RECOGNITION OF ACADIAN OROGENY TECTOPHASES IN TERRESTRIAL STRATA AND CORRELATION WITH THE MARINE IN THE MIDDLE DEVONIAN STRATIGRAPHY OF THE APPALACHIAN BASIN IN CATSKILL STATE PARK, NEW YORK, USA

Middle Devonian terrestrial strata deposited in the Appalachian foreland basin and exposed along Plattekill Creek in southeastern New York exhibit a three-tier hierarchy of depositional cyclicity controlled by tectonic pulses during the Acadian orogeny as the island arc Avalon collided with Laurentia. Through 580 m of section, 206 fluvial aggradational cycles (FACs) are recognized as fining-upward successions that are commonly capped by paleosols, with an erosional contact with overlying coarser-grained deposits. Through cumulative deviation from mean FAC stacking pattern (CDM) and paleosol maturity analysis, 26 decameter-scale fluvial aggradational cycle sets (FAC sets) and 7 fluvial sequences are defined. Within fluvial sequences, transgressive systems-tract equivalents (TE) are characterized by increasing FAC thickness and dominated by sandstones with few paleosols that are relatively immature and poorly-drained. Highstand to falling-stage systems-tract equivalents (HFE) are predominately overbank deposits, with relatively thin FACs, and increase in mature, well-drained paleosols as compared to the TE. Fluvial sequence boundaries separate sequences and are defined by changes in fluvial deposition from suspended-load with mature paleosols to bed-load with few paleosols. Geochemical analysis for selected pedotypes within the section compliment system tract equivalents indicating more mature well-drained paleosols near sequence boundaries and less mature, poorly drained paleosols during TE. Paleo-precipitation proxy CALMAG shows a mean annual precipitation (MAP) of ~1600 mm/year, however, near sequence boundaries lower estimates are found as a result of increased CaO from base-level fall or aquic paleosols. When compared with modeled marine water depths in response to basin subsidence, the CDM trend of increase, decrease, and subsequent increase follows changes in accommodation in the Appalachian Basin through time. The major inflection point in the CDM corresponds to an Acadian orogeny tectophase creating basin subsidence and increased accommodation. The Middle Devonian terrestrial strata in southeastern New York State have a base-level history that corresponds with tectonic pulses related to the Acadian orogeny, which can be correlated from terrestrial to marine sections.