MINERALOGICAL CO-EVOLUTION OF THE GEOSPHERE AND BIOSPHERE

The mineralogy of terrestrial planets evolves as a consequence of varied physical, chemical and biological processes. Initial evolutionary stages include the transition from ~12 nano-scale mineral phases in pre-stellar dense molecular clouds, to ~60 primary chondrite minerals, to ~250 different minerals in altered chondrites, achondrites and differentiated asteroids. Earth’s subsequent prebiotic mineral evolution depended on a sequence of geochemical and petrologic processes, including volcanism and degassing, fractional crystallization, crystal settling, assimilation reactions, regional and contact metamorphism, plate tectonics and associated large-scale fluid-rock interactions. These processes resulted in perhaps 1500 different mineral species.

Biological processes began to affect Earth's surface mineralogy by the Eoarchean, when large-scale surface mineral deposits, including carbonates and banded iron formations, were precipitated under the influences of changing atmospheric and ocean chemistry. The Paleoproterozoic “Great Oxidation Event” and Neoproterozoic increases in atmospheric O₂ transformed Earth’s surface mineralogy and are responsible, directly or indirectly, for most of Earth’s 4300 known mineral species.

Mineral evolution arises from three primary mechanisms: (1) progressive separation and concentration of elements from their original relatively uniform distribution; (2) an increase in range of intensive variables such as pressure, temperature, and the activities of H₂O, CO₂ and O₂; and (3) generation of far-from-equilibrium conditions by living systems. The sequential evolution of Earth’s mineralogy from chondritic simplicity to Phanerozoic complexity introduces the dimension of geologic time to mineralogy and thus provides a dynamic alternate approach to framing the mineral sciences.