Geochemical correlation in an exhumed submarine channel complex (Tabernas Basin, Se Spain): Comparison to sedimentological correlation at various length scales

摘要

Whole-rock, inorganic, geochemical data have previously been used to aid characterization and stratigraphic correlation of fossil-poor clastic sedimentary deposits, although this approach has not yet been calibrated by testing chemostratigraphic correlations against physical stratigraphic correlations from outcrop. Chemical data from a well-exposed siliciclastic succession in a Tortonian (late Miocene) submarine slope channel system in the Tabernas Basin of southern Spain were generated using X-ray fluorescence supplemented by X-ray diffraction, SEM analysis, and light microscopy. Amongst the > 60 elements measured, nearly a quarter of them have proved to be useful or reliable for geochemically based correlation at the tested scales (∼10 m, ∼ 50 m, ∼ 100 m). These elements are SiO, KO, AlO, CaO, and TiO, as well as Zr, Nb, Th, Rb, Cs, As, and the rare earth elements, La, Nd, and Ce. High-resolution, bed-to-bed geochemical correlation is feasible over short distances (∼ 10 m). Geochemical data from sections in beds that are traceable suggest that a given stratigraphic level seems to be geochemically homogeneous with respect to some key elements. Geochemical data also provide a useful aid for high-resolution sedimentary correlation, at distances of several tens of meters up to at least 100 m. Since each individual bed seems to be broadly homogeneous in composition, at a larger scale it is possible to discern a provenance signal in geochemical data. Chemical stratigraphy thus seems to work even in stratigraphically complicated submarine channel complexes.