We assessed sediment coring, data acquisition, and publications from
the North Pacific (north of 30
Paleoceanographic sediments provide the sedimentary, geochemical, and biological evidence of past Earth system changes. Sediment cores produce robust reconstructions of large oceanographic provinces and provide insight into earth system mechanistic hypotheses. However, there is not a common repository for paleoceanographic data and publications, and this lack of centralization limits the efficacy of the earth science community in directing research efforts. For the North Pacific, such ongoing mechanistic hypotheses include deep ocean circulation (e.g., Rae et al., 2014; De Pol-Holz et al., 2006), deep water and intermediate water formation and ventilation (e.g., Knudson and Ravelo, 2015a; Zheng et al., 2000; Cook et al., 2016), and changes in the oceanic-preformed nutrient inventories (e.g., Jaccard and Galbraith, 2013; Knudson and Ravelo, 2015b), as well as more regional mechanisms such as sea ice extent (e.g., Max et al., 2012), upwelling intensity (e.g., Di Lorenzo et al., 2008; Hendy et al., 2004), local surface ocean productivity (e.g., Serno et al., 2014; Venti et al., 2017), and terrigenous and marine fluxes of iron (e.g., Davies et al., 2011; Praetorius et al., 2015).
Paleoceanographers have benefited from the use of large databases of climate data in the past, such as CLIMAP Project Members (1981) (Climate: Long-Range Investigation, Mapping, Prediction), which produced globally resolved temperature records for the Last Glacial Maximum (LGM) and aimed to determine climate system sensitivity from paleoclimate reconstructions (Hoffert and Covey, 1992). The PaleoDeepDive project employed a similar approach to the systematic extraction of archival data and constructed a new way to assess and engage with paleobiological data (Zhang, 2015). These projects are examples of international research teams approaching the same limit – extraction and organization of dark data – that arises when creating comprehensive paleoreconstructions.
A clear need exists for high quality paleoenvironmental reconstructions to fit the North Pacific into a climate global framework because the role this enormous ocean basin plays in earth system changes remains relatively unclear in comparison to the Southern and Atlantic oceans. To address the collective need, we present here a new database of North Pacific paleoceanographic research efforts along with the broad findings of our census of coring metadata, age model development, and proxy publications. We address the following questions in this paper to supplement and provide context for our database:
Where have sediment cores been extracted from the North Pacific
seafloor (north of 30 For sediment cores with published age models, what lines of
evidence were used to develop the chronological age of the sediment,
what is the age range from core top to core bottom, and what are the
sedimentation rates? What lines of sedimentary, geochemical, isotopic, and biological
proxy evidence are available for each sediment core? How has the state of North Pacific research efforts and
reporting changed since the beginning of paleoceanographic
expeditions?
Marine sedimentary age models tie the sedimentary depth (in meters below sediment surface) to calendar age (ka, thousands of years and/or Ma, millions of years). Not all sedimentary chronologies are of the same quality, and often age models are iteratively refined. Age models are developed with many different dating techniques, which are dependent upon the quality, preservation, and age of the sediments, as well as the investigative priorities of research teams and the proximity of other well-developed sedimentary chronologies. Paleoceanographic proxies, including biological, isotopic, geochemical, and sedimentary observations and measurements, address large thematic questions in the reconstruction of ocean environments, including ocean temperature, paleobiology, seafloor geochemistry, sea ice distribution, and additional sedimentary analyses.
Sediment cores are often represented by their cruise–core unique
identifier, which has the general format “cruise name-core
number”. The cruise number is generally indicative of the research
vessel employed and the year of the expedition. For example, L13-81 is
the 13th cruise of S. P. Lee in 1981, MR06-04 is the 4th cruise of
R/V
Location and recovery year of marine sediment cores from the
North Pacific and marginal seas.
Here we assembled a database from peer-reviewed publications, publicly available online cruise reports, and print-only cruise reports available through the University of Washington library network. Detailed metadata were reported for cores where it is available, commonly from cruise reports, including water depth (in meters), recovery year, latitude and longitude, coring technology, and core length (in meters). Summary details regarding affiliated research vessels and institutions were gathered from publications or cruise reports. Cruise reports were commonly available for research expeditions affiliated with JAMSTEC, GEOMAR, and the Scripps Institution of Oceanography and were less commonly available for older cores. All evidence used in age model development was reported along with sedimentation rates and the sedimentary age ranges to provide investigators with the capacity to quickly evaluate specific cores that meet the investigative priorities. For each core, paleoceanographic proxies and associated publications are documented to provide an efficient resource for assessing the availability and quality of different lines of paleoenvironmental information. In addition, we evaluated the annual number of age models published (using any dating technique), age models published specifically with radiocarbon dating, publications generated, sediment cores collected, research cruises completed, and the mean number of proxies generated per core.
