Experimental dissolution of molybdenum‐sulphides at low oxygen concentrations: A first‐order approximation of late Archean atmospheric conditions

摘要: The abundance of atmospheric oxygen and its evolution through Earth's history is a highly debated topic. earliest change the Mo concentration isotope composition marine sediments are interpreted to be linked onset accumulation free O2 in atmosphere. needed dissolve significant amounts water not yet quantified, however. We present laboratory experiments on pulverized surface-cleaned molybdenite (MoS2) hydrothermal breccia enriched Mo-bearing sulphides using glove box setup. Duration an experiment was 14 days, first signs oxidation subsequent dissolution compounds start occur above 72 ± 20 ppmv (i.e., 2.6 4.6 × 10−4 level (PAL)). This experimentally determined value coincides with published model calculations supporting concentrations between 1 × 10−5 3 × 10−4 PAL prior Great Oxidation Event sets upper limit molecular trigger variations recorded sediments. In combination rock record, this result implies 2.76 Ga below 72 ± 20 ppmv.