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Water on early Mars: Possible subaqueous sedimentary deposits covering ancient cratered terrain in western Arabia and Sinus Meridiani
Author(s) -
Edgett Kenneth S.,
Parker Timothy J.
Publication year - 1997
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 - 10.1029/97gl02840
Subject(s) - geology , mars exploration program , martian , sedimentary rock , evaporite , sedimentary depositional environment , geochemistry , terrain , geomorphology , astrobiology , geography , physics , cartography , structural basin
Western Arabia and northern Sinus Meridiani (30°N–10°S; 40°W–40°E) are almost entirely covered by wind‐eroded, horizontally‐bedded, sedimentary layers that lap against local topographic features. This portion of Mars' ancient cratered terrain is relatively low (< 1 km elevation) and flat (sloping westward 0.7 m/km over 3,000 km). The region lacks valley network channels. We propose that at some time in early Martian history, this region was under water. The water hypothesis is strengthened by the presence of (1) a shore‐like contact between smooth‐surfaced deposits and ancient cratered terrain in central Sinus Meridiani, (2) polygonal structures in northern Sinus Meridiani, and (3) sand (which cannot be from airfall), possibly reworked by wind from the underlying sedimentary units. The September 1997 arrival of Mars Global Surveyor's thermal emission spectrometer offers an opportunity to begin to test this hypothesis by searching for carbonate and evaporite minerals among the sediment covering the region.