Initial Reports of the Deep Sea Drilling Project, 85

Mayer, Larry A.; Theyer, Fritz; Barron, John A.; Dunn, Dean A.; Handyside, Tim; Hills, Scott; Jarvis, Ian; Nagrini, Catherine A.; Pisias, Nicklas G; Pujos, A.; Saitō, Tsunemasa; Stout, Paul M; Thomas, Ellen; Weinreich, Norbert; Wilkens, Roy H

doi:10.2973/dsdp.proc.85.1985

Cited by 176 publications

(11 citation statements)

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“…The new chronology for Site 849 results in a mean temporal sample resolution of 780 years and an average linear sedimentation rate of 2.6 cm kyr −1 (Figure c) for the time interval between 2.65 and 2.4 Ma (MIS G1 to 94). These sedimentation rates are in close agreement with those of other records published for the late Pliocene/early Pleistocene from the EEP region (e.g., Deep Sea Drilling Project Site 572: 2.1 cm kyr −1 [ Mayer et al ., ] (Figure a) and ODP Site 849: 2.5–3.0 cm kyr −1 [ Mix et al ., ]).…”

Section: Resultsmentioning

confidence: 99%

“…There, both equatorial upwelling and coastal upwelling contribute to conditions that support more than 10% of the global biological production in the present-day oceans [Pennington et al, 2006]. Relatively high year-round primary productivity levels are responsible for relatively high sedimentation rates on the order of 2.5 to 3.0 cm kyr À1 for the past 5 Myr [Mayer et al, 1985;Mix et al, 1995], allowing the generation of highly temporally resolved proxy records in this region. However, given the supply of upwelled nutrient-rich waters, modern biological production in the EEP is not as high as we might expect because of iron limitation [Coale et al, 1996], characterizing the EEP Ocean as a high-nutrient, low-chlorophyll (HNLC) region.…”

Section: Introductionmentioning

confidence: 99%

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Plio‐Pleistocene glacial‐interglacial productivity changes in the eastern equatorial Pacific upwelling system

et al. 2016

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The eastern equatorial Pacific Ocean (EEP) upwelling system supports >10% of the present-day global ocean primary production, making it an important component in Earth's atmospheric and marine carbon budget. Traditionally, it has been argued that since intensification of Northern Hemisphere glaciation (iNHG,~2.7 Ma), changes in EEP productivity have predominantly depended on trade wind strength-controlled upwelling intensity. An alternative hypothesis suggests that EEP productivity is primarily controlled by nutrient supply from the high southern latitudes via mode waters. Here we present new high-resolution data for the latest Pliocene/early Pleistocene from Ocean Drilling Program Site 849, located within the equatorial divergence system in the heart of the EEP upwelling regime. We use carbon isotopes in benthic and planktic foraminiferal calcite and sand accumulation rates to investigate glacial-interglacial (G-IG) productivity fluctuations between 2.65 and 2.4 Ma (marine isotope stages (MIS) G1 to 94). This interval includes MIS 100, 98, and 96, three large-amplitude glacials (~1‰ in benthic δ 18 O) representing the culmination of iNHG. Our results suggest that latest Pliocene/early Pleistocene G-IG productivity changes in the EEP were strongly controlled by nutrient supply from Southern Ocean-sourced mode waters. Our records show a clear G-IG cyclicity from MIS 100 onward with productivity levels increasing from full glacial conditions and peaking at glacial terminations. We conclude that enhanced nutrient delivery from high southern latitudes during full glacial conditions together with superimposed intensified regional upwelling toward glacial terminations strongly regulated primary productivity rates in the EEP from MIS 100 onward.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plio‐Pleistocene glacial‐interglacial productivity changes in the eastern equatorial Pacific upwelling system

et al. 2016

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“…This study used sediments from eastern equatorial Pacific HPC sites 572 and 573 from the Deep Sea Drilling Project. Complete Pliocene sections of siliceous calcareous ooze and chalk units were recovered at these locations [Mayer et al, 1985] (Table 1, Figure 1). Sites 572 and 573 presently lie [Barron, 1985;Nigrini, 1985].…”

Section: Methodsmentioning

confidence: 99%

Paleoceanography of the eastern equatorial Pacific during the Pliocene: A High‐Resolution Radiolarian Study

