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

Abstract

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

Carbon cycle history through the Jurassic–Cretaceous boundary: A new global δ13C stack

“…Hungary compared with datasets from other Tethyan, Atlantic and Pacific locations (Weissert and Channell, 1989;Weissert and Mohr, 1996;Katz et al, 2005;Coimbra and Olóriz, 2012;Žák et al, 2011).…”

“…To serve both purposes, Late Jurassic-Early Cretaceous carbon isotope stratigraphies have been developed extensively from pelagic sediments of the Tethys Ocean and Atlantic (e.g., Weissert and Channell, 1989;Bartolini et al, 1999;Katz et al, 2005;Tremolada et al, 2006;Michalík et al, 2009;Coimbra et al, 2009;Coimbra and Olóriz, 2012). Weissert and Channell (1989) documented how the Late Jurassic carbonate carbon isotopic composition shifts from δ 13 C values of around 2.5‰ in the…”

Regression trees for modeling geochemical data—An application to Late Jurassic carbonates (Ammonitico Rosso)

“…Isotopic values are reported in the standard δ-notation in per mil (‰) relative to Vienna-Pee Dee Belemnite (V-PDB) and elemental abundance in absolute values (ppm). All geochemical measurements were performed at the facilities of the Institute for Geology, Mineralogy and Geophysics, Ruhr University Bochum (Germany), for details on used equipments and analytical precision see Coimbra et al (2009Coimbra et al ( , 2014 and Coimbra and Olóriz (2012b). Photomicrographs of thin sections produced from each hand specimen provided a quantitative estimate of skeletal abundance by means of pixel counting (Coimbra and Olóriz, 2012a and examples shown in Fig.…”

“…This contribution reports the application of regression trees to a previously explored ancient carbonate record (Coimbra et al, 2009(Coimbra et al, , 2014Coimbra and Olóriz, 2012b). This approach is, to the knowledge of the authors, attempted here for the first time.…”

“…This is well exemplified in near-shore areas where a marked continental influence can result in mixed terrestrial and marine geochemical signals (e.g., Vincent et al, 2006). In more distal, increasingly open marine settings, global trends can often be recognized in marine carbonate records (e.g., Weissert and Mohr, 1996;Dera et al, 2011), but local and regional signals may also be superimposed (e.g., Immenhauser et al, 2002;Swart, 2008;Coimbra and Olóriz, 2012b). Spatial differences can then be expected when dealing with materials that cover a wide range of marine depositional environments.…”