Depleted Organic Matter in Banded Iron Formations Provides Clues for Extraterrestrial Life Biosignatures

Banded Iron Formation

An example of a banded iron formation (BIF). The Soudan Iron-Formation is a Neoarchean-aged BIF unit in the Vermilion Greenstone Belt of northeastern Minnesota, USA. Credit: James St. John, Wikimedia Commons

Examining how banded iron formations (BIFs) became depleted in organic matter.

A new study supported in part by the NASA Astrobiology program is providing details about how banded iron formations (BIFs) were deposited on the ancient Earth to become part of the planet’s geological record. Understanding the origin of BIFs is important to astrobiologists because these geological features could be a record of ancient microbial communities in Earth’s past, and would provide clues about the types of biosignatures that future missions could look for on other worlds like Mars.

BIFs are layers of sediment that are rich in iron and date to the Precambrian. Theories suggest that they are they resulted from the interplay of microbial metabolisms that involved the biogeochemical cycling of iron and organic matter (OM). However, BIFs found on Earth today are depleted in OM. The new study examines whether or not the depletion of OM could be the result of the oxidation of this material during the process of iron reduction.

The study, “Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships,” was published in the journal Nature Communications on November 4, 2019. The work was supported by NASA Astrobiology through the Exobiology Program and the NASA Astrobiology Institute. This newly-revealed science is also a critical part of NASA’s work to understand the Universe, advance human exploration, and inspire the next generation. As NASA’s Artemis program moves forward with human exploration of the Moon, the search for life on other worlds remains a top priority for the agency.

Reference: “Minimal biomass deposition in banded iron formations inferred from organic matter and clay relationships” by Matthew S. Dodd, Dominic Papineau, Franco Pirajno, Yusheng Wan and Juha A. Karhu, 4 November 2019, Nature Communications.
DOI: 10.1038/s41467-019-12975-z

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