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Age model of sediment core from Lake Prata (São Miguel, Azores, Portugal)
No full textThe location of the Azores Archipelago makes this group of islands an excellent setting for investigating past long-term temperature and precipitation changes in the central North Atlantic region. Lake Prata (37º48'23''N, 25°44'12''W; 520 m a.s.l.) is found on the island of São Miguel, more precisely in the western sector of the Picos fissure system, 5 km SE of the Sete Cidades caldera, and it fills the crater of a scoria cone older than 5000 years. The lake is currently a Sphagnum/Eleocaris-dominated peatland. In January 2021, a 4.5-m long core was collected from Lake Prata using a Russian corer with a 50 cm long and 7 cm diameter sampler. The core was packed in PVC trays and covered in plastic film before being transported to the CIBIO's paleolimnology laboratory (University of Azores). The core was dated using ¹⁴C and produced a multi-proxy dataset of geochemical and biological analyses that we used to uncover paleoenvironmental changes on Lake Prata in the last ca. 1200 years
Oxygen isotopes (δ18O) of sediment core from Lake Prata (São Miguel, Azores, Portugal)
No full textThe location of the Azores Archipelago makes this group of islands an excellent setting for investigating past long-term temperature and precipitation changes in the central North Atlantic region. Lake Prata (37º48'23''N, 25°44'12''W; 520 m a.s.l.) is found on the island of São Miguel, more precisely in the western sector of the Picos fissure system, 5 km SE of the Sete Cidades caldera, and it fills the crater of a scoria cone older than 5000 years. The lake is currently a Sphagnum/Eleocaris-dominated peatland. In January 2021, a 4.5-m long core was collected from Lake Prata using a Russian corer with a 50 cm long and 7 cm diameter sampler. The core was packed in PVC trays and covered in plastic film before being transported to the CIBIO's paleolimnology laboratory (University of Azores). The core was dated using ¹⁴C and produced a multi-proxy dataset of geochemical and biological analyses that we used to uncover paleoenvironmental changes on Lake Prata in the last ca. 1200 years
B/Ca, δ¹¹B and calcifying fluid carbonate chemistry reconstruction of Porites sp. fromTonga (TNI2)
No full textSamples were collected from two Porites sp. coral cores in the Southwestern Pacific, specifically at Nomuka Iki Island (Tonga). Parameters measured in this study include boron stable isotope analysis (δ11B) and Boron/Calcium (B/Ca) ratios. The Tonga coral core (TNI2) yielded 224 samples covering the period from 1777 to 2004 out of which 123 were analyzed for δ11B.
δ11B measurements were conducted on NuPlasma II MC-ICP-MS and boron was concentrated using the micro-distillation (sublimation) method. B/Ca was originally analyzed in every to every second millimeter resolution, providing approximately bimonthly resolution, on Analytik Jena PlasmaQuant Elite ICP-MS. That data was annualized for this study and here it is attached in its annual resolution. The carbonate chemistry of the calcifying fluid was reconstructed using δ11B and B/Ca ratios yielding reconstructions of pHcf (calcifying fluid pH), pHsw (seawater pH), [CO3²] (carbonate ion concentration), DIC (dissolved inorganic carbon), and Ωcf (aragonite saturation state). Reconstructions of [CO3²], DIC and Ωcf were calculated using boronsysarag (DeCarlo et al., 2018;doi:10.5194/bg-15-2819-2018) and seacarb (Gattuso et al., 2021; https://cran.r-project.org/web/packages/seacarb/index.html) packages in R statistical software (R Core team, 2021; https://www.r-project.org/foundation/)
The original and interpolated time series of dinoflagellate cysts export flux and multiple environmental factors off Cape Blanc, Northwest Africa
No full textDerived from multiple sources of high-resolution data that covered a time span from mid-2003 until early 2020, this dataset consists of dinoflagellate cysts (dinocysts) export flux time series obtained by a Honjo-type sediment trap offshore Cape Blanc and key environmental factors time series in the Canary Current upwelling ecosystem, Northwest Africa. The dinocyst time series comprises absolute abundances of all identified dinocyst taxa and four main groups showcasing particular ecological signals. Meanwhile, the time series of environmental factors originated from land observations (Nouadibhou Airport) of dust storm activity, surface wind speed, and surface wind direction, as well as satellite-based observations of aerosol dust frequency, sea surface temperature, and sea surface temperature anomaly. The resolution of each time series was standardised, and new time series were interpolated to meet the requirement of wavelet time series analysis, which could determine the common cyclical patterns in the time series of dinocysts and environmental factors. This approach aimed to distinguish climatic-driven changes by linking the interannual variations that occurred in environments and the dinocyst export flux cycles
Beryllium concentrations and ratios (10Be/9Be) of sediment cores PS67/197-1, PS75/054-1, and PS97/085-3
No full textWe obtained high resolution records of authigenic 10Be/9Be ratios in order to study the different impacts on 10Be deposition in marine sediments compared to ice cores. As changes in the atmospheric production of cosmogenic 10Be leave a global fingerprint in 10Be deposition fluxes this represents a powerful tool for the synchronization of climate archives. During the Laschamps geomagnetic field low (~ 41 ka BP) the global production rate of 10Be is expected to double. We therefore chose the depth intervals covering this period (PS67/197-1 8.51 – 16.31 m; PS75/054-1 1.80 – 8.30 m; PS97/085-3 3.80 – 7.60 m). For Be measurements 0.5 – 3.0 g of freeze dried samples of the cores were leached (Gutjahr et al., 2007), purified (Loftfield et al., 2024), and measured via ICP-OES (9Be) and AMS (10Be; Lachner et al., 2023 and Rugel et al., 2016). High resolution paleo- and mineralmagnetic measurements were performed on the 2.37 m – 15.36 m (~ 27 – 82 ka BP) interval of PS75/054-1 in order to improve the age model of that core. The magnetic susceptibility and paleomagnetic measurements of PS67/197-1 and PS97/085-3 have been described and published by Xiao et al. (2016) and Wu et al. (2021), respectively. For age model construction the time scales of EDC and EDML were updated to AICC2023
