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  • 1
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    (Table 1) Age determination of sediment core MD02-2515
    PANGAEA
    In:  Supplement to: Pichevin, Laetitia; Ganeshram, Raja S; Reynolds, Ben C; Prahl, Frederick G; Pedersen, Thomas F; Thunell, Robert C; McClymont, Erin L (2012): Silicic acid biogeochemistry in the Gulf of California: Insights from sedimentary Si isotopes. Paleoceanography, 27(2), 319-333, https://doi.org/10.1029/2011PA002237
    Details
    Publication Date: 2023-06-27
    Description: Iron is considered to play a large role in the cycling of Si in Fe-limited regions of the ocean, but little is known about its role in Si biogeochemistry outside these areas. Here, we present published sediment trap data, new nutrient profiles and high resolution sedimentary records (Si isotopes, Biogenic silica%, N% and C%) from the Gulf of California, a non-Fe-limited region, to investigate the history of Si cycling in this highly productive basin. Modern nutrient profiles show that silicic acid in subsurface waters is in excess relative to nitrate and is therefore incompletely utilized during moderate winter upwelling events. Modern data, however, suggest that during intense upwelling episodes, silicic acid is preferentially utilized relative to nitrate by the biota, which we suggest reflects transient iron limitation. Our new d30Si record from the Guaymas Basin shows dramatic variations at millennial timescales. Low δ30Si values synchronous with Heinrich events are interpreted as resulting from the decline in Si(OH)4 utilization at times of decreased upwelling strength, while nearly complete Si(OH)4 utilization was observed at times of invigorated upwelling and increased opal burial during the Holocene, the Bølling-Allerød and the last glacial period. We attribute the complete utilization of Si(OH)4 to the occurrence of transient Fe limitation at these times. Our study highlights the importance of Fe limitation on Si and C cycling in coastal upwelling regions and suggests that upwelling dynamics, in combination with Fe availability, have the potential to modulate marine Si distribution and opal burial even at short timescales.
    Keywords: Age, 14C AMS; Age, 14C calibrated; Age, dated; Age, dated material; Age, dated standard deviation; Calendar age; CALYPSO; Calypso Corer; DEPTH, sediment/rock; Guaymas Basin; IMAGES VIII - MONA; Marion Dufresne (1995); MD022515; MD02-2515; MD126
    Type: Dataset
    Format: text/tab-separated-values, 112 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 2
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    Geochemistry on core 202-1240A (2009)
    PANGAEA
    In:  Supplement to: Pichevin, Laetitia; Reynolds, Ben C; Ganeshram, Raja S; Cacho, Isabel; Pena, L; Keefe, K; Ellam, Rob M (2009): Enhanced carbon pump inferred from relaxation of nutrient limitation in the glacial ocean. Nature, 459, 1114-1117, https://doi.org/10.1038/nature08101
    Details
    Publication Date: 2024-01-09
    Description: The modern Eastern Equatorial Pacific (EEP) Ocean is a large oceanic source of carbon to the atmosphere1. Primary productivity over large areas of the EEP is limited by silicic acid and iron availability, and because of this constraint the organic carbon export to the deep ocean is unable to compensate for the outgassing of carbon dioxide that occurs through upwelling of deep waters. It has been suggested that the delivery of dust-borne iron to the glacial ocean could have increased primary productivity and enhanced deep-sea carbon export in this region, lowering atmospheric carbon dioxide concentrations during glacial periods. Such a role for the EEP is supported by higher organic carbon burial rates documented in underlying glacial sediments but lower opal accumulation rates cast doubts on the importance of the EEP as an oceanic region for significant glacial carbon dioxide drawdown. Here we present a new silicon isotope record that suggests the paradoxical decline in opal accumulation rate in the glacial EEP results from a decrease in the silicon to carbon uptake ratio of diatoms under conditions of increased iron availability from enhanced dust input. Consequently, our study supports the idea of an invigorated biological pump in this region during the last glacial period that could have contributed to glacial carbon dioxide drawdown. Additionally, using evidence from silicon and nitrogen isotope changes, we infer that, in contrast to the modern situation, the biological productivity in this region is not constrained by the availability of iron, silicon and nitrogen during the glacial period. We hypothesize that an invigorated biological carbon dioxide pump constrained perhaps only by phosphorus limitation was a more common occurrence in low-latitude areas of the glacial ocean.
    Keywords: 202-1240A; DRILL; Drilling/drill rig; Joides Resolution; Leg202; North Pacific Ocean; Ocean Drilling Program; ODP
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 3
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    (Table 1) Estimated e-Nd(0) input calculated using the relative fraction of ODP Hole 105-647A amphibole grains originated from different provinces of the North America (2006)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Description: Many marine radiogenic isotope records show both spatial and temporal variations, reflecting both the degree of mixing of distinct sources in the oceans and changes in the distribution of chemical weathering on the continents. However, changes in weathering and transport processes may themselves affect the composition of radiogenic isotopes released into seawater. The provenance of physically weathered material in the Labrador Sea, constrained through the use of Ar-Ar ages of individual detrital minerals, has been used to estimate the relative contributions of chemically weathered terranes releasing radiogenic isotopes into the Labrador Sea. A simple box-model approach for balancing observed Nd-isotope variations has been used to constrain the relative importance of localised input in the Labrador Sea, and the subsequent mixing of Labrador Sea Water into North Atlantic Deep-Water. The long-term pattern of erosion and deep-water formation around the North Atlantic seems to have been a relatively stable feature since 1.5 Ma, although there has been a dramatic shift in the nature of physical and chemical weathering affecting the release of Hf and Pb isotopes. The modelled Nd isotopes imply a relative decrease in water mass advection into the Labrador Sea between 2.4 and 1.5 Ma, accompanied by a decrease in the rate of overturning, possibly caused by an increased freshwater input into the Labrador Sea.
