Gilbert Klapper

Devonian eustatic fluctuations in Euramerica

The Devonian System of Euramerica contains at least 14 transgressive-regressive (T-R) cycles of eustatic origin. These are separated into three groups (or depophases) and from Carboniferous cycles by three prominent regressions. Twelve post-Lochkovian T-R cycles are recognized, and they commonly appear to result from abrupt deepening events followed by prolonged upward shallowing. Deepening events in the western United States (especially Nevada), western Canada, New York, Belgium, and Germany have been dated in the standard conodont zonation and are demonstrably simultaneous in several or all five regions. This synchroneity indicates control by eustatic sea-level fluctuations rather than by local or regional epeirogeny. Facies shifts in shelf sedimentary successions are more reliable indicators of the timing of sea-level fluctuations than are strandline shifts in the cratonic interior, because the latter are more influenced by local epeirogeny. Strandline shifts are most useful in estimating the relative magnitude for sea-level fluctuations. Devonian facies progressions and the three prominent regressions are of a duration and an order of magnitude that could have been caused by episodes of growth and decay of Devonian oceanic ridge systems. The described T-R cycles could have formed in response to mid-plate thermal uplift and submarine volcanism. The latter process may have been a control on small-scale (1–5 m thick), upward-shallowing cycles within the major T-R cycles. Continental glaciation could have been a factor in sea-level fluctuations only in the Famennian and could not have been responsible for the Devonian facies progressions or the numerous T-R cycles. The Frasnian extinctions were apparently cumulative rather than due to a single calamity. Two rapid sea-level rises occurred just before, and one at, the Frasnian-Famennian boundary. It is probable that this series of deepening events reduced the size of shallow-shelf habitats, caused repeated anoxic conditions in basinal areas, and drowned the reef ecosystems that had sustained the immensely diverse Devonian benthos.

Upper Devonian conodonts from the Timan-Pechora region, Russia, and correlation with a Frasnian composite standard

A Frasnian composite standard provides a refined scaling for the thirteen-fold conodont zonation first developed in the Montagne Noire, France, but since replicated in North America, Australia, and now the Timan-Pechora region of Russia. Zones 4–13 are identifiable in seven cores from the Ukhta area of southern Timan and a core from the Bagan Field of the Khoreyver Basin. Scaling of the zones through graphic correlation demonstrates the diachronism in different sections of the bases of many conodont species, including those of zonally defining Palmatolepis. This can be effectively shown in a correlation diagram scaled to a composite standard based on graphic correlation, whereas it is obscured by the assumption of synchronism inherent in conventional zonal correlation charts. Newly described species occurring in the Timan-Pechora region and elsewhere are Ozarkodina nonaginta, Ancyrognathus amplicavus, Mesotaxis johnsoni, Palmatolepis amplificata, P. mucronata, P. ormistoni , and P. timanensis. A number of other species described earlier from the region also occur outside Russia, mainly in Canada and Australia. Distribution patterns in the composite standard indicate close faunal connections between the Timan-Pechora, western Canada, and Western Australia.

FRASNIAN (UPPER DEVONIAN) CONODONT SUCCESSION AT HORSE SPRING AND CORRELATIVE SECTIONS, CANNING BASIN, WESTERN AUSTRALIA

Abstract The Horse Spring conodont succession in the Canning Basin replicates zones 6 through 13 of the thirteen-fold Frasnian zonation. Horse Spring, together with other Canning Basin sections, demonstrates the widespread application of the zonation. Furthermore, the recently formalized three-fold subdivision of Zone 13, which has been recognized in the Montagne Noire, Moroccan Meseta, and northern Ontario, is developed at Horse Spring and other Canning Basin sections. The Canning Basin Frasnian is noteworthy for the high quality of preservation of the conodont faunas, the extremely low CAI values, and the abundance of elements in most collections. The emphasis in this paper is on the taxonomy of Frasnian Palmatolepis. Newly described species are: Palmatolepis beckeri, P. feisti, P. housei, P. klugi, P. nicolli, P. playfordi, P. uyenoi, and Polygnathus kirchgasseri. Complete and partial multielement apparatuses have been reconstructed for Palmatolepis playfordi and P. nicolli.

