GEOLOGICAL MAPPING AND CHARACTERIZATION OF THE NW-PHOEBE VOLCANO-MAGMATIC CENTER ON VENUS

Detailed geological mapping (at 1:500,000 scale) of the area located in the eastern part of the BAT Regio, northwest of the Phoebe Regio (∼ 4°N to 1°S; ∼85° to 78°W) using Magellan SAR images has distinguished 48 volcano-tectonic units and 22 structural units. Stratigraphically, the oldest units are represented by fragments of the tesserae, densely lineated plains and other plains units. Younger units include lobate flow fields oriented in various directions (NE, E, SW) and flows associated with shield clusters. The post-tesserae evolutionary model proposed for this region distinguishes two Stages, early (I) and late (II), and explains the sequence of formation of all the geological features in terms of intraplate magmatism. Stage I consists of multiple corona structures and associated volcanism that are widely dispersed over the study area. Stage II consists of an intermediate-scale volcano with multiple lava flows radiating approximately from its center, and a field of small shield volcanoes near the summit. The units of Stage II appear to be approximately coeval and to define a distinct volcanic event covering an areal extent of ⁓250,000 km2, that we have termed the NW-Phoebe event. •Detailed geological mapping (1:500,000 scale) NW of Phoebe Regio plume center•48 volcano-tectonic & 22 structural units distinguished & divided into two Stages•Stage II defines a distinct volcanic event covering about 250,000 km2.