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  • 2020-2024  (26)
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  • 1
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    Late Pliocene to early Pleistocene climate dynamics in western North America based on a new pollen record from paleo-Lake Idaho (2021)
    Allstädt, Frederik J. ; Koutsodendris, Andreas ; Appel, Erwin ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-08-24
    Description: Marked by the expansion of ice sheets in the high latitudes, the intensification of Northern Hemisphere glaciation across the Plio/Pleistocene transition at ~ 2.7 Ma represents a critical interval of late Neogene climate evolution. To date, the characteristics of climate change in North America during that time and its imprint on vegetation has remained poorly constrained because of the lack of continuous, highly resolved terrestrial records. We here assess the vegetation dynamics in northwestern North America during the late Pliocene and early Pleistocene (c. 2.8–2.4 Ma) based on a pollen record from a lacustrine sequence from paleo-Lake Idaho, western Snake River Plain (USA) that has been retrieved within the framework of an International Continental Drilling Program (ICDP) coring campaign. Our data indicate a sensitive response of forest ecosystems to glacial/interglacial variability paced by orbital obliquity across the study interval, and also highlight a distinct expansion of steppic elements that likely occurs during the first strong glacial of the Pleistocene, i.e. Marine Isotope Stage 100. The pollen data document a major forest biome change at ~ 2.6 Ma that is marked by the replacement of conifer-dominated forests by open mixed forests. Quantitative pollen-based climate estimates suggest that this forest reorganisation was associated with an increase in precipitation from the late Pliocene to the early Pleistocene. We attribute this shift to an enhanced moisture transport from the subarctic Pacific Ocean to North America, confirming the hypothesis that ocean-circulation changes were instrumental in the intensification of Northern Hemisphere glaciation.
    Description: Deutsche Forschungsgemeinschaft (DE)
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:561 ; Plio/Pleistocene transition ; North America ; Paleo-Lake Idaho ; Northern Hemisphere glaciation ; Glacial/interglacial cycles ; Climate reconstruction
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
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    Labrador Sea bottom water provenance and REE exchange during the past 35,000 years (2020)
    Elsevier
    Details
    Publication Date: 2023-02-08
    Description: Highlights • Exchange between pore and bottom water with sediment affects authigenic REE in the Labrador Sea (LS). • REE-based correction allows reconstruction of past bottom water ϵNd signatures. • Evidence for lack of southern sourced water in the LS through the last 35 ka. • Glacial LS bottom waters were less radiogenic than today with ϵNd = −16 ± 1. • Similarity to Nordic Seas ϵNd record suggests uninterrupted supply of overflow waters. Abstract Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures. We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS. We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The corrected ϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized.
    Type: Article , PeerReviewed
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Intensification of Asian dust storms during the Mid-Pliocene Warm Period (3.25–2.96 Ma) documented in a sediment core from the South China Sea (2022)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Dust storms are an important component of the global climate system. At the same time, they also bear a risk for human health by causing pulmonary diseases. Today, East Asian dust storms account for as much as half of the global dust emissions and temporarily affect highly populated areas. Therefore, understanding their mechanisms and predicting their evolution under warmer near-future climate conditions is of major interest. The mid-Pliocene Warm Period (mPWP; 3.264–3.025 Ma) is considered one of the best analogues from the past for anthropogenic climate change. Consequently, understanding the climate dynamics and associated environmental change during the mPWP can help with predicting the environmental effects of warmer-than-present climates. In order to reconstruct Asian dust storm evolution during the mPWP we have analyzed a sediment core from the northern South China Sea (SCS) for its elemental composition, grain-size variations and radiogenic isotope signature for the interval spanning from 3.69 to 2.96 Ma. We show that shortly after the first strong northern hemisphere glaciation (Marine Isotope Stage [MIS] M2; 3.25 Ma) atmospherically transported dust appeared in the northern SCS and this dust deposition prevailed throughout the mPWP. Atmospheric dust input further intensified with the onset of the MIS KM2 glaciation at 3.15 Ma, with distinct and strong dust storms occurring periodically from that time onwards. The increase in atmospherically transported dust can be attributed to the cooling and drying of interior Asia over the course of the mPWP along with an intensification of the East Asian Winter Monsoon and a potential southward shift of the westerlies.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    XRF core scanning, TOC, CN, 13C, and macro-charcoal counts from a fresh water mountain lake (Cueifong Lake), northeastern Taiwan (2023)
    PANGAEA
    Details
    Publication Date: 2023-05-18
    Description: The dataset comprises X-ray fluorescent (XRF) core scanning, TOC, C/N, δ13Corg, and macro-charcoal counts of bulk sediment from the sediment core CFL-3. The purpose of this dataset is to reconstruct the sedimentation environment change after the large-scale deforestation. The lake sediment core CFL-3 was taken in Cueifong Lake, northeastern Taiwan in 2017, with a Russian Corer set. The XRF core scanning signals were normalized as described in Lin et al., 2023. The age model was established with 210Pb dating results, augmented by 137Cs dating results. The experiment and analyze detail were described Lin et al., 2023.
