Paleohydrology on Mars constrained by mass balance and mineralogy of pre-Amazonian sodium chloride lakes

Mohit Melwani Daswani, Edwin S. Kite
(Submitted on 27 Sep 2017)

Chloride-bearing deposits on Mars record high-elevation lakes during the waning stages of Mars’ wet era (mid-Noachian to late Hesperian). The water source pathways, seasonality, salinity, depth, lifetime, and paleoclimatic drivers of these widespread lakes are all unknown. Here we combine reaction-transport modeling, orbital spectroscopy, and new volume estimates from high-resolution digital terrain models, in order to constrain the hydrologic boundary conditions for forming the chlorides. Considering a T = 0 degrees C system, we find: (1) individual lakes were >100 m deep and lasted decades or longer; (2) if volcanic degassing was the source of chlorine, then the water-to-rock ratio or the total water volume were probably low, consistent with brief excursions above the melting point and/or arid climate; (3) if the chlorine source was igneous chlorapatite, then Cl-leaching events would require a (cumulative) time of >10 yr at the melting point; (4) Cl masses, divided by catchment area, give column densities 0.1 – 50 kg Cl/m^2, and these column densities bracket the expected chlorapatite-Cl content for a seasonally-warm active layer. Deep groundwater was not required. Taken together, our results are consistent with Mars having a usually cold, horizontally segregated hydrosphere by the time chlorides formed.

Comments:    46 pages, 10 figures, 3 tables
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Journal reference:    Journal of Geophysical Research: Planets, 122 (2017)
DOI:    10.1002/2017JE005319
Cite as:    arXiv:1709.09687 [astro-ph.EP]     (or arXiv:1709.09687v1 [astro-ph.EP] for this version)
Submission history
From: Mohit Melwani Daswani 
[v1] Wed, 27 Sep 2017 18:19:05 GMT (2100kb)
https://arxiv.org/abs/1709.09687