On the Diversity and Formation Modes of Martian Minerals

• Published in: Journal of geophysical research. Planets 2023-09, Vol.128 (9)
• Main Authors: Hazen, Robert M., Downs, Robert T., Morrison, Shaunna M., Tutolo, Benjamin M., Blake, David F., Bristow, Thomas F., Chipera, Steve J., McSween, Harry Y., Ming, Doug, Morris, Richard V., Rampe, Elizabeth B., Thorpe, Michael T., Treiman, Allan H., Tu, Valerie M., Vaniman, David T.
• Format: Article
• Language: English
• Subjects: Atmospheric pressure; Crystallization; Dehydration; Earth; Fractional crystallization; Freeze drying; Igneous rocks; Lander vehicles; Mars; Mars missions; Mars surface; Metamorphic rocks; Metamorphism; Metamorphism (geology); Meteorites; Meteors & meteorites; Mineralization; Mineralogy; Minerals; Oxidation; Phases; Planetary evolution; Plate tectonics; Plates (tectonics); Precipitation; Shock metamorphism; SNC meteorites; Tectonics; Terrestrial planets; Weathering
• ISSN: 2169-9097; 2169-9100
• DOI: 10.1029/2023JE007865

A systematic survey of 161 known and postulated minerals originating on Mars points to 20 different mineral‐forming processes (paragenetic modes), which are a subset of formation modes observed on Earth. The earliest martian minerals, as on Earth, were primary phases from mafic igneous rocks and their ultramafic cumulates. Subsequent primary igneous minerals were associated with products of limited fractional crystallization, including alkaline and quartz‐normative lithologies. Significant mineral diversification occurred via precipitation of primary phases from aqueous and atmospheric fluids, including authigenesis, hydrothermal and cryogenic precipitation, and evaporites, including freeze drying during eras of low atmospheric pressures. In particular, hydrothermal mineral formation associated with both volcanic fluids and sustained hydrothermal activity in impact fracture zones may have triggered significant mineral diversification, though as yet undocumented. At least 65 such primary minerals have been identified by flown missions to Mars and from martian meteorites. A host of secondary martian minerals were produced by near‐surface processes related to water/rock interactions, including hydration/dehydration, oxidation/reduction, serpentinization, metasomatism, and a variety of diagenetic alterations. Additional mineral diversity resulted from metamorphic events, including thermal and shock metamorphism, lightning, and bolide impacts. However, several dominant sources of mineral diversity on Earth, including (a) extensive fluid/rock interactions and element concentration associated with plate tectonics; (b) high‐pressure regional metamorphism associated with plate tectonics; and (c) biologically mediated mineralization—are not known to be in play on Mars. Consequently, we estimate the total mineral diversity of Mars to be an order of magnitude smaller than on Earth. A half‐century of investigations of the martian surface by orbiters, landers, and rovers, amplified by studies of martian meteorites, reveal more than 160 confirmed or likely minerals. These diverse phases represent a range of at least 20 mineral‐forming processes, including the production of dozens of primary igneous, sedimentary, and near‐surface metamorphic rocks, as well as numerous secondary weathering and alteration minerals. In many respects, the more than 4.5‐billion‐year mineral evolution of Mars mirrors that of Earth and other terrestrial planets and moons. In each case, the earli