2 results for late quaternary sediment core
Contributors: Jones, Samantha E, Burjachs, Francesc, Fernández-López de Pablo, Javier
sediment deflocculation and to bleach non-charcoal organic material. ...core)...sediment cores. The Holocene 8 (1), 113-117. Talon, B., Carcaillet, C...Late Quaternary case study from south-eastern, Spain. Quaternary Science...Quaternary Research 30 (1), 67-80. Jones S.E., Burjachs, F. Ferrer-García...Late Quaternary case study from south-eastern, Spain. Quaternary Science ... 1. Data set, and sampling methods This data set contains the quantification of sedimentary charcoal from the VL3 record of the Villena Paleolake (Villena, Alicante, Spain). The analyzed section covers the Early and Middle Holocene section of this deposit according (Jones et al., 2018), depths between -120 a -400 cm, with centimetric sampling interval which has produced a total number of 281 samples. 2. Treatment The samples have been treated as follows, adapting the methods published by Rhodes (1998) and Talon et al.(1998): Samples were soaked in 10% H2O2 for 12h for sediment deflocculation and to bleach non-charcoal organic material. After this first step, it was noted if the samples contained shell fragments. A 10% HCl solution was used in samples with high carbonate content. Then samples were sieved (150µ) under a soft-water jet. The samples were stored in distilled water for later counting. 3. Quantification procedures Each sample was washed with distilled water, employing a 150 micron sieve. The wet sample was examined under binocular microscope Stereomicroscopy CETI STEDDY-T at 40 magnification, using a reference grid with squares of different size categories (cat. 0,5; cat. 1, cat. 2, cat. 3, cat. 4 and cat. 5). The total number of examined charcoal was also calculated. Each size category corresponds to one of the following area categories Cat. 0,5: 0,015625mm2; Cat. 1: 0,0625 mm2 (0,25 mm*0,25 mm); Cat. 2: 0,0125 mm2; Cat. 3: 0,25 mm2; Cat. 4: 0,5625 mm2; Cat. 5: 1 mm2. In the Excel spreadsheet, the area is multiplied by the number of fragments of each category. The sum of the areas is also calculated. In addition, oocytes and insects were also counted. References Carcaillet, C., Bouvier, M., Fréchette, B., Larouche, A. C., Richard, P. J. H. (2001). Comparison of pollen-slide and sieving methods in lacustrine charcoal analyses for local and regional fire history. The Holocene 11 (4): 467- 476. Clark, J. S. (1988). Particle motion and the theory of charcoal analysis: Source area, transport, deposition, and sampling. Quaternary Research 30 (1), 67-80. Jones S.E., Burjachs, F. Ferrer-García C., Giralt, S., Schulte, L., Fernández-López de Pablo, J. (2018). A multi-proxy approach to understanding complex responses of salt-lake catchments to climate variability and human pressure: A Late Quaternary case study from south-eastern, Spain. Quaternary Science Reviews https://doi.org/10.1016/j.quascirev.2017.12.015. Ohlson, M. and Tryterud, E. 2000. Interpretation of the charcoal record in forest soils: forest fires and their production and deposition of macroscopic charcoal. The Holocene, 10(4), 529-525. Rhodes, A. N. (1998). A method for the preparation and quantification of microscopic charcoal from terrestrial and lacustrine sediment cores. The Holocene 8 (1), 113-117. Talon, B., Carcaillet, C., Thinon, M. (1998). Etudes pedoanthracologiques des variations de la limite superieure des arbres au cours de l'Holocene dans les Alpes françaises. Geographie physique et Quaternaire 52 (2), 195-208.
Regional seesaw between the North Atlantic and Nordic Seas during the last glacial abrupt climate events
Contributors: Wary, M., Eynaud, F., Swingedouw, D., Masson-Delmotte, V., Matthiessen, J., Kissel, C., Zumaque, J., Zumaque, J., Rossignol, L., Jouzel, J.
sediment cores from the northern Northeast Atlantic and southern Norwegian ... Dansgaard–Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle. Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48–30 ka interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional palaeorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that re-emerged in the Nordic Seas and provided moisture towards Greenland summit.