Sub-bottom seismic profiler for geoarchaeological and palaeoenvironmental research

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NSERC RTI funding is requested for purchase of an Edgetech 3400 sub-bottom profiling (SBP) system. The sub-bottom profiler employs broad-band (2-16 kHz), frequency-modulated `chirp' sonar pulses to produce  detailed seismic images of the sediment stratigraphy in shallow lakes, lagoons and marine basins. The highly portable (26 kg) Edgetech 3400 system can be deployed from small survey boats (e.g. Zodiac inflatables) and produces high-resolution seismic records in shallow water environments (< 2 m). Seismic penetration of up to 50 m can be achieved in silt and mud and thin sediment layers (< 10 cm) resolved. The new Edgetech SBP equipment is urgently required to replace an obsolete seismic profiling system purchased in 2004. The new Edgetech 3400 SBP system will support multi-disciplinary geological and geoarchaeological research in the Great Lakes and the Mediterranean. In the Great Lakes, the NSERC-funded research will employ measurements of the physical and geochemical properties of lake sediments to better understand the frequency of large storm events in the lower Great Lakes over the past 8000 years. During large storm events, storm waves over top sandy beach barriers depositing distinctive overwash sand layers in coastal lagoons. Storm layers are also deposited in lakes by the flood discharge of rivers. These deposits ('tempestites') can be identified in sediment cores extracted from the lake bed based on their sedimentary characteristics (grain size, microfauna, magnetic properties) and geochemical composition. Radiocarbon dating of pollen in storm event layers provides a detailed chronological record of storms and extreme weather events. Sub-bottom seismic profiling of coastal lagoons with the Edgetech 3400 will allow mapping of the thickness and 3-dimensional arrangement of lagoon sediments and storm layers. The high-resolution lake sediment record will allow McMaster researchers to assess whether the frequency of storms has been different in the past, and whether variability in storminess is linked to climate variables, such as past changes in temperature and precipitation. These data are critical for evaluating predicted changes in storm frequency and will assist in the development of emergency and infrastructure planning for heavily populated areas of the Great Lakes that are at risk from severe weather.  In the Aegean, seismic profiling of nearshore coastal sediments will better resolve sea level changes, paleoshoreline positions and the potential locations of drowned prehistoric coastal settlements and ancient harbour sites. The sub-bottom profiler will provide 8 high-qualified personnel (HQP's) at McMaster and Brock University with critical hands-on skills and field experience in marine seismic survey methods, data processing and interpretation. These HQP skills are broadly applicable in geosciences research and currently in high demand by private and public sector employers.