Marine transgressions and regressions recorded in Middle Devonian shore-zone deposits of the Catskill clastic wedge
The shore zone of the Middle Devonian Catskill clastic wedge in New York State consists of (1) a storm-wave-dominated muddy marine shelf with sandy shoals; (2) sandy, tide-influenced channels with wave-and tide-influenced mouth bars; (3) sandy and muddy tidal flats, including channels, mouth bars, and washovers; and (4) muddy brackish bays, lakes, and flood plains. The spatial organization of these subenvironments suggests a wave- and tide-influenced deltaic shoreline. Meter-scale sequences can be related to processes such as lateral migration and filling of tidal channels, progradation of channel-mouth bars and tidal flats, and filling of coastal bays; these may be related to channel switching. Asymmetrical regressive-transgressive sequences that range from tens of meters to >100 m thick can be correlated over many kilometers with fully marine and fluvial deposits. Such sequences record a combination of eustatic sea-level changes and tectonically induced changes in sediment supply and subsidence rate. However, at present it is very difficult to determine the relative importance of these controls.