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  • 2015-2019  (54)
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  • 1
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    Glacial-interglacial changes in central tropical Pacific surface seawater property gradients (2015)
    AGU (American Geophysical Union) | Wiley
    In:  Paleoceanography, 30 (5). pp. 423-438.
    Details
    Publication Date: 2018-09-12
    Description: Much uncertainty exists about the state of the oceanic and atmospheric circulation in the tropical Pacific over the last glacial cycle. Studies have been hampered by the fact that sediment cores suitable for study were concentrated in the western and eastern parts of the tropical Pacific, with little information from the central tropical Pacific. Here we present information from a suite of sediment cores collected from the Line Islands Ridge in the central tropical Pacific, which show sedimentation rates and stratigraphies suitable for paleoceanographic investigations. Based on the radiocarbon and oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber, we construct preliminary age models for selected cores and show that the gradient in the oxygen isotope ratio of G. ruber between the equator and 8°N is enhanced during glacial stages relative to interglacial stages. This stronger gradient could reflect enhanced equatorial cooling (perhaps reflecting a stronger Walker circulation) or an enhanced salinity gradient (perhaps reflecting increased rainfall in the central tropical Pacific).
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1002/2014PA002746
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Dynamic carbonate sedimentation on the Northern Line Islands Ridge, Palmyra Basin (2016)
    Elsevier
    In:  Marine Geology, 379 . pp. 194-207.
    Details
    Publication Date: 2019-02-01
    Description: The Line Islands Ridge (LIR), located south of the Hawaiian Islands between 7°N and 1°S, is one of the few large central Pacific regions shallower than the regional carbonate compensation depth. Thick sequences of carbonate sediments have accumulated around the LIR despite it being located in the sediment-starved central tropical Pacific. The LIR is an important source of carbonates to the surrounding region and deposition around the LIR has expanded the equatorial Pacific carbonate sediment tongue by about 5% of its total area. Furthermore, sediments on the ridge are potentially important paleoceanographic archives. A recent survey at the crest of the LIR finds evidence for high current activity, significant erosion, but overall net sediment deposition. Currents are strong enough to form sediment waves and lee drifts in the Palmyra Basin, at the northern terminus of the LIR. Sediments along the LIR are pelagic foraminiferal sands that are easily eroded and flow out into the surrounding abyssal plain in active submarine channel systems. As channels migrate, pelagic sediments fill in the abandoned channel arms. Despite significant sediment losses from the top of the ridge, 1.3 km of sediment has accumulated in the upper Palmyra Basin over basement formed 68 to 85 million years ago (Ma). Late Neogene erosion may be more extensive than earlier erosion cycles, in response to reduced sediment production as the Palmyra Basin exited the high productivity equatorial latitudes. Sediments with good stratigraphic order needed for paleoceanographic study are limited in this dynamic sedimentary environment, but can be found with proper survey.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.margeo.2016.06.005
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    High-resolution and high-precision correlation of dark and light layers in the Quaternary hemipelagic sediments of the Japan Sea recovered during IODP Expedition 346 (2018)
    Springer
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Progress in Earth and Planetary Science 5 (2018): 19, doi:10.1186/s40645-018-0167-8.
    Description: The Quaternary hemipelagic sediments of the Japan Sea are characterized by centimeter- to decimeter-scale alternation of dark and light clay to silty clay, which are bio-siliceous and/or bio-calcareous to a various degree. Each of the dark and light layers are considered as deposited synchronously throughout the deeper (〉 500 m) part of the sea. However, attempts for correlation and age estimation of individual layers are limited to the upper few tens of meters. In addition, the exact timing of the depositional onset of these dark and light layers and its synchronicity throughout the deeper part of the sea have not been explored previously, although the onset timing was roughly estimated as ~ 1.5 Ma based on the result of Ocean Drilling Program legs 127/128. Consequently, it is not certain exactly when their deposition started, whether deposition of dark and light layers was synchronous and whether they are correlatable also in the earlier part of their depositional history. The Quaternary hemipelagic sediments of the Japan Sea were drilled at seven sites during Integrated Ocean Drilling Program Expedition 346 in 2013. Alternation of dark and light layers was recovered at six sites whose water depths are 〉 ~ 900 m, and continuous composite columns were constructed at each site. Here, we report our effort to correlate individual dark layers and estimate their ages based on a newly constructed age model at Site U1424 using the best available paleomagnetic datum and marker tephras. The age model is further tuned to LR04 δ18O curve using gamma ray attenuation density (GRA) since it reflects diatom contents that are higher during interglacial high-stands. The constructed age model for Site U1424 is projected to other sites using correlation of dark layers to form a high-resolution and high-precision paleo-observatory network that allows to reconstruct changes in material fluxes with high spatio-temporal resolutions.
