Radiocarbon dating and calibration

Törnqvist, Torbjörn E.; Rosenheim, B. E.; Hu, Ping; Fernández, Álvaro

doi:10.1002/9781118452547.ch23

Cited by 25 publications

(19 citation statements)

References 42 publications

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“…Seventeen samples analyzed in previous studies (see Toth et al, 2018) were dated using standard radiometric dating at the University of Miami Radiocarbon Laboratory, Beta Analytic, Inc., or Geochron Laboratories. We report conventional 14 C ages, corrected for fractionation of 13 C. The δ 13 C of the samples was either measured by University of California, Davis Stable Isotope Laboratory or NOSAMS or, if not measured, was assumed to be 0 ± 3‰ (Törnqvist, Rosenheim, Hu, & Fernandez, 2015). The conventional radiocarbon ages were calibrated in Calib 7.0.2 (https://calib.org/calib/; Reimer & Reimer, 2001) using time-varying estimates of the local reservoir age, ΔR, for the nearshore and open-ocean environments of the FKRT (Toth et al, 2017a(Toth et al, , 2017b).…”

Section: Radiometric Dating Of Holocene Reef Coresmentioning

confidence: 99%

A 3,000‐year lag between the geological and ecological shutdown of Florida's coral reefs

Toth

Kuffner

Stathakopoulos

et al. 2018

Global Change Biology

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The global-scale degradation of coral reefs has reached a critical threshold wherein further declines threaten both ecological functionality and the persistence of reef structure. Geological records can provide valuable insights into the long-term controls on reef development that may be key to solving the modern coral-reef crisis. Our analyses of new and existing coral-reef cores from throughout the Florida Keys reef tract (FKRT) revealed significant spatial and temporal variability in reef development during the Holocene. Whereas maximum Holocene reef thickness in the Dry Tortugas was comparable to elsewhere in the western Atlantic, most of Florida's reefs had relatively thin accumulations of Holocene reef framework. During periods of active reef development, average reef accretion rates were similar throughout the FKRT at ~3 m/ky. The spatial variability in reef thickness was instead driven by differences in the duration of reef development. Reef accretion declined significantly from ~6,000 years ago to present, and by ~3,000 years ago, the majority of the FKRT was geologically senescent. Although sea level influenced the development of Florida's reefs, it was not the ultimate driver of reef demise. Instead, we demonstrate that the timing of reef senescence was modulated by subregional hydrographic variability, and hypothesize that climatic cooling was the ultimate cause of reef shutdown. The senescence of the FKRT left the ecosystem balanced at a delicate tipping point at which a veneer of living coral was the only barrier to reef erosion. Modern climate change and other anthropogenic disturbances have now pushed many reefs past that critical threshold and into a novel ecosystem state, in which reef structures built over millennia could soon be lost. The dominant role of climate in the development of the FKRT over timescales of decades to millennia highlights the potential vulnerability of both geological and ecological reef processes to anthropogenic climate change.

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Section: Radiometric Dating Of Holocene Reef Coresmentioning

confidence: 99%

A 3,000‐year lag between the geological and ecological shutdown of Florida's coral reefs

Toth

Kuffner

Stathakopoulos

et al. 2018

Global Change Biology

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“…Here, we reconstruct late Holocene RSL using geological and tide-gauge data coupled with a new salt-marsh based reconstruction from the central-eastern coast of Croatia that bridges the gap between late Holocene and modern sea-level data. Salt-marsh environments afford a unique ability providing near continuous, decimeter vertical Medioli, 1978, 1980;Horton and Edwards, 2006) and sub-century temporal resolution (T€ ornqvist et al, 2015;Corbett and Walsh, 2015;Marshall, 2015). Their use in reconstructing RSL is well established across regions in Northern (Gehrels et al, 2005;Kemp et al, 2013a;Barlow et al, 2014;Saher et al, 2015) and Southern Hemispheres (Gehrels et al, 2008(Gehrels et al, , 2012Strachan et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Tectonic influences on late Holocene relative sea levels from the central-eastern Adriatic coast of Croatia

