Constraining the stratigraphic fill of Mars’ northern lowlands from buried-crater statistics: implications for resurfacing history and volatile budgets

Mars’ northern lowlands record some of the most extensive resurfacing events on the planet, yet the cumulative thickness and volume of their stratigraphic fill remain poorly constrained. This uncertainty directly affects estimates of volcanic resurfacing rates, the timing and magnitude of major emplacement phases, and the integrated volatile release potentially influencing Noachian–Hesperian environments. Here we reassess the minimum stratigraphic volume of the northern lowlands by combining crater-based reconstruction of buried topography with regional geologic constraints.

We quantify fill volumes through an approach that leverages crater size–frequency distributions and morphometric relationships calibrated on reference terrains, coupled with MOLA topography and CTX imagery to characterize present-day crater geometries and preservation states. Pristine crater shapes are reconstructed to approximate pre-burial morphologies, enabling estimation of the material volume required to bury crater interiors and to raise intercrater plains. We explore conservative end-member scenarios that explicitly bound uncertainty, including (i) present-day vs. reconstructed crater geometries and (ii) plausible intercrater-plain thickness ranges (1–2 km), consistent with independent stratigraphic and geologic considerations.

The resulting bounds indicate a substantially larger cumulative stratigraphic volume for the northern lowlands than many commonly adopted estimates, yielding ~0.8–1.7 × 10^8 km^3 of fill. When interpreted in terms of volcanic emplacement, this implies proportionally larger time-integrated volatile outgassing, with CO₂, H₂O, and SO₂ totals of order 10^21–10^20 g. These revised constraints provide a quantitative basis to (i) refine volcanic resurfacing histories of the northern plains, (ii) reassess the magnitude of volatile contributions to ancient atmospheric budgets, and (iii) improve the geological context for interpreting orbital observations and future exploration of lowland stratigraphy and its interfaces with highland terrains.