Sediment mixing in the tropical Pacific and radiolarian stratigraphy

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doi: 10.1029/2012GC004198
Author(s): Moore, Ted C., Jr.; Mayer, Larry A.; Lyle, Mitchell
Author Affiliation(s): Primary:
University of Michigan, Department of Earth and Environmental Sciences, Santa Cruz, CA, United States
University of New Hampshire, United States
Texas A&M University, United States
Volume Title: Geochemistry, Geophysics, Geosystems - G<sup>3</sup>
Source: Geochemistry, Geophysics, Geosystems - G>3`, 13(8). Publisher: American Geophysical Union and The Geochemical Society, United States. ISSN: 1525-2027
Note: In English. 29 refs.; illus., incl. sketch map
Summary: The reworking of older radiolarian microfossils into near-surface sediments of the tropical Pacific has long been the source of confusion for the development of radiolarian stratigraphy and of puzzlement over the mechanism(s) that could effect such pervasive reworking. Widespread dissolution "pits" in the sediments of the tropical Pacific are believed to be associated with hydrothermal circulation cells in the older oceanic crust and are here linked to processes which expose older sections and inject older non-carbonate material into near-bottom waters. Discharging waters of these circulation cells tend to dissolve carbonate in near-surface sediments; thus, only the non-carbonate material (including radiolarians) is preserved and reworked into younger sediments. Results from the study of two sites in the tropical Pacific indicate that reworked older, stratigraphically important radiolarians are less than 2% of the total radiolarian assemblage. This constitutes a minimum estimate of the amount of reworked, non-carbonate material in the younger sediments. The oldest reworked radiolarians are no more than 10 m.y. younger than the underlying basement, and radiolarians from the entire older section above that level can be found in the reworked material. A time series of the flux of reworked material at one site is not constant but instead has varied by a factor of 3 to 4 over the past 2.5 m.y. During times when the flux of reworked material is particularly low, the proportion of older, more robust radiolarians is larger.
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; 12 Stratigraphy, Historical Geology and Paleoecology; Biostratigraphy; Carbonates; Cenozoic; East Pacific; Equatorial Pacific; Erosion; Expedition 320; Expeditions 320/321; Geophysical methods; Geophysical profiles; Geophysical surveys; Hydrothermal conditions; IODP Site U1334; Integrated Ocean Drilling Program; Invertebrata; Marine sediments; Microfossils; Miocene; Mixing; Neogene; North Pacific; Northeast Pacific; Ocean circulation; Ocean floors; Oceanography; Oligocene; Pacific Ocean; Paleogene; Permeability; Pliocene; Porosity; Protista; Radiolaria; Sediments; Seismic methods; Seismic profiles; Surveys; Tertiary; Tracers
Coordinates: N080000 N080000 W1315824 W1315824
Record ID: 2013081602
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