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  • 1
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    Radiocarbon-age differences among coexisting planktic foraminifera shells
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth (2011): Radiocarbon-age differences among coexisting planktic foraminifera shells: The Barker Effect. Paleoceanography, 26(2), PA2222, https://doi.org/10.1029/2011PA002116
    Details
    Publication Date: 2023-05-12
    Description: For slowly accumulating sediments, a major contrast exists in the radiocarbon-age differences among coexisting shells of planktic foraminifera between those experiencing little dissolution and those experiencing significant dissolution. In the former, the ages generally agree to within a couple of hundred years. In the latter, age differences as large as 1000 years are common. The most likely explanation appears to be the Barker Effect, which involves the preferential fragmentation of dissolution-prone G. sacculifer and G. ruber. The whole shells of these species picked for radiocarbon dating have shorter residence times in the bioturbation zone than those for dissolution-resistant species (including benthics). As low accumulation rate sediment cores often fail to yield reliable radiocarbon-based ocean ventilation ages, where possible, such studies should be conducted on high accumulation rate cores.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 2
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    CaCO3 content in ocean surface sediments
    PANGAEA
    In:  Supplement to: Broecker, Wallace S (2008): A need to improve reconstructions of the fluctuations in the calcite compensation depth over the course of the Cenozoic. Paleoceanography, 23(1), PA1204, https://doi.org/10.1029/2007PA001456
    Details
    Publication Date: 2023-05-12
    Description: Reconstructions based on back-tracked depths of the transition between CaCO3-bearing and CaCO3-depleted sediment suggest that over the last 65 million years the ocean's CaCO3 compensation depth (CCD) has remained within the range 4.0 ± 0.6 km. Taken at face value, these results indicate that depth of the calcite saturation horizon and hence also the product of the Ca2+ and [CO3]2- concentrations have remained nearly constant. In turn, this suggests that the ratio of calcite production to ingredient supply has not undergone large changes. In this paper, the method used to reconstruct the temporal fluctuations and interocean differences in the depth of the calcite saturation horizon is scrutinized. The basis for my concern is that offset between the depth of the calcite saturation horizon and the depth where dissolution reduces the CaCO3 content to 20% (i.e., the CCD) can vary by a half kilometer or so depending on the rain rates of CaCO3 and non CaCO3. When observations on modern ocean sediments are used to test the reliability of these reconstructions, the result is that when averaged over a full glacial cycle, the depth of the CCDs in the Pacific and Indian oceans fall within the long-term range. Reliable documentation of fluctuations around this long-term average requires that additional measurements, such as extent of fragmentation, be used to supplement those of CaCO3 content.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 3
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    Age determination of equatorial Pacific sediments
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth; Barker, Stephen; Hajdas, Irena; Bonani, Georges; Moreno, Eva (2007): Radiocarbon age of late glacial deep water from the equatorial Pacific. Paleoceanography, 22(2), PA2206, https://doi.org/10.1029/2006PA001359
    Details
    Publication Date: 2023-05-12
    Description: Radiocarbon age differences for pairs of coexisting late glacial age benthic and planktic foraminifera shells handpicked from 10 sediment samples from a core from a depth of 2.8 km in the western equatorial Pacific are not significantly different from that of 1600 years calculated from measurements on prenuclear seawater. This places a lower limit on the depth of the interface for the hypothetical radiocarbon-depleted glacial age seawater reservoir required to explain the 190 per mil drop in the 14C/C for atmospheric CO2, which occurred during the mystery interval (17.5 to 14.5 calendar years ago). These measurements restrict the volume of this reservoir to be no more than 35% that of the ocean. Further, 14C measurements on a single Last Glacial Maximum age sample from a central equatorial Pacific core from a depth of 4.4 km water fail to reveal evidence for the required 5- to 7-kyr age difference between benthic and planktic foraminifera shells if the isolated reservoir occupied only one third of the ocean. Nor does the 13C record for benthic forams from this abyssal core yield any evidence for the excess respiration CO2 expected to be produced during thousands of years of isolation. Nor, as indicated by the presence of benthic foraminifera, was the dissolved oxygen used up in this abyssal water.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 4
