Clusters of Late Noachian- Early Hesperian large volcanic constructs across Arabia Terra and Xanthe Terra on Mars
Authors: Chu Yin Yau Yoyo , Michalski Joseph R. , Webb A. Alexander G. 
Published: March 2024

Populations of underrecognized Noachian or Early Hesperian volcanic structure associated with both explosive and effusive volcanism are present within Arabia Terra, Xanthe Terra and perhaps throughout the ancient highlands on Mars. Here we present a compilation of volcanic clusters within Arabia Terra and Xanthe Terra, as well as the significant of their correlation with vast fine-grained, layered deposits across the globe. The majority of these features can be described as &#8220;plains-style caldera complexes&#8221; (Michalski and Bleacher, 2013), that are characterised by deep crustal collapse, presence of flow deposits, potential pyroclastic materials, and more importantly, without a pronounced central edifice. Notable examples of the plains-style caldera complexes includes: Eden Patera (33.5&#176;N, 348.8&#176;E), type-locality of the plains-style caldera complexes; Siloe Patera (35.3&#176;N, 6.55&#176;E), which presents two overlapping classic piston-type caldera collapse; and Hiddekel Cavus (29.4&#176;N, 16.2&#176;E), a narrow, cone-shaped depression with extremely high depth/diameter ratio (Michalski and Bleacher, 2013; Chu et al., 2021 and Chu et al., 2023).Across Arabia Terra, vast abundances of friable and layered deposits were observed (Fassett &amp; Head, 2007; Whelley et al., 2021), and the volcanic constructs proposed in by Michalski and Bleacher (2013) are believed to be responsible of producing large amount of ash fall/ignimbrite deposits that widely distributed in the vicinity (Bro&#382; et al., 2021; Edgett &amp; Malin, 2002; Hynek et al., 2003; Platz et al., 2015; Chu et al., 2021 and Chu et al., 2023), and might also be additional potential sources of the vast ash deposition in the mid latitude regions across the globe.Similarly, a subdued cratered layered unit of potential pyroclastic materials that was widely distributed across Xanthe, Margaritifer, and Meridiani Terrae, were proposed to be volcanic in origin (Chapman and Tanaka, 2002). A variety of volcanic-related features has also been proposed within the area (Meresse et al., 2008; Luzzi et al., 2021; Weitz and Bishop, 2019; Michalski, 2021) and in our latest project, we present a spectrum of volcanic constructs within Xanthe Terra that includes degraded shield structures and irregular crustal collapse constructs that are equivalent to the &#8220;plains-style caldera complexes&#8221; at Arabia Terra, along with evidence that point towards a magmatic origin or related processes for these collapse structures. These features are characterised into three categories of depressions with near-circular to irregular shape: 1) deep cavi with much shorter diameters and extremely high depth-diameter ratio, 2) paterae/chasmata type of large depression that consists of one or multiple depressions and show evidence for extensive structural deformation, and 3) near-circular depressions with huge variation in rim height lying on top of degraded mounts/topographic high area. Together, these depressions represent period(s) of active magmatism around the southern Xanthe Terra that might also provide insights of their linkage with regional tectonic events.