Papers by Kimberly C Meehan
Phytotaxa
Fossil microspherules suspected to be marine algal cysts of varying mineralogy are abundant in Pa... more Fossil microspherules suspected to be marine algal cysts of varying mineralogy are abundant in Paleozoic deposits worldwide. Positive identification of remineralized microspherule fossils is problematic and long debated, particularly for tasmanid species. Several hundred silica-rich microspherules were retrieved through complete maceration of black shale samples from the Givetian Oatka Creek Formation of the Appalachian Basin. Microspherules were analyzed visually through transmitted, incident light, and fluorescence microscopy. The structural features of these microspherules are evident and are interpreted to be Tasmanites sinuous. The images presented herein are the first fluorescence images showing in detail the life cycle stages of the genus Tasmanites. This work also confirms that this tasmanid species does extend into the Givetian as suspected from prior research.
Methane cold-seeps from the Late Cretaceous in the Pierre Shale of South Dakota tend to have dens... more Methane cold-seeps from the Late Cretaceous in the Pierre Shale of South Dakota tend to have dense faunal communities including baculites and inoceramids. These communities depend on intricate relationships between the geochemically driven formation of the seep substrate, pressure gradients allowing for methane migration, anaerobic oxidation of methane combined with sulphate reduction, and interactions between fauna and micro-organisms. These functions are necessary to sustain life within the cold-seep community. American Museum of Natural History (AMNH) loc. 3520A, South Dakota, was gridded into 24 quadrants each approximately 4' by 4', mapped out, and specimens were collected for light isotope analysis, δ 18 O and δ 13 C, and faunal analysis. Nacre from inoceramids and baculites were extracted from larger samples, coated with Au and Pd, and imaged using a Hitachi S4700 FE- scanning electron microscope to determine the preservation index, (PI; quality of preservation). Samp...
Abundant microspherules associated with carbonate concretion beds have been discovered at the con... more Abundant microspherules associated with carbonate concretion beds have been discovered at the contact of the Upper Devonian Rhinestreet and overlying Angola formations of on Eighteenmile Creek of Western New York. Similar objects have also been recovered from near the contact of the Cashaqua Formation and overlying Rhinestreet Formation, also on Eighteenmile Creek. The latter occurrence is associated with an abrupt negative stable carbon isotope excursion that appears to define the termination of the Upper Devonian punctata event in the Appalachian Basin. Microspherules have also been collected from shale and concretions near the Rhinestreet-Hatch contact in the Genesee River Valley. Most spherules are spheroidal or teardrop in shape and range in size from approximately 150 to >500 microns in diameter. Nearly opaque dark and exceptionally clear microspherules occur in both concretions and host shale. However, microspherules were found in higher concentrations within the carbonate concretions; up to several thousand per gram. Evidence of transport is lacking. Electron dispersive microscopy results show that both light and dark glass spherules are Si-Na rich, which differs markedly from the host shale chemical composition. Their origin is still in question as these spherules can be considered either natural (biological or mineral) or an artificial product (fly-ash or contaminants of local manufacturing). However, timing and proximity do not eliminate these as potential evidences for the known Devonian Alamo, Charlevoix or Siljan impact events but may also give credence to the suspected impact event at Panther Mountain, New York.
