Paleohydrology on Mars constrained by mass balance and mineralogy of pre-Amazonian sodium chloride lakes
| Autor: | Daswani, Mohit Melwani, Kite, Edwin S. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Journal of Geophysical Research: Planets, 122 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1002/2017JE005319 |
| Popis: | 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. Comment: 46 pages, 10 figures, 3 tables |
| Databáze: | arXiv |
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