Ridge belt tectonics of Ganiki Planitia on Venus

Abstract

The main major ridge belts of Ganiki Planitia on Venus (Laftma, Ahsonnutli and Pandrosos Dorsa) are part of the fan-shaped ridge belt complex along the 200 ° parallel of longitude. These ridge belts with evidence of crustal shortening support the idea of a large-scale E-W compression. The ridge belt patterns indicate a N-S shear component. These forces are explained by a triangular planitia area which compressed by surrounding terrains. The crustal shortening and ridge belt formation indicates compressional plate movement stresses in the uppermost lithosphere.Three sizes of ridge belt structure are to be found within Ganiki Planitia. (1) The ridge belt spacing of 200-400 km can be used to estimate the depth of the major uppermost homogeneous layer of Venus. There are numerous volcanic coronae, paterae and montes located along the main ridge belts or at their junctions. (2) Mid-size ridge groups or subbelts are to be found within the major ridge belts. These are formed by more local responses to tectonic stresses in the stratified uppermost crust. A wavelength of 40-70 km can be seen as a result of bending of the crustal strata and may relate to its thickness. (3) Small individual ridges are connected with most local stresses, defining places where the surface layers broke along the crests of large ridge belts or mid-scale subbelts. Radial and concentric mare ridge-like structures around eoronae indicate that corona formation was effective at a sufficiently close vicinity to fault the surface.

Poludnista Dorsa, Venus: History and context of a deformation belt

“…Oya Dorsa (155°E, 20°N) (area 2 in Figure 2) lies within eastern Llorona Planitia and forms the southernmost extension of the Vedma Dorsa system of deformation belts that extends to 58°N [ Raitala and Kauhanen , 1991]. Oya Dorsa contains a 50‐km‐wide, 500‐km‐long pervasively deformed core, embedded within a broader, 1‐km‐high warp.…”

Mapping radiating graben-fissure systems and pit crater chains on Venus

“…The majority of work completed in Ganiki Planitia is fairly recent including the publication of a geological map by Grosfils et al (2011). Older material, notably Raitala and Kauhanen (1991), examined the tectonics of the ridge belts located in Ganiki Planitia. Finally, the radiating graben-fissure systems in Ulfrun Regio were thoroughly studied by Studd et al (2011).…”