Mylitta Fluctus, Venus: Rift‐related, centralized volcanism and the emplacement of large‐volume flow units

Abstract

Mylitta Fluctus is a volcanic flow field that covers approximately 300,000 km2 in southern Lavinia Planitia. The flows are typically radar‐bright with uniform surface textures. Central channels are common. Maximum flow lengths range from 400 to 1000 km; flow widths range 30–100 km in the medial and distal portions of the flow field. The total volume of the flow field, based on estimates of flow thickness, is of the order of 2 × 104 km3. The flow field is composed of six smaller flow fields that are interpreted to represent major eruption events in the evolution of Mylitta. An asymmetric shield volcano 200 km in radius with a central caldera has been identified as the single major source. It is located along a possible rift zone at the northern edge of Lada Terra. No evidence for fissure‐fed eruptions is observed, although eruptions may have occurred along fissures within the rift before the main vent centralized. Mylitta is similar in scale to many terrestrial flood basalt provinces, although it is lower in total estimated volume and is distinguished by the presence of a central source edifice. The origin of Mylitta is proposed to be linked to regional extension and possible hotspot activity in a manner similar to that suggested for the origin of terrestrial flood basalts. The lower apparent volume of Mylitta relative to terrestrial flood basalts suggests that the amount of material upwelling from the mantle may have been lower in this case or that the formation of the flow field has not yet finished. Detailed studies of the morphology and distribution of flow fields similar to Mylitta should yield insight into the variation and evolution of hotspot‐related volcanism and the formation of possible flood basalts on Venus.