Depositional Facies and Sequence Stratigraphy of Kodiak Butte, Western Delta of Jezero Crater, Mars

Abstract

High‐resolution 2D and 3D data remotely acquired by SuperCam's Remote Micro‐Imager and Mastcam‐Z aboard the Perseverance rover enabled us to characterize the stratigraphic architecture and sedimentary record of the Kodiak butte, an isolated remnant of the western delta fan of Jezero crater. Using these data, we build up on previous interpretations of the butte interpreted as a prograding Gilbert‐type deltaic series. We characterize three individual stratigraphic Units 0 to 2 on the eastern and northern faces of the butte. Each Unit displays the same vertical succession of prodeltaic/lacustrine bottomsets, delta slope toesets and foresets, and fluvially influenced topsets of a deltaic plain with a braided river pattern, shown by 11 individual sedimentary facies. We infer that these individual Units record the formation of three distinct deltaic mouth bars successively across time and space. For the first time on another planet than Earth, we are able to construct a precise sequence stratigraphic framework to highlight lake‐level fluctuations at the time the Kodiak butte was emplaced, during the latest stages of deltaic activity. We identify four hydrogeological cycles indicated by alternating rises and falls of the lake‐level on the order of 5–10 m. These were most probably linked to climatic events and variations controlling lake water inputs in probable relation to an astronomical control.

Architecture of Fluvial and Deltaic Deposits Exposed Along the Eastern Edge of the Western Fan of Jezero Crater, Mars

“…Compared to Miners Castle, which is bedded, and sorted, the outcrops of boulder deposits at scarps C and D are rather chaotic, structureless and poorly sorted. These scarps are comparable to those observed at the top of the Kodiak remnant butte, where sandstones are similarly truncated by poorly sorted boulder conglomerates (Caravaca et al, 2024;Mangold et al, 2021).…”

“…The topset-foreset transitions both at Moro Rock and scarp C are of ca. 2,490/ 2,500 m, thus is at a similar elevation range to that observed within Kodiak (Caravaca et al, 2024;Mangold et al, 2021). Finally, the uppermost boulder-rich beds display no bedding or sorting.…”

“…2,490/ 2,500 m at the time of deposition. This is the same elevation range as observed at Kodiak (Mangold et al, 2021, Caravaca et al, 2024. Thus, it provides a useful point of comparison from an outcrop that is part of the fan 4 km north of the Kodiak remnant butte, suggesting that these delta lobes prograded to the east almost coevally to those observed at Kodiak, which prograded to the south.…”

“…Indeed, foreset beds at the Eastern Cape are organized in two ∼80-100 m wide antiformal structures (A1 and A2 in Figure 4). Other antiformal structures, similar in scale to those observed at Eastern Cape, are observed on the front of the delta at Cape Nukshak in the outcrop informally named Whale Mountain (Figure 11b) (Gupta et al, 2022), and at Kodiak (Caravaca et al, 2024). These examples show that antiformal structures at the Eastern Cape are not unique to the eastern part of the fan.…”

“…At Moro rock, which is devoid of cobbles, fluvial sandstones (such as Ss in Figure 2c) may have been the main input of sediments rather than the coarse Miners Castle. Nevertheless, some of the foreset beds observed at Kodiak (Caravaca et al, 2024;Mangold et al, 2021) and at Franklin Cliffs (Cg in Figure 11a) display conglomeratic material that indicates a sediment source, which includes a coarse component of the fluvial input such as that observed at Miners Castle.…”