Earth Sciences

Kevin Pickering has been invited to give one of the three keynote plenary session lectures at the 29th International Association of Sedimentologists Meeting in Schladming, Austria, 10th - 13th September 2012. His 1-hour lecture will be an overview on " Identifying tectonic and climatic drivers for deep-marine siliciclastic systems".

ABSTRACT: The analysis of sedimentary records in deep time requires the deconvolution of tectonic and climatic drivers, from cyclic to irregular, and at a range of temporal scales, e.g., instantaneous, seasonal/annual, inter-annual, decadal, centennial, millennial, and millions to tens of millions of years. Any interpreted astronomical forcing should be placed within the context of sufficient insolation changes to drive global climate change to impact on the sedimentary record, including the potential presence of any modulating frequencies. This critically depends upon obtaining high-resolution chronostratigraphic records, ideally in linked sedimentary basins that permit the study of source-to-sink, something that generally becomes increasingly more challenging further back in time. A thorough appreciation of the tectonic processes in the source area, sediment-routing systems and deep-water receiving basin is essential. Additionally, any interpretations of the importance of controls on deposition (and erosion) should recognise the likely changing importance of physical and chemical weathering, and therefore the nature of any source area, during icehouse versus greenhouse (and transitional) periods in Earth history. Landscape modelling with numerically-based simulations of cyclically changing sediment flux, sediment calibre, gradients linked to with tectonics, etcetera, can provide useful insights and possible constraints on the controls on sedimentary systems, such as allocyclic versus autocyclic processes, but should be seen as models that show what is possible and not necessarily reality. Petrographic (including diagenetic), geochemical (including stable isotope) and palaeontological (including trace-fossil) data are also critical to any interpretation of drivers in sedimentary systems. In our attempts to understand the natural world and to reconcile all available data, a combination of detailed observational, experimental and theoretical work in carefully selected linked sedimentary environments is essential. Fieldwork continues to play an extremely important part in this work. Whilst it might seem to some that the applied and theoretical aspects of this research are different, a rigorous and robust understanding of deep-marine systems from sediment-transport and depositional processes, to system and basin-scale development, their drivers and any rate-magnitude changes, benefits all of us who are interested in understanding Earth surface processes for purely intellectual reasons and/or for their economic benefits. This presentation, drawing on my experience in many sedimentary basins in different tectonic settings, focusses on both modern and ancient deep-marine systems, and explores many of the complex issues involved in trying to understand their temporal and spatial development, suggesting where future research efforts might be most profitably directed, for example, through integrated outcrop-subsurface studies.