EVIDENCE FOR THE COLLAPSE AND PARTIAL BURIAL OF A SMALL CRUSTAL PLATEAU IN THE PASOM-MANA TESSERA REGION, VENUS
Evidence for progressive collapse and burial of the area is suggested by synthetic stereo data for the region. Differential vertical motion between the tessera ring and areas both inside and outside the ring is indicated by warping of grabens, warping of flows against the sides of the ring, and warping of flows over the ring. Evidence for differential vertical motion can be documented throughout the post-tessera history of the region to the very latest stages of flooding by young lava flows. Differential vertical motion is most logically explained by subsidence of the central portion of the area and surrounding plains relative to the tessera ring.
Modelling by Nunes and Phillips (2002) suggests that an uncompensated crustal plateau on Venus will collapse and develop a low center, high rims, and a low moat around the rims. The Pasom-Mana Tessera region exhibits precisely the kind of structures and history that would be consistent with collapse and partial burial of a small uncompensated crustal plateau.