Project Details
Projekt Print View

Microbial and diagenetic origins for BIFs mineralogy

Subject Area Palaeontology
Term from 2011 to 2015
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 203718275
 
Final Report Year 2016

Final Report Abstract

The Precambrian chemical sediments, Banded iron formations (BIFs), are the primary repositories of information on the surface environment and biosphere at the time of deposition. Archean BIFs are likely to be formed by anoxygenic photosynthetic bacteria oxidizing Fe(II) ("photoferrotrophs") prior to atmospheric O2, but the low amounts of organic carbon associated with BIFs argued against a strong microbial influence. In this project we showed that BIF mineral assemblages, i.e. magnetite and siderite, are consistent with a photoferrotrophic origin and subsequent diagenesis (moderate heat and pressure) of cells and Fe(III) (oxyhydr)oxides. The mechanisms have been evaluated under Precambrian ocean conditions and compared to the mineral assemblages of BIFs. Trace element analysis (TE; e.g. Mo, Co, Cu, Zn, Ni) aided in evaluating a microbial origin. We used microspectroscopic and spectromicroscopic analyses to quantify trace elements incorporated in photoferrotrophic organic matter vs. minerals after diagenesis. The trace element signature of BIF minerals, partitioning coefficients into sulfide and Fe(III) (hydr)oxide minerals have been determined and used to determine the trace element concentrations of the Precambrian ocean, and to infer which microbial metabolisms were supported.

Publications

 
 

Additional Information

Textvergrößerung und Kontrastanpassung