the surface of Venus and provides an important framework to formulate new working hypotheses of Venus evolution and contribute to planning future studies of the surface of planets.

Geologic Map of Aphrodite Map Area (AMA; I-2476), Venus

“…All published 1:5-M-scale USGS Venus geologic maps (Figure 2) were consulted during map construction including V35/I-2808 (Bleamaster & Hansen, 2005), V37/I-2752 (Hansen & DeShon, 2002), V46/I-2779 (Stofan & Guest, 2003), and V48/SIM 3099 (Bannister & Hansen, 2010). However, in some cases, map interpretations differ, as happens in the case of geologic mapping on Earth.…”

“…Chasmata are more widely spaced and distributed, and less well defined topographically in the southwest, as compared to Diana-Dali Chasmata. Southeastern AMA, a relatively featureless region, hosts Dsonkwa Regio marked by subdued topography (challenging its "regio" moniker), and Mahuea Tholus notable in its isolation, steep local slopes, and well-defined flow features (Moore et al, 1992).…”

“…Mahuea Tholus, southwestern AMA, forms a unique volcanic feature given its isolation from other volcanic features and fracture zones. Moore et al (1992) suggested that Mahuea Tholus flows might be highly siliceous based on the texture of its flow surfaces and terminations, and its isolated location and high topography character relative to the adjacent lowlands. Whatever the composition of Mahuea Tholus flows, distal unit fMhb is deformed by Artemis-concentric wrinkle ridges.…”