Abundance of calcareous nannofossils in ODP Hole 122-761C (Table 1)
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| Formato: | Dataset Open Access |
| Lenguaje: | en |
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PANGAEA
1992
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| _version_ | 1867169021518938112 |
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| author | Pospichal, James J Bralower, Timothy J |
| author_facet | Pospichal, James J Bralower, Timothy J |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | A biostratigraphically complete (all nannofossil biozones present) Cretaceous/Tertiary boundary was recovered at Site 761 on the Wombat Plateau, northwest Australian margin, during Ocean Drilling Program Leg 122. A quantitative study of calcareous nannofossils on closely spaced samples across the boundary reveals a rapid change in assemblages in a similar fashion to other Cretaceous/Tertiary boundary sites. Nannofossil species were placed into three categories: Tertiary, Cretaceous, and 'survivors'. The rapid sequential turnover in these assemblages is as follows: Cretaceous species are abruptly replaced at the boundary by opportunistic survivor species, which in turn are abruptly replaced by newly evolved Tertiary taxa. The uppermost Maestrichtian assemblage is distinctly mid-latitudinal with few Micula murus and rare to few Nephrolithus frequens. The nannofossil assemblage immediately above the boundary is dominated by an abundance bloom of Cyclagelosphaera spp. No Thoracosphaera or Braarudosphaera abundance blooms are present as at many other localities. The change from a survivor- to Tertiary-dominated assemblage is coincident with the CPla/CPlb nannofossil subzonal boundary, which is marked by the simultaneous first occurrence of several species including Cruciplacolithus tenuis and C. primus. The latter is found to first occur below C. tenuis in the most complete Cretaceous/Tertiary sections. A hiatus between Subzones CPla and CPlb is interpreted to explain this discrepancy. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_729258 |
| institution | PANGAEA |
| language | en |
| publishDate | 1992 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Abundance of calcareous nannofossils in ODP Hole 122-761C (Table 1) Pospichal, James J Bralower, Timothy J 122-761C; Actinozygus regularis; Arkhangelskiella cymbiformis; Biantholithus sparsus; Bidiscus rotatorius; Biscutum castrorum; Biscutum sp.; Braarudosphaera bigelowii; Chiasmolithus danicus; Chiastozygus amphipons; Chiastozygus sp.; Chiastozygus spp.; Coccolithus pelagicus; Coccolithus sp.; Coccolithus subpertusus; Corollithion exiguum; Corollithion madagaskarensis; Corollithion rhombicum; Cretarhabdus conicus; Cretarhabdus crenulatus; Cretarhabdus surirellus; Cribrosphaerella daniae; Cribrosphaerella ehrenbergii; Cruciplacolithus primus; Cruciplacolithus tenuis; Cyclagelosphaera reinhardtii; Cylindralithus spp.; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Eiffellithus turriseiffelii; Epoch; Joides Resolution; Kamptnerius magnificus; Lapideacassis sp.; Leg122; Lithraphidites quadratus; Lucianorhabdus cayeuxii; Manivitella pemmatoidea; Markalius apertus; Markalius inversus; Microrhabdulus decoratus; Micula decussata; Micula murus; Nannofossils; Nannofossils, cretaceous; Nannofossils, survivor; Nannofossils, tertiary; Nannofossil zone; Neochiastozygus sp.; Neocrepidolithus fossus; Neocrepidolithus spp.; Nephrolithus frequens; Nephrolithus frequens miniporus; Ocean Drilling Program; ODP; Prediscosphaera arkhangelskyi; Prediscosphaera cretacea; Prediscosphaera grandis; Prediscosphaera spinosa; Prediscosphaera stoveri; Prinsius dimorphosus; Sample code/label; Smear slide analysis; South Indian Ridge, South Indian Ocean; Thoracosphaera spp.; Tranolithus minimus; Vagalapilla aachena; Watznaueria barnesae; Zeugrhabdotus embergeri; Zygodiscus sigmoides; Zygodiscus sp.; Zygodiscus spiralis A biostratigraphically complete (all nannofossil biozones present) Cretaceous/Tertiary boundary was recovered at Site 761 on the Wombat Plateau, northwest Australian margin, during Ocean Drilling Program Leg 122. A quantitative study of calcareous nannofossils on closely spaced samples across the boundary reveals a rapid change in assemblages in a similar fashion to other Cretaceous/Tertiary boundary sites. Nannofossil species were placed into three categories: Tertiary, Cretaceous, and 'survivors'. The rapid sequential turnover in these assemblages is as follows: Cretaceous species are abruptly replaced at the boundary by opportunistic survivor species, which in turn are abruptly replaced by newly evolved Tertiary taxa. The uppermost Maestrichtian assemblage is distinctly mid-latitudinal with few Micula murus and rare to few Nephrolithus frequens. The nannofossil assemblage immediately above the boundary is dominated by an abundance bloom of Cyclagelosphaera spp. No Thoracosphaera or Braarudosphaera abundance blooms are present as at many other localities. The change from a survivor- to Tertiary-dominated assemblage is coincident with the CPla/CPlb nannofossil subzonal boundary, which is marked by the simultaneous first occurrence of several species including Cruciplacolithus tenuis and C. primus. The latter is found to first occur below C. tenuis in the most complete Cretaceous/Tertiary sections. A hiatus between Subzones CPla and CPlb is interpreted to explain this discrepancy. |
| title | Abundance of calcareous nannofossils in ODP Hole 122-761C (Table 1) |
| topic | 122-761C; Actinozygus regularis; Arkhangelskiella cymbiformis; Biantholithus sparsus; Bidiscus rotatorius; Biscutum castrorum; Biscutum sp.; Braarudosphaera bigelowii; Chiasmolithus danicus; Chiastozygus amphipons; Chiastozygus sp.; Chiastozygus spp.; Coccolithus pelagicus; Coccolithus sp.; Coccolithus subpertusus; Corollithion exiguum; Corollithion madagaskarensis; Corollithion rhombicum; Cretarhabdus conicus; Cretarhabdus crenulatus; Cretarhabdus surirellus; Cribrosphaerella daniae; Cribrosphaerella ehrenbergii; Cruciplacolithus primus; Cruciplacolithus tenuis; Cyclagelosphaera reinhardtii; Cylindralithus spp.; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Eiffellithus turriseiffelii; Epoch; Joides Resolution; Kamptnerius magnificus; Lapideacassis sp.; Leg122; Lithraphidites quadratus; Lucianorhabdus cayeuxii; Manivitella pemmatoidea; Markalius apertus; Markalius inversus; Microrhabdulus decoratus; Micula decussata; Micula murus; Nannofossils; Nannofossils, cretaceous; Nannofossils, survivor; Nannofossils, tertiary; Nannofossil zone; Neochiastozygus sp.; Neocrepidolithus fossus; Neocrepidolithus spp.; Nephrolithus frequens; Nephrolithus frequens miniporus; Ocean Drilling Program; ODP; Prediscosphaera arkhangelskyi; Prediscosphaera cretacea; Prediscosphaera grandis; Prediscosphaera spinosa; Prediscosphaera stoveri; Prinsius dimorphosus; Sample code/label; Smear slide analysis; South Indian Ridge, South Indian Ocean; Thoracosphaera spp.; Tranolithus minimus; Vagalapilla aachena; Watznaueria barnesae; Zeugrhabdotus embergeri; Zygodiscus sigmoides; Zygodiscus sp.; Zygodiscus spiralis |
| url | https://doi.org/10.1594/PANGAEA.729258 |