The macromolecules and lipid biomarkers as seen in the archean white mfolozi banded iron formation (BIF): Their biogenicity and possible implications for mars.

The Archean Banded Iron Formation (BIF), in general, is recognized as a significant paleoredox indicator, particularly due to its significant link to the Great Oxidation Event; however, its biogenicity remain inadequately defined. In this study, we employ a comprehensive approach including mineralogy, fluorescence spectroscopy, stable C and N isotope analyses and lipid profiling of BIF to elucidate its biogenic potential. The Ijzermijn Iron Formation (∼2.95 Ga) of the upper Mozaan group of Pongola Supergroup, South Africa is typically laminated and featuring alternating layers of hematite and silica (alongside manganese oxides), indicating a near-shore depositional environment. The δ13C (-28.61‰) and δ14N (1.58±0.1‰) ratio of Mesoarchean BIF align well with global observation of anoxic water column and ammonium-based nitrogen cycling, dominated by methanogenic archaea. The detection of organic macromolecules and methyl ester further consolidated the microbially mediated iron precipitation. Therefore, limited Archean BIF, under special circumstances and in a conducive depositional setting, may retain distinct microbial signatures when analysed to various techniques, including molecular fingerprinting. This underscores their importance for past habitability and the biogenicity of hematite deposit on early Earth and Mars.