Diagenetic silica enrichment and late‐stage groundwater activity in Gale crater, Mars

Abstract

Diagenetic silica enrichment in fracture‐associated halos that crosscut lacustrine and unconformably overlying aeolian sedimentary bedrock is observed on the lower north slope of Aeolis Mons in Gale crater, Mars. The diagenetic silica enrichment is colocated with detrital silica enrichment observed in the lacustrine bedrock yet extends into a considerably younger, unconformably draping aeolian sandstone, implying that diagenetic silica enrichment postdates the detrital silica enrichment. A causal connection between the detrital and diagenetic silica enrichment implies that water was present in the subsurface of Gale crater long after deposition of the lacustrine sediments and that it mobilized detrital amorphous silica and precipitated it along fractures in the overlying bedrock. Although absolute timing is uncertain, the observed diagenesis likely represents some of the most recent groundwater activity in Gale crater and suggests that the timescale of potential habitability extended considerably beyond the time that the lacustrine sediments of Aeolis Mons were deposited.

Ancient Martian aeolian processes and palaeomorphology reconstructed from the Stimson formation on the lower slope of Aeolis Mons, Gale crater, Mars

“…Both the Bradbury group and Murray formation were buried to a substantial depth (hundreds to thousands of metres) and then exhumed by aeolian deflation (Malin & Edgett, ; Day et al ., ). These rocks have been affected by burial diagenesis, including cementation, fracturing and vein mineralization (Frydenvang et al ., ; Yen et al ., ).…”

“…D), were documented on Sol 1092. These targets were associated with an alteration halo indicated by lightened tone of bedrock (Frydenvang et al ., ; Yen et al ., ). The Ivanhoe target was located in an area of intense alteration, Lebo is located 0·65 m away from Ivanhoe where alteration was less intense and Ledger was located largely outside of the area of alteration, 1·2 m from Lebo.…”

Mineral‐Filled Fractures as Indicators of Multigenerational Fluid Flow in the Pahrump Hills Member of the Murray Formation, Gale Crater, Mars

“…Thin white Ca-sulfate veins are present within the Stimson formation, indicating Ca-sulfate fluid stability late in Gale crater's history (Banham et al, 2018;Watkins et al, 2016). Alteration halos surrounding fractures crosscut both the Murray and Stimson formations, indicating interaction with groundwater following the deposition of the aeolian Stimson formation (Frydenvang et al, 2017;Yen et al, 2017). Alteration halos surrounding fractures crosscut both the Murray and Stimson formations, indicating interaction with groundwater following the deposition of the aeolian Stimson formation (Frydenvang et al, 2017;Yen et al, 2017).…”

Identification and Description of a Silicic Volcaniclastic Layer in Gale Crater, Mars, Using Active Neutron Interrogation

“…Unlike Buckskin, these high‐SiO alteration halo samples did not contain tridymite. The association of these alteration halos with fractures indicates their formation is a result of aqueous alteration that post‐dated the lithification of the Stimson formation (Frydenvang et al, ; Yen et al, ). Other light‐toned fracture alteration halos have been observed elsewhere in the Stimson formation (Banham et al, ), in the Murray formation (Frydenvang et al, ; Gasda et al, ; Yen et al, ), and in the Bradbury group.…”