Elastic thickness estimates for coronae associated with chasmata on Venus

Abstract

In this study we investigate the relationship between the local elastic lithospheric thickness and the relative ages of coronae on Venus in an attempt to further understand corona and chasmata formation/evolution. We use Magellan gravity and topography data to estimate the elastic lithospheric thickness in the vicinity of coronae associated with chasmata. The relative timing of corona formation with respect to chasmata formation is classified using superposition relationships between fractures and flows associated with the corona, and the regional fracture sets associated with the chasmata. For the 31 coronae that we here examine (limited by low resolution of the Magellan gravity field in some regions of interest), estimates of elastic thickness appear to be related to the relative timing of corona formation. Coronae that formed after chasmata exhibit smaller values of elastic thickness (0 to 19 km), which may result from their formation on relatively warm and weak lithosphere due to lithospheric extension associated with chasmata formation. Coronae that formed prior to chasmata formation display greater elastic thickness values (0 to 56 km). These coronae are interpreted to have formed on lithosphere that was stronger (colder). However, examples of coronae with small elastic thickness (<5 km) are found in all relative timing groups. Copyright 2005 by the American Geophysical Union.