Siliciclastic and bioclastic contouritic sands: Textural and geochemical characterisation

Abstract The purpose of this study is to differentiate and characterise contouritic sands in two different locations with variable sediment compositions (siliciclastic bioclastic) based on a multiproxy approach that includes the analysis sedimentary texture, semi-quantitative geochemistry, microfacies ichnological information, as well Principal Component Analysis (PCA) applied geochemical data cores. integration sedimentological analyses PCA permits also differentiation between fine-grained deep-water deposits such hemipelagites, muddy contourites hyperpycnites. A depositional model proposed here, characteristics Holocene-highstand Mozambique Channel upper slope sands, glacial-lowstand Corsica Contourite Depositional System middle sands. continental Mozambican margin characterised by siliciclastic sandy contourites, constitute large accumulations well-sorted very fine coarse sand evidences strong winnowing reworking under high-energy conditions. facies represents highstand contourite shows reversely-graded trend. drift Pianosa ridge (eastern flank Trough) consists bioclastic hemipelagites. Bioclastic are made up shallow-marine winnowed bioclasts reversely- normally-graded trend represent lowstand environments —showing distinctive signal— allows for deposits. In marked an accumulation Si, Zr, Sr fine- medium-grained less evident but it Ca Sr. bottom current effects observed at scale. Both types show intermittent conditions depending ichnodiversity, distribution abundance trace fossils. This work useful discriminate similar margins which would contribute better understanding processes deep-marine environments.