    Keywords: 105-647A; AGE; DRILL; Drilling/drill rig; Joides Resolution; Leg105; Number of observations; Ocean Drilling Program; ODP; South Atlantic Ocean; ε-Neodymium (0)
    Type: Dataset
    Format: text/tab-separated-values, 64 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 4
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    (Table DR1) Argon isotope data and dating for individual 〉63 µm amphibole grains from Labrador Sea sediments, ODP Hole 105-647A (2004)
    PANGAEA
    In:  Supplement to: Reynolds, Ben C; Sherlock, Sarah C; Kelley, Simon P; Burton, Kevin W (2004): Radiogenic isotope records of Quaternary glaciations: Changes in the erosional source and weathering processes. Geology, 32(10), 861-864, https://doi.org/10.1130/G20734.1
    Details
    Publication Date: 2024-01-09
    Description: Variations of global and regional silicate weathering rates and paleo-ocean circulation patterns are estimated by using radiogenic isotope records, but the effects of changes in provenance are generally ignored. Here sediment provenance has been constrained through the use of Ar-Ar ages for individual detrital minerals from the Labrador Sea, which can be compared directly to the radiogenic isotope compositions from the same core material. Dramatic changes in the radiogenic isotope composition of North Atlantic Deep Water through the Quaternary Period are shown to reflect discrete changes in both sources and weathering processes accompanying Northern Hemisphere glaciation. Changes in the different radiogenic isotope systems reflect the influence of source, physical weathering, and chemical weathering, and not simply changes in the underlying weathering rate or ocean circulation patterns that are typically inferred.
    Keywords: 105-647A; AGE; Age, dated; Age, dated standard deviation; Argon-36/Argon-39; Argon-36/Argon-39, standard deviation; Argon-37/Argon-39; Argon-37/Argon-39, standard deviation; Argon-38/Argon-39; Argon-38/Argon-39, standard deviation; Argon-39; Argon-40; Argon-40, standard deviation; Argon-40/Argon-39; Argon-40/Argon-39, standard deviation; Calculated; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Infrared laser ablation microprobe (IRLAMP); Joides Resolution; Leg105; Method comment; Number; Ocean Drilling Program; ODP; Sample code/label; South Atlantic Ocean; Standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 4595 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 5
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    Silicon isotopes from sediment core 202-1240A (2009)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Keywords: 202-1240A; AGE; Average; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg202; North Pacific Ocean; Ocean Drilling Program; ODP; Sample code/label; δ29Si; δ29Si, error; δ30Si, biogenic silica; δ30Si, error
    Type: Dataset
    Format: text/tab-separated-values, 198 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 6
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    Geochemistry on sediment core 202-1240A (2009)
    PANGAEA
    Details
    Publication Date: 2024-01-09
    Keywords: 202-1240A; AGE; Calcium carbonate; Carbon, inorganic, total; Carbon, organic, total; Carbon, total; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Joides Resolution; Leg202; Nitrogen, total; North Pacific Ocean; Ocean Drilling Program; ODP; Opal, biogenic silica; Sample code/label; δ13C; δ15N
    Type: Dataset
    Format: text/tab-separated-values, 872 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 7
    Electronic Resource
    Electronic Resource
    Silicon in the Earth’s core (2007)
    [s.l.] : Nature Publishing Group
    Nature 447 (2007), S. 1102-1106 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Small isotopic differences between the silicate minerals in planets may have developed as a result of processes associated with core formation, or from evaporative losses during accretion as the planets were built up. Basalts from the Earth and the Moon do indeed appear to have iron isotopic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature05927
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
  • 8
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    Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean (2012)
    American Geophysical Union
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Geochemical Cycles 26 (2012): GB2035, doi:10.1029/2011GB004141.
    Description: The fractionation of silicon (Si) stable isotopes by biological activity in the surface ocean makes the stable isotope composition of silicon (δ30Si) dissolved in seawater a sensitive tracer of the oceanic biogeochemical Si cycle. We present a high-precision dataset that characterizes the δ30Si distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional and smaller, but resolvable, vertical δ30Si gradients. We show that these gradients are related to the two sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry a high δ30Si signature of ≥+1.7‰ into the deep Atlantic, while Antarctic Bottom Water transports Si with a low δ30Si value of around +1.2‰. The deep Atlantic δ30Si distribution is thus governed by the quasi-conservative mixing of Si from these two isotopically distinct sources. This disparity in Si isotope composition between the North Atlantic and Southern Ocean is in marked contrast to the homogeneity of the stable nitrogen isotope composition of deep ocean nitrate (δ15N-NO3). We infer that the meridional δ30Si gradient derives from the transport of the high δ30Si signature of Southern Ocean intermediate/mode waters into the North Atlantic by the upper return path of the meridional overturning circulation (MOC). The basin-scale deep Atlantic δ30Si gradient thus owes its existence to the interaction of the physical circulation with biological nutrient uptake at high southern latitudes, which fractionates Si isotopes between the abyssal and intermediate/mode waters formed in the Southern Ocean.
