Dike emplacement on Venus and on earth

Attention is given to long linear features visible in SAR images of the surface of Venus. They are shallow graben a few kilometers across. Calculations show that dike emplacement can account for such features if the top of the dikes is a few kilometers below the surface of the planet. The dikes are often curved near their probable sources, and the magnitude of the regional stress field estimated from this curvature is about 3 MPa, or similar to that of earth. On both Venus and earth, dikes often form intersecting patterns. Two-dimensional calculations show that this behavior can occur only if the stress field changes with time. Transport of melt over distances as large as 2000 km in dikes whose width is 30 m or more occurs in some continental shields on earth and can also account for linear features on Venus that extend for comparable distances. Such transport is possible because the viscosity and thermal conductivity of both the melt and the wall rock are small.