Shaw

Plater

Kirby

et al. 2018

Quaternary Science Reviews

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Differential tectonic activity is a key factor responsible for variable relative sea-level (RSL) changes during the late Holocene in the Adriatic. Here, we compare reconstructions of RSL from the central-eastern Adriatic coast of Croatia with ICE-7G_NA (VM7) glacial-isostatic model RSL predictions to assess underlying driving mechanisms of RSL change during the past~2700 years. Local standardized published sea-level index points (n ¼ 23) were combined with a new salt-marsh RSL reconstruction and tide-gauge measurements. We enumerated fossil foraminifera from a short salt-marsh sediment core constrained vertically by modern foraminiferal distributions, and temporally by radiometric analyses providing subcentury resolution within a Bayesian age-depth framework. We modelled changes in RSL using an Errors-In-Variables Integrated Gaussian Process (EIV-IGP) model with full consideration of the available uncertainty. Previously established index points show RSL rising from À1.48 m at 715 BCE to À1.05 m by 100 CE at 0.52 mm/yr (À0.82-1.87 mm/yr). Between 500 and 1000 CE RSL was À0.7 m below present rising to À0.25 m at 1700 CE. RSL rise decreased to a minimum rate of 0.13 mm/yr (À0.37-0.64 mm/yr) at~1450 CE. The salt-marsh reconstruction shows RSL rose~0.28 m since the early 18th century at an average rate of 0.95 mm/yr. Magnitudes and rates of RSL change during the twentieth century are concurrent with long-term tide-gauge measurements, with a rise of~1.1 mm/yr. Predictions of RSL from the ICE-7G_NA (VM7) glacial-isostatic model (À0.25 m at 715 BCE) are consistently higher than the reconstruction (À1.48 m at 715 BCE) during the Late Holocene suggesting a subsidence rate of 0.45 ± 0.6 mm/yr. The new salt-marsh reconstruction and regional index points coupled with glacial-isostatic and statistical models estimate the magnitude and rate of RSL change and subsidence caused by the Adriatic tectonic framework.

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“…The gas bench ages were calibrated with the Marine13 curve (Reimer et al 2013) with the standard global 400 year-marine reservoir applied. While there are distinct potential chemical signatures from multiple drainage basins influencing the study area (Milliken et al 2008, Törnqvist et al 2015) and potential variations of fractionation locally within a single estuary Cherkinsky 2016, 2017), no additional reservoir correction was made for estuarine samples due to limited data available in the northern-central Gulf of Mexico (Reimer et al 2001).…”

Section: Radiocarbon Dating Estimatesmentioning

confidence: 99%

Late Quaternary evolution and stratigraphic framework influence on coastal systems along the north-central Gulf of Mexico, USA

Hollis

Wallace

Miner

et al. 2019

Quaternary Science Reviews

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Coastal systems in the Gulf of Mexico are threatened to reduced sediment supply, storm impacts and relative sea level rise (RSLR). The geologic record can provide insights of geomorphic threshold crossings (formation, progradation, transgression, destruction) to these forcing mechanisms to predict future barrier evolution to climate change. The stratigraphic framework and antecedent topography directly influence coastal evolution over geologic timescales. This study synthesizes ~2100km of geophysical data, 700+ sediment cores, and 63 radiocarbon dates to regionally map two sequence boundaries, multiple ravinement surfaces and fourteen depositional facies. One marine isotope stage (MIS) 6 valley's fill provided up to 300 x10 6 m 3 of sand to modern systems through transgressive ravinement during the Holocene. Repeated storm breaches or tidal inlets correspond to paleotopographic low's in the MIS 2 surface. A Holocene geomorphic evolutionary model was created for Petit Bois and Dauphin Island from available data, highlighting RSLR rates and sediment supply. As the MIS 2 surface was flooded, tidal/wave scour supplied sand to migrating marine shoals. These rapidly transgressing shoals converted drowned paleovalleys to estuaries starting about 9ka. Islands formed in their modern positions about 6ka, when sediment supply was high and RSLR rates were 2mm/yr. Between 4ka-1750 CE. Islands prograded due to RSLR rates of 1-0.4mm/yr and sufficient sand supply from alongshore and inner shelf sources. Currently, the islands experience RSLR rates of 3.61 mm/yr and reduced sediment supply resulting in barrier degradation. This study provides geologic evidence of coastal geomorphic thresholds related to RSLR, sediment supply and antecedent topography. iii ACKNOWLEDGMENTS I would like to thank my advisor, Dr. Davin Wallace for his guidance and great support through this project. I would also like to thank my committee members Dr. Michael Miner and Dr. Jessica Pilarczyk, and lab mates, Clayton Dike, Nina Gal, and Shara Gremillion for their helpful and insightful feedback and guidance. This project was funded by the Bureau of Ocean and Energy Management, as part of a Gulf of Mexico sand resource mapping effort. Thank you to colleagues at the University of Alabama, the Geological Survey of Alabama and USGS for allowing core sampling. The USGS and UTIG shared archive geophysical data. Mollusk bivalve identification was greatly aided by Dr. Jennifer Walker. Dr. John Anderson (Rice) and Dr. Ervin Otvos (USM) also provided valuable insight. iv DEDICATION This thesis is dedicated to friends, family and loved ones especially Bob, Ellen, Joey and Alli. Their love, appreciation and support allowed me to pursue my scientific passion. v

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Radiocarbon dating and calibration

Cited by 25 publications

References 42 publications

A 3,000‐year lag between the geological and ecological shutdown of Florida's coral reefs

A 3,000‐year lag between the geological and ecological shutdown of Florida's coral reefs

Tectonic influences on late Holocene relative sea levels from the central-eastern Adriatic coast of Croatia

Late Quaternary evolution and stratigraphic framework influence on coastal systems along the north-central Gulf of Mexico, USA

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