GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 80-2
Presentation Time: 9:00 AM-5:30 PM


COVLEY, Margaret T.1, NYPAVER, Cole1, ROGERS, KayLeigh A.1, LANG, Nicholas P.1 and THOMSON, Bradley James2, (1)Department of Geology, Mercyhurst University, Erie, PA 16546, (2)Center for Remote Sensing, Boston University, Boston,

Small shield volcanoes are a common type of edifice on Venus (Guest et al., 1992). Given their abundance, they likely play a significant role in the volcanic resurfacing of the planet. Here, we help constrain their role in resurfacing Venus by identifying their areal extent in the Mahuea Tholus quadrangle (V-49). We used Magellan radar images with a resolution of ~100 m/pxl in ArcGIS 10.3 to map small volcanic edifices in the quadrangle. We differentiate between four types: shields, flats, cones, and domes. Shields are identified by a change in backscatter, shallow slope, and a diameter ≤ 20 km. Flats are identified as circular edifies with little topographic expression, diameter of ≤ 20 km, and contrasting radar dark/bright backscatter. Cones are identified by radar brightness, steep slope, and a diameter of ≤ 15 km. Domes are identified by their very circular form, flat tops, and diameter of 20-30km. In V-49, a total of 637 small shield volcanoes are present. Of that 637, 277 are shields (~43%), 209 are cones (~33%), 149 are flats (~23%), and 2 are domes (<<1%). The four types of shields show a range of average diameters; domes: ~36 km (Standard Deviation [SD] of ~0.5 km), flats: ~11km (SD of ~4 km), shields: ~4 km (SD of ~2 km), and cones: ~3 km (SD of ~1 km). The areas of highest density of volcanic edifices (7 to 9 x 10¯⁴ shields/km²) are found in the NW (near 158° E, 30° S) and SW (near 162° E, 49° S). These two sites are associated with Puaulinka crater and Nortia Tesserae. The lowest density of volcanic edifices (0 - 2 x 10¯⁴ shields/km²) can be found in the central area of the quadrangle (near 162° E, 37° S) where shield occurrences are associated with Mahuea Tholus and Urd Tesserae. Shields in V-49 often occur in tight clusters known as shield fields (Crumpler et al., 1997). There are four shield fields identified in the quadrangle located at the following coordinates: (158° E, 30° S) (154° E, 48° S) (161° E, 49° S) (171° E, 39° S). Small volcanic edifices resurfaced ~25,000 km² (.38%) of the 6,500,000 km² quadrangle. Our results suggest that small shields have not played a significant role in large-scale volcanic resurfacing of V-49; instead, volcanic resurfacing here may be related to larger sources (e.g., Diana-Dali and associated features).