A2: UPPER DEVONIAN KELLWASSER EVENTS, DAY 1
D. Jeffrey Over
SUNY Geneseo
Geneseo, NY 14454
over@geneseo.edu
Andrew Bush
Center for Integrative Geosciences
University of Connecticut
Storrs, Connecticut, 06269
andrew.bush@uconn.edu
Gordon C. Baird
205 Jewett Hall
State University of New York at Fredonia
Fredonia, NY 14063
mason@fredonia.edu
James Andrew Beard
james.beard@uconn.edu
Introduction
Earth-system perturbations caused a series of mass extinction events during the Devonian Period, including the Taghanic event in the Givetian, the Lower and Upper Kellwasser events in the Frasnian, and the Hangenberg event in the Famennian (House, 2002; Bambach, 2006). These extinctions occurred against the backdrop of orbitally forced sea-level fluctuations, the Acadian Orogeny (Averbuch et al., 2005), the expansion of plants and animals on land (Algeo et al., 1995), and ecological changes in the marine biosphere (Signor and Brett, 1984; Bambach, 1999). The Frasnian-Famennian boundary in particular represents a significant global crisis, considered one of the “big five” mass extinctions (Raup and Sepkoski, 1982) that led to the demise of the widespread and diverse Devonian reef community (Copper, 2002).
The Appalachian Basin preserves a tremendous record of Devonian stratigraphy, and these rocks have been studied for about 200 years (Aldrich, 2000). They have been, in whole or in part, the inspiration for numerous advances and theories in geology and paleontology, including the concepts of facies (Chadwick, 1935), punctuated equilibrium (Eldredge, 1971), coordinated stasis (Brett and Baird, 1995), and considerable work on paleoecology (Sutton et al., 1970; Bowen et al., 1974; Thayer, 1974; McGhee, 1976; McGhee and Sutton, 1981; 1983; 1985; Sutton and McGhee, 1985; Stigall Rode and Lieberman, 2005). Critical faunas and floras document the invasion of land (Daeschler et al., 1994; Daeschler, 2000; VanAller Hernick, 2003).
In particular, foreland basin sediments provide an exceptionally thick and complete record of the Upper Devonian, and thus the opportunity to examine Late Devonian extinction events. Studies of the late-Frasnian Kellwasser events have been concentrated in the more offshore settings of western New York, where geochronology is well constrained by conodont biostratigraphy and carbon isotope chemostratigraphy (Over, 1997; Murphy et al., 2000; Over, 2002; Tuite and Macko, 2013; Lash, 2017). Specifically, the Pipe Creek Formation is temporally equivalent to the Lower Kellwasser Event (LKW), and a thin black shale bed in the upper Hanover Formation is equivalent to the Upper Kellwasser Event (UKW) (Over, 1997; 2002). Baird, Bush, and students have been investigating the Kellwasser events in shallower-water paleoenvironments further to the east, primarily in Steuben County, New York, and adjacent areas of Pennsylvania (Bush et al., 2015; Beard et al., 2017) (Fig. 1).

A2: UPPER DEVONIAN KELLWASSER EVENTS, DAY 1

Walnut Creek, Silver Creek, NY
(included but not a planned stop for the field trip)

