LAUSR

Abstract Endogenic and exogenic models have been developed over the past 25 years to explain the development of extensive, pervasive, high aspect ratio troughs and graben-like structures (“ribbons”) and short- to long-wavelength folds in tessera terrains, commonly associated with crustal plateaus on Venus. Many of the models are complex, and appear to be both internally contradictory and inconsistent with well-established geological principles. They are based on what amount to assumptions regarding (i) the secular evolution of crustal thickness, (ii) crustal mechanical homogeneity and isotropy, (iii) the mechanics of ribbon formation, and (iv) the relative timing of ribbons in the structural geological sequence of tessera terrains. On the basis of both theoretical and observational considerations, this contribution will suggest that coupling the formation of tessera ribbons to the emplacement of dyke swarms relatively late in the structural development of tessera terrains may provide a resolution for the apparent inconsistencies in those published models.