Comparison between radiocarbon ages obtained on coexisting planktonic foraminifera

Broecker, Wallace S.; Andree, Michael; Bonani, Georges; Wölfli, W.; Klas, Mieczyslawa; Mix, Alan C; Oeschger, H.

doi:10.1029/pa003i006p00647

Cited by 67 publications

(36 citation statements)

References 16 publications

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“…1). Cores 17961-2 and 17964-2=3 (supplemented by VEMA core 35-5; Broecker et al, 1988, andDuplessy et al, 1991) are from the tropical southwesternmost SCS, in front of the mouth of the former 'Molengraaff' River which debouched from the Sunda shelf during times when it was dried up along with glacial low sea level (Molengraaff, 1921;Fig. 1).…”

Section: Selection Of Core Transects and Sediment Samplesmentioning

confidence: 99%

“…Based on a detailed and AMS-14 C-dated stratigraphy for the last glacial cycle, we particularly focus on the short-term, i.e. decadal to centennial, changes in monsoonal climate and trace their timing, phase relationship, and linkages in general to global climate changes such as Heinrich and=or Dansgaard-Oeschger (D-Oe) events defined in the North Atlantic realm (Bond et al, 1992(Bond et al, , 1997Cortijo et al, 1995) and the associated changes in the global thermohaline circulation (Broecker et al, 1988;Sarnthein et al, 1994b;Seidov et al, 1996). Similar teleconnections were recently found and=or postulated by Kennett and Ingram (1995) and Kotilainen and Shackleton (1995) by studying paleoclimatic sediment records from the eastern and northwestern Pacific margins.…”

Section: Introductionmentioning

confidence: 99%

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East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

et al. 1999

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Based on the study of 10 sediment cores and 40 core-top samples from the South China Sea (SCS) we obtained proxy records of past changes in East Asian monsoon climate on millennial to bidecadal time scales over the last 220,000 years. Climate proxies such as global sea level, estimates of paleotemperature, salinity, and nutrients in surface water, ventilation of deep water, paleowind strength, freshwater lids, fluvial and=or eolian sediment supply, and sediment winnowing on the sea floor were derived from planktonic and benthic stable-isotope records, the distribution of siliciclastic grain sizes, planktonic foraminifera species, and the U K 37 biomarker index. Four cores were AMS-14 C-dated. Two different regimes of monsoon circulation dominated the SCS over the last two glacial cycles, being linked to the minima and maxima of Northern Hemisphere solar insolation. (1) Glacial stages led to a stable estuarine circulation and a strong O 2 -minimum layer via a closure of the Borneo sea strait. Strong northeast monsoon and cool surface water occurred during winter, in part fed by an inflow from the north tip of Luzon. In contrast, summer temperatures were as high as during interglacials, hence the seasonality was strong. Low wetness in subtropical South China was opposed to large river input from the emerged Sunda shelf, serving as glacial refuge for tropical forest. (2) Interglacials were marked by a strong inflow of warm water via the Borneo sea strait, intense upwelling southeast of Vietnam and continental wetness in China during summer, weaker northeast monsoon and high sea-surface temperatures during winter, i.e. low seasonality. On top of the long-term variations we found millennial-to centennial-scale cold and dry, warm and humid spells during the Holocene, glacial Terminations I and II, and Stage 3. The spells were coeval with published variations in the Indian monsoon and probably, with the cold Heinrich and warm Dansgaard-Oeschger events recorded in Greenland ice cores, thus suggesting global climatic teleconnections. Holocene oscillations in the runoff from South China centered around periodicities of 775 years, ascribed to subharmonics of the 1500-year cycle in oceanic thermohaline circulation. 102=84-year cycles are tentatively assigned to the Gleissberg period of solar activity. Phase relationships among various monsoon proxies near the onset of Termination IA suggest that summer-monsoon rains and fluvial runoff from South China had already intensified right after the last glacial maximum (LGM) insolation minimum, coeval with the start of Antarctic ice melt Wang et al. / Marine Geology 156 (1999) prior to the δ 18 O signals of global sea-level rise. Vice versa, the strength of winter-monsoon winds decreased in short centennial steps only 3000-4000 years later, along with the melt of glacial ice sheets in the Northern Hemisphere.

