Geological history of the Atira Mons large shield volcano, Beta Regio, Venus

• Published in: Planetary and space science Vol. 244; p. 105879
• Main Authors: Braga, C.H.G., Antropova, E.G., Ernst, R.E., El Bilali, H., Head, J.W., Buchan, K.L.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2024
• ISSN: 0032-0633; 1873-5088
• DOI: 10.1016/j.pss.2024.105879

Atira Mons is a large (∼300,000 km2) low-relief (1.8 km) shield volcano, with individual flows extending up to ∼700 km from the central caldera. It is located about 3000 km NW from the major plume center Beta Regio. Detailed mapping of the flows (at 1:500,000 scale, 10x more detailed than previous mapping) has identified fifty-three flow units which are grouped into eleven packages. Flow units are distinguished based on radar brightness, topography, morphology, continuity, structural modification, and sources, while flow packages group flows with clear stratigraphic relationship affinity. Cross-cutting relationships indicate a complex and multi-episodic eruption history with provisional identification of six mapped stages. The most voluminous flows are concentrated in the early stages, while the younger pulses, with a few exceptions, are shorter and less voluminous. A central caldera hosts the youngest volcanism with flows breaching its eastern side. Multiple stages of caldera collapse are indicated. The volume of the volcano is estimated using various methods and yields values range from ∼47,000 to ∼270,000 km3. The larger estimates are consistent with that of the magma volume of Large Igneous Provinces (LIP) on Earth. An appropriate terrestrial analogue is the Benham Rise Oceanic LIP in the western margin of the Philippine Sea, and particularly the Apolaki Caldera, which is the world's largest known basaltic caldera with a diameter of ∼150 km. •Geological map of large Venusian shield volcano, Atira Mons at 10x finer scale.•53 flow units distinguished and grouped into 11 packages representing 6 stages.•Volume of Atira Mons as large as 270,000 km3, comparable to terrestrial LIPs.•Atira Mons contains a resurgent, asymmetric and elliptical caldera (116 km × 139 km).•Terrestrial analogue is Apolaki Caldera (150 km diam.), Benham Rise Oceanic LIP.