Characterization of storm surge deposits along the shore of the Gulf of Gdańsk (Baltic Sea) applying heavy mineral analysis

Abstract

Recent studies along the southern Baltic Sea coast have revealed sedimentary records of catastrophic storm surges that significantly exceed the magnitude of storms documented by instrumental measurements. The present study aimed to apply heavy mineral analysis for storm surge deposits along coasts of Gulf of Gdańsk (southern Baltic), as well as for contemporary marine, beach, dune and coastal plain sediments, to test the applicability of the method and to provide new insights into the depositional processes and sediment sources of the storm deposits. The transparent, 0.125–0.25 mm heavy mineral fraction (>2.85 g/cm3) in 118 sediment samples was investigated, and the results were subjected to multivariate statistical analyses (cluster, PCA, LDA). Storm deposits showed higher concentrations of heavy minerals comprising enrichment in garnet, zircon, and rutile. General heavy mineral assemblage depended on regional provenance and primary sediment sources. However, flooding regime (overwash or inundation) played a key role in selective hydrodynamic sorting of grains and mineralogical composition of storm deposits. Interpretation of deposits formed in inundation regime was more certain than deposits formed in overwash regime. In the latter case, deposits showed more similarities to adjacent mineral provinces. Statistical analyses proofed that heavy minerals together with other sedimentological descriptors may be a promising proxy for recognition of deposits related to defined sedimentary environment or identification of particular sedimentological process, e.g. event layers resulted from storm surges.