A2: THE MARCELLUS SUBGROUP IN ITS TYPE AREA, FINGER LAKES AREA OF NEW YORK, AND BEYOND
Chuck Ver Straeten
New York State Museum/Geological Survey
3140 Cultural Education Center
Albany, NY 12230
Gordon Baird
Gary Lash
Dept. of Geosciences
SUNY-Fredonia
Fredonia, NY 14063
Carlton Brett
Geology Department
University of Cincinnati
Cincinnati, OH 45221-0013
Jeff Over
Department of Geological Sciences
SUNY-Geneseo,
Geneseo, NY 14454
Ceren Karaca
Teresa Jordan
Department of Earth and Atmospheric Sciences
Snee Hall, Cornell University
Randy Blood
EQT Production
625 Liberty Ave, Ste 1700
Pittsburgh, PA 15222
INTRODUCTION
br /br /The Marcellus “shale” was long one of the neglected “ugly ducklings” of New York stratigraphy that was known mainly for its black shale facies, the cephalopod-rich Cherry Valley Limestone, its potential as a source rock, and occasional interesting fossil finds like the famous Devonaster starfish trove found in upper Marcellus sandstones of the Hudson Valley. Generally, it was seldom the focus of much attention, however, during the last five years Marcellus strata have been the center of scientific and public attention, both as a regional symbol of economic opportunity and of controversy regarding exploitation of hydrocarbons.
The Marcellus in New York State is considered a subgroup of the Hamilton Group, which includes two different major lithofacies suites: the classic thin, black shale/dark gray mudstone succession, with minor carbonates developed in central to western New York; and the thick, coeval synorogenic siliciclastic succession of basinal to marine shoreface and terrestrial deposits in eastern New York. Beginning in underlying upper Onondaga strata, the succession represents two major (“third order”) sea level cycles, which were apparently deposited over a 2-4 million year period. Total Marcellus thickness across the state ranges from less than 7.5 meters in the west near Buffalo to over 580 m in the Hudson Valley region (Rickard, 1989).
Herein we assemble a broad set of perspectives and knowledge on the strata of the Marcellus subgroup in the northern Appalachian Basin. Owing to the complexity of this topic the reader will find the paper divided into four chapters, written by various co-authors, as well the road log and brief stop descriptions at the end.

A2: THE MARCELLUS SUBGROUP IN ITS TYPE AREA, FINGER LAKES AREA OF NEW YORK, AND BEYOND
C.VerStraeten, G.Baird, G.Lash, C.Brett, J.Over, C.Karaca, T.Jordan, R.Blood

STOP 1. Marcellus subgroup at Seneca Stone Quarry
(parking area on left, inside the gate) This large active quarry exposes Devonian strata of the Eifelian and lower Givetian, as well as minor folding and a thrust fault distinctly visible on the southern wall; the Onondaga Limestone is the primary production unit. In the lowest level the Lower Devonian Manlius and Oriskany formations floor the quarry. Four members of the Onondaga are recognized in respective upward succession: Edgecliff, Nedrow, Moorehouse, and Seneca. The Seneca Member is easily recognized on the quarry faces as it is bound by two distinct ash beds that weather and stain the walls orange. The lower ash is the Tioga B – Onondaga Indian Nations Ash, which marks the base of the Seneca; the Tioga F is used to recognize the base of the Marcellus subgroup (Figure RL-1A). The entire Bakoven member of the Union Springs Formation (Figure RL-1B) and the succeeding lower Oatka Creek Formation, consisting of the upward succeeding Hurley, Cherry Valley, East Berne, and Chittenango members (Figure RL-1C) can be clearly seen in the quarry benches and walls.
