Long-term and multi-stage ice accumulation in the martian mid-latitudes during the Amazonian

Subsurface ice in the mid-latitudes of Mars represents one of the largest present-day water ice reservoirs. While atmospheric models predict Late Amazonian (during the past hundreds of millions of years) obliquity-driven ice accumulation, its long-term variations, and the factors influencing accumulation remain unclear. Using geomorphological evidence and numerical modeling, we reveal a southwestern depositional trend within northern mid-latitudinal crater walls and floors. Detailed crater-fill deposit analyses indicate multiple glaciation stages, including an earlier, high-intensity stage followed by a later, lower-intensity stage, both exhibiting this southwestern trend (ca. 640−98 Ma). We conclude that persistent multiple-stage Amazonian glaciations were governed by atmospheric water availability and obliquity-driven climate cycles.