Reef episodes, anoxia and sea-level changes in the Frasnian of the southern Timan (NE Russian platform)

Abstract The development of the Frasnian (Upper Devonian) reef complexes of the southern Timan and Pechora region of northern European Russia is described. Barrier reef complexes progressively prograded eastwards during the Frasnian but the carbonate complexes were interrupted many times by regressive events. Using new conodont and ammonoid biostratigraphical dating, the timing of reef building episodes has been established which enables international correlation with other similar Devonian areas. Basinal anoxic and hypoxic deposits associated with the reef complexes of the Domanik facies provide the major hydrocarbon source rocks of the region and the palaeoenvironmental interpretation of these is discussed. Initial transgressions appear to have been associated with the global Taghanic Onlap of the late Givetian. The new level for the base of the Frasnian and Upper Devonian lies in the Timan Formation, after the deposition of which marine conditions mostly prevailed in the area examined until the late Frasnian when a sharp regression occurred with no evidence of the typical Kellwasser facies of Western Europe and other areas. Transgressive pulses initiated ammonoid biofacies in the Regional Sargaev Stage and the widespread Timan Event was marked by the spread of Timanites faunas. A significant deepening event which initiated the Domanik facies correlates approximately with the Middlesex black shale of New York and the main development of the Domanik facies with the Rhinestreet black shale of New York. There are faunal and floral peculiarities of the area, shown by endemic genera and rather different ranges of cosmopolitan species than elsewhere, which complicates precise international correlation. Nevertheless, several of the main sea-level deepening pulses of the Frasnian, documented in North America, Western Europe, North Africa and Australia, are recognizable and these are thought to represent eustatic events.

Frasnian species of the Late Devonian conodont genus Ancyrognathus

Detailed qualitative analysis of the Pa element and multielement analysis emphasizing the associated Pb element have led to the present revision of the Frasnian species of Ancyrognathus. Diagnostic characters of the Pa element, such as the platform outline, carinal pattern, and shape of the pit, as well as salient features of the Pb element, are the basis of this revision. As a consequence, the restriction in the definition of A. triangularis, formerly a heterogeneous concept including several discrete species, has in turn led to the recognition of a substantially increased number of species of Ancyrognathus. The lowest occurrence of Ancyrognathus primus is used here to delimit the base of Zone 6 of the Montagne Noire Frasnian sequence. The exact relationship of the Montagne Noire zonation to the published standard zonation is problematical. For example, the base of the range of A. triangularis is possibly above the zone for which it is the nominal species in the standard zonation. Two new species are named herein, A. coeni and A. seddoni, both of which have been widely illustrated in the literature, and three new species are recognized in open nomenclature.

CONODONTS OF THE WILLIAMS ISLAND AND LONG RAPIDS FORMATIONS (UPPER DEVONIAN, FRASNIAN-FAMENNIAN) OF THE ONAKAWANA B DRILLHOLE, MOOSE RIVER BASIN, NORTHERN ONTARIO, WITH A REVISION OF LOWER FAMENNIAN SPECIES

Abstract The upper part of cores of the Onakawana B Drillhole in the Moose River Basin in northern Ontario includes the upper part of the upper member of the Williams Island Formation (22.5 m, 16 samples), and the entire overlying Long Rapids Formation (75.1 m, 49 samples). The sequence of conodonts from the drillhole was analyzed by graphic correlation as well as conventional zonation. The upper carbonate member of the Williams Island Formation correlates with lower Frasnian zones 2 to 5. Below this, mixed Frasnian and Famennian conodont faunas occur partly in a brecciated interval within the member and represent stratigraphic leak below the Frasnian. The lower member of the Long Rapids Formation correlates in its lowest part with Zone 5, followed by a hiatus of zones 6 to 8. This is succeeded by zones 9 and 10. Zone 11 is missing, followed by an interval that correlates with upper Frasnian zones 12 and 13 to within the lower Famennian Middle triangularis Zone. The Frasnian-Famennian boundary occurs within a narrow interval in the lower member. The Upper triangularis Zone and perhaps part of the Middle triangularis Zone are missing. The middle member of the Long Rapids Formation correlates with the Lower to Uppermost crepida zones. A sequence from high in the rhomboidea Zone to within the Lower marginifera to perhaps slightly into the Upper marginifera Zone occurs in the upper member of the formation. Sixteen species are described, of which seven are new: Palmatolepis angularis, P. angusta, P. mystica, P. nodosa, P. parva, Palmatolepis n. sp. A, and Mehlina? unica. Two species that affect definition and identification of the Frasnian-Famennian boundary, P. triangularis and P. ultima (=P. praetriangularis), are revised.

Geochemical and isotopic anomalies associated with the Frasnian‐Famennian extinction

The F‐F extinction is known on four continents by the sudden disappearance of shelly benthos, although questions remain regarding precisely when and therefore how suddenly it took place. Studies show that this extinction occurred at the gigas/triangularis zone boundary in Utah and Nevada. U.S.A., Hony and Sinsin sections. Belgium. Montagne Noire. France and Bad Wildungen. Germany. In Medicine Lake and Trout River. Canada, this extinction event has been bracketed between the gigas and Upper triangularis zones. The correlation with an indium anomaly in the Canning Basin. Australia, is suspect and an extinction within the crepida zone in Hunan. China, appears to be facies related. Major biomass reductions at the F‐F extinction are supported by sudden decreases in δ1 3 C values at this horizon at Trout River and Montagne Noire. δ1 3O values in several sections indicate sudden cooling followed by a warming trend. Several F‐F extinctions also coincide with a regression and world‐wide anoxic event. Five sections...