Cretaceous Research, 2018
Investigations into ancient benthic foraminiferal populations are limited, particularly in the La... more Investigations into ancient benthic foraminiferal populations are limited, particularly in the Late Cretaceous methane cold-seeps of the Western Interior Seaway. Poorly lithified shale samples (400 cc) from 8 methane cold-seeps and one coeval non-seep locality from the upper Campanian Pierre Shale in South Dakota were disaggregated, sieved, and examined for specimens (> 150 µm). Seeps yielded between 100-148 specimens per locality. The foraminiferal populations found at seeps and the single non-seep locality contain many of the same species. The most abundant benthic genera found at late Campanian seeps in South Dakota include Guardryina, Haplophragmoides, Trochammina, buliminids (Buliminella and Praebulimina), Lagena, and Gavelinella. Planktic foraminiferal assemblages are much less diverse and dominated by Globigerinelloides. Only two seeps and the non-seep locality contain biserial species, these localities fall in the Baculites compressus zone. The foraminifera from both seeps and the non-seep have Shannon-Weiner (ln) and Fisher's diversity indices that show that the foraminiferal populations are
PALAIOS, 2012
Study of noncalcareous algal fossils is problematic due to their broadly defined taxonomy and lac... more Study of noncalcareous algal fossils is problematic due to their broadly defined taxonomy and lack of preserved features by which modern algae are classified. Four distinct morphologically simple, enigmatic fossils from the Wheeler Formation were analyzed using Raman spectroscopy, and elemental mapping by electron microbeam techniques. These fossils have been interpreted as dissociated algal fragments, and accordingly, were compared to known algal fossils: Yuknessia simplex (green alga; Spence Shale), Marpolia spissa (cyanobacteria; Burgess Shale), and Margaretia dorus (green alga; Burgess and Wheeler formations). All fossils examined were composed of carbonaceous films, at least in part, but varied with respect to secondary mineral coatings: iron oxides were associated with the surfaces of all three algal species to some degree, and in addition, Margaretia dorus exhibited silicification. Fossils characterized by a thin, wispy, filamentous form (Linear Morphotype 2) display mineralogical and morphological similarities with Marpolia spissa, but lack the characteristic longitudinal striping of this species. Filamentous fossils with a coiled form were the only fossils found to contain chlorite. These fossils are interpreted to be fecal strings. Stubby, linear fossils (Linear Morphotype 1) that commonly have been interpreted as fragmented Yuknessia simplex exhibit neither the mineralogical nor the microtextural features of this algal fossil, making this interpretation unlikely. As with Linear Morphotype 1, fossils of Morania fragmenta lack secondary iron oxides and phyllosilicates. Accordingly, they are interpreted to have been composed of labile material that preserves only under inhospitable conditions such as sustained anoxia.
A variety of models have been presented to account for the arrest of decay processes in Burgess S... more A variety of models have been presented to account for the arrest of decay processes in Burgess Shale-type (BST) fossil beds. These models include sustained anoxia, fluctuating oxyclines, and hypersaline brines. Despite being questioned in the published literature, patterns in redox-sensitive metals may differentiate between these chemical environments of deposition. Accordingly, the redox indices V versus Al, V/Sc, Ni/Al, Ni/Co, and Mo were applied to two well-documented North American BST localities: 1) the Wheeler Formation (Utah, USA) with palaeontological characteristics indicating deposition within a fluctuating oxycline; and 2) the Burgess Shale (British Columbia, Canada) with field evidence indicating an association of fossil deposits with hypersaline brine pools. In addition, the chemical characteristics of the Kinzers Formation (Pennsylvania, USA), a BST fossil locality in which details of depositional environment are unclear due to limited outcrop exposure, were compared ...
Swiss Journal of Palaeontology, 2015
Methane seeps in the Upper Cretaceous Pierre Shale of the U.S. Western interior contain a rich fa... more Methane seeps in the Upper Cretaceous Pierre Shale of the U.S. Western interior contain a rich fauna including ammonites (Baculites, Hoploscaphites, Didymoceras, Placenticeras, Solenoceras), bivalves (Lucina), gastropods, sponges, and crinoids. Occasionally, the shell material in the seeps is very well preserved, retaining the original mineralogy and microstructure. We explored two such seeps from the upper Campanian Didymoceras cheyennense and overlying Baculites compressus Zones (74.7-73.5 Ma) in southwestern South Dakota. Light values of d 13 C in the micritic limestones (-11 to-47 %) confirm the impact of anaerobic oxidation of methane on the isotopic composition of the dissolved inorganic carbon reservoir. At the seep from the D. cheyennense Zone, d 13 C values in well-preserved specimens of Hoploscaphites and Baculites are significantly lighter than those measured in specimens from approximately age-equivalent non-seep deposits. In addition, the 87 Sr/ 86 Sr ratio is elevated in the authigenic carbonates and ammonite shells compared with the coeval marine value. This suggests that seep fluids imprinted with a radiogenic Sr signature, perhaps derived from isotopic exchange with granitic deposits at depth associated with the Black Hills uplift, are transported through the surficial sediments into the overlying water. The persistence of these isotopic tracers of seep fluids in the ammonite shells suggests that these mobile animals were likely demersal and were living in close proximity to the seep. A more restricted data set on a single baculite and nautilid from the seep in the B. compressus Zone shows less divergence of d 13 C and 87 Sr/ 86 Sr relative to non-seep values, suggesting that fluid transport was not as strong at that seep.
