Vast volumes of dust deposits dating from the late Paleozoic, from both land areas and marine reefal deposits, record a remarkably dusty atmosphere. Moreover these dust deposits contain unusually high concentrations of reactive iron. This concomitance -- dust with exceptionally high values of bioavailable iron -- implies major ecosystem fertilization and an associated massive drawdown of atmospheric carbon.

The biogeochemical impacts of iron-rich dust to the oceans are known for Earth's recent record but unexplored for deep time, despite recognition of large ancient dust fluxes, particularly during the late Paleozoic. Sur and colleagues report a unique iron relationship for Upper Pennsylvanian mudrock of eolian origin that records lowstand (glacial) conditions within a carbonate buildup of western equatorial Pangaea (now the western United States).

With iron fertilization proposed as a serious geoengineering scheme to control future atmospheric carbon and attendant climate change, authors Sur and colleagues write, "It behooves us to study the consequences of analogous events as archived in Earth's deep-time record."

Story Source: 

The above post is reprinted from materials provided by Geological Society of America. Note: Materials may be edited for content and length. 

Journal Reference:

1. Sohini Sur, Jeremy D. Owens, Gerilyn S. Soreghan, Timothy W. Lyons, Robert Raiswell, Nicholas G. Heavens, Natalie M. Mahowald. Extreme eolian delivery of reactive iron to late Paleozoic icehouse seas.Geology, 2015; G37226.1 DOI: 10.1130/G37226.1