@Article{Mojzsis:2003, author = {S.J. Mojzsis and C.D. Coath and J.P. Greenwood and K.D. McKeegan and T.M. Harrison}, title = {Mass--independent isotope effects in {A}rchean (2.5 to 3.8 {G}a) sedimentary sulfides determined by ion microprobe analysis}, journal = {Geochim. Cosmochim. Acta}, booktitle = {}, editor = {}, publisher = {}, month = {May}, year = {2003}, volume = {67}, number = {}, pages = {1635--1658}, note = {}, annote = {}, keywords = {}, url = {http://sims.ess.ucla.edu/PDF/mojzsis_et_al_GCA_2003.pdf}, doi = {10.1016/S0016-7037(03)00059-0 }, isbn = {}, abstract = {We report sulfur isotope anomalies with $\Delta$$^{33}$S, the deviation from a mass--dependent fractionation line for the three--isotope system ($^{34}$S/$^{32}$S vs. $^{33}$S/$^{32}$S), ranging up to $\pm$ 2$\permil$ within individual Archean sedimentary sulfides from a variety of localities. Our measurements, which are made in situ by multicollector secondary ion mass spectrometry, unequivocally corroborate prior bulk measurements of mass-independent fractionations (MIF) in sulfur and provide additional evidence for an anoxic atmosphere on the Earth before $\sim$ 2 Ga. This technique also offers new opportunities for exploring ancient sulfur metabolisms preserved in the rock record. The presence of MIF sulfur in sulfides from a $>$ 3.8--Ga Fe--rich quartzite from Akilia (island), West Greenland, is consistent with a marine sedimentary origin for this rock.}, }