A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania
Microfossil assemblages and their shell geochemistry are widely used in paleoceanography, but they can be significantly altered by subtle variations in preservation state. Clay-rich, hemipelagic sediments of the Paleogene Kilwa Group of coastal Tanzania host calcareous microfossils that are exceptio...
Published in: | Geological Society of America Bulletin |
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Geological Society of America
2008
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Online Access: | https://orca.cardiff.ac.uk/id/eprint/10122/ https://doi.org/10.1130/B26261.1 |
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ftunivcardiff:oai:https://orca.cardiff.ac.uk:10122 2023-05-15T18:01:00+02:00 A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania Bown, P.R. Jones, T. D. Lees, J.A. Randell, R.D. Mizzi, J.A. Pearson, Paul Nicholas Coxall, Helen Kathrine Young, J.R. Nicholas, C.J. Karega, A. Singano, J. Wade, B.S. 2008 https://orca.cardiff.ac.uk/id/eprint/10122/ https://doi.org/10.1130/B26261.1 unknown Geological Society of America Bown, P.R., Jones, T. D., Lees, J.A., Randell, R.D., Mizzi, J.A., Pearson, Paul Nicholas https://orca.cardiff.ac.uk/view/cardiffauthors/A0179150.html orcid:0000-0003-4628-9818 orcid:0000-0003-4628-9818, Coxall, Helen Kathrine https://orca.cardiff.ac.uk/view/cardiffauthors/A007483I.html, Young, J.R., Nicholas, C.J., Karega, A., Singano, J. and Wade, B.S. 2008. A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania. Geological Society of America Bulletin 120 (1-2) , pp. 3-12. 10.1130/B26261.1 https://doi.org/10.1130/B26261.1 doi:10.1130/B26261.1 GC Oceanography QE Geology Article PeerReviewed 2008 ftunivcardiff https://doi.org/10.1130/B26261.1 2022-10-20T22:34:13Z Microfossil assemblages and their shell geochemistry are widely used in paleoceanography, but they can be significantly altered by subtle variations in preservation state. Clay-rich, hemipelagic sediments of the Paleogene Kilwa Group of coastal Tanzania host calcareous microfossils that are exceptionally preserved, as evidenced by morphological, taxonomic, and geochemical data. The planktonic foraminifera are preserved as glassy, translucent tests with original microgranular wall textures that resemble well-preserved modern specimens, and they arguably yield geochemical values that are relatively unaffected by recrystallization. The calcareous nannofossils are extraordinarily diverse and represented by unique assemblage compositions that include dissolution-susceptible taxa, especially holococcoliths and rhabdoliths, and fragile and very small (<3-μm) heterococcoliths, many of which are new taxa. Notably, the extant, deep-photic-zone taxon Gladiolithus is documented for the first time in the pre-Quaternary fossil record. The Kilwa Group calcareous nannofossil diversities are consistently higher than all coeval assemblages and provide a benchmark against which to compare other Paleogene biodiversity data. Highest diversities are preserved in hemipelagic, clay-rich lithologies and the greatest losses occur in lithified, carbonate-rich sediments. Most of the lost diversity, however, is confined to distinct taxonomic groups (holococcoliths and Syracosphaerales), and in general the preservational potential of Paleogene coccolithophores was greater than in the modern oceans because a larger proportion of the biodiversity fell within the larger size fractions. For both foraminifera and coccolithophores, incorporation into impermeable clay-rich sediments that have never been deeply buried appears to have been critical in producing this Konservat-Lagerstätte preservation. Article in Journal/Newspaper Planktonic foraminifera Cardiff University: ORCA (Online Research @ Cardiff) Geological Society of America Bulletin 120 1-2 3 12 |
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Open Polar |
collection |
Cardiff University: ORCA (Online Research @ Cardiff) |
op_collection_id |
ftunivcardiff |
language |
unknown |
topic |
GC Oceanography QE Geology |
spellingShingle |
