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Grahn et al., 1996

Grahn, Y., Nõlvak, J., Paris, F. 1996. Precise chitinozoan dating of Ordovician impact events in Baltoscandia. Journal of Micropalaeontology 15, 21-35. | DETAILS

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ReferenceGrahn et al., 1996
AuthorGrahn, Y., Nõlvak, J., Paris, F.
TitlePrecise chitinozoan dating of Ordovician impact events in Baltoscandia
JournalJournal of Micropalaeontology
Source typearticle in journal
Remarksei moodusta kollektsiooni

The chitinozoan biostratigraphy of four Ordovician impact craters has been investigated. Three of these (Tvären, Kärdla and Lockne) contain complete sequences of early Caradoc age, while the Granby crater contains rocks of late Arenig age yielding two bentonitic horizons at their top. Chitinozoans, together with graptolites and other planktic organisms, were the first to invade the craters after the impact event. It has therefore been possible to date the impact events with a precision of less than one million years. An immigration of graptolites from Australia during the late Arenig corresponds to an immigration of chitinozoans from Gondwana at this time. Two stratigraphically important taxa, not previously described or discussed, Lagenochitina sp. A aff. capax and Laufeldochitina sp. A aff. striata are commented upon. Three species. Cyathochitina hunderumensis, Spinachitina tvaerenensis and Tartuchitina granbyensis, are described as new.

New taxa described

RankTaxon nameBelongs to
SpeciesCyathochitina hunderumensis Grahn, Nõlvak et Paris, 1996Cyathochitina
SpeciesSpinachitina tvaerensis Grahn, Nõlvak et Paris, 1996Spinachitina
SpeciesTanuchitina granbyensis Grahn, Nõlvak et Paris, 1996Tanuchitina

Sections studied or mentioned

Männamaa F-367 borehole297,9157.3-168.7 m