North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

Abstract

The clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

Investigating the Linkage Between Spiral Trough Morphology and Cloud Coverage on the Martian North Polar Layered Deposits

“…There is also evidence for in situ erosion in the form of pits and scarps across the deposit (Howard et al, 1982;Rodriguez & Tanaka, 2011;Rodriguez et al, 2021). Rodriguez et al (2021) have theorized that with an in situ erosion model, these pits and scarps can grow and integrate overtime to form troughs, similar to some karstic systems here on Earth. While this model cannot explain many of the other surface and subsurface observations that have been made regarding the spiral troughs (see criteria outlined in Smith et al, 2013), it is possible that in situ erosion occurs when katabatic winds are strong enough to erode, but ice deposition does not occur (similar to the net erosional cyclic step model, discussed in reference to the SPLD in .…”

“…For example, insolation can also remove ice from trough walls (Howard, 2000), which depending on the relative amount of accumulation from the atmosphere and sublimation from insolation, could potentially result in more uniform wall heights and slopes on the pole-facing and equator-facing sides of the trough. There is also evidence for in situ erosion in the form of pits and scarps across the deposit (Howard et al, 1982;Rodriguez & Tanaka, 2011;Rodriguez et al, 2021). Rodriguez et al (2021) have theorized that with an in situ erosion model, these pits and scarps can grow and integrate overtime to form troughs, similar to some karstic systems here on Earth.…”

Investigating the Linkage Between Spiral Trough Morphology and Cloud Coverage on the Martian North Polar Layered Deposits

“…There is also evidence for in-situ erosion in the form of pits and scarps across the deposit (Howard, 1982;Rodriguez & Tanaka, 2011;Rodriguez et al, 2021). Rodriguez et al (2021) have theorized that with an in-situ erosion model, these pits and scarps can grow and integrate overtime to form troughs, similar to some karstic systems here on Earth.…”

“…There is also evidence for in-situ erosion in the form of pits and scarps across the deposit (Howard, 1982;Rodriguez & Tanaka, 2011;Rodriguez et al, 2021). Rodriguez et al (2021) have theorized that with an in-situ erosion model, these pits and scarps can grow and integrate overtime to form troughs, similar to some karstic systems here on Earth. While this model cannot explain many of the other surface and subsurface observations that have been made regarding the spiral troughs (see criteria outlined in Smith et al, 2013), it is possible that in-situ erosion occurs when katabatic winds are strong enough to erode, but ice deposition does not occur (similar to the net erosional cyclic step model, discussed in reference to the SPLD in ).…”