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  • Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP  (3)
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  • 1
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    Bering Sea nitrate utilization and stratification since 1.2 Ma analyzed at IODP Site 323-U1342 Holes A, C, and D (2017)
    PANGAEA
    In:  Supplement to: Knudson, Karla P; Ravelo, Ana Christina (2015): Enhanced subarctic Pacific stratification and nutrient utilization during glacials over the last 1.2 Myr. Geophysical Research Letters, 42(22), 9870-9879, https://doi.org/10.1002/2015GL066317
    Details
    Publication Date: 2023-02-24
    Description: The relationship between climate, biological productivity, and nutrient flux is of considerable interest in the subarctic Pacific, which represents an important high-nitrate, low-chlorophyll region. While previous studies suggest that changes in iron supply and/or physical ocean stratification could hypothetically explain orbital-scale fluctuations in subarctic Pacific nutrient utilization and productivity, previous records of nutrient utilization are too short to evaluate these relationships over many glacial-interglacial cycles. We present new, high-resolution records of sedimentary d15N, which offer the first opportunity to evaluate systematic, orbital-scale variations in subarctic Pacific nitrate utilization from 1.2 Ma. Nitrate utilization was enhanced during all glacials, varied with orbital-scale periodicity since the mid-Pleistocene transition, was strongly correlated with enhanced aeolian dust and low atmospheric CO2, but was not correlated with productivity. These results suggest that glacial stratification, rather than iron fertilization, systematically exerted an important regional control on nutrient utilization and air-sea carbon flux.
    Keywords: Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Evidence for enhanced North Pacific Intermediate Water in the Bering Sea during extreme glacials over the past 1.2 Ma from records of stable isotopes analyzed at IODP Site 323-U1342 Holes A, C, and D (2017)
    PANGAEA
    In:  Supplement to: Knudson, Karla P; Ravelo, Ana Christina (2015): North Pacific Intermediate Water circulation enhanced by the closure of the Bering Strait. Paleoceanography, 30(10), 1287-1304, https://doi.org/10.1002/2015PA002840
    Details
    Publication Date: 2023-02-24
    Description: The Bering Strait provides a shallow connection that allows freshwater to flow from the North Pacific into the North Atlantic, but this passage was closed during past glacials when sea level was at least 50 m lower than at present. Climate models investigating Bering Strait closure predict that this mechanism increases the salinity in the North Atlantic and reduces the salinity in the North Pacific, inducing a Pacific-Atlantic seesaw in meridional overturning circulation and poleward heat flux. However, the Pacific circulation response to Bering Strait closure, and thus the seesaw theory, has not been tested by long paleoceanographic records. We present long records of foraminiferal d18O and d13C from Integrated Ocean Drilling Program Site 323-U1342 in the Bering Sea, which provide the first evidence of enhanced North Pacific Intermediate Water when the Bering Strait was closed during each of the extreme glacials of the last 1.2 Myr. These results suggest that orbital-scale variations in North Pacific Intermediate Water are coherent and in phase with variations in upper North Atlantic Deep Water but are unrelated to changes in lower North Atlantic Deep Water. Together, these results provide evidence for systematic, orbital-scale variability in North Pacific Ocean circulation and may challenge the idea of an orbital-scale Pacific-Atlantic seesaw.
    Keywords: Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP
    Type: Dataset
    Format: application/zip, 6 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 3
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    A high-resolution record from IODP Site 323-U1440 (2013)
    PANGAEA
    In:  Supplement to: Schlung, Shilo A; Ravelo, Ana Christina; Aiello, Ivano W; Andreasen, Dyke; Cook, Mea S; Drake, Michelle K; Dyez, Kelsey A; Guilderson, Thomas P; LaRiviere, Jonathan P; Stroynowski, Zuzanna N; Takahashi, Kozo (2013): Millennial-scale climate change and intermediate water circulation in the Bering Sea from 90 ka: A high-resolution record from IODP Site U1340. Paleoceanography, 28(1), 54-67, https://doi.org/10.1029/2012PA002365
    Details
    Publication Date: 2024-04-06
    Description: Millennial-scale climate events in the North Pacific are thought to be related to changes in the circulation of North Pacific Intermediate Water, which may have formed in the Bering Sea in the past. To advance our understanding of the mechanisms that underlie millennial-scale events, Bering Sea sediment cores from the Integrated Ocean Drilling Program site U1340 were used to construct high-resolution, multiproxy climate records of the last 90,000 years. Sediment density records show millennial-scale events resembling Dansgaard-Oeschger events, several of which are laminated. Interstadials were characterized by 3–5 °C warming, increased productivity driven by upwelling, and reduced benthic oxygenation. Bering Sea intermediate water also changed over longer timescales; our records show the presence of intermediate water with lower salinity and higher oxygen content than modern beginning around 60 ka and persisting until the beginning of the deglaciation. The Bølling-Allerød was characterized by high productivity, laminated sediments, and strong denitrification signature. Our data support the idea that productivity-derived changes in oxygenation at intermediate water source regions may have contributed to the intensification of the North Pacific–wide oxygen minima during the Bølling-Allerød.
    Keywords: Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP
    Type: Dataset
    Format: application/zip, 8 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
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