Calibration of amino acid racemization (AAR) kinetics in United States mid-Atlantic Coastal Plain Quaternary mollusks using 87Sr/86Sr analyses: Evaluation of kinetic models and estimation of regional Late Pleistocene temperature history

Wehmiller, John F.; Harris, W. Burleigh; Boutin, Brian S.; Farrell, Kathleen M.

doi:10.1016/j.quageo.2011.09.005

Cited by 34 publications

(9 citation statements)

References 51 publications

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“…These high D/L values from the M27 and M29 Mercenaria may represent slightly different ages, but combined they suggest an early Pleistocene (ca. 1.0-1.5 Ma) age based on calibrated racemization kinetics for this genus (Wehmiller et al, 2012). This early Pleistocene age assignment agrees with the Zone NN19 assignment (Table 1) and with the Sr isotope age estimates.…”

Section: Amino Acid Racemizationsupporting

confidence: 82%

“…Assuming these taxa have comparable racemization rates, this observation suggests that the Ensis samples are older. An estimate of this age difference can be made using the power-law leucine kinetic model (developed by Wehmiller et al, 2012) and mean D/L leucine values of 0.19 (Astarte-Spisula) and 0.285 (Ensis). If the 0.19 D/L values are assigned an age of 80 ka, then the Ensis samples are estimated to be ca.…”

Section: Amino Acid Racemizationmentioning

confidence: 99%

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et al. 2013

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We used cores and logs from IntegratedOcean Drilling Program (IODP) Expedition 313 to generate biostratigraphic, lithofacies, biofacies, and geochemical data that constrain the ages and paleoenvironments of Pleistocene sequences. We integrate sequence stratigraphy on cores with new seismic stratigraphic data to interpret the Pleistocene history of the Hudson shelf valley and paleoenvironmental and sea-level changes on the inner to middle continental shelf. Improved age control compared to previous studies is provided by integrated calcareous nannofossil biostratigraphy, Sr isotopic stratigraphy, and amino acid racemization. We recognize four upper Pleistocene-Holocene sequences: sequence uP1 is correlated with Marine Isotope Chrons (MIC; "chron" is the correct stratigraphic term for a time unit, not "stage") 7 or 5e, sequence uP2 with MIC 5c, sequence uP3 with MIC 5a, and sequence uP4 with the latest Pleistocene to Holocene (MIC 1-2). However, within our age resolution it is possible that sequences uP2 and uP3 correlate with MIC 4-3c and 3a, respectively, as suggested by previous studies. Lower Pleistocene sequences lP1 and lP2 likely correlate with peak interglacials (e.g., MIC 31 and MIC 45 or 47, respectively). Thus, we suggest that preservation of sequences occurs only during peak eustatic events (e.g., MIC 45 or 47, MIC 31, and MIC 5), unless they are preserved in eroded valleys. The architecture of the Pleistocene deposits at Sites M27 and M29 is one of thin remnants of highstand and transgressive systems tracts, with lowstand deposits only preserved in the thalwegs of incised valleys. Incised valleys at the bases of sequences uP3 (IODP Site M27) and uP2 (IODP Site M29) document more southward courses of the paleo-Hudson valley, compared to the more southeastward course of the MIC 1-2 paleo-Hudson valley. The patchy distribution of Pleistocene sequences beneath the New Jersey inner-middle continental shelf is due to low accommodation during an interval of large eustatic changes; this predicts that sequences in such settings will be discontinuous, patchy, and diffi cult to correlate, consistent with previous studies in Virginia and North Carolina.

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Section: Amino Acid Racemizationsupporting

confidence: 82%

Section: Amino Acid Racemizationmentioning

confidence: 99%

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et al. 2013

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“…4) are comparable to the reported D-Ala/D-Glx value of 1.3 ± 0.4 (Kaiser and Benner, 2008), which was derived from a pure bacteria culture that included both marine/fresh and heterotrophic/autotrophic bacteria. Given that Glx has a higher abiotic racemization rate than Ala (Wehmiller et al, 2012), the slightly higher D-Ala/D-Glx slope for river samples relative to fjord samples (i.e., 1.26 vs. 1.21; Fig. 4 from a modern contribution (e.g., bacteria) rather than abiotic racemization in the river basin.…”

Section: Resultsmentioning

confidence: 96%

Organic carbon flux and particulate organic matter composition in Arctic valley glaciers: examples from the Bayelva River and adjacent Kongsfjorden