GC Oceanography QE Geology Bown, P.R. Jones, T. D. Lees, J.A. Randell, R.D. Mizzi, J.A. Pearson, Paul Nicholas Coxall, Helen Kathrine Young, J.R. Nicholas, C.J. Karega, A. Singano, J. Wade, B.S. A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
topic_facet |
GC Oceanography QE Geology |
description |
Microfossil assemblages and their shell geochemistry are widely used in paleoceanography, but they can be significantly altered by subtle variations in preservation state. Clay-rich, hemipelagic sediments of the Paleogene Kilwa Group of coastal Tanzania host calcareous microfossils that are exceptionally preserved, as evidenced by morphological, taxonomic, and geochemical data. The planktonic foraminifera are preserved as glassy, translucent tests with original microgranular wall textures that resemble well-preserved modern specimens, and they arguably yield geochemical values that are relatively unaffected by recrystallization. The calcareous nannofossils are extraordinarily diverse and represented by unique assemblage compositions that include dissolution-susceptible taxa, especially holococcoliths and rhabdoliths, and fragile and very small (<3-μm) heterococcoliths, many of which are new taxa. Notably, the extant, deep-photic-zone taxon Gladiolithus is documented for the first time in the pre-Quaternary fossil record. The Kilwa Group calcareous nannofossil diversities are consistently higher than all coeval assemblages and provide a benchmark against which to compare other Paleogene biodiversity data. Highest diversities are preserved in hemipelagic, clay-rich lithologies and the greatest losses occur in lithified, carbonate-rich sediments. Most of the lost diversity, however, is confined to distinct taxonomic groups (holococcoliths and Syracosphaerales), and in general the preservational potential of Paleogene coccolithophores was greater than in the modern oceans because a larger proportion of the biodiversity fell within the larger size fractions. For both foraminifera and coccolithophores, incorporation into impermeable clay-rich sediments that have never been deeply buried appears to have been critical in producing this Konservat-Lagerstätte preservation. |
format |
Article in Journal/Newspaper |
author |
Bown, P.R. Jones, T. D. Lees, J.A. Randell, R.D. Mizzi, J.A. Pearson, Paul Nicholas Coxall, Helen Kathrine Young, J.R. Nicholas, C.J. Karega, A. Singano, J. Wade, B.S. |
author_facet |
Bown, P.R. Jones, T. D. Lees, J.A. Randell, R.D. Mizzi, J.A. Pearson, Paul Nicholas Coxall, Helen Kathrine Young, J.R. Nicholas, C.J. Karega, A. Singano, J. Wade, B.S. |
author_sort |
Bown, P.R. |
title |
A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
title_short |
A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
title_full |
A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
title_fullStr |
A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
title_full_unstemmed |
A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania |
title_sort |
paleogene calcareous microfossil konservat-lagerstätte from the kilwa group of coastal tanzania |
publisher |
Geological Society of America |
publishDate |
2008 |
url |
https://orca.cardiff.ac.uk/id/eprint/10122/ https://doi.org/10.1130/B26261.1 |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_relation |
Bown, P.R., Jones, T. D., Lees, J.A., Randell, R.D., Mizzi, J.A., Pearson, Paul Nicholas https://orca.cardiff.ac.uk/view/cardiffauthors/A0179150.html orcid:0000-0003-4628-9818 orcid:0000-0003-4628-9818, Coxall, Helen Kathrine https://orca.cardiff.ac.uk/view/cardiffauthors/A007483I.html, Young, J.R., Nicholas, C.J., Karega, A., Singano, J. and Wade, B.S. 2008. A Paleogene calcareous microfossil Konservat-Lagerstätte from the Kilwa Group of coastal Tanzania. Geological Society of America Bulletin 120 (1-2) , pp. 3-12. 10.1130/B26261.1 https://doi.org/10.1130/B26261.1 doi:10.1130/B26261.1 |
op_doi |
https://doi.org/10.1130/B26261.1 |
container_title |
Geological Society of America Bulletin |
container_volume |
120 |
container_issue |
1-2 |
container_start_page |
3 |
op_container_end_page |
12 |
_version_ |
1766170306871820288 |