Cambrian–Ordovician Boundary beds at Tônismägi, Tallinn, North Estonia

Kaljo, Dimitri; Heinsalu, H; Mens, K; Puura, Ivar; Viira, Viive

doi:10.1017/s001675680001308x

Cited by 27 publications

(33 citation statements)

References 2 publications

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“…The oldest conodonts in Estonia come from the upper Cambrian, from sandstones and shales of the lower Pakerort Stage exposed in North Estonia (Heinsalu et al 1987(Heinsalu et al , 1991(Heinsalu et al , 2003Viira et al 1987;Kaljo et al 1988;Mens et al 1989Mens et al , 1996. Conodonts from the clays of the Varangu Stage (middle Tremadocian) were studied by Viira (1970) and Viira et al (1970).…”

Section: Methodsmentioning

confidence: 99%

Ordovician conodont diversity in the northern Baltic

Männik¹,

Viira²

2012

Estonian J. Earth Sci.

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The diversity data presented in this paper are based on recently revised collections of conodonts from outcrops (northern Estonia) and core sections of Estonia and western and northern Latvia. Based on variations in the abundance of taxa, four intervals with different general trends in diversity changes can be recognized in the Ordovician part of the succession: (1) the proavus–crassus zones and (2) crassus–anserinus zones, both intervals forming quite distinct diversity cycles; (3) the variabilis–ventilatus zones, characterized in general by stable diversity values, and (4) the ventilatus Zone–the topmost Ordovician, with a steady increase in diversity up to the ordovicicus Zone, followed by a decline during the End-Ordovician Extinction Event. Diversity was lowest in the earliest and latest Ordovician but reached maximum values at the end of the Early Ordovician radiation of conodonts, in the middle and upper Darriwilian, and just before the start of the End-Ordovician Extinction Event. Four supersequences (transgressive–regressive cycles) are proposed here for the northern Baltic Ordovician succession. The diversity changes recognized in the conodont succession demonstrate general correlation with these supersequences: boundaries between supersequences are characterized by low diversity values; diversity increases more or less rapidly in the lower, transgressive parts of the supersequences and decreases in their upper parts

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Section: Methodsmentioning

confidence: 99%

Ordovician conodont diversity in the northern Baltic

Männik¹,

Viira²

2012

Estonian J. Earth Sci.

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“…It is known from several localities in Laurentia and Baltica, where it appears close to the first appearance of Cordylodus intermedius (Landing in Fortey et al. 1982; Barnes 1988; Kaljo et al. 1986, 1988).…”

Section: The Genus Iapetognathuslanding 1981mentioning

confidence: 96%

“…The genus is pandemic and I . preaengensis has been recognized from Baltica (Kaljo et al. 1986, 1988; Bruton et al.…”

Section: The Genus Iapetognathuslanding 1981mentioning

confidence: 99%

“…1999). I. aengensis (Lindström 1955) has been documented from Baltica (Lindström 1955; van Wamel 1974; Kaljo et al. 1988; Nicoll et al.…”

Section: The Genus Iapetognathuslanding 1981mentioning

confidence: 99%

“…1988; Nicoll et al. 1999), where it may occur as reworked material (Löfgren 1996) but derived from Tremadocian strata that are referred to the Cordylodus angulatus Zone (van Wamel 1974; Olgun 1987; Kaljo et al. 1988).…”

Section: The Genus Iapetognathuslanding 1981mentioning

confidence: 99%

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Re-evaluation of the conodont Iapetognathus and implications for the base of the Ordovician System GSSP

Terfelt¹,

Bagnoli²,

Stouge³

2012

LET

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In 2000, the International Union of Geological Sciences (IUGS) ratified the decision from the International Working Group on the Cambrian-Ordovician Boundary (COBWG) to place the Global boundary Stratotype Section and Point (GSSP) for the base of the Ordovician System in the Green Point section, Newfoundland, Canada, at a point coinciding with the first appearance of the conodont Iapetognathus fluctivagus. However, a restudy of the conodont successions from Green Point shows that this species is not present at the boundary interval, and as a consequence the section does not fulfil the biostratigraphical requirements of a GSSP. The GSSP horizon as now defined is based on a level part-way through the range of I. preaengensis- a species with lower first appearance datum (FAD). The true FAD of I. fluctivagus is above the FAD of planktonic graptolites and well above the FAD of I. preaengensis. As a consequence of these problems, a restudy of the GSSP section and the other sections in the Cow Head Group is necessary. A redefinition of the GSSP horizon is suggested. The following four alternative horizons have potential as new horizons for the GSSP level: the FAD of Cordylodus intermedius; the FAD of Cordylodus andresi; the FAD of Eoconodontus notchpeakensis; and the FAD of the agnostoid Lotagnostus americanus

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Study and Use of Upper Cambrian to Lower Ordovician conodonts in central, southern, and western Laurentia, 1933–2018

Miller

2019

Palaeobio Palaeoenv

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Cambrian–Ordovician Boundary beds at Tônismägi, Tallinn, North Estonia

Cited by 27 publications

References 2 publications

Ordovician conodont diversity in the northern Baltic

Ordovician conodont diversity in the northern Baltic

Re-evaluation of the conodont Iapetognathus and implications for the base of the Ordovician System GSSP

Study and Use of Upper Cambrian to Lower Ordovician conodonts in central, southern, and western Laurentia, 1933–2018

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