    Keywords: 13C; Anthropogenic disturbances; Anthropogenic impact; C/N; charcoal; Deforestation; freshwater lake; Lake sediment core; mountain lakes; Taiwan; TOC; XRF core scanner data; XRF-core scanning
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 5
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    TOC, TOC/TN, and δ13C results from bulk sediment of the top 32 cm of the lake sediment core CFL-3 (2023)
    PANGAEA
    Details
    Publication Date: 2023-05-18
    Keywords: 13C; AGE; Anthropogenic disturbances; Anthropogenic impact; C/N; Carbon, organic, total; Carbon, organic, total/Nitrogen, total ratio; CFL-3; charcoal; Cueifong Lake; Deforestation; DEPTH, sediment/rock; freshwater lake; Lake sediment core; mountain lakes; RUSC; Russian corer; Taiwan; TOC; XRF core scanner data; XRF-core scanning; δ13C, organic carbon
    Type: Dataset
    Format: text/tab-separated-values, 30 data points
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    DATA PANGAEA
  • 6
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    Marco-charcoal counts from the top 32 cm of the lake sediment core CFL-3 (2023)
    PANGAEA
    Details
    Publication Date: 2023-05-18
    Keywords: 13C; AGE; Anthropogenic disturbances; Anthropogenic impact; C/N; CFL-3; charcoal; Counting; Cueifong Lake; Deforestation; DEPTH, sediment/rock; freshwater lake; Lake sediment core; Macrocharcoal; mountain lakes; RUSC; Russian corer; Taiwan; TOC; XRF core scanner data; XRF-core scanning
    Type: Dataset
    Format: text/tab-separated-values, 14 data points
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    DATA PANGAEA
  • 7
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    Authigenic element concentration and neodymium isotope from IODP Sites 303-U1302, 303-U1305, and ODP Site 105--647 (2023)
    PANGAEA
    Details
    Publication Date: 2023-12-01
    Description: Labrador Sea sediment cores IODP 303-U1302, 303-U1305, and ODP 105-647 were investigated for their authigenic trace metal concentrations and neodymium isotope signatures. The sediments are 0 - 35 thousand years old and the authigenic fractions were extracted with weak acid-reductive bulk sediment leaching, with leaching of the decarbonated sediment, and from picked foraminifera samples, and analysed using ICP-QMS and MC-ICP-MS in 2016 - 2019. They were interpreted in terms of exchange with sediment and sea water, and regional climate-induced changes in continental weathering and ocean circulation. Data of three sediment sites were extracted with three different methods. Columns are site and core name, sample depth in cm top and bottom and meters composite depth, sample mass in grams, epsilon Nd signature, two standard deviations uncertainty to epsilon Nd signature, concentrations of 32 elements in µg per gram bulk sediment used, calculated carbonate concentration relative to bulk sediment mass in %, the ratio of heavy to light rare earth elements, mid rare earth element enrichment, cerium anomaly, europium anomaly, sediment age minimum, maximum, and weighted mean in thousand years inferred from sediment datings analysed with the BACON package for the R software, and the sediment classification in terms of IRD events.
