An interval in the shale-dominated lower pan of the Mount Marion ..... 1.7 km SSE of Helderberg L.:'lke; ( 15) Roadcut along Cole Hill Road, 2.0 km southwest of ...
Ver Straeten, C.A., 1994, Microstratigraphy and depositional environments of a Middle Devonian foreland basin: Berne and Otsego Members, Mount Marion Formation, eastern New York State: in Landing, E., ed., Studies in Stratigraphy and Paleontology in Honor of Donald W. Fisher, New York State Museum Bulletin 481, p. 367-380.
Microstratigraphy and depositional environments of a Middle Devonian foreland basin: Berne and Otsego Members, Mount Marion Formation, eastern New York State Charles A. Ver Straeten New York State Geological Survey The State Education Department, Albany. NY 12230 present address: Department of Geological Sciences, University of Rochester Rochester, NY 14627 ontology and on establishing formation- and ml'mhcr-kvd stratigrapltir subdivisions (Darton, 1H94; Prosser. 1894. 1X97; Grabau, 1917, 1919; Cooper, 1933, ll)4J; Chadwick, 193J, 1944; Goldring, 19.~5. 1943; Lane. 195.5) More recent work hy Wolff (1967, 1969, 1979) has concentratell on lithologic l'OITdation of units f'rom thl~ Schoharie Valky to the Hudson Valley. and on recognition of the marine to tluvial transition in the I Iamilton Group rocks along thl~ Cittskill From (Sl'l' Fi g~lrl's I, 2). The purpose ot' this study has been to cJctcn11inl' whether or not relatively thin shell-beds and unique lithostratigraphi(' packages could be traced section to section through a dominantly unfossilifcrous. offshore marine shale interval.
Abstract An interval in the shale-dominated lower pan of the Mount Marion Formation in eastern New York State has at least twenty-three regionally correlatable event beds and shon-tern1 to isochronous faunal and lithologic units within a relatively unfossiliferous, shale-dominated sequence. A local coral-brachiopod biostrome, units with characteristic fossil assemblages, and distinctive sandstone packages allow microstratigraphic subdivision of a 65 m-thick interval of the Fonnation. Key horizons are traceable south to north (Kingston to Clarksville) for 85 km along depositional strike. and 25 km west into this foreland basin to the Schoharie Valley. Formal names are proposed for four key beds within the interval: the Dave Elliott Bed, Halihan Hill Bed, Katsbaan Bed, and Timmerman Hill Bed. Recognition of a shell-bed-rich shale interval at the base of the Otsego Member in the absence of a locally occurring coral-brachiopod biostrome allows correlation of the previously untraceable base of the Member. Regional lithologic and sedimentologic study indicates that the base of the Otsego Member is somewhat diachronous along the outcrop belt. apparently as a result of erosive beveling associated with a relative lowstand in sea level at the Berne-Otsego Member boundary. A revision of the ba."e of the Otsego Member is proposed; this revision places the base at the base of a coral-brachiopod biostrome or shell-bed-rich shale, and not below a locally underlying. massive sandstone unit.
Geological setting Marine siliciclastic rocks of the Mount Marion Fonnation (Middle Devonian Hamilton Group) arc the basinward part of a prograding dastic wedge that accumulated with erosion of the Acadian Orogen (sec Fa ill. ll)X.5; Woodrow, 19X5; Ettcnsohn. I 9R.5a). Lithospheric downwarping associated with teUonic loading ( ~ c· l~ttensohn. llJX5h; Beaumont et al.. 19XX ). com hi ned with a eustatic sea-kvcl risl' (I'- I~ cycle ld of Johnson et al., IYR.5 ). ended carbonate illy '>hale. A few . . cattcred small rugosans, ~orne apparently corroded prior to burial, arc accompanied by crinoidal debris-rich cla