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    Age determination of foraminifera shells
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Barker, Stephen; Clark, Elizabeth; Hajdas, Irka; Bonani, Georges (2006): Anomalous radiocarbon ages for foraminifera shells. Paleoceanography, 21(2), PA2008, https://doi.org/10.1029/2005PA001212
    Details
    Publication Date: 2023-05-12
    Description: The causes for discordant radiocarbon results on multiple species of planktonic foraminifera from high-sedimentation-rate marine sediments are investigated. We have documented two causes for these anomalous results. One is the addition of secondary radiocarbon for which we have, to date, only one firm example. It involves an opal-rich sediment. The other is the incorporation of reworked material. Again, we have, to date, only one firm example. It involves a rapidly deposited ocean margin sediment. However, we have three other examples where reworking is the most likely explanation. On the basis of this study it is our conclusion that, where precise radiocarbon dating of high-deposition-rate marine sediment is required, a prerequisite is to demonstrate that concordant ages can be obtained on pairs of fragile and robust planktic shells. For sediment rich in opal, it is advisable to check for secondary calcite by comparing ages obtained on acid-leached samples with those on unleached samples.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 5
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    Age determination using benthic and planktonic foraminifera of central Pacific Ocean sediment cores
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth; Hajdas, Irena; Bonani, Georges (2004): Glacial ventilation rates for the deep Pacific Ocean. Paleoceanography, 19(2), PA2002, https://doi.org/10.1029/2003PA000974
    Details
    Publication Date: 2023-05-12
    Description: A key constraint in attempts to reconstruct the patterns and rates of the ocean's thermohaline circulation during the last glacial period is the difference between the 14C to C ratio in surface and deep water. While imperfect, it is our best index of past deep-sea ventilation rates. In this paper we review published ventilation rate estimates based on the measured radiocarbon age difference between coexisting benthic and planktic foraminifera from glacial-age Pacific sediments. We also present new results from a series of eastern equatorial Pacific sediment cores. The conclusion is that the scatter in these results is so large that the apparent 14C age of glacial deep Pacific water could lie anywhere between double and half today's. Further, it is not clear what is responsible for the wide scatter in the radiocarbon results.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 6
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    Age determination and stable isotope record of sediment cores at 9°S in the Indian Ocean (2015)
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth; Lynch-Stieglitz, Jean; Beck, Warren; Stott, Lowell D; Hajdas, Irena; Bonani, Georges (2000): Late glacial diatom accumulation at 9°S in the Indian Ocean. Paleoceanography, 15(3), 348-352, https://doi.org/10.1029/1999PA000439
    Details
    Publication Date: 2023-05-12
    Description: A continuous 10-m-long section consisting of roughly two thirds Ethmodiscus rex (a diatom) and one third mixed planktonic foraminifera was identified in a core from 3800 m depth at 9°S on the Indian Ocean's 90°E Ridge. Radiocarbon dates place the onset of deposition of this layer at 〉30,000 years B.P. and its termination at close to 11,000 years B.P. However, precise dating of the foraminifera from the Ethmodiscus layer itself proved to be impossible owing to the presence of secondary calcite presumably precipitated from the pore waters. During the Holocene, high calcium carbonate content ooze free of diatoms was deposited at this locale. As the site currently lies beneath the pathway taken by upper ocean waters entering the Indian Ocean from the Pacific (via the Indonesian Straits), it appears that during glacial time, thermocline waters moving along this same path provided the silica and other nutrients required by these diatoms.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 7
