Geochemical compositional mapping of Lower Jurassic trace fossils: Palaeoenvironmental significance and methodological implications

摘要: Abstract Analyses of X-ray microfluorescence (XRF) elemental maps the ichnofossil assemblages from upper Pliensbachian-lower Toarcian marl-limestone rhythmite South Iberian Palaeomargin (Betic Cordillera, SE Spain) show that compositions burrow infills are geochemically and mineralogically different with respect to surrounding sediment. XRF back-scattered electron images pyrite framboids within burrows enrichment in Fe S relative host This is congruent position beneath redox boundary at time their active or passive sedimentary infilling. Organic matter accumulated seafloor was not preserved due oxidation consumption by benthic organisms. However, located served as traps for organic preservation. The composition fills reflects original signal conditions pore-waters below sediment-water interface, which also some trace fossils limestone marly-limestone intervals contain high concentrations Si, Al, K, Zn, Cr, Ti may reflect clay minerals derived overlying marly layers. work proposes use imaging prior bulk-rock geochemical analyses order evaluate potential biogenic heterogeneity partitioning before sampling. Geochemical analysis represents an additional tool be hydrocarbon exploration.