The Bakoven Member, approximately 4 m thick here, overlies dark gray biowackestones of the Seneca Member and represent deposition in the HST and FSST of the 1d/Eif-2 sequence. The Tioga F Ash, approximately 10 cm thick, defines the base of the Marcellus and Union Springs Formation. The lowest part of the Bakoven is dark gray muddy biowackestones and packstones that contain ostracodes, bivalves, pelmatozoa, and dacryoconarids. Seventy centimeters above the base of the Bakoven is a disconformity that preserves abundant fish material, including acanthodian spines, crassopterygian teeth, and placoderm plates, preserved in thin grainstones that are developed in decimeter-scale wide shallow channels. These channels may be analogs of younger, linear erosional furrows associated with a channeled disconformity surface within the lower part of the dark Levanna Shale Member in Erie County, New York (see:Baird et al., 1999; stop 6). Above this disconformity are finely laminate black shales and thin calcareous beds, where the carbonate material is dominated by Styliolina, other dacryoconarids, and thin brachiopods that sometimes form thin grainstones and packstones. The upper Bakoven contains nodular carbonates and laminated black shales.
The Oatka Creek Formation is comprised of four ascending members: Hurley, Cherry Valley, East Berne, and Chittenango. The base of the 1e/Eif-Giv sequence is the Hurley Member which consists of light-weathering very fossiliferous biopackstone-grainstone, characterized by the proetid trilobite Dechenella, which is amalgamated onto the base of the Cherry Valley Member to form a single ledge-forming carbonate approximately 50 cm thick. The Hurley – Cherry Valley contact is an irregular hardground surface. The Cherry Valley is brown weathering, fossiliferous biopackstone-grainstone, and is remarkable for numerous large, truncated orthicone nautiloids and Agoniatites vanuxemi exposed on a corrosion surface, that based on sedimentological evidence, must have been exposed on the Devonian sea floor. These strata record deposition during the TST.
Black styliolinid-rich shales of the East Berne Member overlie the Cherry Valley Member. Several brachiopod-rich horizons occur in the lower 50 cm, which represent the first appearance of the Hamilton fauna, characterized by diverse corals and brachiopods. The Halihan Hill Bed is a 20 cm thick gray calcareous mudstone that marks the appearance of a more diverse shelly fauna, including Mediospririfer, Ambocoelia, Athyris, Pseudoatrypa, and others, and delineates the base of the Chittenango Member. These strata fall within the late TST of the 1e/Eif-Giv sequence. Based on magnetic susceptibility, the Eifelian- Givetian boundary is placed at the Cherry Valley – East Berne contact. The lower Chittenango is composed of organic-rich black shale containing variably rich styliolinid- and brachiopod-bearing horizons. Three horizons of large – up to 1 m in diameter - calcareous concretions are developed between 3 and 5 m above the base. These concretions are apparently also developed in the lower Chittenango Member at the Oatka Creek type section in LeRoy, NY as well as in strata near Marcellus (Stop 3). The Chittenango represents deposition during the HST and FSST; the base of sequence If/Giv-1 will be examined at Stop 2.
C.VerStraeten, G.Baird, G.Lash, C.Brett, J.Over, C.Karaca, T.Jordan, R.Blood

LUNCH STOP: Cayuga Lake State Park
C.VerStraeten, G.Baird, G.Lash, C.Brett, J.Over, C.Karaca, T.Jordan, R.Blood

STOP 2. Lockwood Family dairy farm quarry, Half Acre/Oakwood
This small quarry exposes strata of the uppermost Oatka Creek Formation (Cardiff Member) and lowermost Skaneateles Formation (Mottville Sandstone Member; Figure RL-2).
Medium dark gray, burrowed silty mudstones of the Cardiff Member (Oatka Creek Formation) comprise the lower approximately 2.3 m of the section here. The Cardiff Member here is slightly calcareous, and poorly fossiliferous. Coiled and straight nautiloid cephalopods are part of the sparse fauna; the “hitch-hiking” bryozoan Reptaria stolonifera was found on one of these.
