Journal Article•
Limitations on the application of the Devonian standard conodont zonation
TL;DR: In this paper, the Frasnian standard conodont zonation based on a phylogenetic succession of species belonging to the pelagic genera Mesotaxis, Palmatolepis and Siphonodella can be used for worldwide correlation.
Abstract: The most commonly used Lower and Middle Devonian conodont zonations that sometimes have been presented as standard zonations are evaluated. The author questions whether the Frasnian standard conodont zonation based on a phylogenetic succession of species belonging to the pelagic genera Mesotaxis, Palmatolepis and Siphonodella can be used for worldwide correlation. He favours the idea of an international conodont reference scale based on a synthesis of well established and documented conodont successions (with figured specimens of first and last occurrences of index-species) from key areas representing a variety of facies. Graphic correlation is likely to be the most objective and precise method to provide such a synthesis represented by the composite standard. Such standards have been already elaborated for the Frasnian and the Middle Devonian. This point of view does not imply that classical biozonations should be abandoned.
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TL;DR: In this article, the authors proposed an approach to establish a preliminary age chronology for complete stages within the Phanerozoic by applying cyclostratigraphic methods that employ high-resolution data sets.
54 citations
Cites background or methods from "Limitations on the application of t..."
...64–67—absolute age assignments based on tie points to uniformly constrain the length of the Lower, Middle and Upper Devonian as published by Weddige (1996) differs from the method in Bultynck (2007) (composite standard units—CSU— based on the graphic correlation method [Shaw, 1964])....
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...In order to make this comparison and to hold the stratigraphic position of the conodont picks constant in the New York composite, it was necessary to adjust slightly the initial conodont zonation from Bultynck (2007) by compressing the upper portion of the conodont zonation (Fig....
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...the adjusted conodont zonation scheme of Bultynck (2007). The MS SRZ reported here...
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...(2005) and (2) based on work by Bultynck (2007) and Gouwy...
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TL;DR: In this paper, an Icriodus subterminus Zone with a threefold subdivision is defined, which correspond approximately to the lower and upper sub-terminus Fauna and the insita Fauna commonly used in N America for the study of shallow-water platform carbonate successions.
Abstract: Late Givetian and early Frasnian conodont communities with Icriodus subterminus have been revised on the basis of collections from Iowa (USA), the Boulonnais and the Ardennes (northern France and Belgium), the Radom-Lublin area and Holy Cross Mountains (Poland), and the Ma'der-Tafilalt region (southeast Morocco). As a result an Icriodus subterminus Zone with a threefold subdivision is defined. The three subzones correspond approximately to the “Lower and Upper subterminus Fauna” and the “insita Fauna” commonly used in N America for the study of shallow-water platform carbonate successions. The base of the subterminus Zone corresponds to a level within the uppermost part of the hermanni Zone; the top is characterized by the occurrence of the earliest Ancyrodella taxa, Montagne Noire Zones MN 1 and the base of MN 2 or slightly above the base of the falsiovalis Zone. The diagnosis of Icriodus subterminus is amended and two morphotypes are recognized. The stratigraphic range of the alpha morphotype i...
39 citations
TL;DR: In this paper, the authors compared the stratigraphical occurrence of 38 Upper Devonian miospore taxa with conodont zones in 28 intercalibrated levels and found that the conodons were available in a few regions of western Europe.
Abstract: Abstract The stratigraphical occurrence of 38 Upper Devonian miospore taxa is compared to some miospore and conodont zones in 28 intercalibrated levels. The accurate position of 15 miospore First Occurrence Biohorizons and one Last Occurrence Biohorizon in terms of the conodonts available in a few regions of western Europe is discussed in detail and their correlation evaluated.
34 citations
Cites background from "Limitations on the application of t..."
...Of course the correlation value depends also on the reliability of the reference conodont fauna itself, a subject which is not discussed here (see Johnson 1992; Bultynck 2007)....
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...Magnetostratigraphy susceptibility correlation of the FFB between the ‘La Serre’ section in southern France and the section of Hony in east Belgium is given by Crick et al. (2002). The obvious conclusion of this correlation is that the BA Oppel Zone plicabilis Interval Zone (see below) extends across the FFB....
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...Magnetostratigraphy susceptibility correlation of the FFB between the ‘La Serre’ section in southern France and the section of Hony in east Belgium is given by Crick et al. (2002). The obvious conclusion of this correlation is that the BA Oppel Zone plicabilis Interval Zone (see below) extends across the FFB. Establishing a miospore zonation is essentially a step by step process and it is important that the zones erected at any given time reflect these steps. Loboziak & Streel (1981) used the ‘phase concept’ of Van der Zwan (1980) as an Oppel Zone that was not yet controlled by application in other localities and which therefore might just have local significance....
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TL;DR: In this article, a detailed regional biozonal scale for the Lochkovian in the Prague Synform is presented, with modification of the global threefold conodont subdivision.
Abstract: Relatively rich conodont faunas from sections in the Prague Synform (Barrandian area, Czech Republic) include a number of indexes and other important guide conodonts that can be correlated with other regions, especially with Nevada and the Spanish Central Pyrenees. The collation and detailed correlation of conodont data from the Lochkovian in two parallel sections in the Požary quarries, together with biostratigraphic control of additional data from several (incomplete) sections with changing facies development, is the basis for a new detailed regional biozonal scale for the Lochkovian in the Prague Synform. The new subdivision follows, with modification, the global threefold conodont subdivision of the Lochkovian. Data from the Prague Synform enable further detailed subdivision of the lower, middle and upper Lochkovian into small-scale units. The conodont distribution shows a large proportional discrepancy between the late Lochkovian elsewhere; the conodont record in the latest Lochkovian in the Prague Synform area, which appears to be rather restricted and requires further discussion. Copyright © 2012 John Wiley & Sons, Ltd.
33 citations
References
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TL;DR: The Devonian System of Euramerica contains at least 14 transgressive-regressive (T-R) cycles of eustatic origin this paper, which are separated into three groups (or depophases) and from Carboniferous cycles by three prominent regressions.
Abstract: 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.
879 citations
01 Jan 2005
124 citations
01 Jan 1988
TL;DR: Eustatic efficacy evidently was a highly significant control on bio-events and caused diversity changes, macrofaunal biofacies shifts, and local and worldwide extinctions as discussed by the authors.
Abstract: Sixteen deepening events, of which 11 were eustatic, and six regressive episodes, of which 3 were eustatic, acted as primary controls on Devonian sedimentation and biotic changes in the Western United States. Many stratigraphic unit boundaries, especially within limestone sequences, resulted from the eustatic rises, and widespread unconformities were produced by eustatic falls. Eustatic efficacy evidently was a highly significant control on bio-events and caused diversity changes, macrofaunal biofacies shifts, and local and worldwide extinctions. An Early Devonian (pesavis Zone) regression, which is here considered as the first intra-Devonian eustatic fall, dramatically changed brachiopod biofacies (also called faunal realms). Late Devonian eustatic falls just before the close of the Frasnian and Famennian Stages presaged worldwide extinctions in conodonts and macrofaunas.
96 citations
01 Jan 1987
89 citations