Red rock and red planet diagenesis: Comparisons of Earth and Mars concretions

Compelling similarities between concretions on Earth and “blueberries” on Mars are used to suggest the blueberries are concretions that formed from a history of watery diagenesis. In the terrestrial examples, groundwater flow produces variations in sandstone color and iron oxide concretions in the Jurassic Navajo Sandstone of Utah. Variations in concretion mineralogy, form, and structure reflect different conditions at chemical reaction fronts, the influence of preferential fluid flow paths, the relative roles of advection and diffusion during precipitation, the presence of multiple events, fluid geochemistry, and time. The terrestrial concretions are analogs that can be used to understand the water-saturated conditions that formed spherical hematite concretions on Mars.