Characterization of buried inundated peat on seismic (Chirp) data, inferred from core information

Abstract

Peat horizons provide a wide range of critical environmental and direct archaeological information for both archaeologists and Quaternary geologists. At present, such data are typically obtained from terrestrial exposures or cores, and occasional offshore cores. These data can provide invaluable and detailed site-specific environmental information but require a relatively high spatial sampling strategy to provide more regional-scale information. Through a comparison of laboratory, in situ acoustic and sedimentary analyses, this paper presents evidence to suggest that peat buried in fine to medium grained, marine, siliciclastic sediments has an easily identifiable acoustic signature. The very low densities recorded by buried peats result in a distinct negative peak in the reflectivity series. Comparison of synthetic seismograms with in situ seismic data confirms that this negative peak can be easily identified from seismic profiles. Reanalysis of a decade of Chirp (sub-bottom) data, acquired from the Solent Estuary, indicates that possible extensive peat deposits, dating from the Late-glacial to early Holocene, can be traced at depth in this estuary using geophysical methods. The results of this study could be significant for future research into submerged landscape reconstructions