Researchers in paleontological and paleoecological sciences often need complete disaggregation of... more Researchers in paleontological and paleoecological sciences often need complete disaggregation of rock materials for certain lines of investigation. However, complete disaggregation of more lithified sedimentary rock is known to be problematic. A complete shale disaggregation method implementing quaternary ammonium surfactants, widely used in paleontological sciences for poorly lithified shale and mudstone, was successfully used on well lithified Devonian shale in the Appalachian Basin of Western New York. Over 50 Devonian gray and black shale samples were collected from multiple localities in western New York (Cashaqua, Rhinestreet, Skaneateles, Windom, and Ludlowville), coarsely crushed, and fully immersed in a quaternary ammonium surfactant until complete disaggregation was achieved (5–14 days); aliquots were run through a series of nested sieves. The sieved sediments contained hundreds of well-preserved microfossils released from the shale: ostracods, dacryoconarids, and previou...
Journal of Foraminiferal Research, 2021
ABSTRACTBeyond yielding signals of extinction or stressed ecological conditions, modern and ancie... more ABSTRACTBeyond yielding signals of extinction or stressed ecological conditions, modern and ancient foraminiferal assemblages reflect specific marine depositional environments and depths. Foraminiferal predominance facies and benthic foraminiferal depth zonation has been successfully used to identify specific marine environments dating back to the Carboniferous. Using insights from modern equivalents, correlative assemblages allow for paleoecological analysis and insights. Middle to Late Devonian (Frasnian) black and gray shale beds of western New York contain hundreds of diminutive calcareous and agglutinated foraminifera. The genera within these beds are reminiscent of shallow modern predominance facies. These foraminiferal assemblages and their associated predominance facies correlate well with prior lithologic and geochemical investigations that establish this portion of the Appalachian Basin as a deltaic setting but suggest it is likely inner neritic zone. Dominant genera inclu...
The approximate fluid flow rate of ancient methane cold-seeps can be determined by an examination... more The approximate fluid flow rate of ancient methane cold-seeps can be determined by an examination of the seep structure and mineralogy of seep cements. Modern methane cold-seeps contain differing mineralogies and conduit complexity with varying rates of continuous fluid flow. Previous investigations of ancient methane seeps have also shown shifts in mineralogy and seep structure depending on the ‘stage of development’ often referred to as early and late stages of maturity. Within the Pierre Shale, South Dakota, cold-seeps contain an even greater disparity in structure complexity and mineralogical assemblages than those already documented and do not necessarily reflect a natural progression of stages. A total of 10 seep deposits were measured in height and width and conduit intricacy and 25 seep cements were analyzed using electron dispersive spectrometry to determine their mineral assemblages. There are three distinct mineralogies present: clay-rich (smectite or kaolinite), calcite-rich, and Mg-calcite-rich. These mineralogies correlate with increases in structural complexity and a shift from a taller, singular conduit system to a more intricate and wider based seep system with the shift from a soft, clay-based substratum to a hard substratum which reflects changes in apparent fluid flow. Through this investigation we have determined that a seep which has a greater high height to width ratio, displaying few to no secondary conduits and is clay-dominated is reflective of high fluid flow, seeps with nearly equal height to width ratios, with few secondary conduits and containing calcite-rich cements are reflective of moderate fluid flow, and seeps with a high width to height ratio with numerous secondary conduits containing Mg-calcite-rich cements is reflective of low fluid flow. No seeps included in this investigation display multiple structure systems or mineralogies, which suggests that the structure and complexity of seeps is more contingent on the fluid flow rate rather than the duration of emission.