    Description: This work was supported by a grant from IODP Exp. 346 After Cruise Research Program, JAMSTEC, awarded to TR, IK, Irino T, Itaki T, ST, KY, SS, and KA and from JSPS KAKENHI grant number 16H01765 awarded to TR.
    Keywords: Quaternary sediments ; Japan Sea ; Inter-site correlation ; High-resolution age model ; IODP ; Expedition 346 ; U1424 ; U1425 ; U1426 ; U1430
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
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    Neoglacial climate anomalies and the Harappan metamorphosis (2018)
    Copernicus Publications on behalf of the European Geosciences Union
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Climate of the Past 14 (2018): 1669-1686, doi:10.5194/cp-14-1669-2018.
    Description: Climate exerted constraints on the growth and decline of past human societies but our knowledge of temporal and spatial climatic patterns is often too restricted to address causal connections. At a global scale, the inter-hemispheric thermal balance provides an emergent framework for understanding regional Holocene climate variability. As the thermal balance adjusted to gradual changes in the seasonality of insolation, the Intertropical Convergence Zone migrated southward accompanied by a weakening of the Indian summer monsoon. Superimposed on this trend, anomalies such as the Little Ice Age point to asymmetric changes in the extratropics of either hemisphere. Here we present a reconstruction of the Indian winter monsoon in the Arabian Sea for the last 6000 years based on paleobiological records in sediments from the continental margin of Pakistan at two levels of ecological complexity: sedimentary ancient DNA reflecting water column environmental states and planktonic foraminifers sensitive to winter conditions. We show that strong winter monsoons between ca. 4500 and 3000 years ago occurred during a period characterized by a series of weak interhemispheric temperature contrast intervals, which we identify as the early neoglacial anomalies (ENA). The strong winter monsoons during ENA were accompanied by changes in wind and precipitation patterns that are particularly evident across the eastern Northern Hemisphere and tropics. This coordinated climate reorganization may have helped trigger the metamorphosis of the urban Harappan civilization into a rural society through a push–pull migration from summer flood-deficient river valleys to the Himalayan piedmont plains with augmented winter rains. The decline in the winter monsoon between 3300 and 3000 years ago at the end of ENA could have played a role in the demise of the rural late Harappans during that time as the first Iron Age culture established itself on the Ghaggar-Hakra interfluve. Finally, we speculate that time-transgressive land cover changes due to aridification of the tropics may have led to a generalized instability of the global climate during ENA at the transition from the warmer Holocene thermal maximum to the cooler Neoglacial.
    Description: This work was supported by the NSF OCE grant no. 0634731 and internal WHOI funds to Liviu Giosan, NSF MGG grant no. 1357017 to Marco J. L. Coolen, Valier Galy and Liviu Giosan; and a C-DEBI grant no. OCE-0939564 to William D. Orsi.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
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    Climatically driven changes in the supply of terrigenous sediment to the East China Sea (2018)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 19 (2018): 2463-2477, doi:10.1029/2017GC007339.
    Description: We examine the paleoceanographic record over the last ∼400 kyr derived from major, trace, and rare earth elements in bulk sediment from two sites in the East China Sea drilled during Integrated Ocean Drilling Program Expedition 346. We use multivariate statistical partitioning techniques (Q‐mode factor analysis, multiple linear regression) to identify and quantify five crustal source components (Upper Continental Crust (UCC), Luochuan Loess, Xiashu Loess, Southern Japanese Islands, Kyushu Volcanics), and model their mass accumulation rates (MARs). UCC (35–79% of terrigenous contribution) and Luochuan Loess (16–55% contribution) are the most abundant end‐members through time, while Xiashu Loess, Southern Japanese Islands, and Kyushu Volcanics (1–22% contribution) are the lowest in abundance when present. Cycles in UCC and Luochuan Loess MARs may indicate continental and loess‐like material transported by major rivers into the Okinawa Trough. Increases in sea level and grain size proxy (e.g., SiO2/Al2O3) are coincident with increased flux of Southern Japanese Islands, indicating localized sediment supply from Japan. Increases in total terrigenous MAR precede minimum relative sea levels by several thousand years and may indicate remobilization of continental shelf material. Changes in the relative contribution of these end‐members are decoupled from total MAR, indicating compositional changes in the sediment are distinct from accumulation rate changes but may be linked to variations in sea level, riverine and eolian fluxes, and shelf‐bypass processes over glacial‐interglacials, complicating accurate monsoon reconstructions from fluvial dominated sediment.
