My main research focus is detection and characterization of ancient microbial biosignatures in the rock record, including investigation of past habitability and taphonomic potential of rock sequences. My research emphasizes field geology and the multidisciplinary analysis of returned samples. I have worked on Early Archean age stromatolites of the Pilbara Craton, and associated sedimentary, hydrothermal and aqueously altered igneous rocks. I am interested in the nature and origin of Archean organic materials, trace element geochemistry of chemical sediments, bulk and in situ carbon isotopes of Archean organic/inorganic carbon. I am also interested in morphological and chemical biosignatures in evaporite rocks and have studied Messinian evaporitic gypsum-hosted stromatolites of the Mediterranean region.
At JPL, I also work on instrument development for future missions and am Principal Investigator for PIXL, the Planetary Instrument for X-ray Lithochemistry. PIXL is a rover-arm-mounted micro-X-ray fluorescence spectrometer for studying the elemental chemistry of rocks and soils.