A VIRTUAL FIELD TRIP TO VENUS'S ARTEMIS—OUR SOLAR SYSTEM'S LARGEST PLUME / SUPER-PLUME: A JOURNEY ACROSS THE CRUST AND TO THE CORE

Artemis, a circular feature on Venus, has perplexed researchers for decades. Pioneer mission data showed a topographic high surrounded by a circular trough and an ~2,400 km diameter outer rise. However recent regional to global-scale mapping indicates that this is only the center ‘seed pod’ of an expansive axisymmetric structure with an additional 5,000 km diameter trough and suites of radial dikes and concentric wrinkle ridges extending in petal-like fashion, with diameters of 12,000 and 13,000 km, respectively. The true character of Artemis can only be appreciated by projecting mappedgeologic relations on a virtual global. Geologic features preserved within Artemis‚ interior, chasma, and adjacent exterior formed as genetically related features, each evolving through time, and related to the evolution of a plume-lithosphere interaction.

The global-scale extent of Artemis would seem to suggest that the plume that formed Artemis as traditionally defined, was likely part of a larger super-plume system, adding the evolution of the 12,000 km diameter radial dike swarm affecting a broad area comprising ~25% of Venus’s surface. These dikes distributed magma over a huge area, although lava did not leak to the surface everywhere within the region, as evidenced by the surface expression (and preservation) of portions of the radial dike system. Emergent lava flows were later deformed by wrinkle ridge structures, together with other pre-existing surface deposits that formed from a wide range of eruptive centers active over a broad period of time. The formation of the wrinkle ridges across a 13,000 km diameter region, and that of the broad topographic trough (~ 5,000 km diameter), likely resulted from the decay, relaxation, and cooling of a broad, deep super-plume. The incredible size and radial nature of the dike swarm, and the concentric nature of the wrinkle ridge pattern, provide evidence of a huge axisymmetric global stress field.

In this digital poster we take viewers on a virtual field journey across Venus’s surface, with field stops at key locations within the global-scale Artemis structure; we reveal the planet’s interior from crust to core in order to examine global-scale 3D relations and interactions with lithosphere-scale features that both pre-date and post-date the formation of the Artemis plume and super-plume.