Organic-Rich Facies in Paraglacial Barrier Lithosomes of Northern New England: Preservation and Paleoenvironmental Significance

Abstract

ABSTRACT Geological controls on the origin and preservation of organic-rich facies in Holocene barrier sequences of northern New England are documented using sedimentological and geophysical databases. In addition to backbarrier marsh interfingering with washover/aeolian deposits, several distinct modes of organic accumulation are recognized in association with clastic barrier facies. These include: 1) basal lake gyttja or wetland peats (thickness: 0.1–2.5 m); 2) intra-barrier saltwater/freshwater horizons (0.01–1.2 m); and 3) foreshore peat exposures (up to 1.2 m). Freshwater peat and gyttja underlying barrier lithosomes below contemporaneous Mid-Holocene sea level suggest extensive backbarrier lake and wetlands, possibly due to a wetter climate. Present freshwater organics accumulate up to several meters below lake level, which is controlled by the elevation of groundwater table and, over the long term, sea level trends. In some areas, the saltwater-freshwater peat transition is attributed to cessation ...