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    14C ages of core top samples from Ontong-Java Plateau
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth; McCorkle, Daniel C; Hajdas, Irka; Bonani, Georges (1999): Core Top 14C ages as a function of latitude and water depth on the Ontong-Java Plateau. Paleoceanography, 14(1), 13-22, https://doi.org/10.1029/1998PA900009
    Details
    Publication Date: 2023-05-12
    Description: Radiocarbon measurements on core tops from the Ontong-Java plateau confirm a previous finding by Berger and Killingley [1982] that at any given water depth, cores taken on the equator have higher accumulation rates and younger core top ages than their off-equator counterparts. Further, these new results fortify the conclusion by Broecker et al. [1991] that the increase in core top radiocarbon age with water depth rules out homogeneous dissolution within the pore waters as the dominant mechanism. Either most of the dissolution must occur prior to burial or it must occur during the first pass through the respiration-CO2-rich upper pore waters after which the calcite grains become armored against further dissolution. A puzzling aspect of this new data set is that despite the sizable difference in accumulation rate, the extent of dissolution as measured by either the CaCO3 content or the ratio of CaCO3 in the 〉150-µm size fraction to that in the 〈 63-µm fraction is no different off than on the equator. In order to reconcile the results of this study with those obtained by Hales and Emerson [1996] using in situ electrodes, it is necessary to call upon calcite armoring.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 8
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    (Table 2) Age determination of sediment cores TTN13-18 and TTN13-61
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Keywords: Age, 14C AMS; Age, dated; Age, dated material; Age, dated standard deviation; Central Pacific; DEPTH, sediment/rock; Event label; Gravity corer (Kiel type); PC; Piston corer; SL; TTN13-18; TTN13-61
    Type: Dataset
    Format: text/tab-separated-values, 174 data points
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  • 9
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    (Table 2) Age determination of sediment cores TTN13-18 and TTN13-19
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Keywords: Age, 14C AMS; Age, dated; Age, dated material; Age, dated standard deviation; Central Pacific; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Event label; MUC; MultiCorer; PC; Piston corer; TTN13-18; TTN13-19
    Type: Dataset
    Format: text/tab-separated-values, 60 data points
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  • 10
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    Shorebased measurements during the GEOSECS Indian Ocean expedition
    PANGAEA
    Details
    Publication Date: 2023-05-12
    Keywords: Barium; Bottle number; Campaign of event; Carbon dioxide; Cast number; Comment; CTD/Rosette; CTD-RO; Date/Time of event; DEPTH, water; Event label; Gear; Geochemical Ocean Sections Study; GEOSECS; GEOSECS_Indian_Ocean_3; GEOSECS_Indian_Ocean_4; GEOSECS_Indian_Ocean_5; GEOSECS_Indian_Ocean_6; GEOSECS_Indian_Ocean_7; GEOSECS404; GEOSECS405; GEOSECS407; GEOSECS408; GEOSECS409; GEOSECS410; GEOSECS411; GEOSECS412; GEOSECS413; GEOSECS415; GEOSECS416; GEOSECS417; GEOSECS418; GEOSECS419; GEOSECS420; GEOSECS421; GEOSECS422; GEOSECS423; GEOSECS424; GEOSECS425; GEOSECS426; GEOSECS427; GEOSECS428; GEOSECS429; GEOSECS430; GEOSECS431; GEOSECS432; GEOSECS433; GEOSECS434; GEOSECS435; GEOSECS436; GEOSECS437; GEOSECS438; GEOSECS439; GEOSECS440; GEOSECS441; GEOSECS442; GEOSECS443; GEOSECS444; GEOSECS445; GEOSECS446; GEOSECS447; GEOSECS448; GEOSECS449; GEOSECS450; GEOSECS451; GEOSECS452; GEOSECS453; GEOSECS454; Helium; Helium, standard deviation; Indian Ocean; Latitude of event; Lead-210; Lead-210, dissolved; Lead-210, dissolved, standard deviation; Lead-210, particulate; Lead-210, particulate, standard deviation; Lead-210, standard deviation; Leg 3; Leg 4; Leg 5; Leg 6; Leg 7; Longitude of event; Melville; Neon; Neon, standard deviation; Polonium-210, dissolved; Polonium-210, dissolved, standard deviation; Polonium-210, particulate; Polonium-210, particulate, standard deviation; Pressure, water; Radium-226; Radium-226, standard deviation; Radium-228; Radium-228, standard deviation; Salinity; Temperature, water; Tritium; Tritium, standard deviation; Δ Helium/Neon; Δ Helium/Neon, standard deviation; δ13C; δ14C; δ18O; δ18O, dissolved oxygen; δ Helium-3; δ Helium-3, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 27171 data points
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