Temporal and spatial distribution of biozones and facies relative to geochemically correlated K-bentonites in the Middle Ordovician Taconic Foredeep

The Middle Ordovician rocks of the Taconic foredeep in the Mohawk Valley, New York, contain numerous altered volcanic ash beds (K-bentonites). These synchronous beds have the potential to link disparate facies in a way that is not feasible with biostratigraphy or sequence stratigraphy alone. Geochem...

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Bibliographic Details
Published in:Geology (Boulder) 1994-08, Vol.22 (8), p.715-718
Main Authors: Mitchell, Charles E, Goldman, Daniel, Delano, John W, Samson, Scott D, Bergstrom, Stig M
Format: Article
Language:English
Subjects:
basins
bentonite
biostratigraphy
biozones
central New York
chemostratigraphy
clastic rocks
correlation
fore-arc basins
framework silicates
geochemistry
Geology
Graptolithina
Herkimer County New York
inclusions
Invertebrata
K-bentonite
lithofacies
lithogeochemistry
Marine
Middle Ordovician
Mohawk Valley
Montgomery County New York
New York
Ordovician
Paleozoic
phenocrysts
Plate tectonics
quartz
sedimentary rocks
silica minerals
silicates
spatial distribution
Stratigraphy
Taconic Orogeny
temporal distribution
United States
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Summary:The Middle Ordovician rocks of the Taconic foredeep in the Mohawk Valley, New York, contain numerous altered volcanic ash beds (K-bentonites). These synchronous beds have the potential to link disparate facies in a way that is not feasible with biostratigraphy or sequence stratigraphy alone. Geochemical fingerprinting of glass inclusions within volcanic quartz phenocrysts permits unambiguous matching of the compositionally unique ash layers. The resulting correlations demonstrate that time lines based on the graptolite biozones and transgressive-regressive facies patterns parallel the K-bentonite isochrons. They also demonstrate that much of the upper Trenton Group is older than previously believed and facies relations are markedly different from previous interpretations. Although some facies patterns appear to be synchronous across the region, the likely existence of substantial structural control on facies development in the basin suggests that it is unwise to attribute these patterns to eustatic sea-level changes.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1994)022<0715:TASDOB>2.3.CO;2