CONJUGATE SHEAR FRACTURES ON VENUS

Conjugate shear fractures (CSF) represent an important manifestation of stress and strain. The acute bisector of the fracture pairs records the orientation of not only the maximum compressive principal stress but also that of the maximum shortening strain. Identification of these fracture systems, therefore, provides an excellent data set for interpreting the stress and strain history of a region. Previous workers have identified CSF on Venus, but neither were these studied systematically, nor was their significance related to the various tectonic environments in particular. Thus, a fuller study in different tectonic environments was appropriate. The main source of data was provided by radar images from NASA’s Magellan satellite imaging survey of Venus. Six localities comprising five different tectonic environments on Venus were investigated. The CSF were identified on planitia, tessera, caldera, nova and corona, separately. In each locality, the geological structures were described and interpreted on local and regional scales. From the strain relations it was possible to deduce the plausible stress patterns that caused the structures to form. Thus, the overall structure and dynamics of each tectonic region studied could be analyzed and interpreted in detail.