Geochemical evidence for sediment provenance in mudstones and fossil‐poor wackestones (Upper Jurassic, Majorca Island)

Terra Nova, 24, 437–445, 2012 Abstract The notion that diagenetic imprint on ancient carbonates significantly compromises palaeoenvironmental interpretations is revealed as an oversimplification. The enigmatic case at the core of this research is an extended, homogeneous, macrofossil‐poor deposit showing distinctive dark brown colour and very fine grain size (Aumedrá Fm., Majorca Island). This markedly contrasts with standard ammonitico rosso (AR) facies known from Jurassic epioceanic swells. Geochemical analysis of matrix micrite, carbonate cements and belemnite rostra are used to interpret the Aumedrá carbonates. Stable (Carbon and Oxygen) isotopes and elemental abundance are compared with data from under‐ and overlying deposits, and coeval sections. Conspicuously higher than expected C and O isotope signature, together with strontium enrichment and a typically low iron and manganese concentrations favour a distant, shallower, probably aragonitic sedimentary supply. Modern and ancient examples of carbonate deposition are integrated with possible hydrodynamic conditions justifying transport over the studied area. A potential NE source is envisaged Terra Nova, 00, 1–9, 2012