Large variations in the Holocene marine radiocarbon reservoir effect reflect ocean circulation and climatic changes

Hua, Quan; Webb, Gregory E.; Zhao, Jian‐xin; Nothdurft, Luke D.; Lybolt, Matthew; Price, Gilbert J.; Opdyke, Bradley N.

doi:10.1016/j.epsl.2015.03.049

Cited by 54 publications

(61 citation statements)

References 80 publications

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“…A combination of U-series and radiocarbon dating of corals from Heron Reef and Moreton Bay has been employed by Hua et al [2015] to investigate changes in the regional marine reservoir correction (ΔR) of the southwest Pacific. Large variability observed in ΔR between 8 and 5.4 ka has been attributed to variations in the contribution of Subantarctic Mode Water into the tropical eastern Pacific.…”

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Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Sadler¹

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In order to accurately predict future climate variations induced by natural and anthropogenic forcings, we require a detailed understanding of the Earth's climate system. With such temporally limited instrumental records, proxy-based reconstructions are an invaluable source of climate information. Current paleoclimate databases indicate a lack of records representing the southern hemisphere and tropics; key regions that can be represented by high resolution, coral geochemistry-based climate reconstructions.Reef coring techniques allow the recovery of significant proportions of coral material from throughout the Holocene, Pleistocene and beyond. Given the high species diversity of IndoPacific coral reefs, the presence of massive Porites commonly used for climate reconstruction is likely to be limited in reef cores. Corymbose Acropora, however, displays a high abundance in modern and fossil reef records and thus could act as a major source of new climate information from the Earth's recent history.Previous investigations of Acropora geochemistry have focused on branches, with significant levels of secondary thickening smoothing environmental signals otherwise recorded by the Sr/Ca ratio paleothermometer. This project investigates the potential of Acropora interbranch skeleton as a climate archive, following the identification of annual density banding patterns in computed tomography scans. Scanning electron microscopy based documentation of structure and growth patterns reveal that inter-branch skeleton is atypical for Acropora.Low linear extension rates, a simplified skeletal structure with limited secondary aragonite deposition, approximately horizontal density bands and seasonal cyclicity in Sr/Ca ratios bear a greater resemblance to massive corals such as Porites. These observations, combined with a high abundance in past and present Indo-Pacific reefs, suggest that inter-branch skeletal growth in Acropora may prove to be a valuable source of untapped paleoclimate information.A site-specific calibration for Acropora inter-branch skeleton Sr/Ca ratios to water temperature was conducted using modern corymbose Acropora colonies and concomitant instrumental water temperature records from the lagoon and fore-reef slope of Heron Reef, southern Great Barrier Reef (GBR). Large inter-colony differences in Sr/Ca ratios were observed in the modern cores, suggesting that inter-branch skeleton may not be a suitable archive for absolute temperature reconstruction. Normalisation of each Sr/Ca record to the corresponding core mean does, however, remove these inter-colony differences and allows the reconstruction of the seasonal water temperature amplitude with a sensitivity of −0.05 ii mmol/mol/°C. Application of the resulting transfer equation to the modern inter-branch skeleton Sr/Ca record successfully identified the greater seasonal temperature range of the lagoon compared to the adjacent reef slope. A site-specific calibration also was completed for southern GBR Porites at Heron Reef using the reef slope water te...

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Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Sadler¹

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“…Earth-Moon distances periodically influenced Earth-Sun distances at ~133-yr intervals at the time of the Metonic lunations [ Figure 5.11], when reduced Earth-Moon distances occurred close to a modelled perigee-perihelion return at 125 yrs [ Figure 5. Hua et al, 2015), the timing and variability of Bond IRD events (Section 7.2.5), and equivalences to millennial-scale periods of ENSO events (Section 7.2.5). Significantly, the occurrence of Bond events during the period of research, corresponded with times of maximum gravitational forcing at perigee and close to perihelion [ Figure 5.13].…”

Section: Earth-moon Distancementioning

confidence: 99%

“…Hua et al, 2015). Marine reservoir values are used to adjust radiocarbon-dated material derived from marine sources, which are generally older than contemporary terrestrial counterparts (Hua et al, 2015). These values are the difference (Δr) between contemporaneous terrestrial and surface ocean material, and are generally assumed constant for different regions.…”

