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Biostratigraphy and evolution of Miocene Discoaster spp. from IODP Site U1338 in the Equatorial Pacific Ocean

Marina Ciummelli, Isabella Raffi and Jan Backman
Biostratigraphy and evolution of Miocene Discoaster spp. from IODP Site U1338 in the Equatorial Pacific Ocean
Journal of Micropalaeontology (2016) 36 (2): 137-152

Abstract

Assemblages of upper lower through upper Miocene Discoaster spp. have been quantified from Integrated Ocean Drilling Program (IODP) Site U1338 in the eastern equatorial Pacific Ocean. These assemblages can be grouped into five broad morphological categories: six-rayed with bifurcated ray tips, six-rayed with large central areas, six-rayed with pointed ray tips, five-rayed with bifurcated ray tips and five-rayed with pointed ray tips. Discoaster deflandrei dominates the assemblages prior to 15.8 Ma. The decline in abundance of D. deflandrei close to the early-middle Miocene boundary occurs together with the evolution of the D. variabilis group, including D. signus and D. exilis. Six-rayed discoasters having large central areas become a prominent member of the assemblages for a 400 ka interval in the late middle Miocene. Five- and six-rayed forms having pointed tips become prominent in the early late Miocene and show a strong antiphasing relationship with the D. variabilis group. Discoaster bellus completely dominates the Discoaster assemblages for a 400 ka interval in the middle late Miocene. Abundances of all discoasters, or discoasters at the species level, show only (surprisingly) weak correlations to carbonate contents or oxygen and carbon isotopes of bulk sediment when calculated over the entire sample interval.


ISSN: 0262-821X
EISSN: 2041-4978
Serial Title: Journal of Micropalaeontology
Serial Volume: 36
Serial Issue: 2
Title: Biostratigraphy and evolution of Miocene Discoaster spp. from IODP Site U1338 in the Equatorial Pacific Ocean
Affiliation: PetroStrat, Conwy, United Kingdom
Pages: 137-152
Published: 2016
Text Language: English
Publisher: British Micropalaeontological Society, London, United Kingdom
References: 55
Accession Number: 2017-006368
Categories: PaleobotanyStratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, 2 plates
N02°30'28" - N02°30'28", W117°58'11" - W117°58'11"
Secondary Affiliation: Universita Gabriele d'Annunzio di Chieti-Pescara, ITA, ItalyStockholm University, SWE, Sweden
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201705
Program Name: IODPIntegrated Ocean Drilling Program
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