Banded Iron Formation: Distribution in Time and Paleoenvironmental Significance

A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars

“…The potentially young age of clay formation (and habitability) does not invalidate the general trend that most rocks that interacted with water early in Mars' history produced clays, and those that interacted later produced sulfates. However, much like Earth's time--dependent records of iron formation (95,96) and carbonates (97,98), it points to the need to understand those special conditions which allow a distinctive aqueous environment to persist for broad spans of geologic time, or to recur when the favorable conditions again emerge. Curiosity's detection of a relatively young, and strikingly Earth--like habitable environment at Gale crater underscores the biologic potential of relatively young fluvio--lacustrine environments.…”

Continentally-derived solutes in shallow Archean seawater: Rare earth element and Nd isotope evidence in iron formation from the 2.9Ga Pongola Supergroup, South Africa

“…/j.gca.2007 Two broad types of IF are generally recognized: the Algoma type which is often found in greenstone belts, and the Superior type associated with stable sedimentary basins and cratonic margins (Gross, 1983). When considering the mass of sediment deposited, Superior-type IFs contain far more Fe than Algoma-type IFs (James and Trendall, 1982;Klemm, 2000), although this may represent a preservation bias due to their proposed tectonic settings. The association of Superior-type IFs with shelf deposits such as quartzites, carbonates, and shales is consistent with their depositional model, and Superior-type IFs are particularly useful for constraining trace element distributions in shallow Archean seawater.…”

The Gaia Hypothesis - Fact or Fancy?

“…Other profound changes, such as the swing from an anaerobic to an aerobic atmosphere, which certainly involved the biota, may have had similar genesis. The apparently oscillatory changes in the oxidative state of the biosphere, recorded as remarkably regular sedimentary banding in the Banded Iron Formations deposited 2-6 to 1-8 billion years ago, are perhaps understandable in these terms (Eichler, 1976;James & Trendall, 1982;Holm, 1987).…”