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Missing salts on early Mars
Author(s) -
Milliken R. E.,
Fischer W. W.,
Hurowitz J. A.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl038558
Subject(s) - noachian , hesperian , mars exploration program , martian , geology , weathering , basalt , amazonian , geochemistry , astrobiology , martian surface , clay minerals , dissolution , earth science , regolith , chemistry , ecology , amazon rainforest , physics , biology
Our understanding of the role of water on Mars has been profoundly influenced over the past several years by the detection of widespread aqueous alteration minerals. Clay minerals are found throughout ancient Noachian terrains and sulfate salts are abundant in younger Hesperian terrains, but these phases are rarely found together in the early Martian rock record. Full alteration assemblages are generally not recognized at local scales, hindering our ability to close mass balance in the ancient crust. Here we demonstrate the dissolution of basalt and subsequent formation of smectite results in an excess of cations that should reside with anions such as OH − , Cl − , SO 3 2− , SO 4 2− , or CO 3 2− in a significant reservoir of complementary salts. Such salts are largely absent from Noachian terrains, yet the composition and/or fate of these ‘missing salts’ is critical to understanding the oxidation state and primary atmospheric volatile involved in crustal weathering on early Mars.