Section: Radiometric Dating and Chronological Variabilitymentioning

confidence: 99%

“…These values are the difference (Δr) between contemporaneous terrestrial and surface ocean material, and are generally assumed constant for different regions. However, marine Δr used in the adjustment of radiocarbon dates were shown to be variable (Hua et al, 2015). Variations in these reservoir values result from interaction between surface ocean, deeper ocean waters, and the atmosphere.…”

Section: Radiometric Dating and Chronological Variabilitymentioning

confidence: 99%

Section: Radiometric Dating and Chronological Variabilitymentioning

confidence: 99%

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Astronomical forcing of sub-Milankovitch climate oscillations during the late Quaternary

Kelsey¹

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A climate signal of ~1500-yr quasi-periodicity (e.g., Bond events) has been found from the Arctic to Antarctica, in palaeoclimatic data derived from a range of environmental proxy records. Solar and lunar forcing have individually been suggested as the cause of this millennial-scale signal, although some contend that it is little more than stochastic resonance within the climate system. Also debated is whether this climate signal is forced by the ocean-atmosphere dynamics of the North Atlantic or the tropical Pacific, as well as relevant climatic teleconnections. The cause of this cycle is elusive as no known solar cycle of this length exists, whilst forcing due to lunar gravitation has been dismissed as being too weak.The most likely cause of any periodic climate signal is an astronomical one, as demonstrated in Milankovitch cycles. This thesis explores a potential astronomical cause of millennial-and centennial-scale periodicities and variability, based on a combination of solar and lunar forcing.Conceptual and trigonometric models, physical models of insolation, solar irradiance, and gravitation, and astronomical data were used in this exploration. Identified as a possible cause of the ~1500-yr climate cycle is precession. Precession changes the timing of Earth's seasons relative to our calendar and external reference points, such as the fixed stars and the closest point in Earth's orbit to the Sun

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A comparison of U/Th and rapid‐screen ¹⁴C dates from Line Island fossil corals

Grothe

Cobb

Bush

et al. 2016

Geochem Geophys Geosyst

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Time‐consuming and expensive radiometric dating techniques limit the number of dates available to construct absolute chronologies for high‐resolution paleoclimate reconstructions. A recently developed rapid‐screen 14C dating technique reduces sample preparation time and per sample costs by 90%, but its accuracy has not yet been tested on shallow‐water corals. In this study, we test the rapid‐screen 14C dating technique on shallow‐water corals by comparing 44 rapid‐screen 14C dates to both high‐precision 14C dates and U/Th dates from mid‐ to late‐Holocene fossil corals collected from the central tropical Pacific (2–4°N, 157–160°W). Our results show that 42 rapid‐screen 14C and U/Th dates agree within uncertainties, confirming closed‐system behavior and ensuring chronological accuracy. However, two samples that grew ∼6500 years ago have calibrated 14C ages ∼1000 years younger than the corresponding U/Th ages, consistent with diagenetic alteration as indicated by the presence of 15–23% calcite. Mass balance calculations confirm that the observed dating discrepancies are consistent with 14C addition and U removal, both of which occur during diagenetic calcite recrystallization. Under the assumption that aragonite‐to‐calcite replacement is linear through time, we estimate the samples' true ages using the measured 14C and U/Th dates and percent calcite values. Results illustrate that the rapid‐screen 14C dates of Holocene‐aged fossil corals are accurate for samples with less than 2% calcite. Application of this rapid‐screen 14C method to the fossil coral rubble fields from Kiritimati Island reveal significant chronological clustering of fossil coral across the landscape, with older ages farther from the water's edge.

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Large variations in the Holocene marine radiocarbon reservoir effect reflect ocean circulation and climatic changes

Cited by 54 publications

References 80 publications

Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Astronomical forcing of sub-Milankovitch climate oscillations during the late Quaternary

A comparison of U/Th and rapid‐screen ¹⁴C dates from Line Island fossil corals

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Large variations in the Holocene marine radiocarbon reservoir effect reflect ocean circulation and climatic changes

Cited by 54 publications

References 80 publications

Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Reef cores as records of Holocene water temperatures of the southern Great Barrier Reef: Geochemical analysis of traditional (Porites) and non-traditional (Acropora) reef building corals

Astronomical forcing of sub-Milankovitch climate oscillations during the late Quaternary

A comparison of U/Th and rapid‐screen 14C dates from Line Island fossil corals

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A comparison of U/Th and rapid‐screen ¹⁴C dates from Line Island fossil corals