Mapping topography of venus for testing crustal plateau formation models

Abstract

This study contributes to new mapping data of the selected tessera highlands and the comparison of mapping with Magellan Left Looking SAR image and Right Looking SAR image in Venus. Selected tessera highlands include Western Ovda Regio, Ovda Regio, Thetis Regio, Tellus Regio, and Alpha Regio. The formation of crustal plateaus on Venus are yet to be known. Decent number of origin hypothesis was proposed by different research. The key to formation of crustal plateaus would be an oldest terrain on Venus, namely tessera highlands in or originated from crustal plateaus. Each formation hypothesis provides predictions in internal deformation, marginal deformation, shape of crustal plateaus, and the boundary relationship with the surrounding units, especially the tessera-to-plain transition. Five formation hypotheses including downwelling model, upwelling model, pulsating continent model, heat-pipe model, and lava pond and bolide impact model have been tested out in different crustal plateaus. A system of structural mapping and stratigraphic mapping should be executed in order to provide enough mapping results from all tessera highlands in order to testify the proposed formation models. Among the tested highlands, Ishtar Terra is the most well studied and testified by other research, so it was excluded in this study. Magellen SAR image in both looking direction with resolution of 75 meters/pixel and the stereo topographic data are used. A schematic process of mapping all tessera highlands margins is done with categorizing the tessera margins into embayment, linear and mixed type. Zoomed in areas are also selected for detailed mapping comparison between mapping with Left and Right looking SAR image. Left Looking SAR image has a very good coverage and provide a bigger contrast in between bright units representing deformations and structures, and dark lava plain units which suits stratigraphic mapping better. Right Looking SAR image with a darker shade in general compared to Left Looking image providing better view in identifying individual lineaments, is more suitable in structural mapping where individual lines matter. However, the coverage of Right Looking SAR image has a poor coverage due to data transfer lost from the mission. More mapping work must be done in detail for any conclusion in testifying the hypothesis.