A 400-km-scale strike-slip zone near the boundary of Thetis Regio, Venus

We present a structural analysis of an area of Venus’ surface centred on 3°S, 116°E. The area is dominated by a wide zone of deformation striking 050°N, distinguished from the terrain on either side of it by markedly different structural and morphological characteristics. The deformation zone contains two principal fault sets defined by form, position and orientation. Members of the first set are present along the length of the deformation zone. They are discontinuous, consistently right-stepping, and are interpreted as Riedel shears in a sinistral strike-slip regime. Members of the second fault set are interpreted as normal faults and are often seen in pairs forming extensional grabens. These faults are most prominent in the central region of the deformation zone, and coincide with a deflection in strike of both the first fault set and the boundaries of the deformation zone. A detailed kinematic analysis of all fault orientations and the boundaries of the deformation zone fit the predictions of transtensional theory, supporting the hypothesis that this sinistral strike-slip zone contains an extensional jog. This interpretation is further supported by analysis of the interaction between faults belonging to the two sets. Variation in intercept geometry, kinematic linking of the two fault sets, and rotation of fault strike between the two fault sets all strongly suggest simultaneous development of these structures, and therefore a common tectonic origin. A driving mechanism for such large-scale horizontal deformation on Venus has yet to be established.