Genesis of banded iron formations: A series of experimental simulations

A series of experimental simulations of the genetic mechanism of banded iron formations has been conducted using a suite of self-designed glassware to model the hypergene circulation of surface water. The simulation process involved two parts: in the first part, the weathering and leaching of basalt by strongly acidic meteoric water during early Precambrian volcanism would have resulted in amorphous silica precipitation and strongly acidic ore-bearing solutions (pH < 1.25). And in the second part, during quiescent volcanism, the weathering and leaching of basalt by CO2-saturated meteoric water without contamination of other volcanic gases would increase the pH value of the solution. When the pH increased to 1.25-5.50, ferric hydroxides and amorphous silica would alternately precipitate owing to periodic heating and continuous addition of high-pH basalt-leaching solutions. This is a possible explanation of the genetic mechanism of the Algoma-type banded iron formations. (C) 2014 Elsevier B.V. All rights reserved.