Quantitative Stratigraphy of Sedimentary Sequences
285
2. The isotopie excursions in both studied Estonian sections are contemporaneous, coinciding with an episode of increased extinction rate of ostracodes.
3. The ostracode radiation event in the late Viruan was preceded by a positive
shift in carbonate stable carbon isotope ratio (O l3 e).
Acknowledgements
This study was supported by the Estonian Science Foundation (grant No. 951).
The authors wish to thank F. Gradstein for the critical reading of the manuscript
and useful suggestions.
References
Agterberg, F. P., 1990. Automated Stratigraphic Correlation. Developments in Palaeontology and Stratigraphy, 13. Elsevier, Amsterdam, 424 p.
Ainsaar, L., Kirsimae, K. and Martma, T., 1995. Sedimentological and chemical changes associated with the Oandu Event (Caradoc, Ordovician) in Estonia. In: Kohonen, T. and
Lindberg, B. (eds). The 22nd Nordic Geological Winter Meeting, 8-11 January 1996,
Turku, Finland. Abstracts. Turku, p. 4.
Ainsaar, L., Kirsimae, K. and Meidla, T., 1996. Regression in Caradoc: Evidences from
southwestern Estonia (Ristikiila core). In: Stouge, S. (ed.). WOGOGOB-94 Symposium.
Working Group on Ordovician Geology of Baltoscandia, Bornholm - 94. Geological Survey of Denmark and Greenland, Report 98, p. 5-12.
Guex, J., 1987. Correlations biochronologiques et associations unitaires. Presses Poly techniques Romandes, Lausanne, 244 p.
Hatch, J. R., Jacobson, S. R., Witzke, B. J., Risatti, J. B., Anders, D. E., Watney, W. L., Newell,
K. D. and Vuletich, A. K., 1987. Possible late Middle Ordovician carbon isotope excursion: Evidence from Ordovician oils and hydrocarbon sourcerocks, Mid-Continent and
East-Central United States. American Association of Petroleum Geologists Bulletin, 71,
p. 1342-1354.
Hints, L., Meidla, T., N6lvak, J. and Sarv, L., 1989. Some specific features of the Late Ordovician evolution in the Baltic basin. Proceedings of the Academy of Sciences of the Estonian SSR. Geology, 38, p. 83-87.
Hints, L., Meidla, T. and N6lvak, J., 1995. Ordovician sequences of the East European Platform. Geologija, 1994, 17, p. 58-63.
Holland, C. H., 1989. Synchronology, taxonomy and reality. In: Chaloner, W. G. and Hallam,
A. (eds). Evolution and Extinction. Cambridge University Press, p. 263-277.
Jaanusson, v., 1973. Aspects of carbonate sedimentation in the Ordovician of Baltoscandia.
Lethaia, 6, p. 11-34.
Jaanusson, V., 1976. Faunal dynamics in the Middle Ordovician (Viruan) of Balto-Scandia.
In: Basset, M. G. (ed.). The Ordovician System: Proceedings of a Palaeontological Association Symposium, Birmingham, September 1974. University of Wales Press, Cardiff, p.
301-326.
Jacobson, S. R., Finney, S. c., Hatch, J. R. and Ludvigson, G. A., 1995. Gloeocapsomorpha prisca-driven organic carbon isotope excursion, late Middle Ordovician (Rocklandian),
North American mid-continent: new data from Nevada and Iowa. In: Cooper, J. D., Droser, M. L., and Finney, S. C. (eds). Ordovician Odyssey: Short Papers for the Seventh International Symposium on the Ordovician System, Las Vegas, Nevada, USA, June 1995.
The Pacific Section Society for Sedimentary Geology, Fullerton, p. 305-308.
Kaljo, D. and Nestor, H. (eds), 1990. Field Meeting, Estonia 1990. An Excursion Guidebook.
Tallinn, 209 p.
285
2. The isotopie excursions in both studied Estonian sections are contemporaneous, coinciding with an episode of increased extinction rate of ostracodes.
3. The ostracode radiation event in the late Viruan was preceded by a positive
shift in carbonate stable carbon isotope ratio (O l3 e).
Acknowledgements
This study was supported by the Estonian Science Foundation (grant No. 951).
The authors wish to thank F. Gradstein for the critical reading of the manuscript
and useful suggestions.
References
Agterberg, F. P., 1990. Automated Stratigraphic Correlation. Developments in Palaeontology and Stratigraphy, 13. Elsevier, Amsterdam, 424 p.
Ainsaar, L., Kirsimae, K. and Martma, T., 1995. Sedimentological and chemical changes associated with the Oandu Event (Caradoc, Ordovician) in Estonia. In: Kohonen, T. and
Lindberg, B. (eds). The 22nd Nordic Geological Winter Meeting, 8-11 January 1996,
Turku, Finland. Abstracts. Turku, p. 4.
Ainsaar, L., Kirsimae, K. and Meidla, T., 1996. Regression in Caradoc: Evidences from
southwestern Estonia (Ristikiila core). In: Stouge, S. (ed.). WOGOGOB-94 Symposium.
Working Group on Ordovician Geology of Baltoscandia, Bornholm - 94. Geological Survey of Denmark and Greenland, Report 98, p. 5-12.
Guex, J., 1987. Correlations biochronologiques et associations unitaires. Presses Poly techniques Romandes, Lausanne, 244 p.
Hatch, J. R., Jacobson, S. R., Witzke, B. J., Risatti, J. B., Anders, D. E., Watney, W. L., Newell,
K. D. and Vuletich, A. K., 1987. Possible late Middle Ordovician carbon isotope excursion: Evidence from Ordovician oils and hydrocarbon sourcerocks, Mid-Continent and
East-Central United States. American Association of Petroleum Geologists Bulletin, 71,
p. 1342-1354.
Hints, L., Meidla, T., N6lvak, J. and Sarv, L., 1989. Some specific features of the Late Ordovician evolution in the Baltic basin. Proceedings of the Academy of Sciences of the Estonian SSR. Geology, 38, p. 83-87.
Hints, L., Meidla, T. and N6lvak, J., 1995. Ordovician sequences of the East European Platform. Geologija, 1994, 17, p. 58-63.
Holland, C. H., 1989. Synchronology, taxonomy and reality. In: Chaloner, W. G. and Hallam,
A. (eds). Evolution and Extinction. Cambridge University Press, p. 263-277.
Jaanusson, v., 1973. Aspects of carbonate sedimentation in the Ordovician of Baltoscandia.
Lethaia, 6, p. 11-34.
Jaanusson, V., 1976. Faunal dynamics in the Middle Ordovician (Viruan) of Balto-Scandia.
In: Basset, M. G. (ed.). The Ordovician System: Proceedings of a Palaeontological Association Symposium, Birmingham, September 1974. University of Wales Press, Cardiff, p.
301-326.
Jacobson, S. R., Finney, S. c., Hatch, J. R. and Ludvigson, G. A., 1995. Gloeocapsomorpha prisca-driven organic carbon isotope excursion, late Middle Ordovician (Rocklandian),
North American mid-continent: new data from Nevada and Iowa. In: Cooper, J. D., Droser, M. L., and Finney, S. C. (eds). Ordovician Odyssey: Short Papers for the Seventh International Symposium on the Ordovician System, Las Vegas, Nevada, USA, June 1995.
The Pacific Section Society for Sedimentary Geology, Fullerton, p. 305-308.
Kaljo, D. and Nestor, H. (eds), 1990. Field Meeting, Estonia 1990. An Excursion Guidebook.
Tallinn, 209 p.