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    High palaeolatitude (Hodh, Mauritania) recovery of graptolite faunas after the Hirnantian (top Ordovician) extinction event

    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.

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    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 Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Sarah Hall
    Date Deposited: 28 May 2019 10:19
    Last Modified: 06 Aug 2019 11:39
    URI: http://eprints.bbk.ac.uk/id/eprint/27654

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