We documented 2134 sediment cores and 283 marine geology research cruises
above 30
Regional summary of sediment core database for the Bering Sea, North Pacific, Sea of Japan, and Sea of Okhotsk, including number of cores recovered, the regional percent (%) of cores reported with latitude and longitude, number of research cruises, total regional publication count, count of cores with no peer-reviewed publications or cruise report, the range of core recovery years, the regional percent (%) of cores reported with recovery years, and the range of recovered core water depths (m b.s.l.).
Percent of regional cores reported with coring technology and the number of cores recovered in the North Pacific and marginal seas by coring technology. Additional reported coring technologies include the less often utilized hydrostatic cores, kasten cores, Asura cores, pressure cores, and trigger cores.
In the North Pacific, 519 marine sediment cores have published age
models, and 266 of these chronologies are generated with the radiocarbon
dating (
Age model development for sediment cores in the North Pacific
and marginal seas.
Summary statistics on core chronology, including the
number of cores with radiocarbon dating (
From all reported sediment cores in the North Pacific and marginal
seas, only 40 % of cores have published proxy data (Figs. 3
and 5). Stable isotope stratigraphy was available for 293 cores,
including oxygen, carbon, or nitrogen isotopes (
Published paleoceanographic proxies in the North Pacific.
Published planktonic and benthic foraminiferal oxygen isotope
stratigraphy for sediment core age models.
The marine geology cruise and
paleoceanographic research progress through time for the North Pacific and marginal seas, wherein the
lead–lag timing of cruise reporting and core publication is assumed
for the most recent years. We utilize peer-reviewed publications to
locate cores, and there is a lag between publication and core
extraction.
Regional summary of isotopic, geochemical, biological, and sedimentary proxies. Benthic and planktonic isotopic analysis is for all cores, including, but not limited to, isotope analysis used in core chronology development.
We recorded paleothermometry data for 234 cores, including planktonic
foraminifera oxygen isotopes, magnesium to calcium ratios from planktonic
foraminifera, and alkenones
We cataloged 565 peer-reviewed publications and cruise reports and evaluated the progress of paleoceanographic research using a suite of annual metrics of cruise and core metadata and publications (Fig. 5). The state of North Pacific paleoceanographic investigations has evolved incrementally in the 65-year history of research in the region, and we characterize the history into two distinct phases (before and after the early 1990s). Cruise reports were not publicly available for every cruise or core, and information on many cores cited in cruise reports was never published in peer-reviewed literature. The majority of cores (1210 cores or 57 % of all cores extracted from the North Pacific) lack any publication.
Core recovery rates were high and publication rates were low from
1951 to 1988, which is a period when expeditions were driven by
individual institutions and peer-reviewed publication was not the
primary research outcome (Fig. 5). Annual rates of cruise completion
and sediment core extraction peaked in 1965–1968, and this is
a consequence of the temporal overlap in peak research efforts by
the Scripps Institute of Oceanography (1951–1988), the Lamont–Doherty Earth
Observatory (1964–1975), Oregon State University (1962–1972), and
the Deep Sea Drilling Project (1971–1982). Annual rates of
publication (peer-reviewed and cruise reports), including those
publications with age models, increased around 1995 (Fig. 5). In this
later period, research cruise efforts were dominated by international
research team efforts and resulted in increased peer-reviewed
publications, sediment core chronology constructions, and the
proliferation of radiocarbon dating. There are 41 cores with very
focused investigation (
Number of affiliated publications and cruise reports for each core. The maximum publication count for an individual core is 23.
