Buffered and unbuffered dike emplacement on Earth and Venus - Implications for magma reservoir size, depth, and rate of magma replenishment

摘要: Models of the emplacement lateral dikes from magma chambers under constant (buffered) driving pressure conditions and declining (unbuffered) indicate that two scenarios lead to distinctly different styles dike emplacement. In unbuffered case, lengths widths laterally emplaced will be severely limited highly dependent on chamber size; this dependence suggests average length can used infer dimensions source reservoir. Probable examples Earth case are flanking rift zones shield volcanoes such as Hawaiian Kilauea East Rift Zone, in which less than a meter extend for several km central part edifice. contrast, produce have sizes very large, independent size. For relatively shallow chambers, buffered is expected graben fixed associated with eruptive fissures long, large volume lava flows. A decline supply rate loss buffering during later stages eruptions may give rise caldera formation/collapse events. Deeper not likely erupt but surface variable length. Therefore, edifices or swarms show an extremely wide variation fracture been formed conditions. On Earth, characteristics many mafic-dike suggest they were (e.g., Mackenzie swarm Canada some within Scottish Tertiary). Venus, distinctive radial fractures surrounding circular oval features size scales extending hundreds over thousand candidates