Evolution of calcareous nannofossil genus Discoaster in the Miocene; data from Equatorial Pacific deep-sea sediments (IODP Expedition 320/321, Site U1338)

Author(s): Ciummelli, Marina; Raffi, Isabella; Backman, Jan
Author Affiliation(s): Primary:
Universita "G. d'Annunzio" di Chieti-Pescara, Dipartimento di Ingegneria e Geologia, Pescara, Italy
Other:
Stockholms Universitet, Sweden
Volume Title: 34th international geological congress; abstracts
Source: International Geological Congress [International Geological Congress, Abstracts = Congrès Géologique International, Résumés, Vol.34, p.508; 34th international geological congress, Brisbane, Queensl., Australia, Aug. 5-10, 2012. Publisher:], [location varies], International CODEN: IGABBY
Note: In English
Summary: Neogene calcareous nannofossils of the genus Discoaster are considered oligotrophic taxa that preferably thrive in warm/tropical water masses. Throughout their stratigraphic range, starting in the lower Cenozoic (mid-Paleocene), Discoaster assemblages underwent significant modifications, expressed by episodes of speciations and extinctions of taxa. These changes were pronounced in the Miocene and Pliocene, and resulted in a series of distinct biohorizons, useful in the general nannofossil biostratigraphy. The aim of this study is to depict in detail the evolutionary events within Neogene Discoaster assemblages and document the links and interactions of this taxonomic evolution with the dynamic environmental evolution in the equatorial Pacific. Biometric and quantitative abundance analyses are used for providing cleartaxonomy of the Discoaster species and for delineating in detail the evolutionary trends within the genus. We discuss possible relationships between the evolution of the Discoasters and the global and local paleoenvironmental events such as: the different stages of the middle Miocene climatic transition (developed into the major growth of the East Antarctic Ice Sheet, and associated Antarctic cooling and changes in ocean circulation); the middle late Miocene "carbonate crash" (sharp decrease in carbonate MARs in the eastern and central equatorial Pacific, and the Caribbean region); and the deposition of diatom enriched intervals in the eastern equatorial Pacific.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Biologic evolution; Biostratigraphy; Calcareous algae; Cenozoic; Deep-sea environment; Discoasteridae; East Pacific; Equatorial Pacific; Expedition 321; Expeditions 320/321; IODP Site U1338; Integrated Ocean Drilling Program; Marine environment; Microfossils; Miocene; Morphology; Nannofossils; Neogene; North Pacific; Northeast Pacific; Pacific Ocean; Paleoenvironment; Plantae; Tertiary
Coordinates: N023028 N023028 W1175811 W1175811
Record ID: 2014074763
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