Transects of SIMS analyses are shown in back-scattered SEM images above, and isotopic compositions corresponding to these analyses below. Growth direction of calcite is from left to right. (a) Calcite with episodic methanogenesis-related signature (positive δ13C, blue symbol). This is the dominant appearance of methanogenesis-related calcite, related to δ18O with marine-influenced signature followed by lighter δ13C and δ18O. (b–e) AOM-related calcite (green symbols) with typical associated increase in δ18O values from the earlier growth zone (indicative of increased marine influence). (d,e) AOM-related calcite succeeded by calcite with significantly heavier δ13C and lighter δ18O (fresh water, with large glacial component, especially in e). (f) δ34S evolution with growth from core to rim in pyrite from three different fractures. The symbol sizes are generally larger than the analytical uncertainties (except for δ18O, where error bars are shown). Scale bars (a) 300 μm, (b) 200 μm, (c) 200 μm, (d) 100 μm, (e) 200 μm, (f) 50 μm.