A combined carbon and oxygen isotopic analysis of ALH84001 carbonates with NanoSIMS

Abstract

ALH84001 is the oldest known martian meteorite we have on Earth (4.56 Ga) [1], the carbonates within ALH84001 precipitated ~3.9 Ga [2]. Of all the current martian meteorites ALH84001 has the largest quantity of carbonates (1 % vol) and variations in mineralogy, especially the carbonate “rosettes”, with an ankerite core commonly surrounded by an alternating layer of siderite-magnesite siderite. The age, quantity, isotope range and diverse mineralogy make ALH84001 carbonates ideal candidates to provide insights into the primordial martian conditions