MINERALOGICAL ANOMALIES AS PALEO-ENERGY PROXIES IN LATE HOLOCENE COASTAL LITHOSOMES OF ESTONIA AND LITHUANIA

Hydrometeorological anomalies along the eastern Baltic Sea coast are archived in sedimentological record, such as heavy-mineral concentrations (HMCs) that range in thickness and magnitude. The ferrimagnetic fraction (mostly magnetite), as well as paramagnetic minerals (garnet, ilmenite, and others) were identified and mapped using bulk low-field magnetic susceptibility (MS) of two Holocene strandplains of the Estonian archipelago (Hiiumaa and Saaremaa Islands) and the originally anthropogenic foredune of the Curonian Spit, Lithuania. MS measurements were obtained both in situ (upper beach, foredune front, trench walls) and on core subsamples. At the northern Hiiumaa site, Late Holocene strandplain sections are dominated by diamagnetic (quartz-rich) lithosomes characterized by very low MS values (<20 μSI; rarely exceeding 100 μSI). On the western Saaremaa site, compound ridges formed since the early 1700s show an inverse MS relationship with age, with MS values commonly exceeding 300 μSI. Similarly, along the northern Curonian Spit, the majority of MS values range between 100-400 μSI. Some anomalies at the two latter sites exceed 1000 μSI. These findings show that despite the proximity between the two largest Estonian islands, differences in source lithologies and mineralogical density segregation of glacially derived and subsequently reworked sand fraction produced a vastly contrasting coastal lithosome compositions there, compared to larger-scale trends along the E/SE Baltic Sea coast (Estonia-Latvia-Lithuania-Russia-Poland). Mineralogical anomalies can be used to quantitatively constrain near-surface shear stress for energy conditions just below the erosional regime recorded as disconformities. In addition, MS anomalies produce high-amplitude electromagnetic signal response in ground-penetrating radar images (70-400 MHz survey datasets), thereby providing subsurface continuity and guiding coring and luminescence dating efforts. Our research establishes magnetic susceptibility as a rapid and effective means of not only assessing sediment provenance, but also for quantifying spatial and temporal changes in overall wave/wind climate and extreme events on decadal to millennial scales.