Underwood, Charlie J. and Deynoux, M. and Ghienne, J.-F. (1998) High palaeolatitude (Hodh, Mauritania) recovery of graptolite faunas after the Hirnantian (top Ordovician) extinction event. Palaeogeography, Palaeoclimatology, Palaeoecology 142 (3-4), pp. 91-105. ISSN 0031-0182.
Abstract
Marine shales directly overlying lower Hirnantian (uppermost Ordovician) glacially related sediments in Mauritania (northwest Africa) have produced a rich graptolite fauna spanning the Ordovician–Silurian boundary in an area of high palaeolatitude. The lowermost transgressive sandy shales are barren of graptolites, but overlying shales show a sudden appearance of a diverse fauna indicative of the terminal Ordovician persculptus Zone, suggesting that with improving conditions, colonisation by a relatively cold-tolerant fauna was possible. This fauna is replaced by a low-diversity assemblage dominated by long-ranging taxa, probably representing the basal Silurian acuminatus and atavus Zones. With the extinction of the persculptus Zone fauna, conditions were still hostile to warm water Silurian graptolites, and a Normalograptus fauna was again established. A sudden influx of fairly diverse taxa marks the base of the acinaces Zone and the establishment of a typical Lower Silurian fauna with the establishment of warmer water conditions.
Metadata
| Item Type: | Article |
|---|---|
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Depositing User: | Sarah Hall |
| Date Deposited: | 28 May 2019 10:19 |
| Last Modified: | 02 Aug 2023 17:51 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/27654 |
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