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Section: Selection Of Core Transects and Sediment Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

et al. 1999

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“…However, data show problems other than bioturbation in using foraminifera as a dating material. Reports appear in the literature of age inversions, high core-top ages (Jones et al 1989) and deviating 14C ages for sample pairs of different (planktonic) foraminiferal species (Broecker et al 1988(Broecker et al , 1989Bard et al 1989;Jones et al 1989). It seems that the reliability of foraminifera as a dating tool in establishing sediment chronologies has not been tested as thoroughly as "traditional" dating samples, such as mollusk shells and wood-often due to the absence of such reference material for cross-checking.…”

Section: Introductionmentioning

confidence: 99%

Radiocarbon Dating of Shells and Foraminifera from the Skagen Core, Denmark: Evidence of Reworking

et al. 1995

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ABSTRACT. We report on 69 radiocarbon dates of mollusk shells and benthic foraminifera from the upper 132 m of the marine shelf sediments of the Skagen Core (220 m total length). The dated sequence covers the Late Glacial and the Holocene (from 15 ka BP to Recent). Sedimentation rates range from 1 to 70 m ka'1. The macrofossil shell dates follow a smooth curve constituting an age model for dating the sediments. The foraminiferal dates fall into two groups: those that agree exactly with the mollusk shells and those that deviate substantially, always being older than the shells by as much as 5 ka. One mixed foraminiferal sample consisted of members from both groups, and as a result, the age deviation of the sample turned out to be some weighted average. The data indicate that the age deviations are due to admixtures of reworked older foraminifera.

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“…Broecker et al 1988a). In this case, a systematic mean age difference of 890 yr was observed between Gs.…”

Section: Discussionmentioning

confidence: 49%

“…This finding was interpreted to reflect preferential dissolution of the dissolution-susceptible species Gs. sacculifera (Broecker et al 1988a). In part because a nearby core yielded a much smaller offset of 190 yr, the possibility of reworked older P. obliquiloculata was considered (Broecker et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Paired AMS ¹⁴C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity

Flower

Randle

2011

Radiocarbon

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ABSTRACT.A series of recent papers has called for multiple radiocarbon dates on planktic foraminifera to assess stratigraphic continuity in deep-sea sediment cores. This recommendation comes from observations of anomalous 14 C dates in planktic foraminifera from the same stratigraphic level. Potential reasons include bioturbation, downslope transport, secondary calcification, carbonate dissolution, and differential preservation. In this study, paired 14 C dates on dissolution-susceptible Globigerinoides ruber and dissolution-resistant Neogloboquadrina dutertrei are used to evaluate a Gulf of Mexico sediment core. Fourteen of 15 pairs (between 8815 and 12,995 uncorrected 14 C yr BP) yield concordant uncorrected 14 C ages (mean difference -2 ± 75 yr), attesting to continuous deposition at high accumulation rates (>35 cm/kyr). For 1 pair, N. dutertrei is nearly 1000 yr younger, which is difficult to explain by any combination of dissolution and bioturbation or downslope transport, given the excellent carbonate preservation and persistent laminations. The concordant ages underscore the utility of paired 14 C dates in planktic foraminifera as a means of assessing stratigraphic continuity in deep-sea sediment sequences.

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Comparison between radiocarbon ages obtained on coexisting planktonic foraminifera

Cited by 67 publications

References 16 publications

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

Radiocarbon Dating of Shells and Foraminifera from the Skagen Core, Denmark: Evidence of Reworking

Paired AMS ¹⁴C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity

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Comparison between radiocarbon ages obtained on coexisting planktonic foraminifera

Cited by 67 publications

References 16 publications

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

Radiocarbon Dating of Shells and Foraminifera from the Skagen Core, Denmark: Evidence of Reworking

Paired AMS 14C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity

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Paired AMS ¹⁴C Dates on Planktic Foraminifera from a Gulf of Mexico Sediment Core: An Assessment of Stratigraphic Continuity