The journal of college science teaching, 2016
New York State Geological Association, 2021
The Devonian Period experienced many changes within the environmental and biological realms and t... more The Devonian Period experienced many changes within the environmental and biological realms and terminated with one of the largest mass extinctions of the Phanerozoic. The Appalachian Basin of western New York contains several alternating successions of gray and black shale, many of which mark marine crises culmination in the end-Devonian mass extinction. The causes for the formation (e.g., anoxia, flooding, biological production changes) of the black shale sequences has long been debated within the basin. This period was characterized by major changes in both the terrestrial and marine biospheres and terminated with one of the largest mass extinctions of the Phanerozoic Era (Kaiser et al., 2016). Middle Devonian terrestrial environments saw tremendous increases in biomass and complexity with the evolution of vascular and seed-producing plants, trees, and the formation of deeply weathered and thicker soils (Beerbower et al., 1992). The Devonian marine realm has long been suspected to have been heavily affected by bottom water anoxia, enhanced organic carbon burial rates, dramatic shifts in primary production, and an extended biotic crisis. The biotic crises and related marine extinction events have been attributed to many factors including bolide impacts (McLaren, 1982), tectonism and climate change (Ettensohn et al., 1988), oceanic overturn and/or euxinic conditions (Kelly et al., 2019; Haddad et al., 2016; Boyer et al., 2021), cold water oceans and dysaerobic conditions (Copper, 1986), marine ecosystem collapse (McGhee, 2013), eustatic change (Johnson and Sandberg, 1988), and more recently linking the marine phenomena to coeval developments in the terrestrial realm (Algeo et al., 1995; Algeo and Scheckler, 1998; Algeo et al., 2000).
Algeo et al. (1995) presented the hypothesis that the Middle-to-Late Devonian marine biotic crisis and mass extinction of benthic communities were precipitated by the evolutionary development of vascular land plants; terrestrial floras appeared in the Middle Ordovician, and these land plants were small, either non-rooted or shallowly rooted, and ecologically limited to moist lowland habitats (Cascales-Miñana, 2016). Evolutionary innovations of these floras in the Devonian allowed them to interact with substrates and strongly influence weathering processes, hydrologic cycling that would have changed the amount of run-off and peak discharge (Schumm, 1977; Algeo and Scheckler, 1998), and has been suspected by some researchers to have resulted in geochemical fluxes and the formation of carbon-rich black shale beds within the Appalachian Basin. While flooding events in the Appalachian Basin have received much attention recently (Kelly et al., 2019; Haddad et al., 2016; Lash, 2019; Bartlett et al., 2021 (in press)), by no means is there a consensus on the causes of formation of black shale sequences and other major shifts in lithology during this global event (see Kaiser et al., 2016).
Over 100 years of research of the Devonian Appalachian Basin has led to the construction of one of the most detailed litho-stratigraphic frameworks of a Paleozoic foreland system that has allowed for detailed interpretations of sea level history and shifts in sedimentation rates (Dana, 1894; Wanless, 1947; Brett and Baird, 1986; House and Kirchgasser, 1993; Brett, 1995; Ver Straeten and Brett, 1995; Brett et al., 2011; Ver Straeten et al., 2011). As a result, a tremendous amount of geochemical proxy data from these gray and black shale sequences has shown that the perception that the Devonian black shales were deposited under anoxic conditions holds true, thus far, for only one black shale unit (Werne et al., 2002), the Oatka Creek Shale, and that intervals of terrestrial fresh water flux were not as prevalent as previously thought and that primary production plays a strong role in many, if not all black shale beds of the Appalachian Basin (Arthur and Sageman, 2005).
More recent research on intercalcated deposits described in ancient and modern marine settings (e.g., Cretaceous Western Interior Seaway and Eastern Atlantic Ocean, Pleistocene North Atlantic, Neogene Mediterranean, modern Black Sea) has focused on eutrophic conditions and the effects of organic input, climate variations, primary production changes and seasonal riverine input and has made clear that the formation of carbonaceous and organic-carbon-deficient layers is anything but straightforward. The same is true of investigations attempting to derive the mechanisms behind the gray and black sequences in the Devonian Appalachian Basin (Werne et al., 2002; Sageman et al., 2003; Arthur and Sageman, 2005; Ver Straeten et al., 2011; Wilson and Schieber, 2015; Kelly et al., 2019; Smith et al., 2019; Haddad et al., 2016; Lash, 2019; Boyer et al., 2021; Bartlett et al., 2021 (in press)).
