Late Amazonian-aged volcanic cones of explosive origin in Ceraunius fossae, Tharsis, Mars

Pieterek, Bartosz and Jones, Thomas and Ogbuagu, Chiedozie (2025) Late Amazonian-aged volcanic cones of explosive origin in Ceraunius fossae, Tharsis, Mars. Icarus: 116870. ISSN 0019-1035 (In Press)

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Abstract

Detailed volcanological studies continue to enhance our understanding of Martian eruptive styles and their associated volcanic products. Growing evidence points to the involvement of mildly explosive eruptions as one of the eruption styles that contributed to the formation of distributed volcanic edifices in the volcanic province, Tharsis. This highlights a complex and dynamic eruptive evolution that occurred during the late Amazonian volcanism. Therefore, here, we report on the presence of small-scale, conical-shaped volcanic edifices located at the edge of Ceraunius Fossae in Tharsis. The association of the N-S aligned cones with a rough-surfaced lava flow enabled us to constrain the minimum age of their volcanic activity at ca. 48 Ma. Although they superficially resemble Martian scoria cones, their morphometric parameters indicate that they have a distinct and separate origin. They comprise coarser pyroclastic material such as spatter, and display an accumulation of likely volcanic bombs on the cones' slopes and at their bases, observable in the high-resolution images. Combining the sizes and distribution of the mapped individual volcanic bombs with a ballistic emplacement model enables us to calculate the exit velocity and maximum height for a given bomb density at a given launch angle. This provides a means to improve our understanding of ballistic trajectories and distances over which the pyroclastic material can be transported on Mars. Moreover, we argue that the portfolio of Martian volcanic edifices is more diverse than currently recognized. The use of high-resolution remotely sensed volcanological mapping could provide critical information about volcanic products and, consequently, the magma fragmentation, which depends on the eruptivity, controlled by magma composition and volatile contents.