OPTIMISING INSIGHT INTO SEDIMENTARY SYSTEMS USING MULTI-PROXY PROVENANCE APPROACHES (Invited Presentation)

The supply and transit of sand into and through sedimentary systems is controlled by the complex interaction of a number of factors, including the nature of the bedrock, climate, tectonics and paleogeography. Provenance studies often focus on constraining the primary sources of sediment but, ideally, they should also offer insight into these underlying controls. Unfortunately, regardless of the provenance technique employed, such studies are hampered by a range of common problems. By its very nature, the source of detritus no longer exists and correlation/comparison of provenance signals relies on the preservation of a remnant with the same signature. Even if such a remnant is preserved, some commonly applied tools can produce equivocal results as the potential remnant source areas may be inadequately characterised. Furthermore, the abundance of mineral phases in the source/s (fertility) varies depending on the lithology. In addition, certain approaches can fail to identify and/or quantify mixing of multiple sources or incorporation of polycyclic sand grains. Provenance signals recorded by specific minerals can be modified during transport, intermediate storage or post-deposition. Each of these factors has the potential to obscure information that can otherwise better constrain the evolution of modern/ancient drainage systems, sedimentary basin infill and surrounding hinterlands.

However, an integrated, multi-proxy approach can overcome some of these issues. For example, provenance fingerprints (e.g. U-Pb age, trace element and / or isotopic data) from individual sand components with a range of stability - from robust zircon grains, through apatites (unstable in acidic weathering conditions), to labile feldspars - can be interrogated, such that the roles of sedimentary recycling, mixing and signal alteration can be evaluated. Understanding the sedimentological context of individual samples is also key as detritus can be fractionated or mixed in sedimentary environments within the same system.

The aim of this presentation is to explore how cryptic factors like those outlined above might be identified and quantified through the application of a bespoke multi-proxy approach, using examples of provenance studies from Upper Paleozoic - Mesozoic sedimentary basins onshore and offshore NW Europe.