Times associated with source-to-sink propagation of environmental signals during landscape transience

Abstract

<p>Sediment archives in the terrestrial and marine realm are regularly analyzed to infer past changes in climate and tectonic boundary conditions. However, contradictory observations have been made regarding whether short period events are faithfully preserved in stratigraphic record. For example, short period events were hypothesized to be non-detectable in terrestrially derived sediments offshore large river system due to buffering during sediment transport. Other studies, however, have detected signals of short period events in sediments that were transported along large river systems. We think that this apparent discrepancy is related to the lack of a differentiation between different types of signals and the lack of distinction between river response times and times related to signal propagation.</p><p>To overcome these issues, we propose to define environmental signals more generally as “a measurable change in any sedimentary parameter of interest through time that can be linked to an environmental change” and to further group signals in sub-categories related to hydraulic grain-size characteristics. Also, we review the different types of ‘times’ and suggest a precise and consistent terminology for future use to clearly distinguish times of landscape response from times of signal transfer. We compile and discuss factors influencing the times of signal transfer along sediment-routing systems, how those times vary with hydraulic grain-size characteristics, as well as consequences regarding signal preservation in stratigraphy.</p><p>Unravelling different types of signals and distinctive time periods related to signal propagation addresses the discrepancies mentioned above and allows a more comprehensive exploration of event preservation in stratigraphy – a prerequisite for reliable environmental reconstructions from terrestrially derived sedimentary records.</p>