The database can be found online at
Extensive cruise and research efforts have focused on the marine geology of the North Pacific. Often, the cruise and core metadata from these efforts are unpublished, though they are integral to collaboration, continued research, and publication. Here we present a database with 2134 sediment cores, 283 research cruises, and 565 peer-reviewed publications related to paleoceanographic research (Table 1). We cataloged 519 publications with sedimentary age models, and of those age models, 266 utilized radiocarbon dating, 201 utilized planktonic foraminiferal oxygen isotope stratigraphy, and 129 utilized benthic foraminiferal oxygen isotope stratigraphy (Figs. 2 and 4). Throughout the North Pacific, Bering Sea, Sea of Okhotsk, and Sea of Japan, the techniques for reconstructing sedimentary age models varied regionally. We documented a community-wide shift away from singular dating techniques toward age models that incorporate several techniques. Multiproxy approaches hold merit through verifying or constraining the results of a singular proxy and thereby disentangling multiple environmental drivers and providing redundancy in order to create robust records of climate and ocean conditions (Mix et al., 2000; Mann, 2002). Age model development has moved through the last 60 years to more detailed high-resolution age models constructed to investigate millennial and submillennial paleoceanographic variability (Figs. 5 and 6).
Databases are integral to facilitate efficient, hypothesis-based investigations into earth system mechanisms. Public access to databases facilitate a higher volume of research by a diverse range of scientists (Harnad and Brody, 2004). The necessity for databases to encompass a wide array of data over large oceanographic provinces is also largely recognized. Open access tools from PANGAEA support database-dependent research because hypothesis-based investigations can be more efficient through public data access. For example, content from online databases has contributed to research in atmospheric forcing (e.g., Shaffer et al., 2009), the Atlantic Meridional Overturning Circulation (AMOC; e.g., Schmittner and Galbraith, 2008), and Southern Ocean ventilation (e.g., Yamamoto et al., 2015). The metadata in these databases must be thorough, as data are impractical without the affiliated identifier, location, and methods (Lehnert et al., 2000). Database management should be a priority in any field that incorporates the contents of online repositories of knowledge and research. The disconnect between the research goals of the paleoceanographic community and the metadata produced here can be described as a “breakdown” that limits the progress of paleoceanographic research (Tanweer et al., 2016). These breakdowns allow us to self-assess and move forward with insight into best practices. Metadata are produced from data sets that are inherently human in design and are therefore not inerrant. Assessment of the errors in metadata reporting can directly reveal the need for community-wide improvements. As an example, all cores should be reported with latitude and longitude; the absence of these specific metadata significantly impairs further work. The database presented here and others like it consolidate the research effort of an entire community into an efficient tool for future investigative purposes.
Ocean sediment records are one of the primary tools for understanding earth's history, and the documentation of these records benefits the entire community of earth scientists. The publications and cruise reports here represent a large body of research completed on North Pacific sediment records; however, this may not constitute the entire body of work. There was no preexisting common repository for cruise reports and coring data in the North Pacific beyond the individual institutional archival processes. This database serves as the most complete archive of publicly available cruise reports and publications in which available DOIs and URLs are reported. We demonstrate a need for more thorough, accessible documentation of marine geology and paleoceanographic research. In our examination of publications, cruise reports, and notes from research cruises, we gained insights into past inconsistencies in marine sediment record reporting. We recommend a suite of actions to ensure efficient, comprehensive sediment core collection, metadata documentation, and the publication of chronologies and proxies. We propose that each publication thoroughly reports metadata on all cores discussed and their associated cruises, including core unique identifier numbers, cruise name and number, vessel name, geographic coordinates, core recovery date, core length, core recovery water depth (m b.s.l.), sampling resolution, sampling volume, core archival repository, and the link (if existing) to public cruise reports. We also suggest summarizing each core's metadata, age model, and publication history in the methods section in order to provide a frame of reference for new findings, especially in the context of iterative age model revisions.
SEM and CVD initiated the building of this database. MB and SEM built the database and were joined by KASM in producing figures and analysis for this paper. All authors wrote the paper.
The authors declare that they have no conflict of interest.
The authors would like to thank the University of Washington Library oceanography collection, namely Louise Richards and Maureen Nolan. We also wish to acknowledge the support for this publication provided by the University of Washington Purple and Gold Scholarship, the UW School of Oceanography Lowell K. and Alice M. Barger Endowed Scholarship, the Clarence H. Campbell Endowed Lauren Donaldson Scholarship, the UW College of the Environment Student Travel Grant, and NSF grant OCE-1458967. KAS Mislan was supported by the Washington Research Foundation Fund for Innovation in Data-Intensive Discovery and the Moore/Sloan Data Science Environments Project at the University of Washington. Edited by: Attila Demény Reviewed by: Baolin Liu and Thomas M. Cronin