Precambrian Research 182 (2010) v–ix Contents lists available at ScienceDirect Precambrian Research journal homepage: www.elsevier.com/locate/precamres Insights from isotope stratigraphy Alcides N. Sial a,∗ , Juha A. Karhu b , Valderez P. Ferreira a a NEG-LABISE, Department of Geology, Federal University of Pernambuco, C.P. 7852, 50670-000, Brazil b Department of Geosciences and Geography, P.O. Box 64 (Gustaf Hällströmin katu 2), FIN-00014, University of Helsinki, Finland article info Article history: Received 7 August 2009 Received in revised form 20 January 2010 Accepted 4 August 2010 Keywords: Isotope stratigraphy Precambrian Carbon isotopes Sulfur isotopes Strontium isotopes Neodymium isotopes A symposium on Precambrian isotope stratigraphy was held within the frame of the 33rd IGC held at Oslo, Norway, August 2008. This symposium spawned the idea for a special issue on this theme and ultimately to the ten papers assembled here. This special issue provides the results of some of the latest cutting edge research on traditional (C, Sr, S) isotope chemostratigraphy and introduce some newer isotope systems (REE, Ca) and Hg chemostratigraphy as a potential tracer for glacial events and estimate of the buildup of volcanic gases (including CO 2 ) during glaciations. Moreover, it pro- vides a distribution of studies that are broad in both space and time, highlighting chemical events from the Palaeoproterozoic (Africa, South America, Europe and India), Mesoproterozoic (South Amer- ica), and Cryogenian-Ediacaran (North America, South America and India). Special attention is given to Neoproterozoic chemostratigra- phy and problems with reliability of the use of carbon isotopes for Neoproterozoic stratigraphic correlation. A special focus is given to the atmospheric, climatic, and biogeochemical changes in both ends of the Proterozoic Eon. The use of chemostratigraphy as a tool in the correlation of global events in the Precambrian followed the pioneer research by William T. Holser on ancient ocean water chemistry (Kaufman et al., 2007). Several researchers focused on carbon isotope varia- tions across thick successions to investigate long-term fluctuations in the chemistry of the seawater (Veizer et al., 1980; Magaritz et al., 1986 and references therein). However, despite widespread ∗ Corresponding author. Tel.: +55 81 2126 8243; fax: +55 81 2126 8242. E-mail address: sial@ufpe.br (A.N. Sial). effects of late diagenesis on the isotope record, important isotope events could be demonstrated on a global scale (Magaritz et al., 1986; Holser, 1997, among many others) as it became evident that contemporaneous, apparently well-preserved, geographically distant marine strata registered similar isotopic compositions. Thereafter, chemostratigraphy has served as one of the princi- pal means of intra- and extra-basinal stratigraphic correlation to assemble Precambrian stratigraphic record from fragments pre- served in scattered successions. It is as an important tool in providing a time line compesating for poor biostratigraphic res- olution of Precambrian fossils (Veizer et al., 1980; Magaritz et al., 1986; Knoll et al., 1986; Knoll and Walter, 1992; Kaufman et al., 1997; Corsetti and Kaufman, 2003; Halverson et al., 2005). Correlations established through chemostratigraphy can be used to comment on biogeochemical and climate changes through time. The determination of the base of the Ediacaran Period was largely based on chemostratigraphy of cap carbonates that overlie glacial diamictites (Knoll et al., 2006) and have been accumulated during post-glacial transgression, recording the most profound carbon, sulfur, and strontium isotope variations in Earth history, and being the central focus for the ‘snowball Earth’ hypothesis (Kirshvink, 1992; Hoffman et al., 1998; Bekker et al., 2005). The lack of radiometric constraints on the absolute age of most of these extreme isotope excursions has led to debates on their tempo- ral equivalence (Kaufman et al., 1997; Kennedy et al., 1998). The number of studies relying on isotope stratigraphy has grown sub- stantially over the past 25 years and it is worth noting that in the case of carbon isotope stratigraphy, this method can be applied, 0301-9268/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.precamres.2010.08.001