Paper No. 219-11
Presentation Time: 9:00 AM-6:30 PM
MINERALOGICAL ANOMALIES AS STORM INDICATORS ALONG NONTIDAL (BLACK AND BALTIC SEA COASTS) AND MICRO-TIDAL (CENTRAL NEW JERSEY, USA) COASTS: RECENT OBSERVATIONS AND GEOLOGICAL EVIDENCE
Mineralogical density lag deposits, especially when associated with other sedimentological and morphological features, serve as reliable indicators high-energy events on sandy coasts. Regardless of provenance, heavy-mineral concentrations (HMCs) provide valuable information about the waning stage storm dynamics, prevailing aeolian and hydrodynamic conditions, and accretionary-erosional processes. This research focuses on HMC occurrence following intense storms at time scales from 2 weeks (Storm Felix, 2015; Curonian Spit, Baltic Sea, Lithuania) to 30 months (Hurricane Sandy, 2012; Island Beach State Park, New Jersey USA), as well as for historical storms (Odessa region, Black Sea, Ukraine). Low-field magnetic susceptibility (MS) served as a proxy for ferrimagnetic and paramagnetic components. Repeated measurements at the Curonian Spit site, showed that lower MS values prevail two weeks following the storm as sediment is undergoing active transport, with near doubling recorded ten weeks later. The New Jersey overtop deposit experienced decimeter-scale deflation and reworking of Hurricane Sandy HMC laminae (basal parts of surge couplets) into a variety of bedforms and patchy accumulations. Along the baymouth barriers of southwestern Ukraine, in situ MS values of garnet-rich horizons within 100-200-year-old beach-ridge deposits are two orders of magnitude greater than those on the modern berm, the latter likely the result of persistent wave or aeolian winnowing. Our findings demonstrate the importance of considering time averaging and post-depositional processes when utilizing mineralogical anomalies in paleotempestological research.