    Keywords: 105-647B; 303-U1302B; 303-U1302C; 303-U1302D; 303-U1302E; 303-U1305B; 303-U1305C; AGE; Age, maximum/old; Age, minimum/young; Aluminium; authigenic sediment fraction; BACON age modeling; Barium; Calcium; Calculated; Carbonates; Cerium; Cerium anomaly; Cobalt; Comment; Copper; Depth, composite; Device type; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Dysprosium; Erbium; Europium; Europium anomaly; Event label; Exp303; Gadolinium; Half; Heavy rare-earth elements/light rare-earth elements ratio; Holmium; IODP; Iron; Joides Resolution; Labrador Sea; Lanthanum; Lead; Leg105; Lutetium; Magnesium; Manganese; marine sediment; Middle rare-earth elements anomaly; Neodymium; Neodymium isotopes; Nickel; North Atlantic Climate 1; ocean circulation; Praseodymium; Rare earth elements; Rubidium; Samarium; Sample code/label; Sample mass; Scandium; See Device type column; South Atlantic Ocean; Strontium; Terbium; Thulium; Titanium; trace metals; Treatment; Uranium; Ytterbium; Yttrium; Zinc; Zirconium; ε-Neodymium; ε-Neodymium, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 4898 data points
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    DATA PANGAEA
  • 8
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    Geochemical data from sediment core ORI-891-16-P1 (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-02
    Description: The here presented data comprises the dry bulk density in g/cc, the total organic content (TOC) in %, the total inorganic content (TIC) in %, the total carbon content (TC) in %, the calcium carbonate content (CaCO3) in %, the terrigenous influx rate in g kyr-1 cm-2 and the z-score normalised XRF data counts for the elements Si, K, Ti, Mn, Fe, Br, Rb, Sr and Zr from sediment core ORI-891-16-P1 (19° 33.36'N, 116° 6.77'E; 1595 m water depth). Data is provided against age.
    Keywords: ORI-891-16-P1; PC; Piston corer
    Type: Dataset
    Format: application/zip, 3 datasets
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    DATA PANGAEA
  • 9
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    Element analysis from sediment core ORI-891-16-P1 (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-02
    Description: The here presented data comprises the z-score normalised XRF data counts for the elements Si, K, Ti, Mn, Fe, Br, Rb, Sr and Zr from sediment core ORI-891-16-P1 (19° 33.36'N, 116° 6.77'E; 1595 m water depth). Data is provided against age.
    Keywords: AGE; Bromine, normalized; Calcium, normalized; Iron, normalized; Manganese, normalized; ORI-891-16-P1; PC; Piston corer; Potassium, normalized; Rubidium, normalized; Silicon, normalized; Strontium, normalized; Titanium, normalized; X-ray fluorescence (XRF); Zirconium, normalized
    Type: Dataset
    Format: text/tab-separated-values, 7310 data points
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    DATA PANGAEA
  • 10
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    ln-Titanium/Calcium ratio from sediment core ORI-891-16-P1 (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-02
    Description: The here presented data contains the ln(Ti/Ca) ratio against core depth (m) and age (kyr) from sediment core ORI-891-16-P1 (19° 33.36'N, 116° 6.77'E; 1595 m water depth). The XRF core scanning measurements were conducted at the National Taiwan University (NTU) using an Itrax Cox XRF core scanner. The measurements were conducted using a generator setting of 30 kV, a current of 50 mA and a count time of 5 s. To eliminate non-linear matrix effects and constant-sum constraints, we used logratios to account for a statistically more robust representation of element ratio. The ln(Ti/Ca) element ratio is considered a proxy for terrigenous input, with Ti being dominated by the presence of various heavy minerals e.g. ilmenite, perovskite, rutile and titanite. In contrast, Ca contents have been related to biogenic carbonate variability which is considered a background pelagic signal.
    Keywords: AGE; DEPTH, sediment/rock; East Asian summer monsoon; ln-Titanium/Calcium ratio; ORI-891-16-P1; PC; Piston corer; South China Sea; X-ray fluorescence (XRF); XRF data
    Type: Dataset
    Format: text/tab-separated-values, 731 data points
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    DATA PANGAEA
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