    Description: U.S. National Science Foundation Grant Numbers: NSF‐EAR1434175, NSF‐EAR1433665, NSF‐EAR1434138
    Keywords: East China Sea ; Bulk sediment ; Provenance ; Multivariate statistics ; East Asian Monsoon ; Loess
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 6
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    Cenozoic global cooling and increased seawater Mg/Ca via reduced reverse weathering (2017)
    Nature Publishing Group
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 8 (2017): 844, doi:10.1038/s41467-017-00853-5.
    Description: Authigenic clay minerals formed on or in the seafloor occur in every type of marine sediment. They are recognized to be a major sink of many elements in the ocean but are difficult to study directly due to dilution by detrital clay minerals. The extremely low dust fluxes and marine sedimentation rates in the South Pacific Gyre (SPG) provide a unique opportunity to examine relatively undiluted authigenic clay. Here, using Mg isotopes and element concentrations combined with multivariate statistical modeling, we fingerprint and quantify the abundance of authigenic clay within SPG sediment. Key reactants include volcanic ash (source of reactive aluminium) and reactive biogenic silica on or shallowly buried within the seafloor. Our results, together with previous studies, suggest that global reorganizations of biogenic silica burial over the Cenozoic reduced marine authigenic clay formation, contributing to the rise in seawater Mg/Ca and decline in atmospheric CO2 over the past 50 million years.
    Description: Funding for this research was provided by the U.S. National Science Foundation to R.W.M. (OCE1130531) and to J.A.H. (OCE1654571).
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 7
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    Quantifying K, U, and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DV JOIDES Resolution (2017)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Geochemistry, Geophysics, Geosystems 18 (2017): 1053–1064, doi:10.1002/2016GC006715.
    Description: During International Ocean Discovery Program (IODP) expeditions, shipboard-generated data provide the first insights into the cored sequences. The natural gamma radiation (NGR) of the recovered material, for example, is routinely measured on the ocean drilling research vessel DV JOIDES Resolution. At present, only total NGR counts are readily available as shipboard data, although full NGR spectra (counts as a function of gamma-ray energy level) are produced and archived. These spectra contain unexploited information, as one can estimate the sedimentary contents of potassium (K), thorium (Th), and uranium (U) from the characteristic gamma-ray energies of isotopes in the 40K, 232Th, and 238U radioactive decay series. Dunlea et al. (2013) quantified K, Th, and U contents in sediment from the South Pacific Gyre by integrating counts over specific energy levels of the NGR spectrum. However, the algorithm used in their study is unavailable to the wider scientific community due to commercial proprietary reasons. Here, we present a new MATLAB algorithm for the quantification of NGR spectra that is transparent and accessible to future NGR users. We demonstrate the algorithm's performance by comparing its results to shore-based inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-emission spectrometry (ICP-ES), and quantitative wavelength-dispersive X-ray fluorescence (XRF) analyses. Samples for these comparisons come from eleven sites (U1341, U1343, U1366-U1369, U1414, U1428-U1430, and U1463) cored in two oceans during five expeditions. In short, our algorithm rapidly produces detailed high-quality information on sediment properties during IODP expeditions at no extra cost.
    Keywords: IODP ; Physical properties ; Natural gamma radiation ; Downhole logging
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
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    Geochemical measurements of bulk sediment from IODP Hole 346-U1428A (2019)
    PANGAEA
    Details
    Publication Date: 2023-12-11
    Keywords: 346-U1428A; AGE; Aluminium oxide; Antimony; Asian Monsoon; Barium; Beryllium; Bulk Sediment; Cadmium; Caesium; Calcium oxide; Cerium; Chromium; Cobalt; Copper; DEPTH, sediment/rock; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Erbium; Europium; Exp346; Gadolinium; Hafnium; Holmium; ICP-MS; ICP-OES; ICP-OES and ICP-MS; Integrated Ocean Drilling Program / International Ocean Discovery Program; IODP; IODP Expedition 346; Iron oxide, Fe2O3; Joides Resolution; Lanthanum; Lead; Lithium; Lutetium; Magnesium oxide; Manganese oxide; Molybdenum; Neodymium; Nickel; Niobium; Phosphorus pentoxide; Potassium oxide; Praseodymium; Rubidium; Samarium; Sample code/label; Scandium; Silicon dioxide; Sodium oxide; Strontium; Tantalum; Terbium; Terrigenous; Thorium; Thulium; Tin; Titanium dioxide; Uranium; Vanadium; Ytterbium; Yttrium; Zinc; Zirconium
    Type: Dataset
