Nonmarine facies of the Middle and Late Devonian Catskill coastal alluvial plain

Abstract

Nonmarine Catskill facies were deposited by many rivers flowing northwestward from an eastern source area and comprise a suite of sedimentary rocks that (1) thin and decrease in average grain size from southeast to northwest, (2) increase in average grain size from base to top, (3) are dominantly red in color, (4) are variable both laterally and vertically, and (5) were deposited mainly by either meandering or braided streams. The marine to nonmarine transition is a complex interval composed of various facies that represent repeated alternations of marine and nonmarine depositional environments. It is frequently many tens of meters thick. Meandering-stream deposits comprise sandy to gravelly, crossbedded, channel facies and finer-grained, overbank facies arranged in fining-upward sequences. Delta-plain meandering-stream deposition was by streams of low gradient, high sinuosity, shallow water depth, and low erosional capability. The cycles generated are usually only a few meters thick and are dominated by finer-grained floodbasin sediments. Alluvial-plain meandering-stream deposition was by streams of moderate to high gradient, moderate sinuosity, moderate water depth, and moderate to large erosional capability. The generated cycles are frequently many meters thick, dominated by the coarse-grained, channel facies, and show evidence of considerable channel erosion. The braided-stream facies comprises trough-crossbedded sand deposited in shallow to moderate water depths on an alluvial plain. These deposits are almost exclusively gray in color and are sandwiched between the delta-plain and alluvial-plain meandering-stream sequences. The end of Catskill deposition was accompanied by local erosion of the alluvial plain, basin-wide transgression, and demise of the Acadian Mountains as a source area.

Late Devonian glacigenic and associated facies from the central Appalachian Basin, eastern United States

“…These glacigenic deposits both rest on and are overlain by alluvial-plain strata that contain highsinuosity fl uvial facies (Sevon, 1985;Bjerstedt and Kammer, 1988;Brezinski, 1989b), which were deposited very near the marine seaway (Pepper et al, 1954) (Fig. 2A).…”

“…The coarse-grained sand and granule-to pebblesize clasts and planar to trough cross-bedding that characterize this facies are typical of lowsinuosity streams of braided fl uvial environments (Miall, 1977). Based upon the low-relief geologic setting proposed for the lower Rockwell and Spechty Kopf Formations (Sevon, 1985;Bjerstedt and Kammer, 1988;Brezinski, 1989b), the presence of low-sinuosity streams tends to suggest a river system that may have been sediment-choked (Miall, 1977;Edwards, 1978;Miller, 1989Miller, , 1996Hambrey, 1994;Benn and Evans, 1998). Thus, the pebbly sandstone facies is interpreted as braided fl uvial deposits formed in an outwash plain environment in which the streams were choked with sediments from the melting ice (Table 1).…”

“…The recent recognition of Late Devonian glacially derived strata from the eastern United States is signifi cant (Cecil et al, 2004;Brezinski et al, 2008). These interpreted glacial deposits are contained within facies that had been previously interpreted as lowgradient alluvial-plain deposits (Sevon, 1985), at a time when the Appalachian Basin was inferred to be between 30°S (Scotese, 2008) to 45°S (Heckel and Witzke, 1979;Blakey, 2008). The current study describes and interprets the facies and facies architecture of the diamictite succession, which suggest that these rock units are not the typical ancient glacial sediments reworked by marine processes and resedimented, but are in situ terrestrial glacigenic deposits.…”

First Articulated Phyllolepid Placoderm from North America, with Comments on Phyllolepid Systematics

“…Climate regimes were tropical with alternating wet and dry seasonality. High rates of sedimentation in the basin formed a series of fluvial and deltaic systems of the Catskill Delta Complex (Sevon, 1985).…”

A Mechanism for Tectonic Inheritance at Transform Faults of the Iapetan Margin of Laurentia

“…Lower Mississippian coalbearing sandstones and Middle Mississippian redbeds and evaporites prograded cratonward and southwestward along the continental margin over the Catskill redbeds (Thomas and Schenk 1988). Successive depocentres shifted progressively southwestward along the continental margin from the Pennsylvania embayment onto the Virginia promontory in response to dextral transpression of the tectonic load (Ettensohn 1985(Ettensohn , 2008Sevon 1985;Ferrill and Thomas 1988;Thomas and Schenk 1988).…”