Zhu

Liu

et al. 2016

Biogeosciences

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Abstract. In the face of ongoing global warming and glacier retreat, the composition and flux of organic matter in glacierfjord systems are key variables for updating the carbon cycle and budget, whereas the role of Arctic valley glaciers seems unimportant when compared with the huge Greenland Ice Sheet. Our field observations of the glacier-fed Bayelva River, Svalbard, and the adjacent Kongsfjorden allowed us to determine the compositions of particulate organic matter from glacier to fjord and also to estimate the flux of organic carbon, both for the river and for Svalbard in general.Particulate organic carbon (POC) and dissolved organic carbon (DOC) in the Bayelva River averaged 56 and 73 µM, respectively, in August, 2012. Amino acids (AAs) and phytoplankton carbon accounted for ∼ 10 % of the bulk POC in the Bayelva River, while AAs represented > 90 % of particulate nitrogen (PN) in fjord surface water, suggesting the strong in situ assimilation of organic matter. Bacteria accounted for 13 and 19 % of the POC in the Bayelva River and the Kongsfjorden, respectively, while values for PN were much higher (i.e., 36 % in Kongsfjorden).The total discharge from the Bayelva River in 2012 was 29 × 10 6 m 3 . Furthermore, we calculated the annual POC, DOC, and PN fluxes for the river as 20 ± 1.6 tons, 25 ± 5.6 tons, and 4.7 ± 0.75 tons, respectively. Using the POC content and DOC concentration data, we then estimated the annual POC and DOC fluxes for Svalbard glaciers. Although the estimated POC (0.056 ± 0.02 × 10 6 tons year −1 ) and DOC (0.02 ± 0.01 × 10 6 tons year −1 ) fluxes of Svalbard glaciers are small in amount, its discharge-weighted flux of DOC was over twice higher than other pan-Arctic glacier systems, suggesting its important role as a terrestrial DOC source.

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“…This would result in lower effective diagenetic temperatures (e.g. Wehmiller et al 2012) in Copenhagen, and therefore a slower rate of amino acid racemization may be assumed for Copenhagen. Using this argument, the ratios from Copenhagen are more compatible with a MIS 7 age than a MIS 5e age.…”

Section: Luminescence Dating Amino Acid Analysis Biostratigraphy Anmentioning

confidence: 99%

New interglacial deposits from Copenhagen, Denmark: marine Isotope Stage 7

Bennike

Hedenäs

High

et al. 2018

Boreas

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During a pre‐site survey and construction of a new metro route and station in Copenhagen, fossiliferous organic‐rich sediments were encountered. This paper reports on multidisciplinary investigations of these organic sediments, which occurred beneath a sediment succession with a lower till, glacifluvial sand and gravel, an upper till and glacifluvial sand. The organic sediments were underlain by glacifluvial sand and gravel. The organic‐rich sediments, which were up to 0.5 m thick, accumulated in a low‐energy environment, possibly an oxbow lake. They were rich in plant fossils, which included warmth‐demanding trees and other species, such as Najas minor, indicating slightly higher summer temperatures than at present. Freshwater shells were also frequent. Bithynia opercula allowed the sediments to be put into an aminostratigraphical framework. The amino acid racemization (AAR) ratios indicate that the organic sediments formed during Marine Isotope Stage 7 (MIS 7), which is consistent with optically stimulated luminescence dating that gave ages of 206 and 248 ka from the underlying minerogenic deposit. The assemblages from Trianglen are similar to interglacial deposits from the former Free Port (1.4 km away) in Copenhagen, except that Corbicula and Pisidium clessini were not found at Trianglen. The presence of these bivalves at the Free Port and the ostracod Scottia tumida at Trianglen indicates a pre‐Eemian age. AAR data from archived Bithynia opercula from the Free Port were almost identical to those from Trianglen, indicating that the two sites are contemporary. We suggest the Trianglen interglacial be used as a local name for the MIS 7 interglacial deposits in Copenhagen. MIS 7 deposits have rarely been documented from the region, but MIS 7 deposits may have been mistaken for other ages. The use of AAR ratios in Bithynia opercula has a great potential for correlation of interglacial non‐marine deposits in mainland northern Europe.

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Calibration of amino acid racemization (AAR) kinetics in United States mid-Atlantic Coastal Plain Quaternary mollusks using 87Sr/86Sr analyses: Evaluation of kinetic models and estimation of regional Late Pleistocene temperature history

Cited by 34 publications

References 51 publications

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Organic carbon flux and particulate organic matter composition in Arctic valley glaciers: examples from the Bayelva River and adjacent Kongsfjorden

New interglacial deposits from Copenhagen, Denmark: marine Isotope Stage 7

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