Volcanology and inflation structures of an extensive basaltic lava flow in the Payenia Volcanic Province, extra-Andean back arc of Argentina

Abstract

The El Puesto lava flow is located in the Payenia Volcanic Province (central-western Argentina), has a length of 70 km and is Middle Pleistocene in age (0.200±0.027 Ma). The flow shows a P-type pahoehoe structure and exhibits several inflation structures, mainly tumuli and also inflation ridges and lava rises. Lava rise pits and radial or annular clefts are common features associated with inflation structures. The gentle slope on which the flow moved (≈0.5°) allowed the lateral coalescence of lobes at the flow front and the development of an external rigid crust that insulated the liquid core. Lava tunnels are frequent and the lava tunnel named “Cueva de Halada” which is located at its medium portion is the best example of a drainage master tube which formed from the cooling of the crust around a stable inflated flow. Tumuli alignments and long inflation ridges reveal the existence of larger tunnels within the flow. Inflation structures may occur in high concentration belts that converge on a single main belt which is assigned to an anastomosed network of internal flow pathways within the main lava body. The development of inflation structures and lava tunnels require low to moderate effusion rates. An average lava supply rate of 1.8x10-4 m3/s and an inflation time of about 15 days were estimated for an average tumulus of this flow. A high and sustained supply of low viscosity lava (η’=1550 - 483 Pa s) was inferred that initially generated a sheet flow of great areal extension. The reduction in effusion rates could then allowed the development of tunnels that carried lava to the distal fronts, generating localized inflation phenomena throughout the lava flow.

Ring‐Moat Dome Structures (RMDSs) in the Lunar Maria: Statistical, Compositional, and Morphological Characterization and Assessment of Theories of Origin

“…Our compositional mapping results show that RMDSs preferentially form in more Ti‐rich magmas, which have lower values of viscosity compared with low‐Ti basalts (Williams et al, 2000). This is consistent with terrestrial observations that the inflation process tends to occur in low‐viscosity basaltic eruptions (e.g., Bernardi et al, 2019; Rader et al, 2017). The lower gravity on the Moon and the absence of an atmosphere result in a propensity of lava flows to retard lateral spreading and produce less resistance to upward inflation, causing considerably greater thicknesses and widths of lunar lava flows than is common on Earth (Keszthelyi et al, 2000; Keszthelyi & Self, 1998).…”

Mantle Xenoliths from Huanul Volcano (Central-West Argentina): A Poorly Depleted Mantle Source under Southern Payenia

“…Payenia is located between 460 to 540 km east of the Chile Trench and comprises the largest Neogene-Quaternary volcanic province of South America. The volcanism is manifested as numerous basaltic cinder cones, few andesitic-dacitic composite volcanoes, and lava flows, several of which are extraordinarily long, up to 180 km (e.g., [25,[35][36][37]).…”

“…El Corcovo consists of alkaline basalts with a K-Ar age of 0.84 ± 0.05 Ma [40]. Detailed information on the Huanul volcanism and eruption types are reported by [28,35,41,42]. Here, we summarize the characteristics of the Huanul lava flow from which our xenoliths were collected.…”