High-temperature seafloor hydrothermal circulation over geologic time and archean banded iron formations

Abstract

Under the assumption of simple plate tectonics with a range of continental growth scenarios, we construct models of global lithospheric heat loss, hydrothermal heat loss and hydrothermal iron flux to the ocean as functions of geologic time from 4.0 Ga to present. The models show that lithospheric heat loss scales with the square root of the plate creation rate, whereas hydrothermal heat loss scales linearly with that rate. Thus during the Archean lithospheric and hydrothermal heat losses were ≈3 and ≈10 times greater than present, respectively. Straightforward extrapolation of hydrothermal Fe flux from the present to the Archean using these models indicates that hydrothermal Fe may not have been sufficient to supply the large Superior-type Banded Iron Formations deposited between 2.7 and 1.8 Ga.