Markes E. Johnson
Relationship of Silurian sea-level fluctuations to oceanic episodes and events

Keywords
Silurian System, paleocommunities, eustasy, oceanic events, paleoshores, chemostratigraphy, proximality analysis

Abstract
Eight distinct highstands in sea level emerged from the author’s study of the Silurian System on a continent-to-continent basis during the 1980s and 1990s. Some emendations are needed to accommodate other trends recognized since that time, but the overall pattern is strong. Five major highstands and one minor highstand fit the Lower Silurian (Llandovery and Wenlock series). Three major highstands fit the Upper Silurian (Ludlow and Prídolí series). Three separate episodes of glaciation correspond to drops in sea level from the Lower Silurian but fluctuations recorded in the Upper Silurian have no clear cause. Many oceanic events share common trends when the relationship with sea-level fluctuations is tested against a tight biostratigraphic framework. The Sandvika Event correlates with a sea-level drop between the second and third highstands from the Llandovery Series. An unnamed secundo-primo event overlaps the fall between the third and fourth highstands. The Ireviken Event corresponds to a drop near the basal Wenlock. The Boge Event matches a minor draw down superimposed on the fifth rise from the Sheinwoodian Stage. The Mulde Event partly fits a drop in the Lower Homerian Stage. The Linde Event corresponds to the low between the sixth and seventh peaks from the Ludlow Series and the Klev Event fits the lowstand between the seventh and eighth peaks near the Ludlow–Prídolí boundary. The Lau Event, however, appears to adjoin the seventh highstand. No known event corresponds to the draw down between the first and second sea-level peaks recorded in the Llandovery Series.

Author info
Department of Geosciences, Williams College, Williamstown, Massachusetts, 01267, USA; markes.e.johnson@williams.edu

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