The blooming icehouse

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Author(s): Wade, Bridget S.; Khalid, Abdul; Moore, Ted C.
Author Affiliation(s): Primary:
University College London, Department of Earth Sciences, London, United Kingdom
University of Leeds, United Kingdom
University of Michigan-Ann Arbor, United States
Volume Title: Geological Society of America, 2013 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 45(7), p.846; Geological Society of America, 2013 annual meeting & exposition, Denver, CO, Oct. 27-30, 2013. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: The Eocene-Oligocene transition was a time of major climatic change, associated with extinctions of aquatic and terrestrial life forms, decrease in atmospheric carbon dioxide levels, drop in the calcite compensation depth and establishment of a continental ice-sheet on Antarctica. Integrated Ocean Drilling Program Expedition 320/321 recovered an expanded succession of Paleogene sediments in the equatorial Pacific Ocean. At Site U1334 there is a 'bloom' in the diatom species Coscinodiscus excavatus in the earliest Oligocene. The aim of this project was to document the size and abundance of these distinctive diatoms during a time of environmental change, with the following objectives: 1) Determine the distribution of Coscinodiscus excavatus from Site U1334 2) Document the maximum size of Coscinodiscus excavatus through quantitative morphometric analysis 3) Establish the timing and rapidity of size changes and relationship (if any) to environmental factors Here we present quantitative abundance and morphometric analysis of 1200 specimens of Coscinodiscus excavatus from Site U1334. Samples were analysed at 1.5 metre intervals (90 kyr). Diatoms increase in size and abundance in the early Oligocene from 33.69 Ma. Specimens ranged in size from <120 microns to maximum sizes of 530 microns at 31.8 Ma. This was followed by a rapid decrease in size, with all specimens <150 microns from 31.10 Ma. Relative abundance data indicate a direct correlation between diatom abundance and maximum size. We use multispecies planktonic foraminiferal stable isotopes to reconstruct water column through this interval and explore the mechanism for the dramatic increase in diatom size in the earliest Oligocene.
Year of Publication: 2013
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Carbon dioxide; Cenozoic; Climate change; East Pacific; Eocene; Expedition 320; Expeditions 320/321; IODP Site U1334; Icehouse effect; Integrated Ocean Drilling Program; North Pacific; Northeast Pacific; Oligocene; Pacific Ocean; Paleoatmosphere; Paleoclimatology; Paleoecology; Paleogene; Tertiary
Coordinates: N080000 N080000 W1315824 W1315824
Record ID: 2014064089
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States