ANALYSIS OF WIND AND WAVE DATA FROM THE LIMITED-FETCH EPICONTINENTAL LACUSTRINE SETTING OF THE SOUTHERN LAKE MICHIGAN BASIN AS A POTENTIAL ANALOG FOR ANCIENT EPICONTINENTAL MARINE WAVE-DOMINATED REGIMES

Analysis of high-resolution wave data from western Atlantic marine buoys has been shown to demonstrate mono-modal spectral density functions. This observation, derived from a decade of data from dozens of buoys, has been utilized to challenge the long-held notion of differentiation in sedimentary processes experienced along shorelines between “fair-weather” and “storm” conditions. This important contribution does not, however, address the fact that many of the sedimentological features interpreted to differentiate shoreface (fair-weather oscillatory flow) from transitional (storm combined oscillatory and unidirectional flow) depositional systems have been identified within inland seas rather than along divergent margin marine settings such as the modern Atlantic seaboard. Therefore, we have undertaken an analysis of wind and wave data from the limited-fetch epicontinental lacustrine setting of the southern Lake Michigan basin as a potential analog for ancient epicontinental marine wave-dominated regimes.

The southern basin of Lake Michigan provides an ideal setting to evaluate the validity of the distinction between fair and storm weather processes due to the presence of several meteorological buoys positioned around the southern shoreline recording near-shore processes as well as a buoy located in the center of the southern basin recording open lake conditions.

Preliminary analysis of wind and wave data from the 2016 ice-free season at Station 45168, South Haven Buoy along the eastern shore of Lake Michigan (42.397 N, 86.331W, 20.4 m water depth), demonstrate pronounced bimodality in the frequency of occurrence of wave periods. Modal peaks are identified in the wave length bands between 2.0 and 2.5 m and 3.0 and 4.0 m. Importantly, these distinct peaks in wave length spectral density are found to also record distinctly different wave directions and wave heights. On-going analysis will consider the other near-shore and central basis buoy data in order to construct a composite model of ancient epicontinental, limited-fetch, wave-dominated depositional settings.