Mars & Earth Basaltic Volcanism & Why We Need to Put Geologists on Missions

Dr. Graziella Caprarelli

University of Technology, Sydney

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Abstract: Mars is the fourth planet in the solar system, and the one which more closely resembles planet Earth both astronomically and geologically. Recent exploratory missions have expanded our geophysical knowledge of Mars, but there are still many unanswered questions related to the composition of Martian rocks, their sources and their evolution. This carries important implications for our understanding of the formation and early evolution of the crust and mantle of Mars, which in turn has broad repercussions with regard to future missions to Mars. In particular, a sound understanding of geological processes on Mars is fundamental to set up a strategy for resource acquisition, a necessary first step to plan a permanent human presence on Mars.

Rocks of basaltic composition cover most of the surface of Mars. A global perspective on the processes that have influenced the geological history of Mars can be deduced from studies of basaltic analogues from Earth. These can be compared and contrasted also to the shergottites - nakhlites - chassignites (SNC) group of meteorites, that have been identified as fragments of the Martian crust and upper mantle.

Based on the general mineralogy of the SNC, on the likelihood of existence of a Martian magma ocean in the early stages of planetary evolution, on numerical models of thermal evolution of Mars, and inferences about the possible processes that may have caused Martian volcanism, the flood basalts of the Columbia River Basalt Group (CRBG) of north-west USA (Washington - Idaho - Oregon) can be considered a suitable analogue for Martian basalts. A study of the chemical and physical evolution of the CRBG is presented to illustrate a procedure that allows us to reconstruct the mantle - crust processes presiding to the genesis and evolution of these rocks. Results of this and similar studies on the CRBG rocks can be thought of as the blue-print for studies of Martian rocks likely to be recovered in future missions to the planet.

Plausible reconstructions of fundamental planetary processes require exploration enterprises employing also field practices currently applied by geologists in their studies of planet Earth.

PROFILE: Dr Graziella Caprarelli is an igneous petrologists / geochemist and planetary scientist who works on convergent margin magmatism and tectonism. Since joining UTS in September 1996 her research has focused on the east Australian South New England Fold Belt Palaeozoic basalts and on the NW-USA Columbia River Basalt Group. She uses mineral and bulk rock compositions to determine the physical conditions of formation and evolution of basaltic magmas, and applies her methodologies also to the study of Martian basaltic magmatism. She is an Honorary Fellow of the Pacific Northwest National Laboratories (Richland, USA), and has been a research associate at the Johnson Space Center of NASA (Houston, USA). She held post-doctoral positions at the Geological Survey of Japan (Tsukuba, Japan), and at the Earth and Planetary Science Department of the Tokyo Institute of Technology (Tokyo, Japan). She obtained her PhD in Rome (Italy) for her geochemical work on the nature of fluid-rock interaction in the geothermal field of Campi Flegrei. She is a member of the Geological Society of Australia (GSA), and of its Special Groups (SG) in Geochemistry - Mineralogy - Petrology, Solid Earth Geophysics, and the newly constituted (and as yet informal) SG in Planetary Sciences, and of the American Geophysical Union. In 2002-2003 she served as Honorary Chair of the NSW Division of the GSA. She is a member of the Editorial Board of the Australian Journal of Earth Sciences, and is Principal Guest Editor of a thematic issue on Mars research. She held seminars at various research institutions, including: CSIRO, NASA, the International Research School of Planetary Sciences (IRSPS). She drafted departmental and faculty policy documents and has been actively involved in their implementation by serving as a Chair and member of various committees. In 2004 she is a member of the DES Honours Management Committee and of the Faculty Library Committee.