Large‐scale volcanic activity at Maat Mons: Can this explain fluctuations in atmospheric chemistry observed by Pioneer Venus?

Abstract

Magellan (and Pioneer Venus Orbiter (PVO)) found high mountain terrains on Venus (∼2.5 km above 6051 km planetary radius) exhibit anomalously low radiothermal emissivity. This is thought to result from weathering of primary Venus rock, which at high altitudes produces a distinctive high‐dielectric‐constant mineral assemblage. Deviations from the nominal altitude‐emissivity pattern have been used as a crude chronometric tool with which to date Venusian landforms. This technique indicates Maat Mons (an unusually large shield volcano, standing 9.17 km above 6051 km planetary radius, at 2.1°N, 194.3°E) has undergone a “recent” episode of large‐scale volcanic activity; a deduction also implied morphologically. The present paper investigates whether a plinian eruption at Maat Mons could explain the enhanced concentrations of SO 2 gas in the upper atmosphere of Venus that were detected by the Pioneer Venus UV spectrometer. The results show for a minimum vent radius of 156 m, a minimum eruption temperature of 1200 K, and a magmatic volatile content of ∼5 wt%, a plinian eruption at the summit of Maat Mons can explain the anomalous concentration of SO 2 gas. This would mean Maat Mons is an active volcano.