Hays¹,

Pisias²,

Roelofs³

1989

Paleoceanography

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Pliocene sediments from hydraulic piston cores of Deep Sea Drilling Project sites 572 and 573 in the eastern equatorial Pacific provide material for a high‐resolution stratigraphic and paleoceanographic study during a period of time from 2.4 to 3.7 Ma. Radiolarian stratigraphy of these two sites reveals two major faunal events. The older event involves the gradual disappearance of five species and the appearance of three equatorial surface‐dwelling radiolarian species and occurs at the Gauss/Gilbert paleomagnetic reversal boundary which is coincident with the time of the closing of the Isthmus of Panama around 3.5 Ma [Berggren and Hollister, 1974; Keigwin, 1978, 1982a, b]. The younger event involves a disappearance and appearance of two mainly Subarctic species and occurs at 2.9 Ma, prior to the onset of northern hemisphere glaciation as dated in North Atlantic sections. Analysis of quantitative radiolarian data for extant species divides the Pliocene fauna into two assemblages which are composed of radiolarian species that are abundant in the surface sediments of central and eastern equatorial regions. From the time series variations of these fauna, the variability of these factors has remained constant over the time interval at the eastern site but underwent a stepwise decrease at the western site. Paleotemperature transfer function techniques provided quantitative comparisons between Pliocene and Pleistocene paleooceanographic variability. At the more western site, a shift in paleotemperature estimates occurred. Using the modern day observation that the slope of the thermocline is related to the magnitude of westward wind stress, this change corresponds to an increase in wind stress. This event has been dated at about 2.8 Ma and may represent an important oceanic and atmospheric precursor to the major onset of northern hemisphere glaciation at 2.4 Ma. From the modern relationship between seasonal differences in temperatures at each site the Pliocene gradient in seasonally has been compared with the Pleistocene (and modern) gradients. Relative to the Pleistocene, seasonal differences in temperature were the same for the more eastern site but lower at the western site. The Pliocene gradient in seasonally was thus located farther east toward the South American continent than during the Pleistocene. No influence of the final closure of the Isthmus of Panama is seen in the extant radiolarian data for sites 572 and 573 during the time interval from 2.4 Ma to 3.7 Ma.

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“…Sediments recovered at Leg 85 Sites 572, 573, and 574 consist of calcareous oozes and chalks [Mayer et al, 1985b]. Average calcium carbonate contents vary from 82.0% and 77.2% at Sites 573 and 574, respectively, to 72.6% at Site 572.…”

Section: Where's the Basement?mentioning

confidence: 87%

“…Nearly complete and undisturbed sections of calcareous sediments in the equatorial Pacific were recovered during DSDP Leg 85 [Mayer et al, 1985b] and relatively complete profiles of closely spaced shipboard physical properties measurements are available from Leg 85 sites [Wilkens and Handyside, 1985]. At Site 574, these physical properties data, after mechanical rebound corrections to assumed in situ values, were used to constrain detailed correlations between core lithostratigraphy and seismic horizons in reflection profiles [Mayer et al, 1985a[Mayer et al, , 1986].…”

Section: Our Work Has Shown That the Ojp Corrections Are Generally Bmentioning

confidence: 99%

In situ velocities in pelagic carbonates: New insights from Ocean Drilling Program Leg 130, Ontong Java Plateau

Urmos¹,

Wilkens²

1993

J. Geophys. Res.

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Ocean Drilling Program Leg 130 returned an extensive suite of in situ borehole logging and closely spaced shipboard physical properties measurements from four sites drilled in carbonate‐rich pelagic oozes and chalks on the Ontong Java Plateau. Using these data, we evaluated factors responsible for observed differences between laboratory data and in situ values. Laboratory and log differences for bulk density/porosity are small and nearly constant and can be accounted for by hydraulic rebound of pore fluid following sediment recovery. Evidence for mechanical rebound of sediments was not observed. Velocity‐porosity relationships cannot be used to indirectly correct laboratory velocities to in situ because fundamental assumptions required for rebound corrections are not satisfied. Velocity‐porosity systematics are also complicated by foraminiferal intraparticle porosity variations. We derived empirical laboratory velocity corrections using log and laboratory velocity differences expressed as functions of depth and effective pressure. We tested the velocity corrections using data for carbonates recovered from Ocean Drilling Program Sites 704, 722, and 762; comparisons with logs show that corrected velocities accurately estimate in situ values for oozes and chalks (CaCO3 >60%). For applications to unlogged Deep Sea Drilling Project Leg 85 sites, igneous basement travel times calculated using corrected velocities agree with acoustic basement travel times from seismic records, implying that corrected velocities are realistic in situ estimates. At Site 574, we used our corrected velocities to reevaluate previous lithostratigraphic and seismostratigraphic correlations based on mechanical rebound‐corrected velocities. The new velocities correlate reflectors to progressively greater core depths. Although changes are minor above 200 m below seafloor, the lowest assigned reflector is shifted 36 m deeper to more closely coincide with a diagenetic boundary and acoustic basement correlates with igneous basement instead of with postulated high‐impedance reflectors within the sediments.

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Initial Reports of the Deep Sea Drilling Project, 85

Cited by 176 publications

References 0 publications

Plio‐Pleistocene glacial‐interglacial productivity changes in the eastern equatorial Pacific upwelling system

Plio‐Pleistocene glacial‐interglacial productivity changes in the eastern equatorial Pacific upwelling system

Paleoceanography of the eastern equatorial Pacific during the Pliocene: A High‐Resolution Radiolarian Study

In situ velocities in pelagic carbonates: New insights from Ocean Drilling Program Leg 130, Ontong Java Plateau

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