Transient episodes of mild environmental oxygenation and oxidative continental weathering during the late Archean

Fig. 1 Stratigraphic and chemostratigraphic trends in the Mount McRae Shale.
Ratios of highly reactive iron (Fe_HR) to total iron (Fe_T) greater than 0.22 (blue bar) point to anoxic bottom waters, whereas the ratio of pyrite iron (Fe_PY) to Fe_HR distinguishes between ferruginous (<0.7 to 0.8) and euxinic (>0.7 to 0.8; green bar) conditions (59). Filled circles show data from Reinhard et al. (15), recalculated according to Raiswell et al. (60), whereas open squares show results from quantitative x-ray diffraction analysis (60). Black shales dated using Re-Os geochronology were deposited from anoxic and euxinic bottom waters. Red and blue dashed lines indicate average Mo concentration in Archean and Proterozoic euxinic black shales, respectively (1). TOC, total organic carbon.
Fig. 2 Re-Os isochron diagrams for the Mount McRae Shale.
(A) Interval of 145.22 to 148.32 m in core ABDP-9. (B) Interval of 128.71 to 129.85 m in core ABDP-9. MSWD, mean square of weighted deviates. The age uncertainty includes the ¹⁸⁷Re decay constant uncertainty. RPT, replicate analysis.

Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/10/e1500777/DC1
Table S1. Re-Os abundance and isotope data for the Mount McRae Shale, Western Australia (drill core ABDP-9).

Supplementary Materials