STOP 1. Beaver Meadow Creek (Baird, Over)
The strata exposed in Beaver Meadow Creek at Java Village (which are on private land) include the uppermost Angola and Nunda formations of the West Falls Group, the type locality of the Java Group (Pipe Creek Formation, including an anomalous “Nunda” facies, and Hanover Formation, including the initial coarser clastic strata that thicken to the east), and the lower portion of the Dunkirk Formation of the Canadaway Group. Approximately 50 m of strata are exposed along the bank, bed, and in several waterfalls. (Note that Fig. 1C suggests that these Nunda beds may actually correlate with the Wiscoy; until this question is examined in more detail, however, we continue to refer to them as Nunda.)
Two thick-bedded sandstone units are visible in Angel Falls in Java Village (Fig. 4). This is the uppermost part of the greater Nunda Sandstone succession characterized by light gray thin to thick bedded cross-laminated and bioturbated (Planolites and Skolithos) coarse silt–very-fine quartz sand. The gray sandstones and silty mudstones at the base of the falls are separated from the upper sandstone that forms the top of the falls by a thin (10 cm-thick) black shale that marks the base of the Pipe Creek Shale, the basal unit of the Java Group. The lower and medial part of the Nunda Formation interfingers and grades westward into the Angola Shale. The upper sand is stratigraphically distinct, designated “Nunda,” as it interfingers and toes out westward within the Pipe Creek Shale (Baird and Jacobi, 1999) (Fig. 5). The base of the “Nunda” sharply overlies the thin basal black shale bed; the top is interbedded and mixed with black shale.
The brownish lumpy sandstone of the topmost “Nunda” and superajacent Pipe Creek Shale show chaotic bedding, irregular sandstone masses, and complex swirly interlayering of micaceous sandstone and sandy black shale. Diffuse breccia clasts of black shale within brown sandstone matrix suggests emplacement of fluidized sand into variable water-rich, surficial black mud deposits. The thick “Nunda” sandstone seems to be a major fan lobe sand unit (Jacobi et al., 1994; Baird and Jacobi, 1999). The “Nunda” flow event scoured the lowest Pipe Creek Shale as indicated by olistoliths of Pipe Creek Shale within the massive unit at several localities. The uppermost chaotic and diffuse “Nunda” Sandstone may represent later, smaller flow events. These sands were also reworked by storm waves as indicated by hummocky cross-stratification.
At Beaver Meadow Creek the Pipe Creek Formation is 6.2 m of organic-rich shale and the underlying 3 m of fine quartz sand of the “Nunda.” A deep recessive bed at ~1.1 m is a possible tephra bed; a tephra was also described from the upper Pipe Creek at Eighteenmile Creek, as well as the upper Pipe Creek along PA 287 (Ver Straeten et al., in revision). The Pipe Creek has a limited benthic fauna consisting mainly of inarticulate brachiopods. Nektic fauna/flora consists of dacryoconarids, cephalopods, and algal spores; conodonts are uncommon, consisting of Ancyrodella, Palmatolepis, and Polygnathus indicative of FZ 12 (Over, 1997).
The Hanover Formation along Beaver Meadow Creek is 37.5 m thick consisting of intensely bioturbated gray shale interbedded with argillaceous nodular carbonate beds, calcareous nodules, and organic-rich laminated shales (Fig. 4). Concretion horizons, some with concretions ranging up to 0.7 m in diameter, are common in the lower half of the section. Similar to Walnut Creek strata, gray shale and thinner black shales and carbonates occur in near-meter scale cycles. These correspond to ~20 ka precession cycles as seen at Walnut Creek; the longer scale cycles are also evident in the organic- and less-organic-rich strata packages.
Calcareous concretions in the lowermost Hanover contain a diverse nektic and low-diversity benthic fauna of acrotretid brachiopods, ostracodes, tentaculitids, the goniatites Delphinites cataphractus and Sphaeromanticoceras, and notably the conodont Palmatolepis bogartensis which indicates the base of FZ 13, the highest Frasnian conodont zone. The overlying gray shales contain a pyritized molluscan fauna dominated by gastropods. The middle Hanover is notably siltier, both in the gray shales and organic-rich shales, indicative of a more proximal source area compared to Walnut Creek. A thin carbonate bed at 24.5 m in the section yielded abundant conodonts, including Pa. hassi s.s. and Pa. juntianenesis. Other carbonate horizons contain crinoid debris and the small solitary rugose coral Metriophyllum. The Point Gratiot Bed rests on a long platform above the last waterfall. The base of the Dunkirk Formation is 4.5 m higher.
The Frasnian-Famennian boundary horizon is at or just below the top of a 10-cm organic-rich black shale bed that has distinct 1-2 cm wide light colored horizontal Thalassinoides burrows (cf. Boyer et al., 2014). This bed rests on a 0.7 m thick organic-rich black shale—the Pt. Gratiot Bed—that has a recessive weathering lamination at the base that is possibly equivalent to the Center Hill Tephra in Tennessee (Fig. 6). The top of the Pt. Gratiot Bed is a disconformable surface that yields abundant coalified wood and fish material, including an articulated skeleton of the placoderm Coccosetus? (similarly, part of an arthrodire carcass, possibly Dunkleosteus, was excavated from the Pt. Gratiot Bed at Point Gratiot in the 1980s). The nowakiid Homoctenus is relatively common to abundant on bedding planes, and has been recovered above the boundary in several places. These are some of the last dacryoconarids documented.
The Hanover Formation above the Pt. Gratiot Bed consists of bioturbated gray shales with thin interbeds of black shale, siltstones, and fine sandstones. Approximately 1.5 m above the Frasnian-Famennian boundary is a thin shell-rich bed that contains abundant articulate brachiopods, notably Retichonetes, Tylothyris, and Praewaagenoconchia, as well as the lingulid Barroisella (Day and Over, 2002). A thin sand just below the Dunkirk represents a bed of Canaseraga facies before the IIe deepening.

