ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Publisher
Years
  • 1
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 2
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 3
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 4
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 5
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 6
    facet.materialart.
    Unknown
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 7
    facet.materialart.
    Unknown
    (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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 8
    facet.materialart.
    Unknown
    (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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 9
    facet.materialart.
    Unknown
    CaCO3 size distribution in surface sediments
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Clark, Elizabeth (1999): CaCO3 size distribution: A paleocarbonate ion proxy? Paleoceanography, 14(5), 596-604, https://doi.org/10.1029/1999PA900016
    Details
    Publication Date: 2023-05-12
    Description: Lysocline reconstructions play an important role in scenarios purporting to explain the lowered atmospheric CO2 content of glacial time. These reconstructions are based on indicators such as the CaCO3 content, the percent of coarse fraction, the ratio of fragments to whole foraminifera shells, the ratio of solution-susceptible to solution-resistant species, and the ratio of coarse to fine CaCO3. All assume that changes with time in the composition of the input material do not bias the result. However, as the composition of the input material does depend on climate, none of these indicators provides an absolute measure of the extent of dissolution. In this paper we evaluate the reliability of the ratio of 〉63 µm CaCO3 to total CaCO3 as a dissolution indicator. We present here results that suggest that in today's tropics this ratio appears to be determined solely by CO3= ion concentration and water depth (i.e., the saturation state of bottom waters). This finding offers the possibility that the size fraction index can be used to reconstruct CO3= ion concentrations for the late Quaternary ocean to an accuracy of ±5 µmol/kg.
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
  • 10
    facet.materialart.
    Unknown
    (Table 1) Radiocarbon ages of foraminifera from a Piston and a Trigger Weight from Ceara Rise
    PANGAEA
    In:  Supplement to: Broecker, Wallace S; Matsumoto, Katsumi; Clark, Elizabeth (1999): Radiocarbon age differences between coexisting foraminiferal species. Paleoceanography, 14(4), 431-436, https://doi.org/10.1029/1999PA900019
    Details
    Publication Date: 2023-05-12
    Description: Radiocarbon-age measurements on single species of foraminifera from a core on the Ceara Rise demonstrate the importance of the joint effect of bioturbation and variable rain abundance of foraminifera. The relatively high mixed layer ages for Pulleniatina obliquiloculata reflect, at least in part, an early Holocene peak in its abundance while the relatively young ages for Globorotalia menardii reflect the delay until mid Holocene of its reappearance in the Atlantic Ocean. These results clearly demonstrate that core-top sediment samples need not be representative foraminifera falling from today's surface ocean. Rather, at least on the Ceara Rise, such samples consist of a composite of changing species groupings. These results also reconfirm the pitfalls associated with attempts to reconstruct the radiocarbon age of deep ocean water on the basis of benthic-planktonic foraminiferal age differences.
    Keywords: Age, 14C milieu/reservoir corrected (-400 yr); Age, 14C milieu/reservoir corrected (-800 yr); Age, dated; Ceara_Rise; Ceara Rise; Core; DEPTH, sediment/rock; Foraminifera, benthic; Globigerinoides sacculifer; Globorotalia menardii; Neogloboquadrina dutertrei; Pulleniatina obliquiloculata
    Type: Dataset
    Format: text/tab-separated-values, 128 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...