Preliminary analysis of frasnian, late devonian conodont biogeography

Although conodont endemism was not as high in the Frasnian as in earlier Devonian intervals, analysis of a limited number of intensively collected sections in the Montagne Noire, the United States and Canada, Western Australia, and the Russian Platform demonstrates levels of endemism ranging from about 30 to 35% in three composites of two zones each. Graphic correlation of sections in these regions provides the biostratigraphic framework. Endemic species occur in both the Palmatolepisand Polygnathusbiofacies, suggesting that the Frasnian was not a time of conodont cosmopolitanism throughout Devonian tropical regions, even within the widespread Palmatolepisbiofacies. Using the Probabilistic Index of Similarity of Raup and Crick (1979), all significantly dissimilar pairs are comparisons between faunas representing different biofacies, and all significantly similar pairs are faunas of the same biofacies. Although conodont biofacies were thus a major controlling factor, the statistically significant similarit...

Siluro-Devonian Boundary in North America

The writers note a convergence of opinion on a world-wide scale favoring placement of the Siluro-Devonian boundary at the base of the Gedinnian. This boundary is coincident with the base of the Monograptus uniformis and Icriodus woschmidti zones. It is recognizable in the brachiopod-coraltrilobite succession by the disappearance of pentamerids, Atrypella, Gracianella, halysitids, and Encrinurus and by the incoming of terebratulids, Cyrtina, and common Schizophoria. Insofar as the Pridoli-Lochkov boundary in Bohemia can be revised to correspond to this boundary, the Pridoli is recognized as the uppermost Silurian Stage. In North America, the base of the Devonian, defined as the base of the Gedinnian, is located at what is probably the most satisfactory level because it lies at or near the base of the Helderbergian, which has traditionally been regarded as the lower-most Lower Devonian stage in eastern North America. Seven regions in North America are chosen for discussion because they are representative and form standards of a sort, with which most other fossiliferous sections in North America can be compared. Only in one region does the Siluro-Devonian boundary appear to coincide with a formation boundary, namely, at the base of the St. Alban Formation of eastern Gaspe. It falls within the Stonehouse Formation of Arisaig, Nova Scotia; the Rondout Formation of New York and New Jersey; the Keyser Limestone of western Maryland and vicinity; the Roberts Mountains Formation of central Nevada; the Prongs Creek Formation of Yukon Territory; and the Devon Island and Cape Phillips Formations in the Canadian Arctic Islands.

THE MIDDLE DEVONIAN (GIVETIAN) AMMONOID PHARCICERAS FROM THE NEW ALBANY SHALE, KENTUCKY

PHARCICERAS Hyatt, 1884 is the diagnostic ammonoid of the late middle Givetian Stage of the Middle Devonian Series. It occurs in the Rhenish Massif in Germany, the Montagne Noire in southern France, and in equivalent strata in the Anti-Atlas in southern Morocco. Verified North American occurrences of Pharciceras are confined to the New York succession, where the appearance of the ancestral species P. amplexum (Hall, 1886) in the Upper Tully Limestone represents an important and well-established biostratigraphic datum within the Taghanic onlap interval (see Aboussalam and Becker, 2001 for discussion). In this note we describe a second, distinctly younger, North American species, Pharciceras barnetti n. sp., from the New Albany Shale in east-central Kentucky that provides new evidence on the Taghanic onlap interval (Upper Tully/Geneseo Sequence of Baird and Brett, 2003) in the central Appalachian Basin. This occurrence is particularly significant because of its association with conodonts that provide a basis for refined correlations between the central Appalachian Basin and the Taghanic onlap succession in New York. Representatives of Pharciceras barnetti n. sp. were recovered from the Trousdale Member of the New Albany Shale at the J. K. Smith Power Plant, 3.7 km (2.3 mi) west of Trapp, Clark County, Kentucky. Here, the Trousdale sequence consists of 2.4 m of massive, platy black shale that disconformably overlies thinly interbedded argillaceous dololutites and black dolomitic shales of the Portwood Member of the New Albany Shale and is unconformably overlain by interbedded black and greenish gray shales of the Camp Run Member of the New Albany Shale (see Brett et al., 2004 for a sequence stratigraphic analysis of the Portwood and Trousdale members in central Kentucky). Ammonoids occur singly and in thin, 1–3 cm thick, pyritic chert lenses in the lower half of the Trousdale, 1.4–1.9 m above the top …