The dark gray mudstones of the Cardiff are overlain by buff-colored, calcareous very fine sandstones of the Mottville Member. In this area, basal Skaneateles strata are in a transition from sandstone- to limestone-dominated facies (coeval Mottville and Stafford members, respectively). Baird et al. (1999) used the term Stafford Member here. Closer examination in the lab indicate an apparent greater percent sand to calcite at this locality, so the term Mottville Member is better applied.
Relatively low in the Mottville Member here a thin, fossiliferous highly calcareous sandstone bed 3.2 m above the base of the section, termed the Mottville A bed (Figure RL-2), is characterized by very fine to lower fine sand-size grains, and benthic fossils including the brachiopods Cupularostrum, Emanuella and Devonochonetes, auloporid corals, and other fauna. The upper part of the Mottville Member here, including the Mottville B bed, is less fossiliferous; however, at least some parts of it are heavily bioturbated by the trace fossil Zoophycos which may, alternatively mark even shallower water conditions than the Mottville A bed below. The greater degree of Zoophycos churning of the Mottville B interval may actually indicate the shallowest water conditions, and mark the Ie/Eif-Giv - If /Giv-1 sequence boundary. Although all of the buff-colored, calcareous sand-rich strata have been assigned to the Skaneateles Member, technically all of the strata below the shallowest point in the Mottville are progradational strata that are a part of the Sequence Ie/Eif-Giv FSST and belong to the Oatka Creek Formation. See Baird et al. (1999) for more details of Mottville Member facies and correlations.

STOP 3. Marcellus subgroup
Along NY 175/NY 174 near Slate Hill Road, Marcellus, NY
This roadcut along the east side of NY Routes 174 and 175 at the northwestern base of Slate Hill exposes the lower black shales of the Oatka Creek Formation (Chittenango Member). Additional nearby sections, however, expose most of, or all, of the Marcellus in its type area, around Slate Hill (Figure RL-3). Hall (1839) did not name a specific type section, but it likely would have been placed at Slate Hill.
Cherty fossiliferous limestones of upper part of the Seneca Member (Onondaga Limestone) are visible in roadcuts on either side of the highway to the north. Intervening strata of the Union Springs Formation and lowest Oatka Creek Formation (including the Hurley, Cherry Valley and East Berne members and the Halihan Hill Bed) are covered southward along the highway to Slate Hill Road.
However, the top Seneca, entire Union Springs through basal East Berne succession, and during some years the Halihan Hill Bed, is exposed in a nearby creek bed, approximately 500 m (0.3 miles) east of the intersection of Slate Hill Road and NY 174-175. The Onondaga-Marcellus contact is sharp here, with no K-bentonite bed at the contact. Topmost beds of the Seneca Member are overlain by 3.1 meters of Bakoven Member black shales with styliolinid to bedded/concretionary diagenetic limestones; the shale/limestone ratio approximates 3:1. These Union Springs strata are capped by a 70 cm-thick ledge of the Hurley and Cherry Valley limestones. Only one 12 cm-thick bed of the Hurley Member is recognized along the stream. Several centimeters of the overlying East Berne black shales were recently observed above the Cherry Valley ledge, and in earlier years the Halihan Hill Bed was also visible along the creek.
Beginning in the ditch near the intersection with Slate Hill Road is an extensive exposure of black, rusty-weathering pyritic fissile shale with multiple levels of small-to-large discoidal septarian concretions. The base of this succession in the lower Chittenango Member is likely close to the top of the Cherry Valley Member and the overlying Halihan Hill Bed. The cut continues to exhibit the same lithology up through the section, exposed southward along NY 174-175 for several 100 meters.
