Abstract: Facies Distribution and Stratigraphy of the Sauk Sequence
(Cambro-Ordovician) of Niagara County (Western New York)
Mossbah M. Kolkas, Gerald M. Friedman
The Sauk Sequence
(Cambro-Ordovician) of Niagara County (Western New York) is represented by the Beekmantown Group which rests unconformably on Precambrian basement complex and is separated from the overlying Tippecanoe
Sequence
by an interregional unconformity, called post-Sauk Unconformity. The Beekmantown Group consists of the Potsdam, Theresa, and Little Falls formations. The older is being Potsdam and the younger is Little Falls. However, the stratigraphic boundaries between these three formations are still uncertain.
Petrographic analysis
of the core samples that were collected from Waste Disposal Test
Well
# 1, Niagara County, New York indicates that the Beekmantown Group (Sank
Sequence
) of this region was deposited in a shallow marine of tidally influenced environment. A shalllowing upward
sequence
of six different lithofacies has been recognized. These lithofacies are as follows: 1) conglomeratic sandstone; 2) interbedded silty glauconitic limestone; 3) stromatolitic dolostone; 4) highly bioturbated dolostone; 5) irregularly laminated silty dolostone; and 6) coarse-grained dolomitic quartz sand. Each of these lithofacies has been divided into sublithofacies on the basis of mineralogy, texture, sedimentary microstructures, and fabrics.
Continuous fluctuation of sea level during the Cambro-ordovician period controlled the cyclic sequence
within the lithofacies.
Irregular porosity throughout the facies is due to varying depositional conditions and different diagenetic modifications.
AAPG Search and Discovery Article #90954©1995 AAPG Eastern Section, Schenectady, New York