Caldera Collapse and Volcanic Resurfacing in Arabia Terra Provide Hints of Vast Under‐Recognized Early Martian Volcanism. Issue 15 (3rd August 2021)

• Record Type: Journal Article
• Authors: Chu, Yin Yau Yoyo; Michalski, Joseph R.; Wright, Shawn P.; Webb, A. Alexander G.
• Is Part Of: Geophysical research letters. Volume 48:Issue 15(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-03
• Subjects: Mars -- volcanism -- pyroclastic -- caldera -- collapse; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL093118
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Arabia Terra is an ancient, geologically complex region of Mars. It is not typically described as volcanic because it lacks prominent, easily recognizable shield volcanoes. However, Arabia Terra contains flood lavas and widespread layered materials that might represent airfall pyroclastics from unknown sources. Here we explore the geology of some complex topographic depressions in Arabia Terra previously hypothesized to represent collapse features termed "plains style caldera complexes, " an enigmatic category of volcanic feature on Mars characterized by surface collapse rather than construction of topographic shields. Geomorphological observations and geologic mapping carried out here support a volcanic origin of these features, providing a possible source for volcaniclastic sediments. The identification of caldera complexes in Arabia Terra raises the questions of how they are linked to the geotectonic setting of the region and whether similar features might be much more abundant in the ancient Martian crust than is currently recognized. Plain Language Summary: The most recognizable volcanoes on Mars correspond to large topographic shields, similar to Hawaiian volcanoes. These are constructional features built by layer upon layer of lava, with a summit caldera. It is possible that Mars contains many other volcanoes that are less recognizable, however, because they consist only of the caldera complex without the topographic rise built by lava. These calderas could signify much more explosive volcanism or collapse due to migration of magma in the subsurface, or both. In this work, we describe more identifications of plains style caldera complexes, which are collapsed calderas without the easily recognizable shield topography. We describe the geology of these calderas in the Arabia Terra region, their possible links to tectonic setting there, and the possibility that similar features are much more common on Mars than is currently understood. Key Points: Collapsed calderas are recognized in eastern Arabia Terra Ancient Martian crust may have far more collapsed calderas than commonly recognized Plains style caldera complexes could be a source of huge volumes of volcaniclastic materials on Mars