Identifying the Source of Martian Meteorites Provides Access to Early Planetary Evolutionary Records

A partial crater map of Mars with the origin of NWA 7034 circled in red. Credit: Lagain et al., 2022.

Mars provides a unique, accessible record of early planetary formation and differentiation processes obscured by subsequent evolution on Earth, e.g., by erosion, internal differentiation, and plate tectonics. Currently, studies rely on spacecraft or evidence from martian meteorites to locate these rare records.

The martian meteorite breccia Northwest Africa (NWA) 7034 (โ€œBlack Beautyโ€) and its paired stones preserve the only known meteoritic records of early formation and environmental conditions on Mars. Locating its source would provide a target for future missions to study the formation and differentiation of Mars in the first 10 million years after its accretion, and by extension, all terrestrial planets.

A team of scientists led by Anthony Lagain at Curtin University identified the source crater of NWA 7034 โ€”ย out of 94 million craters cataloged on Mars โ€” using a custom-designed machine-learning algorithm and a supercomputer at the Pawsey Supercomputing Research Centre. The current consensus is that NWA 7034 originated from the Noachian Highlands based on its magnetic field; elevated potassium (K), thorium (Th), and iron (Fe) abundances; the ages of its oldest minerals (~4.5 Ga); and visible-infrared spectra. Trace elements in zircons indicate that the breccia formed from the Amazonian impact crater (~1.5 Ga) ejecta that was later lithified. Of the studied craters, only one crater was superimposed on a Noachian geological unit that displayed the required magnetic and elemental signatures and was near the ejecta zone of an earlier Amazonian impact crater (called Khujirt). This previously unnamed crater (~5-10 Ma), now called Karratha, is in the Terra Cimmeria-Sirenum province of Mars. Identifying the sources of martian meteorites provides access to rare evolutionary records and turns the martian meteorite collection into a database equivalent to sample return missions, an important goal for the scientific community. READ MORE