Earth Science Frontiers ›› 2024, Vol. 31 ›› Issue (1): 111-126.DOI: 10.13745/j.esf.sf.2023.11.8

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The disappearance of banded iron formations: Research progress and perspectives on the origin of rhythmic Fe-rich/Si-rich laminae

WANG Ruimin(), SHEN Bing*()   

  1. MOE Key Laboratory of Orogenic Belt and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China
  • Received:2023-10-20 Revised:2023-11-06 Online:2024-01-25 Published:2024-01-25

Abstract:

Banded iron formations (BIFs) are chemical sediments consisting of rhythmic Fe-rich and Si-rich laminae that are millimeters to centimeters thick. BIFs not only are an important iron resource, but also record the Earth's early evolution, early microbial activity, and atmosphere-ocean redox status. First appeared prior to 3.8 Ga, BIFs were common in the Archean and Paleoproterozoic, but they started to disappear about 1.8-0.8 Ga and were absent throughout the rest of Earth's history except for a brief appearance in the Cyogenian during global glaciation. The traditional model suggests that the abundance of BIFs is mainly controlled by dissolved Fe(II) contents in the ocean, and weakened tectonic/magmatic/hydrothermal activities, ocean oxidation, or oceanic euxinia about 1.8-0.8 Ga were responsible for the depletion of Fe (II) in the mid-Proterozoic ocean to drive to BIFs to disappear. However, geochemical evidence revealed that mid-Proterozoic ocean was predominantly ferruginous (Fe2+ rich) with large amounts of non-BIF ironstone deposits, challenging the traditional model. Here, we argue that the disappearance of BIFs in the mid-Proterozoic might result from changes in rhythmic deposition of Fe-rich/Si-rich laminae. We review the geological characteristics of BIFs and discuss different deposition models in detail. Additionally, we comprehensively review recent researches on the origin of rhythmic Fe-rich/Si-rich laminae in BIFs focused on Fe (II) source, Fe(II) oxidation, and Fe(III) preservation in sediments. Based on this, we attempt to identify possible directions for solving the mystery of BIFs’ disappearance by considering the coupling between iron and silicon biogeochemical cycles, so as to develop new insights into the evolution of the early Earth.

Key words: banded iron formation, Fe cycle, Si cycle, rhythmic laminae, Precambrian

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