QUATERNARY AND JURASSIC TERRESTRIAL SPRING DEPOSITS AS ANALOGS FOR ANCIENT AQUEOUS ENVIRONMENTS ON MARS

The investigation into whether life exists or once existed on Mars has been met with many challenges. NASA’s strategy has been to “follow the water” in an effort to determine if life existed on Mars in the past. The detection of phyllosilicates and carbonates on the surface of Mars confirm that environmental conditions could sustain prolonged periods with liquid water. High quantities of silica have also been detected on the surface of Mars. The discovery of silica on Mars could be critical to understanding whether life existed on the surface of Mars due to the possibility of any organic material being preserved during the silicification process. Conditions may have been mild enough for life to have evolved and thrived on the surface during this time. Silica as well as carbonates could potentially provide a record of early biological activity on Mars. The focus of this work is to identify and describe biotic macro- and micro-structures as well as determine how well preserved these features are over different timescales. Another goal of this research is to provide criteria for identifying ancient spring systems on Mars.

The upper part of the Jurassic Brushy Basin Member of the Morrison Formation in Ten Mile Graben, southern Utah hosts a <10 m thick carbonate hypothesized to represent a small hot spring-fed lake. The carbonate layer is underlain by 30.0 m of variegated smectitic clays and tuff with thinly bedded layers of silica. The Ten Mile Graben region also hosts a Quaternary cold spring system that has been active for hundreds of thousands of years. Striking similarities between the outcrops at Ten Mile Graben and the deposits detected on Mars include mineralogy, sedimentary facies, and sedimentary structures. The presence of these silica and carbonate mineral assemblages suggest that short-lived springs and lakes existed when Mars had a warmer and wetter climate.