Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa

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dc.contributor.advisorTaylot, Wendyen_ZA
dc.contributor.advisorBordy, Emese Men_ZA
dc.contributor.authorReid, Mhairien_ZA
dc.date.accessioned2017-09-26T14:56:12Z
dc.date.available2017-09-26T14:56:12Z
dc.date.issued2017en_ZA
dc.description.abstractThe Lower Devonian Voorstehoek Formation is a fossil-rich, siliciclastic unit (Ceres Subgroup, Bokkeveld Group, Cape Supergroup) in South Africa. This Emsian unit contains a highly endemic benthic fossil biota characteristic of the cool to cold water Malvinokaffric Realm of southwestern Gondwana. The palaeontological and sedimentological investigations of the Voorstehoek Formation suggest that deposition took place in a shallow marine environment within the storm influenced, proximal part of an offshore transition zone. A relatively diverse, ophiuroid–stylophoran assemblage, well-preserved in the Karbonaatjies obrution bed, was excavated at the study site in the Hex River Pass, Western Cape. In this study the taphonomy, taxonomy and the palaeoautecology of Palaeozoic ophiuroids and stylophorans was investigated using micro CT scans. Over 60 samples were scanned, manually segmented and stitched together to create a virtual 3D model of a portion of the Karbonaatjies obrution bed. This method allowed for the determination of the degree of fossil articulation, fossil orientation and faunal counts, without damaging the delicate echinoderm fossils. Furthermore, the ability to digitally analyse the fossil-rich bed has revealed an echinoderm assemblage composed of over 700 articulated ophiuroids dominated by a proposed new genus and species Gamiroaster tempestatis, over 145 articulated mitrate stylophorans Paranacystis cf. petrii Caster, 1954 and eight Placocystella africana (Reed, 1925). Taphonomic analysis of this ophiuroid–stylophoran assemblage indicates this obrution deposit formed due to rapid burial that smothered a potentially gregarious community during a single storm event. Additionally, the admixture of skeletal debris and intact echinoderms present in the Karbonaatjies obrution bed reflects a complex history with significant time-averaging. This unique assemblage provides a taphonomic window into the marine ecosystems of the Early Devonian, including the structure of an unusual, echinoderm-dominated benthic community that forms part of a much wider fossil biota from the Falkland Islands and Precordillera of Argentina, which formed part of SW Gondwana.en_ZA
dc.identifier.apacitationReid, M. (2017). <i>Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/25404en_ZA
dc.identifier.chicagocitationReid, Mhairi. <i>"Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2017. http://hdl.handle.net/11427/25404en_ZA
dc.identifier.citationReid, M. 2017. Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Reid, Mhairi AB - The Lower Devonian Voorstehoek Formation is a fossil-rich, siliciclastic unit (Ceres Subgroup, Bokkeveld Group, Cape Supergroup) in South Africa. This Emsian unit contains a highly endemic benthic fossil biota characteristic of the cool to cold water Malvinokaffric Realm of southwestern Gondwana. The palaeontological and sedimentological investigations of the Voorstehoek Formation suggest that deposition took place in a shallow marine environment within the storm influenced, proximal part of an offshore transition zone. A relatively diverse, ophiuroid–stylophoran assemblage, well-preserved in the Karbonaatjies obrution bed, was excavated at the study site in the Hex River Pass, Western Cape. In this study the taphonomy, taxonomy and the palaeoautecology of Palaeozoic ophiuroids and stylophorans was investigated using micro CT scans. Over 60 samples were scanned, manually segmented and stitched together to create a virtual 3D model of a portion of the Karbonaatjies obrution bed. This method allowed for the determination of the degree of fossil articulation, fossil orientation and faunal counts, without damaging the delicate echinoderm fossils. Furthermore, the ability to digitally analyse the fossil-rich bed has revealed an echinoderm assemblage composed of over 700 articulated ophiuroids dominated by a proposed new genus and species Gamiroaster tempestatis, over 145 articulated mitrate stylophorans Paranacystis cf. petrii Caster, 1954 and eight Placocystella africana (Reed, 1925). Taphonomic analysis of this ophiuroid–stylophoran assemblage indicates this obrution deposit formed due to rapid burial that smothered a potentially gregarious community during a single storm event. Additionally, the admixture of skeletal debris and intact echinoderms present in the Karbonaatjies obrution bed reflects a complex history with significant time-averaging. This unique assemblage provides a taphonomic window into the marine ecosystems of the Early Devonian, including the structure of an unusual, echinoderm-dominated benthic community that forms part of a much wider fossil biota from the Falkland Islands and Precordillera of Argentina, which formed part of SW Gondwana. DA - 2017 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2017 T1 - Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa TI - Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa UR - http://hdl.handle.net/11427/25404 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/25404
dc.identifier.vancouvercitationReid M. Taphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2017 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/25404en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Geological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherGeologyen_ZA
dc.titleTaphonomy, palaeoecology and taxonomy of an ophiuroid-stylophoran obrution deposit from the Lower Devonian Bokkeveld Group, South Africaen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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