The Cretaceous-Tertiary boundary biotic crisis in the Basque country
The Zumaya section has been selected as a classic locality for the study of the Cretaceous-Tertiary (K-T) boundary due to its richness in microfaune, macrofaune, and nannoflora. The sections present similar good conditions for the study of the K-T boundary. The sedimentary rocks of the Uppermost Maa...
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ftnasantrs:oai:casi.ntrs.nasa.gov:19890011974 2023-05-15T18:00:33+02:00 The Cretaceous-Tertiary boundary biotic crisis in the Basque country Lamolda, M. A. Unclassified, Unlimited, Publicly available JAN 1, 1988 application/pdf http://hdl.handle.net/2060/19890011974 unknown Document ID: 19890011974 Accession ID: 89N21345 http://hdl.handle.net/2060/19890011974 No Copyright CASI GEOPHYSICS Lunar and Planetary Inst., Global Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality; p 102-103 1988 ftnasantrs 2015-03-15T05:57:13Z The Zumaya section has been selected as a classic locality for the study of the Cretaceous-Tertiary (K-T) boundary due to its richness in microfaune, macrofaune, and nannoflora. The sections present similar good conditions for the study of the K-T boundary. The sedimentary rocks of the Uppermost Maastrichtian from the Basque Country are purple or pink marls and marls-tones. Above it is found a clayed bed, 40 to 29 cm thick, grey or dark grey in its basal part, of Lowermost Danian age. Above there is alternation of micritic grey-pink limestones and thin clay beds of Dano-Montian age. The average sedimentation is 7 to 8 times higher during the Upper Maastrichtian than in the Dano-Montian. The macrofauna underwent a decrease since the Campanian and was not found in the last 11 m of the Zumaya section; it was associated with changes in paleoceanographic conditions and primary productivity of the oceans. The microfossil assemblages in the K-T transition allows the recognition of several phases of a complex crisis between two well established planktonic ecosystems. In the Mayaroensis Zone there is a stable ecosystem with 45 to 47 planktonic foraminifera species. The disappearance of A. mayaroensis starts a degradation of the ecosystem. The number of planktonic foraminiera species decreases between 20 and 45 percent. The next phase of the crisis was the result of main extinction events in the planktonic calcareous ecosystem. There are several cretaceous planktonic foraminifera species, probably reworked, whose numbers decrease upward. The next and last phase of the biotic crisis shows a diversification of the ecosystem; the number of planktonic foraminifera is 2 to 3 times higher than before and it is noted the first appearance of Tertiary nannoflora species, while Cretaceous species decrease and persisting species are still the main ones. Other/Unknown Material Planktonic foraminifera NASA Technical Reports Server (NTRS) |
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NASA Technical Reports Server (NTRS) |
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GEOPHYSICS |
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GEOPHYSICS Lamolda, M. A. The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
topic_facet |
GEOPHYSICS |
description |
The Zumaya section has been selected as a classic locality for the study of the Cretaceous-Tertiary (K-T) boundary due to its richness in microfaune, macrofaune, and nannoflora. The sections present similar good conditions for the study of the K-T boundary. The sedimentary rocks of the Uppermost Maastrichtian from the Basque Country are purple or pink marls and marls-tones. Above it is found a clayed bed, 40 to 29 cm thick, grey or dark grey in its basal part, of Lowermost Danian age. Above there is alternation of micritic grey-pink limestones and thin clay beds of Dano-Montian age. The average sedimentation is 7 to 8 times higher during the Upper Maastrichtian than in the Dano-Montian. The macrofauna underwent a decrease since the Campanian and was not found in the last 11 m of the Zumaya section; it was associated with changes in paleoceanographic conditions and primary productivity of the oceans. The microfossil assemblages in the K-T transition allows the recognition of several phases of a complex crisis between two well established planktonic ecosystems. In the Mayaroensis Zone there is a stable ecosystem with 45 to 47 planktonic foraminifera species. The disappearance of A. mayaroensis starts a degradation of the ecosystem. The number of planktonic foraminiera species decreases between 20 and 45 percent. The next phase of the crisis was the result of main extinction events in the planktonic calcareous ecosystem. There are several cretaceous planktonic foraminifera species, probably reworked, whose numbers decrease upward. The next and last phase of the biotic crisis shows a diversification of the ecosystem; the number of planktonic foraminifera is 2 to 3 times higher than before and it is noted the first appearance of Tertiary nannoflora species, while Cretaceous species decrease and persisting species are still the main ones. |
format |
Other/Unknown Material |
author |
Lamolda, M. A. |
author_facet |
Lamolda, M. A. |
author_sort |
Lamolda, M. A. |
title |
The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
title_short |
The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
title_full |
The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
title_fullStr |
The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
title_full_unstemmed |
The Cretaceous-Tertiary boundary biotic crisis in the Basque country |
title_sort |
cretaceous-tertiary boundary biotic crisis in the basque country |
publishDate |
1988 |
url |
http://hdl.handle.net/2060/19890011974 |
op_coverage |
Unclassified, Unlimited, Publicly available |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
CASI |
op_relation |
Document ID: 19890011974 Accession ID: 89N21345 http://hdl.handle.net/2060/19890011974 |
op_rights |
No Copyright |
_version_ |
1766169683497582592 |