GSA abstracts with programs, 2021
Beyond yielding signals of extinction or stressed ecological conditions, modern and ancient foram... more Beyond yielding signals of extinction or stressed ecological conditions, modern and ancient foraminiferal assemblages reflect specific marine depositional environments & depths. Similarly, applying other paleontological findings, such as palynomorphs & non-pollen palynomorphs, offers a secondary view of water source origination & flux and acts as a biological bathymetric proxy within monotonous deposits. Long considered barren, the black and gray shale sequences within the Catskills deltaic sequences of the Appalachian Basin have rendered many microfossils previously unreported in western New York deposits. 50 shale samples from Frasnian sequences from outcrops in Erie County, New York, sampled at 10cm-1m intervals (10cm contacts; 0.5-1m sampling monotonous deposits). The uppermost 1m of the Cashaqua, 12m Rhinestreet Formation, the lowermost 6m & uppermost 4m of the Angola , Pipe Creek (~1m outcrops in WNY), and lowermost 8m of the Hanover Formations were sampled at two locations in Eighteenmile Creek, Eden, NY, & along Rt 219 & Zimmerman Ave, Boston, NY. Shales were macerated by the methods of Meehan et al. (2020). Sieved sediments between 63-325µm rendered several types of microfossils from both the marine and freshwater realms: agglutinated & calcareous foraminifera, organic walled fossils (OWF), & portions of Characae and charophytes (oogonia & antheridia).
Stratigraphy, 2021
The presence of microtektites, indicative of a single short-lived event, may be a useful tool for... more The presence of microtektites, indicative of a single short-lived event, may be a useful tool for constraining the timing of barren and monotonous beds thereby enabling more accurate long-distance correlation. While the Paleozoic Laurentian epeiric seas have been studied for more than a century, their geologically complex histories, large areal expanse, and seeming monotony of
PALAIOS, 2016
Study of ancient cold-methane seep deposits provides insight into the changes in seep communities... more Study of ancient cold-methane seep deposits provides insight into the changes in seep communities over the lifetime of a seep, which are otherwise difficult to observe in modern settings. We studied 24 cold-methane seep deposits in the Upper Cretaceous (Campanian) Pierre Shale of southwestern South Dakota. These deposits were subdivided into three categories depending on their physical characteristics: (1) those with a single main conduit, few secondary pipes and concretionary bodies, and no carbonate cap, implying strong advective flow to the sedimentwater interface; (2) those with a single main conduit, a moderate number of secondary pipes and concretionary bodies, and a small carbonate cap, implying both advective and diffusive flow to the sediment-water interface; and (3) those with a single main conduit, a high number of secondary pipes and concretionary bodies, and a broad carbonate cap, implying extensive flow, but dampening at the sediment-water interface due to the presence of the large carbonate cap. We analyzed the faunal composition at all 24 seeps. The number of species ranges from five to 20. All of the seeps are dominated by baculitid ammonites, inoceramids, and lucinids (‘‘foundation’’ organisms). These species are the same as those in time-equivalent non-seep sites in the Pierre Shale and are not seep-obligate. However, in seep categories 2 and 3, the number and kind of secondary organisms increases in association with the development of the large carbonate cap. These organisms include oysters, gastropods, echinoids, sponges, crinoids, and scaphitid ammonites. We infer that these organisms appear because (1) the carbonate hardground provides a more diverse habitat allowing attachment and encrustation and (2) the bottom waters are better oxygenated and/or the level of hydrogen sulfide is reduced because the methane rich fluids are diverted away from the carbonate cap, thus providing a more suitable habitat for organisms such as scaphitid ammonites that require a well-oxygenated environment. However, even at these seeps, the number of secondary organisms usually does not exceed that of foundation organisms.
