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To achieve a more robust interpretation of sediment conditions and transport based on grain size, this study combines the perspectives of two different interpretation techniques that have been developed separately and applied in the literature: (i) ‘grain size trend analysis’ interprets changes between interrelated sampling sites assuming that sediment in the direction of transport should become either coarser, better sorted and more positively skewed, or finer, better sorted and more negatively skewed; and (ii) the ‘population anomalies’ method, which estimates the balance between erosion and accumulation processes at each sampling site based on individual site deviations compared with average values for grain-size parameters in the area of interest. The simultaneous use of both approaches enables sedimentological conditions and transport alternatives to be distinguished. This improvement is necessary because site-specific changes and general textural trends provide information that complements the strengths and weaknesses of each perspective. The methods are implemented here using two-dimensional Geographic Information System tools and illustrated for the Lithuanian coast. Grain-size characteristics of 712 surface samples of sandy sediments are used to interpret sediment transport pathways and predominant sedimentological conditions in the Lithuanian coastal zone. In general, coast-parallel sediment transport dominates the entire investigation area, although wave-induced movement perpendicular to the coastline is inferred in the shallow nearshore zone. The deepest areas offshore are characterized by sea floor erosion in the north, whereas an accumulation zone occurs in the relatively deep central part of the study area.

A quantitative provenance approach is developed and in this study applied for the silt and clay fractions of sandy, coastal deposits. Mineralogical composition of 37 surface samples was determined by X-ray diffraction (XRD). Grain-size distributions were obtained by standard dry sieving and pipette techniques. The characterization of mineralogical provenance is based upon known compositional information of possible sources, logical models for mineral combinations related to regional geological provinces and processes, and geographical features of the documented mineral distribution in the area of investigation. These interpretations are further supported by results of correlation and principal component analyses of mineral varieties, grain-size parameters and bathymetric features of the area. Partitioning of source contributions specific for each site of deposition is derived by solving simultaneous equations. Then, the quantified mineral composition at the initial source is reconstructed in the SE Baltic Sea along the Lithuanian coast, exemplifying this new methodology for quantification of sediment sources. The main sources supplying sediment to the area are: 1) Sambian Peninsula to the south (erosion of Pleistocene till and “Blue Earth” Paleogene sediments), supplying 33% of fine-grained sediment on average, 2) Nemunas River, the discharge of which passes through Curonian Lagoon and supplies an average 17% of the coastal fine sediments, and 3) Pleistocene till, eroded on the sea floor in the north and at the Olando Kepurė shore cliff and contributing an average of 50% of the sediment. Although we use the mineralogy within the environmentally important fine-grained fraction, this mathematically simple approach could be used with any other parameters characterizing the identified sources. A quantification of the separate source contributions to each individual site of accumulation studied, using the stable, mineralogical components of the “sediment archive”, offers a time-integrated, net-effect reflection of the combined processes of an entire environmental system.

Mineralogical analysis of the silt and clay fraction of sandy deposits of 37 surface samples and grain-size data are used to interpret sediment sources acting in the SE Baltic Sea along the Lithuanian coast. Mineralogical composition was determined using X-ray diffraction (XRD) methods. Grain-size distribution was obtained by standard dry sieving and pipette techniques. For identification of sources we combined known compositional information of possible sources with logical models for mineral combinations related to regional geological provinces and processes, supported by results of correlation and factor (principal component) analyses between minerals, grain-size parameters and bathymetric features of the area. The main sources supplying sediment into the area are: 1) the Sambian Peninsula to the south, 2) the Nemunas River, whose discharge passes through the Curonian Lagoon, and 3) Late Pleistocene till erosion on the sea floor in the north and at the Olando Kepure shore cliffs. The general pattern of spatial distribution related to the identified sources for the fine-grained sediment fraction is interpreted as a shore-parallel transport of suspended matter, flowing northwards in the southeastern part of the Baltic Sea.