Geology Club Seminar

Fe/Mg clays and hydrated/opaline silica are the most common hydrated mineral groups detected on Mars and record a substantial portion of that planet's aqueous history. Both mineral groups are unique in that they can undergo mineral diagenesis, where varying exposure to water will convert Fe/Mg smectite to chlorite, and amorphous opal-A to more crystalline opal-CT and quartz. Distinguishing these mineral forms therefore allows us to infer the persistence of past aqueous conditions. Here we present evidence for widespread diagenesis on Mars based on orbital detections of geochemically mature phases (chlorite and opal-CT) relative to their immature counterparts (smectite and opal-A). We discuss implications for more persistent aqueous conditions, previously thought to be very limited, on Mars and relations to observations by landed missions, such as Curiosity at Gale crater.