STOP 2. Wiscoy Creek, Wiscoy, NY
Wiscoy Creek is the type location of the Wiscoy Formation, and the section has been illustrated and discussed by many authors (e.g., Pepper and de Witt, 1950; Pepper and de Witt, 1951; Smith and Jacobi, 2000; 2001; 2006; Bush et al., 2015). Overlying the Wiscoy Formation is a black shale unit that has often been correlated with the Dunkirk Formation (Pepper and de Witt, 1950; 1951; Smith and Jacobi, 2000; 2001; 2006), but that Bush et al. (2015) correlated with the Pipe Creek Formation (Fig. 7).
Smith and Jacobi (2001) interpreted the depositional environment of the Wiscoy as lower shoreface, transitioning to more offshore environments in the upper part of the formation. (They also suggested a lagoon or bay as a possibility, but given our observations of the Wiscoy in more proximal settings, that is less likely.) Body fossils are scarce, but trace fossils are abundant in the Wiscoy; Smith and Jacobi (2001) noted the presence of Skolithos, Arenicolites, Teichichnus, Planolites, Rhizocorallium, and Zoophycos.
The dark shale that we correlate with the Pipe Creek Formation, and that previous authors have correlated with the Dunkirk Formation, is visible on the north bank by the dam. It consists of dark, silty shale interpreted as an offshore environment, possibly with low oxygen levels (Smith and Jacobi, 2001). It is overlain by sandstones or siltstones, visible above the dam, that could be correlative with the Hammond Member of the Canaseraga Formation, as defined by Beard et al. (2017).

STOP 3.Mills Mills, Wiscoy Creek, Fillmore, NY
The Mills Mills locality (Fig. 8) is also located along Wiscoy Creek, upstream from Location 2. The upper part of the Canaseraga Formation is exposed along the creek on private land, downstream from the parking area, and the Dunkirk Formation (“Hume Shale”) is exposed along Pond Road and adjacent roads. Smith and Jacobi (2001) indicated that there is approximately 30 m of section between the Pipe Creek and the base of the exposure at Mills Mills.
A meter or two of sandstone and siltstone are exposed at the base of the Mills Mills outcrop, followed by a dark silty shale with interbedded siltstones (Fig. 8). This is overlain abruptly by a thick amalgamated sandstone. Smith and Jacobi (2001, 2006) defined this sandstone as the base of the Mills-Mills Formation, and Beard et al. (2017) treated it as the base of the Mills Mills Member of the Canaseraga Formation. Smith and Jacobi (2001) interpreted these sandstone beds as “TA/B starting turbidites (proximal) that represent channel deposits” in “a channel-levee complex in a prograding deep sea fan. The interbedded shales and siltstones may represent interchannel deposits.” An additional sandstone bed at the top of the Mills Mills was interpreted similarly. Much of the remainder of the Mills Mills consists of gray and black shales, interpreted as representing the beginnings of the deepening that culminated in the Dunkirk (“Hume”) Shale.
Given the correlations proposed by Bush et al. (2015) (Fig. 1C), the UKW plausibly is exposed at the Mills Mills section, somewhere within the upper Canaseraga Formation. There are numerous intervals of black or dark gray shale that could be correlative with the Point Gratiot Bed. Carbon isotope analysis (in progress) may resolve this question. Below the top of the Beaver Meadow Creek section is a thick, falls-capping bundle of turbiditic beds, followed by a major transgressive kick to black shale approximately 25 - 30 m above the top of the UKW. If the turbiditic bundle and highest black shale interval on Beaver Meadow Creek are respectively correlative to the Mills Mills and Hume divisions, then this should provide a clue as to the best interval along Wiscoy Creek for searching for the UKW on Wiscoy Creek, knowing the aggregate thickness of the Canaseraga interval at that locality. Moreover, the conspicuous lithologic change from intensely bioturbated, nodular, gray mudrock (lower–middle Hanover interval) below the F-F transition into variably turbiditic, dark shale facies above it at Beaver Meadow Creek, should still be quite findable on Wiscoy Creek, given the modest 25 km distance between the two sections. The shell-rich “recovery bed” above the UKW, noted by Jeff Over at Glade and Beaver Meadow creeks, might also be similarly present above the UKW on Wiscoy Creek and better developed in this upslope setting.