About the Spherules 2007 Project

Spherules are observed in the Atacama desert at Salar Grande, Guanaco, and Monturaqui. The sites are marked by aqueous, volcanic and impact processes, respectively. They show characteristics of the Martian "blueberries" the formation of which is still debated. Our goal is to understand the processes that generated the various types of spherules in the Atacama, and help constrain the origin of the blueberries. Our objectives are to:

(1) Characterize their geological context, formation, emplacement, and evolution using multi-spectral orbital imagery for context prior to field work. Field surveys will include: Geology, (materials, sequences, position in outcrops, exposure and detachment mode), mineralogy, and ground-penetrating radar;

(2) Assess the role and magnitude of processes through the study of facies and units (morphology, sedimentology, composition);

(3) Document their composition using VNIR spectroscopy, XRD, XRF; infer the origin of their diversity through petrography, mineralogy, geochemistry and isotopes, to characterize structure, texture, chemistry and isotope variations. Petrography will constrain microstratigraphic variations in banding thickness, mineralogical variations within spherules, and identify common trends reflecting pervasive phases of deposition. We will focus on the chemical micro-stratigraphic record preserved within individual spheres by conducting electron microprobe traverses for major element concentrations, and trace element analyses by in-situ LA-ICP-MS along the same tracks to link major and trace element variations. We will sample discrete bands within spherules for O2 stable isotope analyses to characterize variations in source and chemistry of fluid flux and temperature of formation. This data will be linked to the geochemical analysis of the host material to provide information on the source for circulating fluids (meteoric water, magmatic fluids, other).

This project characterizes processes associated with the formation of spherules on Earth, thereby documenting plausible formation processes for blueberries on Mars.

Photos

Photos courtesy of Gerhard Hueldepohl. Please visit his website at: http://www.atacamaphoto.com