Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

The origin of Venusian steep-sided domes

Nathan Thomas Bridges, University of Massachusetts Amherst

Abstract

Steep-sided domes are interesting and enigmatic landforms on Venus. Despite superficially resembling silicic lava domes on Earth, they are much larger. Their compositions and eruptive styles have important implications for Venusian geology. Geologic mapping shows that the domes formed shortly after global resurfacing. The oldest domes on Venus are more tectonized and embayed than younger domes. Accurate heights derived from raw Magellan altimetry and stereo measurements show that many previous investigations have underestimated dome heights and that the oldest domes are also the shortest. An investigation of 390 seamounts off the coast of Hawaii finds that 55% possess steep-sides and flat-tops, similar to the Venusian domes. The seamounts and domes also have comparable ancillary attributes, such as summit pits and mounds, truncated edges, merged boundaries with adjacent seamounts/domes, landslides, and superposed graben. Of all the possible terrestrial analogs, seamounts are most like the domes. Models of lava flow properties predict that basalts on Venus and the seafloor have similar rheologies and gross shapes. Taken together, these results support the hypothesis that Venusian steep-sided domes are made of basalt and formed shortly after global resurfacing atop a relatively thin lithosphere.

Subject Area

Geology

Recommended Citation

Bridges, Nathan Thomas, "The origin of Venusian steep-sided domes" (1997). Doctoral Dissertations Available from Proquest. AAI9737508.
https://scholarworks.umass.edu/dissertations/AAI9737508

Share

COinS