Much of the rest of the Oatka Creek Formation can be studied along a small gully that ascends the northwest side of Slate Hill, beginning at a culvert toward the south end of the roadcut. The section, most of which is exposed in and along the creek bed, rises approximately 40 meters (130 feet) above the road level. The upper part of the succession transitions into dark gray mudstones (Cardiff Member) in the vicinity of a large bend in the creek roughly 23 m in elevation above the road, but the top-Cardiff contact with the overlying Mottville Member is not reached in this locality. The Mottville Member forms the cap of a steep cascade near the top of a deep gorge – “Jacknife Ravine” - approximately 1 km (0.7 miles) to the southeast of the roadcut. This ravine has yet to be fully explored and has potential to yield the most complete Marcellus section in the area.

STOP 4. Upper Onondaga Formation and lower Marcellus subgroup
At Hanson-Jamesville Quarry
Outcrops at the far southeast end of the Hanson Aggregates quarry at Jamesville expose the Onondaga Limestone and the lower part of the Marcellus subgroup. Key features at this site include a thinner Seneca Member at the top of the Onondaga Formation, a prominent bone bed just above the Onondaga Marcellus contact, and black shales of the Bakoven Member (Union Springs Formation).
Between the Seneca Stone and Jamesville quarries (Stops 1 and 4), the Seneca Member thins from 7.1 m to 5.4 m. Regional correlation of the Tioga A-G K-bentonites indicate that while the Tioga F bed lies at the Onondaga-Marcellus contact at Stop 1, both the Tioga E and F beds are missing from the section. A 5-8 cm-thick bed below the topmost Onondaga Limestone bed is the Tioga D bed. The eastward thinning and top-down absence of Tioga K-bentonites and upper Onondaga strata continues to the Albany area (Seneca Member = 3.2 m at Oriskany Falls; 2.0 m at Cherry Valley; and zero in the Helderbergs). This is indicative of diachronous east to west tectonic-load induced subsidence of proximal areas of the foreland basin during the renewed onset of orogenesis in the Acadian mountain belt.
Given the absence of the Tioga F Ash at Jamesville, the Onondaga-Marcellus contact is placed at the highest Onondaga-like limestone (32 cm thick, above the Tioga D Ash bed). The contact is overlain by a 0-5 cm-thick lag bed rich in phosphatic debris with numerous fish bone fragments and teeth. This bed marks a prominent sediment-starved surface, associated with the end of carbonate production and transport in this region, and the concentration of resistant phosphatic lag material on the sea floor.
The sharp upper surface of the bone bed is overlain by black shales of the Bakoven Member of the Union Springs Formation. Only the lower part of the Bakoven is exposed much here. At times in the past, the top of the Cherry Valley Member could be found in the weeds at the south end of the black shale exposure, 6.5 m above the top of the Onondaga Limestone.
In a nearby creek exposure on private land (south of NY 173 and east of Sweet Road), the Onondaga- Marcellus contact, and approximately 1.3 m of lower Bakoven Member black shales, are succeeded by shales interbedded with thin packages of limestone, followed, in turn, by a covered interval. Upper Bakoven strata are again visible in the stream still farther upsection, where black shales and concretionary to thin-bedded limestones appear to be difficult to correlate between separate stream forks.
In the upper part of this creek section, the prominent Hurley-Cherry Valley limestones ledge (10 and 73 cm-thick, respectively) is capped by black shales of the East Berne Member. The Halihan Hill Bed is found at the top of the creek exposure, 73 cm above the top of the Cherry Valley. Here it is comprised of two distinct layers, a lower 13 cm-thick dacryoconarid-rich bed, and an upper 16 cm-thick layer with brachiopods and other normal marine benthic fauna, indicative of well-oxygenated conditions on the sea floor at that time. The base of the Hurley Member and the base of the brachiopod-rich upper Halihan Hill Bed mark the base of two of three fourth order sequences within the Oatka Creek Formation (Sequence Ie/ Eif-Giv).
A near by abandoned quarry, also on private land, exposes a thick succession of mid (?) to upper Oatka Creek dark gray mudrock facies, mostly corresponding to the Cardiff Member interval. The Mottville Sandstone, the basal member of the Skaneateles Formation, is not seen in the quarry.