Journal of Foraminiferal Research, 2021
Beyond yielding signals of extinction or stressed ecological conditions, modern and ancient foram... more Beyond yielding signals of extinction or stressed ecological conditions, modern and ancient foraminiferal assemblages reflect specific marine depositional environments and depths. Foraminiferal predominance facies and benthic foraminiferal depth zonation has been successfully used to identify specific marine environments dating back to the Carboniferous. Using insights from modern equivalents, correlative assemblages allow for paleoecological analysis and insights. Middle to Late Devonian (Frasnian) black and gray shale beds of western New York contain hundreds of diminutive calcareous and agglutinated foraminifera. The genera within these beds are reminiscent shallow modern predominance facies. These foraminiferal assemblages and their associated predominance facies correlate well with prior lithologic and geochemical investigations that establish this portion of the Appalachian Basin as a deltaic setting but suggest are likely an inner neritic zone. Dominant genera include several species of Ammobaculites and Saccammina which suggest that paleodepths did not exceed 50 m throughout the Frasnian. Opportunistic genera reflect a muted crisis associated with the punctata isotopic event (Rhinestreet Event) and Lower Kellwasser (Pipe Creek) events. While there are definite shifts in the diversity of assemblages between gray and black shale, the foraminiferal type and feeding mode, indicative of depth and oxygen availability respectively, there is little variation between the distinct shale units. No significance was found between total organic carbon and foraminiferal type of feeding mode. Identification at the species level is problematic but suggest that the depositional environment was stressed. However, the effects of these marine crisis events were not significant for these foraminifera in comparison to those frequently reported; we find that there was no local extinction for foraminifera at least through the lower Hanover Shale, just prior to the Hangenberg marine crisis event, within this deltaic complex of the Appalachian Basin of the western New York.
Stratigraphy, 2020
Researchers in paleontological and paleoecological sciences often need complete disaggregation of... more Researchers in paleontological and paleoecological sciences often need complete disaggregation of rock materials for certain lines of investigation. However, complete disaggregation of more lithified sedimentary rock is known to be problematic. A complete shale disaggregation method implementing quaternary ammonium surfactants, widely used in paleontological sciences for poorly lithified shale and mudstone, was successfully used on well lithified Devonian shale in the Appalachian Basin of Western New York. Over 50 De-vonian gray and black shale samples were collected from multiple localities in western New York (Cashaqua, Rhinestreet, Skaneateles, Windom, and Ludlowville), coarsely crushed, and fully immersed in a quaternary ammonium surfactant until complete disaggregation was achieved (5-14 days); aliquots were run through a series of nested sieves. The sieved sediments contained hundreds of well-preserved microfossils released from the shale: ostracods, dacryoconarids, and previously unreported palymorphs, charophytes, agglutinated foraminifera, miospores, and other microspherules. These microfossils were easily found within disaggregated and sieved samples but were unrecognizable on the shale surface and destroyed in prior investigations of whole rock thin sections. In addition to more traditional approaches, inclusion of this complete rock disaggregation method may assist in a more complete analysis of material, increase our under-standings of ancient basin systems and have important implications on our understanding of the paleoecology during the Late Devonian marine biotic crises.
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Papers by Kimberly C Meehan
Algeo et al. (1995) presented the hypothesis that the Middle-to-Late Devonian marine biotic crisis and mass extinction of benthic communities were precipitated by the evolutionary development of vascular land plants; terrestrial floras appeared in the Middle Ordovician, and these land plants were small, either non-rooted or shallowly rooted, and ecologically limited to moist lowland habitats (Cascales-Miñana, 2016). Evolutionary innovations of these floras in the Devonian allowed them to interact with substrates and strongly influence weathering processes, hydrologic cycling that would have changed the amount of run-off and peak discharge (Schumm, 1977; Algeo and Scheckler, 1998), and has been suspected by some researchers to have resulted in geochemical fluxes and the formation of carbon-rich black shale beds within the Appalachian Basin. While flooding events in the Appalachian Basin have received much attention recently (Kelly et al., 2019; Haddad et al., 2016; Lash, 2019; Bartlett et al., 2021 (in press)), by no means is there a consensus on the causes of formation of black shale sequences and other major shifts in lithology during this global event (see Kaiser et al., 2016).
