Southern chryse planitia on mars as a potential landing site: investigation of hypothesized sedimentary volcanism

Introduction: Future Mars exploration programs focus on detection of life or traces of life [1, 2, 3]. Asides from the question of if life ever existed on Mars, the detection of extant life or traces of past life presents a great challenge for the scientific and technological communities involved in those exploration programs. Sedimentary volcanism (also termed as mud volcanism on Earth where hydrocarbon is frequently associated) if ever operated on Mars would be a potentially interesting target for such investigation by future landing missions as it would allow us to understand volatile and sediment migration in the crust and the potential for astrobiology [e.g., 5, 6, 7, 8]. This is because mud intrusion and extrusion on Earth are well-known phenomena causing an ascent of fluidrich, fine-grained sediments within a lithologic succession [4] and providing a suitable environment for the wide range of microbial life. Topographic features interpreted to be sedimentary volcanoes (SVs) (or mud volcanoes) occur at various locations in the northern plains of Mars, including Isidis Planitia, Utopia Planitia, the Utopia/Isidis overlap, Acidalia Planitia, Arabia Terra, and Chryse Planitia. None of them has been fully confirmed to be SVs but improved spacecraft data provide further support for the purported SVs in some areas. The edifices’ formation ages are equal or postdate the surface ages of the northern plains that are post-Noachian, but their more precise ages are not determined due to their small sizes. Here, we discuss rationale for in-situ investigation of purported sedimentary volcanism in southern Chryse Planitia. The geological context of southern Chryse Planitia: Chryse Planitia is a >1600-km wide circular plains region occupying a basin of probable impact origin. It is part of the northern plains and is located at the dichotomy boundary. The basin has been a depo center for sediment of diverse sources (a thick accumulation of fluvial, marine, aeolian, and glacial sediments). A large quantity of sediment was transported in via circum-Chryse outflow channels [e.g., 9]. Paleo-oceans have been hypothesized to have filled the basin with variable sea levels [e.g., 10] and tsunami may have occurred multiple times due to impact into the oceans [e.g., 11]. The plains’ surface records evidence for compressional tectonics in the form of widespread wrinkle ridges. Morphological features hypothesized to be SVs occur extensively in southern Chryse Planitia, and they are particularly concentrated in the plains beyond the mouths of large outflow channels, Ares, Tiu and Simud [12, 13, 14] (Fig. 1). These features exhibit a wide variety of morphological types, from cones, steep-sided domes, pie-like to flow-like features, and their sizes range from hundreds of m to km in basal diameter and up to hundreds of m in height (Fig. 2). If they are indeed SVs, it was proposed that their formation might be linked to the high sedimentation rates in the basin.