A re-evaluation of the stratigraphy and sedimentology of the Day Point Formation (Chazy Group): A new look at old reefs

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5767854

Falkenberg, J; Mehrtens, C J ^[1]

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1. Vermont Univ., Burlington, VT (United States). Dept. of Geology

The Day Point Formation (Chazy Group, Middle Ordovician) outcrops in the Champlain Valley of New York and Vermont. The stratigraphy of the Day Point Formation is complex, containing lithologic sequences that are unique at different localities around the Champlain Valley. The formation exhibits complex lateral interfingering of seven lithofacies: (1) Highly bioturbated sandstone with symmetrical and bifurcating ripples. (2) Bioturbated, brachiopod rich, wackestone facies. (3) Planar cross-bedded, interlayered sand and sandy packstone. (4) Interlayered sand and shale grading into sand and limestone layers. (5) Grainstone which, at some localities, contains mound-shaped bryozoan reefs, at other localities thin non-reefal sheet-like layers are present. The grainstone also has planar laminated and cross stratified beds. (6) Fine-grained, calcareous sandstone with planar and herringbone cross bedding, which in places contains small bryozoan reefs and thin sheet-reefs. (7) Planar cross bedded packstone containing bryozoan reefs and thin sheet-like non-reefal layers. The thin reefal layers are found where the mound-shaped reefs are absent. The sand units are found only in the lower portion of the Day Point Formation. The bryozoan reefs and non-reefal layers are associated with the sand beds in the lower portion of the Day Point Formation, and either live within the sand or on top of it. The bryozoans that form the non-reefal layers, found in the limestones, are contained within thin layers of sand. In contrast, no sand is found in the upper section of the Day Point Formation, yet the bryozoan reefs flourish.

• OSTI ID: 5767854
• Report Number(s): CONF-9303211--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ANIMALS
AQUATIC ORGANISMS
BRYOZOA
CARBONATE ROCKS
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
INVERTEBRATES
LIMESTONE
LITHOLOGY
NEW YORK
NORTH AMERICA
ORDOVICIAN PERIOD
PALEONTOLOGY
PALEOZOIC ERA
PETROLOGY
REEFS
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
STRATIGRAPHY
USA
VERMONT