Geosphere and biosphere dynamics during late Ordovician climate change
The late Ordovician was a period of major climatic and biological change, much of which is poorly understood. Global cooling began in the Caradoc (early Katian) with the build-up of ice in southern polar regions of the palaeocontinent of Gondwana. Cooling continued into the Ashgill (late Katian) but...
Main Author: | |
---|---|
Format: | Thesis |
Language: | unknown |
Published: |
2008
|
Subjects: | |
Online Access: | http://etheses.dur.ac.uk/2529/ http://etheses.dur.ac.uk/2529/1/2529_540.pdf |
id |
ftunidurhamethes:oai:etheses.dur.ac.uk:2529 |
---|---|
record_format |
openpolar |
spelling |
ftunidurhamethes:oai:etheses.dur.ac.uk:2529 2023-05-15T16:41:23+02:00 Geosphere and biosphere dynamics during late Ordovician climate change Challands, Thomas J. 2008 application/pdf http://etheses.dur.ac.uk/2529/ http://etheses.dur.ac.uk/2529/1/2529_540.pdf unknown oai:etheses.dur.ac.uk:2529 http://etheses.dur.ac.uk/2529/1/2529_540.pdf Challands, Thomas J. (2008) Geosphere and biosphere dynamics during late Ordovician climate change. Doctoral thesis, Durham University. http://etheses.dur.ac.uk/2529/ Thesis NonPeerReviewed 2008 ftunidurhamethes 2022-09-23T14:12:20Z The late Ordovician was a period of major climatic and biological change, much of which is poorly understood. Global cooling began in the Caradoc (early Katian) with the build-up of ice in southern polar regions of the palaeocontinent of Gondwana. Cooling continued into the Ashgill (late Katian) but may have been interrupted by a brief period of global warming, the Boda Event, in the Cautleyan-Rawtheyan immediately prior to the Hirnantian glacial maximum. The proceeding Hirnantian Stage of the Upper Ordovician was a period of abrupt global change in the biosphere, climate and ocean geochemistry. These events are marked by: (1) an abrupt positive Hirnantian isotopie carbon excursion (HICE); (2) one of the three global Phanerozoic mass extinctions and (3) an extensive drop in sealevel associated with the maximum extent of the Gondwanan ice sheet. Biostratigraphic correlation for the Late Ordovician between basin and shelf sections in the Welsh Basin is limited. The current study describes three new chitinozoan taxa, Spinachitina penbryniensis, Belonechitina reticulatus and Belonechitina ceredigionensis and developed a chitinozan biostratigraphic scheme for the Welsh Basin. Four of the six Avalonian Ashgill chitinozoan biozones are recognized: the bergstroemi fossensis, umbilicata and taugourdeaui Biozones. The Baltoscandian and Laurentian index taxon Hercochitina gamachiana is recorded for the first time in Avalonia and a new lower Hirnantian regional biozone, the new Belonechitina reticulatus n. sp. Biozone is erected. The Cautleyan-Rawtheyan (late Katian) rugata Biozone was not recorded. Four depth-facies biotopes for chitinozoa from the upper Katian-Hirnantian (Upper Ordovician) of Avalonia have been identified herein. These are: 1) an open ocean shallow-water epipelagic biotope which includes Cyathochitina campanulaeformis; 2) an open ocean middle-depth mesopelagic biotope comprising Hercochitina and Spinachitina; 3) an open ocean deep-water meso-bathypelagic biotope characterized by Bursachitina umbilicata ... Thesis Ice Sheet Durham University: Durham e-Theses Boda ENVELOPE(48.867,48.867,-68.083,-68.083) |
institution |
Open Polar |
collection |
Durham University: Durham e-Theses |
op_collection_id |
ftunidurhamethes |
language |
unknown |
description |
The late Ordovician was a period of major climatic and biological change, much of which is poorly understood. Global cooling began in the Caradoc (early Katian) with the build-up of ice in southern polar regions of the palaeocontinent of Gondwana. Cooling continued into the Ashgill (late Katian) but may have been interrupted by a brief period of global warming, the Boda Event, in the Cautleyan-Rawtheyan immediately prior to the Hirnantian glacial maximum. The proceeding Hirnantian Stage of the Upper Ordovician was a period of abrupt global change in the biosphere, climate and ocean geochemistry. These events are marked by: (1) an abrupt positive Hirnantian isotopie carbon excursion (HICE); (2) one of the three global Phanerozoic mass extinctions and (3) an extensive drop in sealevel associated with the maximum extent of the Gondwanan ice sheet. Biostratigraphic correlation for the Late Ordovician between basin and shelf sections in the Welsh Basin is limited. The current study describes three new chitinozoan taxa, Spinachitina penbryniensis, Belonechitina reticulatus and Belonechitina ceredigionensis and developed a chitinozan biostratigraphic scheme for the Welsh Basin. Four of the six Avalonian Ashgill chitinozoan biozones are recognized: the bergstroemi fossensis, umbilicata and taugourdeaui Biozones. The Baltoscandian and Laurentian index taxon Hercochitina gamachiana is recorded for the first time in Avalonia and a new lower Hirnantian regional biozone, the new Belonechitina reticulatus n. sp. Biozone is erected. The Cautleyan-Rawtheyan (late Katian) rugata Biozone was not recorded. Four depth-facies biotopes for chitinozoa from the upper Katian-Hirnantian (Upper Ordovician) of Avalonia have been identified herein. These are: 1) an open ocean shallow-water epipelagic biotope which includes Cyathochitina campanulaeformis; 2) an open ocean middle-depth mesopelagic biotope comprising Hercochitina and Spinachitina; 3) an open ocean deep-water meso-bathypelagic biotope characterized by Bursachitina umbilicata ... |
format |
Thesis |
author |
Challands, Thomas J. |
spellingShingle |
Challands, Thomas J. Geosphere and biosphere dynamics during late Ordovician climate change |
author_facet |
Challands, Thomas J. |
author_sort |
Challands, Thomas J. |
title |
Geosphere and biosphere dynamics during late Ordovician climate change |
title_short |
Geosphere and biosphere dynamics during late Ordovician climate change |
title_full |
Geosphere and biosphere dynamics during late Ordovician climate change |
title_fullStr |
Geosphere and biosphere dynamics during late Ordovician climate change |
title_full_unstemmed |
Geosphere and biosphere dynamics during late Ordovician climate change |
title_sort |
geosphere and biosphere dynamics during late ordovician climate change |
publishDate |
2008 |
url |
http://etheses.dur.ac.uk/2529/ http://etheses.dur.ac.uk/2529/1/2529_540.pdf |
long_lat |
ENVELOPE(48.867,48.867,-68.083,-68.083) |
geographic |
Boda |
geographic_facet |
Boda |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_relation |
oai:etheses.dur.ac.uk:2529 http://etheses.dur.ac.uk/2529/1/2529_540.pdf Challands, Thomas J. (2008) Geosphere and biosphere dynamics during late Ordovician climate change. Doctoral thesis, Durham University. http://etheses.dur.ac.uk/2529/ |
_version_ |
1766031822260535296 |