Over 100 years of research of the Devonian Appalachian Basin has led to the construction of one of the most detailed litho-stratigraphic frameworks of a Paleozoic foreland system that has allowed for detailed interpretations of sea level history and shifts in sedimentation rates (Dana, 1894; Wanless, 1947; Brett and Baird, 1986; House and Kirchgasser, 1993; Brett, 1995; Ver Straeten and Brett, 1995; Brett et al., 2011; Ver Straeten et al., 2011). As a result, a tremendous amount of geochemical proxy data from these gray and black shale sequences has shown that the perception that the Devonian black shales were deposited under anoxic conditions holds true, thus far, for only one black shale unit (Werne et al., 2002), the Oatka Creek Shale, and that intervals of terrestrial fresh water flux were not as prevalent as previously thought and that primary production plays a strong role in many, if not all black shale beds of the Appalachian Basin (Arthur and Sageman, 2005).
More recent research on intercalcated deposits described in ancient and modern marine settings (e.g., Cretaceous Western Interior Seaway and Eastern Atlantic Ocean, Pleistocene North Atlantic, Neogene Mediterranean, modern Black Sea) has focused on eutrophic conditions and the effects of organic input, climate variations, primary production changes and seasonal riverine input and has made clear that the formation of carbonaceous and organic-carbon-deficient layers is anything but straightforward. The same is true of investigations attempting to derive the mechanisms behind the gray and black sequences in the Devonian Appalachian Basin (Werne et al., 2002; Sageman et al., 2003; Arthur and Sageman, 2005; Ver Straeten et al., 2011; Wilson and Schieber, 2015; Kelly et al., 2019; Smith et al., 2019; Haddad et al., 2016; Lash, 2019; Boyer et al., 2021; Bartlett et al., 2021 (in press)).
Algeo et al. (1995) presented the hypothesis that the Middle-to-Late Devonian marine biotic crisis and mass extinction of benthic communities were precipitated by the evolutionary development of vascular land plants; terrestrial floras appeared in the Middle Ordovician, and these land plants were small, either non-rooted or shallowly rooted, and ecologically limited to moist lowland habitats (Cascales-Miñana, 2016). Evolutionary innovations of these floras in the Devonian allowed them to interact with substrates and strongly influence weathering processes, hydrologic cycling that would have changed the amount of run-off and peak discharge (Schumm, 1977; Algeo and Scheckler, 1998), and has been suspected by some researchers to have resulted in geochemical fluxes and the formation of carbon-rich black shale beds within the Appalachian Basin. While flooding events in the Appalachian Basin have received much attention recently (Kelly et al., 2019; Haddad et al., 2016; Lash, 2019; Bartlett et al., 2021 (in press)), by no means is there a consensus on the causes of formation of black shale sequences and other major shifts in lithology during this global event (see Kaiser et al., 2016).
Over 100 years of research of the Devonian Appalachian Basin has led to the construction of one of the most detailed litho-stratigraphic frameworks of a Paleozoic foreland system that has allowed for detailed interpretations of sea level history and shifts in sedimentation rates (Dana, 1894; Wanless, 1947; Brett and Baird, 1986; House and Kirchgasser, 1993; Brett, 1995; Ver Straeten and Brett, 1995; Brett et al., 2011; Ver Straeten et al., 2011). As a result, a tremendous amount of geochemical proxy data from these gray and black shale sequences has shown that the perception that the Devonian black shales were deposited under anoxic conditions holds true, thus far, for only one black shale unit (Werne et al., 2002), the Oatka Creek Shale, and that intervals of terrestrial fresh water flux were not as prevalent as previously thought and that primary production plays a strong role in many, if not all black shale beds of the Appalachian Basin (Arthur and Sageman, 2005).
More recent research on intercalcated deposits described in ancient and modern marine settings (e.g., Cretaceous Western Interior Seaway and Eastern Atlantic Ocean, Pleistocene North Atlantic, Neogene Mediterranean, modern Black Sea) has focused on eutrophic conditions and the effects of organic input, climate variations, primary production changes and seasonal riverine input and has made clear that the formation of carbonaceous and organic-carbon-deficient layers is anything but straightforward. The same is true of investigations attempting to derive the mechanisms behind the gray and black sequences in the Devonian Appalachian Basin (Werne et al., 2002; Sageman et al., 2003; Arthur and Sageman, 2005; Ver Straeten et al., 2011; Wilson and Schieber, 2015; Kelly et al., 2019; Smith et al., 2019; Haddad et al., 2016; Lash, 2019; Boyer et al., 2021; Bartlett et al., 2021 (in press)).