On the thickness of the oxidized layer of the Martian regolith

被引:53
作者
Zent, AP [1 ]
机构
[1] NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA
关键词
D O I
10.1029/98JE01895
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
A revised model of the diffusion of H2O2 through the Martian regolith is presented, which argues that oxidant diffusion may be more efficient than previously thought. Recent models of the adsorption of H2O at Mars-like conditions indicate that it adsorbs more poorly than previously believed. H2O adsorption is a necessary proxy for peroxide adsorption; hence the adsorptive slowing of peroxide diffusion is modeled as less efficient. Because the peroxide has a finite lifetime, it has a finite extinction depth as well. The effects of regolith gardening by impacts are quantitatively estimated and combined with the effects of oxidation by atmospheric gases to produce estimates of the degree of oxidation of the Martian surface with depth. We explore the effects of different crater production populations along with variations in H2O2 extinction depths, and hydrothermal oxidation of ejects. In very select circumstances involving very early onset of oxidizing conditions during heavy bombardment, 150-200 m of regolith could be fully oxidized. More likely scenarios for the crater production population, onset of oxidizing conditions, and oxidant extinction depth yield estimates of no more than a few meters to putative reducing material. In addition, uncertainties remain regarding the degree to which hydrothermal or other high-temperature chemistry might oxidize materials in ejecta blankets. The trade-off between accessing unlithified sediments or rock interiors must be considered.
引用
收藏
页码:31491 / 31498
页数:8
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