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 the Niobe Planitia Region (I‐2467), Venus

“…Topographically the NMA ranges in altitude from over 5 km above mean planetary radius (MPR) in the equatorial highland regions to around 2.5 km below MPR in the lowlands of Leda and Atalanta Planitiae within northwestern and northeastern NMA, respectively. Llorona, Niobe, and Sologon Planitiae, located north of the equatorial crustal plateaus, may form the northern part of a broad Artemis‐concentric topographic trough (Hansen & López, 2020). Akhtamar Planitia occupies southwestmost NMA, whereas Rusalka Planitia occupies the southeast corner.…”

“…Four suites of distributed lineaments (interpreted broadly herein as fractures) also occur within the planitiae: (1) a fracture suite radial to Artemis Chasma to the south; (2) a suite of NW‐tending lineaments that marks the western termination of Ganis Chasma to the east (Senske et al, 1992); (3) a suite of closely‐space NE‐trending lineaments; and (4) a suite of closely‐spaced NW‐trending lineaments. The perspective gained through the collaborative mapping of the AMA (Hansen & López, 2020) and the NMA allows us to assign the regional tectonic suites within the NMA to two groups: (a) suites related to the Artemis superstructure (Hansen & Olive, 2010) and (b) other regional suites.…”

“…Structural suites related to the Artemis superstructure include extensive areal footprints (Hansen & López, 2018, 2020; Hansen & Olive, 2010): Artemis radial fractures (ARF; 12,000 km diameter) and Artemis concentric wrinkle ridges (ACWR, 13,000 km diameter). The first suite is broadly defined to include fractures, graben, dikes, lineaments, pit chains, and stoping troughs and describes a pattern radial to Artemis Chasma.…”

“…The only fracture zone in the NMA is associated with the northwestern termination of Ganis Chasma, contrary to the AMA where fracture zones define an extensive tectonic domain (Hansen & López, 2020). The part of Ganis Chasma expressed in the NMA lacks the topographic expression and fracture density that characterize the chasma closer to Atla Regio from which it radiates.…”

“…In this work we present a geologic map of the 1:10M Niobe Planitia Map Area (I‐2467; 0°N–57°N/60°E–180°E). This map is part of a collaborative mapping project that includes the companion Aphrodite Map Area (AMA, I‐2476), the object of a separate contribution (Hansen & López, 2020). Together, both maps cover >25% of Venus.…”