    Description: This work was supported by Swiss National Science Foundation grants 200021-116473 and 200020-130361.
    Description: 2012-12-19
    Keywords: Atlantic Ocean ; Southern Ocean ; Silicon isotopes
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: text/plain
    Format: application/vnd.ms-excel
    Format: application/pdf
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 9
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    Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean (2012)
    AGU (American Geophysical Union)
    In:  Global Biogeochemical Cycles, 26 (2). GB2035.
    Details
    Publication Date: 2017-07-28
    Description: The fractionation of silicon (Si) stable isotopes by biological activity in the surface ocean makes the stable isotope composition of silicon (δ30Si) dissolved in seawater a sensitive tracer of the oceanic biogeochemical Si cycle. We present a high-precision dataset that characterizes the δ30Si distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional and smaller, but resolvable, vertical δ30Si gradients. We show that these gradients are related to the two sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry a high δ30Si signature of ≥+1.7‰ into the deep Atlantic, while Antarctic Bottom Water transports Si with a low δ30Si value of around +1.2‰. The deep Atlantic δ30Si distribution is thus governed by the quasi-conservative mixing of Si from these two isotopically distinct sources. This disparity in Si isotope composition between the North Atlantic and Southern Ocean is in marked contrast to the homogeneity of the stable nitrogen isotope composition of deep ocean nitrate (δ15N-NO3). We infer that the meridional δ30Si gradient derives from the transport of the high δ30Si signature of Southern Ocean intermediate/mode waters into the North Atlantic by the upper return path of the meridional overturning circulation (MOC). The basin-scale deep Atlantic δ30Si gradient thus owes its existence to the interaction of the physical circulation with biological nutrient uptake at high southern latitudes, which fractionates Si isotopes between the abyssal and intermediate/mode waters formed in the Southern Ocean. Key Points: - Deep Atlantic Ocean displays gradient in Si isotopic composition of silicic acid - The gradient is caused by quasi-conservative mixing of Si from NADW and AABW - Contrasting isotope signature of NADW and AABW due to interaction of biology and MOC
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1029/2011GB004141
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 10
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    Factors controlling the silicon isotope distribution in waters and surface sediments of the Peruvian coastal upwelling (2012)
    Elsevier
    In:  Geochimica et Cosmochimica Acta, 99 . pp. 128-145.
    Details
    Publication Date: 2019-09-23
    Description: We present the first systematic study of the silicon isotope composition in the water column (δ30SiSi(OH)4) and in diatoms (δ30Sidiatom) from the underlying surface sediments in a coastal upwelling region. The surface waters upwelling on the shelf off Peru are mainly fed by southward flowing subsurface waters along the coast, which show a mean δ30SiSi(OH)4 of +1.5‰. The concentration of dissolved silicic acid (Si(OH)4) increases towards the south in these waters and with increasing water depth, suggesting lateral mixing with water masses from the south and intense remineralisation of particulate biogenic silica (bSiO2) in the water column and in the surface sediments. Surface waters in the realm of the most intense upwelling between 5°S and 15°S have only marginally elevated δ30SiSi(OH)4 values (δ30SiSi(OH)4 = +1.7‰) with respect to the source Si isotope composition, whereas further north and south, where upwelling is less pronounced, surface waters are more strongly fractionated (δ30SiSi(OH)4 up to +2.8‰) due to the stronger utilisation of the smaller amounts of available Si(OH)4. The degree of Si(OH)4 utilisation in the surface waters along the shelf estimated from the Si(OH)4 concentration data ranges from 51% to 93%. The δ30Sidiatom values of hand-picked diatoms in the underlying surface sediments vary from +0.6‰ to +2.0‰, which is within the range of the expected fractionation between surface waters and diatoms. The fractionation signal in the surface waters produced during formation of the diatoms is reflected by the δ30Sidiatom values in the underlying sediments, with the lowest δ30Sidiatom values in the main upwelling region. The silicon isotope compositions of bSiO2 (δ30SibSiO2) from the same surface sediment samples are generally much lower than the δ30Sidiatom signatures indicating a significant contamination of the bSiO2 with biogenic siliceous material other than diatoms, such as sponge spicules. This shift towards lighter δ30SibSiO2 values by up to −1.3‰ compared to δ30Sidiatom signatures for the same surface sediment samples potentially biases the interpretation of δ30Si paleorecords from sediments with low bSiO2 concentrations, and thus the reconstruction of past Si(OH)4 utilisation in surface waters.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.gca.2012.09.038
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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