    Format: text/tab-separated-values, 1150 data points
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    DATA PANGAEA
  • 9
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    Geocehmical analysis of inorganic bulk sediment from two sites in the East China Sea drilled during IODP Exp346 (2019)
    PANGAEA
    In:  Supplement to: Anderson, Chloe H; Murray, Richard W; Dunlea, Ann G; Giosan, Liviu; Kinsley, C W; McGee, David; Tada, Ryuji (2018): Climatically Driven Changes in the Supply of Terrigenous Sediment to the East China Sea. Geochemistry, Geophysics, Geosystems, 19(8), 2463-2477, https://doi.org/10.1029/2017GC007339
    Details
    Publication Date: 2023-12-11
    Description: We examine the paleoceanographic record over the last ∼400 kyr derived from major, trace, and rare earth elements in bulk sediment from two sites in the East China Sea drilled during Integrated Ocean Drilling Program Expedition 346. We use multivariate statistical partitioning techniques (Q‐mode factor analysis, multiple linear regression) to identify and quantify five crustal source components (Upper Continental Crust (UCC), Luochuan Loess, Xiashu Loess, Southern Japanese Islands, Kyushu Volcanics), and model their mass accumulation rates (MARs). UCC (35–79% of terrigenous contribution) and Luochuan Loess (16–55% contribution) are the most abundant end‐members through time, while Xiashu Loess, Southern Japanese Islands, and Kyushu Volcanics (1–22% contribution) are the lowest in abundance when present. Cycles in UCC and Luochuan Loess MARs may indicate continental and loess‐like material transported by major rivers into the Okinawa Trough. Increases in sea level and grain size proxy (e.g., SiO2/Al2O3) are coincident with increased flux of Southern Japanese Islands, indicating localized sediment supply from Japan. Increases in total terrigenous MAR precede minimum relative sea levels by several thousand years and may indicate remobilization of continental shelf material. Changes in the relative contribution of these end‐members are decoupled from total MAR, indicating compositional changes in the sediment are distinct from accumulation rate changes but may be linked to variations in sea level, riverine and eolian fluxes, and shelf‐bypass processes over glacial‐interglacials, complicating accurate monsoon reconstructions from fluvial dominated sediment.
    Keywords: Bulk Sediment; IODP Expedition 346; Terrigenous
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 10
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    Geochemistry of inorganic bulk sediment and end-members measurements of eolian dust in the East Asian Monsoon and aridification of Asia (2019)
    PANGAEA
    In:  Supplement to: Anderson, Chloe H; Murray, Richard W; Dunlea, Ann G; Giosan, Liviu; Kinsley, C W; McGee, David; Tada, Ryuji (2019): Aeolian delivery to Ulleung Basin, Korea (Japan Sea), during development of the East Asian Monsoon through the last 12 Ma. Geological Magazine, 1-12, https://doi.org/10.1017/S001675681900013X
    Details
    Publication Date: 2023-12-11
    Description: We reconstruct the provenance of aluminosilicate sediment deposited in Ulleung Basin, Japan Sea, over the last 12 Ma at Site U1430 drilled during Integrated Ocean Drilling Program Expedition 346. Using multivariate partitioning techniques (Q-mode factor analysis, multiple linear regressions) applied to the major, trace and rare earth element composition of the bulk sediment, we identify and quantify four aluminosilicate components (Taklimakan, Gobi, Chinese Loess and Korean Peninsula), and model their mass accumulation rates. Each of these end-members, or materials from these regions, were present in the top-performing models in all tests. Material from the Taklimakan Desert (50–60 % of aluminosilicate contribution) is the most abundant end-member through time, while Chinese Loess and Gobi Desert components increase in contribution and flux in the Plio-Pleistocene. A Korean Peninsula component is lowest in abundance when present, and its occurrence reflects the opening of the Tsushima Strait at c. 3 Ma. Variation in dust source regions appears to track step-wise Asian aridification influenced by Cenozoic global cooling and periods of uplift of the Tibetan Plateau. During early stages of the evolution of the East Asian Monsoon, the Taklimakan Desert was the major source of dust to the Pacific. Continued uplift of the Tibetan Plateau may have influenced the increase in aeolian supply from the Gobi Desert and Chinese Loess Plateau into the Pleistocene. Consistent with existing records from the Pacific Ocean, these observations of aeolian fluxes provide more detail and specificity regarding the evolution of different Asian source regions through the latest Cenozoic.
    Keywords: Bulk Sediment; Eolian; IODP Expedition 346; Terrigenous
    Type: Dataset
    Format: application/zip, 2 datasets
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    DATA PANGAEA
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