MRCSP Phase I Geologic Characterization Report - Midwest ...

APPENDIX A: NIAGARAN/LOCKPORT THROUGH ONONDAGA INTERVAL
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Oriskany Sandstone—Harper and Patchen (1996); Opritza (1996);
Patchen and Harper (1996); Janssens (1997)
Bois Blanc Formation—Summerson and Swann (1970); Janssens
(1997)
Sylvania Sandstone—Gardner (1974)
Huntersville Chert—Weed (1982); Sherrard and Heald (1984);
Flaherty (1996)
Needmore Shale—Inners (1975)
Onondaga Limestone—Van Tyne (1996a); Janssens (1997); Bruner
and Smosna (2002)
Columbus Limestone—Janssens (1997)
Lucas Formation—Janssens (1997)
NATURE OF LOWER AND UPPER CONTACTS
Because this interval is a complex series of groups and formations,
the contacts are quite variable locally. The lower contact of
the entire interval is generally gradational with underlying strata,
which typically are clastics (shales and some sandstones). In Ohio,
where it has been examined in outcrop, the contact between the
Lockport Dolomite and underlying Rochester Shale is sharp and
conformable (Janssens, 1977). In other areas, such as northwestern
Pennsylvania, the contact is transitional between the underlying
shale and the dolostone.
In most localities in the MRCSP study area, the uppermost portion
of the Niagaran/Lockport through Onondaga Interval is overlain
by impermeable dark-gray to black shales or carbonates of the
Middle or Upper Devonian. The Middle Devonian Marcellus Formation
caps the interval in the east. A regional unconformity at the
boundary between the Middle and Upper Devonian (the Taghanic
unconformity) separates Upper Devonian shales of the “upper”
Olentangy Formation from similar lithology of the “lower” Olentangy
Formation in Ohio. This contact is variably sharp, particularly
where the unconformity cuts out Middle Devonian strata between
the Onondaga equivalent rocks and the “upper” Olentangy, but in
some cases the contact appears to be gradational. Along the flanks of
the Cincinnati arch, subaerial exposure and erosion at the Taghanic
unconformity progressively truncated rocks from Middle Devonian
(Onondaga) to Ordovician. Subaerial exposure resulted in porosity
development in some areas, and unconformity traps formed where
Upper Devonian black shales were buried the unconformity surface
(Meglen and Noger, 1996).
LITHOLOGY
Most of the strata in the Niagaran/Lockport through Onondaga
Interval are carbonates, variably dolostone and limestone, with
smaller amounts evaporates, and relatively minor amounts of
sandstones and shales. Great thicknesses of evaporates, mostly
anhydrite and halite, occur in the central Michigan basin and the
northern Appalachian basin. Shale is a minor component in this
interval, except in the east, in central Pennsylvania and Maryland,
and northward into New York. Sandstone is important locally (i.e.,
the Newburg sandstone of West Virginia and Ohio, and the Keefer
Sandstone of central Pennsylvania, Maryland, and eastern West Virginia),
although it typically is not very thick. The carbonate rocks
vary extremely in composition, with petrophysical textures ranging
from dense, laminated dolomicrites, to very porous and recrystallized
grainstones. In some cases, these grainstones are dolostones or
dolomitic limestones, whereas in others, they are limestones.
The Lockport is a fine- to medium-crystalline, slightly argillaceous
and fossiliferous dolostone that originated as a carbonate
shelf deposit that contained numerous scattered patch reefs. Ooid
bars, skeletal sand shoals, patch reef bioherms, lagoons, mud banks,
and sabkhas were also associated with this depositional setting
(Noger and others, 1996). Patch reefs consisted of corals, stromatoporoids,
bryozoans, and crinoids as the primary skeletal grains.
The facies change from reef to sand shoal is east to west (Smosna
and others, 1989). In Ohio, the Lockport consists of a lower white
to light-gray, coarsely crystalline, fossiliferous, vuggy dolostone,
whereas the upper part of the formation consists of very light- to
medium-brown, microcrystalline dolostone containing chert locally
(Janssens, 1977).
In Ohio and Michigan, the Salina Group consists of interbedded
dolostone, evaporite, and shale, and is subdivided into seven
units designated A through G in ascending order (Ulteig, 1964;
Clifford, 1973; Janssens, 1977; Mesolella, 1978; Tomastik, 1997)
(Figure A8-2). Recognition of evaporite beds on geophysical logs
allows for regional subsurface correlation of these units. In Ohio,
the Salina Group is present throughout most of the state, but the salt
beds are restricted to the eastern third (Clifford, 1973). Unit A, the
lowermost unit, is typically composed of dolostone with interbedded
anhydrite and thin shale beds. Halite is present within units B,
D, and F, whereas Unit C typically consists of shale. Unit G, the
uppermost unit, is mainly composed of shale, but is capped with
a thick anhydrite deposit that is called the Bertie Dolomite in New
York. In Pennsylvania, the thickest salt beds occur in northwestern
and north-central parts of the state, with bedded salt exceeding 200
feet in units B and D and 400 feet in Unit F. The entire Salina Group
exceeds 1,900 feet in southwestern Pennsylvania, where the rocks
consist mostly of clastics and anhydrite, and greater than 2,000 feet
in northeastern Pennsylvania (Fergusson and Prather, 1968). In
West Virginia, the Salina and its eastern facies equivalent become
thinner to the south and east from a maximum thickness of 800 feet
in the northern panhandle to 300 feet in the southeastern outcrops
(Smosna and Patchen, 1978). Lithologically, halite and anhydrite
deposition were restricted to northwestern West Virginia; the salt
basin is ringed by dolomite and limestone to the south and east.
Four principal lithologies intergrade within the Wabash Formation:
1) calcareous gray, dense to fine grained, and massive, silty dolostone
and dolomitic silty limestone in the lower part of the formation;
2) light colored, mostly finely granular, cherty but otherwise fairly
pure, and slabby bedded limestone, dolomitic limestone, and dolostone
in the upper part of the formation; 3) light tan to dark brown to
greenish and grayish, micritic to fine-grained, generally nonfossiliferous,
color banded, and thinly laminated dolostone and dolomitic
limestone in the upper part of the formation; and 4) light-colored,
granular, massive, vuggy, nearly pure dolostone and limestone with
bluish-gray, carbonate mudstone distributed in bank, reef, reefdetrital,
and biohermal facies throughout much of the formation
(Indiana Geological Survey, 1997).
In northwestern Pennsylvania and northern Ohio, the Bass Islands
Dolomite consists of between 70 and 150 feet of laminated, dull,
brown to buff to gray, argillaceous, micritic, dolomitic limestone
and calcareous dolostone that commonly contains a pelletal, oolitic,
brecciated texture (Ulteig, 1964; Fergusson and Prather, 1968). In
the Michigan basin, the formation consists of 150 to 600 feet of
dolostone with minor amounts of anhydrite and halite (Catacosinos
and others, 2001).
The Helderberg Formation (or Group) in the Appalachian basin
is a mixed siliciclastic-carbonate sedimentary sequence (Dorobek
and Read, 1986). It consists of four principal lithofacies: 1) light
to medium gray, fine- to coarse-grained, medium to thick bedded,
fossiliferous calcarenites that typically are free of chert; 2) cherty,