scholarly journals Coastal Upwelling and Radiocarbon—Evidence for Temporal Fluctuations in Ocean Reservoir Effect off Portugal During the Holocene

Radiocarbon ◽  
2006 ◽  
Vol 48 (1) ◽  
pp. 45-60 ◽  
Author(s):  
António M Monge Soares ◽  
João M Alveirinho Dias
Keyword(s):  
Coastal Upwelling ◽  
Climatic Factors ◽  
Marine Mollusk ◽  
Reservoir Effect ◽  
Temporal Fluctuations ◽  
The Holocene ◽  
Mollusk Shells ◽  
Portuguese Coast ◽  
Strong Intensity ◽  
Terrestrial Material

This paper focuses on the use of the radiocarbon content of marine shells collected along the Portuguese coast as a proxy for the intensity of coastal upwelling off of Portugal. Differences in the 14C ages of closely associated marine mollusk shells and terrestrial material (charcoal or bones) from several Portuguese archaeological contexts seem to be significant throughout the Holocene. ΔR values range from 940 ± 50 to −160 ± 40 14C yr. Five of these values are significantly higher than the modern value (250 ± 25 14C yr), while the remaining values are lower. The modern value was calculated by measuring the 14C content of live-collected, pre-bomb marine mollusk shells. This value is in accordance with an active upwelling of strong intensity that currently occurs off of Portugal. Some primary observations based on data presented here can be made: i) during the Holocene important changes have occurred in the ocean reservoir effect off the Portuguese coast; ii) these fluctuations may be correlated with regional oceanographic changes, namely with changes in the strength of coastal upwelling; and iii) these changes suggest some sort of variability of the climatic factors forcing coastal upwelling off of Portugal.

Marine radiocarbon reservoir effect along the northern Chile–southern Peru coast (14–24°S) throughout the Holocene

2011 ◽  
Vol 75 (1) ◽  
pp. 91-103 ◽  
Author(s):  
Luc Ortlieb ◽  
Gabriel Vargas ◽  
Jean-François Saliège
Keyword(s):  
Coastal Upwelling ◽  
Major Influence ◽  
Northern Chile ◽  
Subtropical Anticyclone ◽  
Reservoir Effect ◽  
Subtropical Water ◽  
The Holocene ◽  
Southern Peru ◽  
Subsurface Waters ◽  
Terrestrial Material

AbstractThrough an extensive sampling and dating of pairs of associated shells and charcoal fragments combined with reanalysis of all the available previous data, we reconstruct the evolution throughout the Holocene of the regional marine radiocarbon reservoir effect (ΔR) values along the northern Chile–southern Peru area (14°–24°S). After elimination of the cases in which the terrestrial component yielded older ages than the marine shells to which they were associated, the study is based upon data from 47 pairs of associated marine and terrestrial material.Our results suggest major changes in both the magnitude and variability range of ΔR during the whole Holocene Period: (1) between 10,400 and 6840 cal yr BP, high values (511 ± 278 yr) probably result from a strengthened SE Pacific subtropical anticyclone and shoaling of equatorial subsurface waters during intensified upwelling events; (2) between 5180 and 1160 cal yr BP, lower values (226 ± 98 yr) may reflect a major influence of subtropical water and diminished coastal upwelling processes; (3) during the last ~ thousand years, high values (between 355 ± 105 and 253 ± 207 yr) indicate an increased influence of 14C-depleted water masses and of ENSO. For the early twentieth century a ΔR value of 253 ± 207 yr was calculated.

scholarly journals Marine Radiocarbon Reservoir Effect of Coastal Waters Off Cape Verde Archipelago

Radiocarbon ◽  
2011 ◽  
Vol 53 (2) ◽  
pp. 289-296 ◽  
Author(s):  
António M Monge Soares ◽  
José M Matos Martins ◽  
João Luís Cardoso
Keyword(s):  
Coastal Waters ◽  
Coastal Upwelling ◽  
Mean Value ◽  
Cape Verde ◽  
Weighted Mean ◽  
Reservoir Effect ◽  
Mollusk Shells ◽  
Marine Samples ◽  
Oceanographic Conditions ◽  
Marine Shell

Quantification of the marine radiocarbon reservoir effect (ΔR) is essential in order to calibrate conventional 14C dates from marine shell samples with reliability. ΔR also provides information concerning the intensity of coastal upwelling in marine regions influenced by this phenomenon. 14C ages of closely associated marine samples (mollusk shells) and terrestrial samples (goat bones) from São Vicente Island, Cape Verde Archipelago, permitted the first calculation of the marine 14C reservoir effect in this region. A ΔR weighted mean value of 70 ± 70 14C yr was obtained. This value is in accordance with the previously published oceanographic conditions of the region indicating the existence of a seasonal active upwelling regime.

scholarly journals Apparent 14C Ages of Marine Mollusk Shells from a Greek Island: Calculation of the Marine Reservoir Effect in the Aegean Sea

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 963-973 ◽  
Author(s):  
Yorgos Facorellis ◽  
Yannis Maniatis ◽  
Bernd Kromer
Keyword(s):  
Calibration Curve ◽  
Radiocarbon Dating ◽  
Aegean Sea ◽  
Human Settlement ◽  
Marine Mollusk ◽  
Reservoir Effect ◽  
Mollusk Shells ◽  
Marine Samples ◽  
Terrestrial Origin ◽  
Greek Island

The excavation of the Cyclope cave, situated on the deserted island of Youra in the Northern Sporades (39°22'N, 24°10'E), revealed material of marine and terrestrial origin in undisturbed layers, suitable for radiocarbon dating. In some cases, material from different reservoirs was found together in the same archaeological layer. This research had two aims. The first was the dating of charcoal-seashell pairs in order to determine the marine reservoir effect in this region, based on samples with ages spanning from the end of the 8th millennium to the beginning of the 7th millennium bc. The second aim was dating the stratigraphy of this site, by using the calculated δR value in conjunction with the marine calibration curve. This enabled the accurate calibration of the 14C ages of marine samples found in layers without charcoal pieces. The results show that this is the oldest human settlement ever found on an island in the Aegean Sea.

scholarly journals Improving the 14C Dating of Marine Shells from the Canary Islands for Constructing More Reliable and Accurate Chronologies

Radiocarbon ◽  
2012 ◽  
Vol 54 (3-4) ◽  
pp. 943-952 ◽  
Author(s):  
José M Matos Martins ◽  
Alfredo Mederos Martín ◽  
Paulo J Cesário Portela ◽  
António M Monge Soares
Keyword(s):  
Canary Islands ◽  
Radiocarbon Dating ◽  
Coastal Upwelling ◽  
Mean Value ◽  
The Other ◽  
Weighted Mean ◽  
14C Dating ◽  
Marine Mollusk ◽  
Terrestrial Material ◽  
Charred Wood

Radiocarbon dating of closely associated marine mollusk shells and terrestrial material (charred wood or bone) collected from archaeological contexts on Tenerife and Fuerteventura islands allowed us to quantify the marine 14C reservoir effect (ΔR) around the Canary Archipelago. Coastal Fuerteventura has a positive weighted mean ΔR value of +185 ± 30 14C yr, while for Tenerife a range of negative and positive values was obtained, resulting in a ΔR weighted mean value of 0 ± 35 14C yr. These values are in accordance with the hydrodynamic system present off the Canary Islands characterized by a coastal upwelling regime that affects the eastern islands (Fuerteventura and Lanzarote) but not the other islands of the archipelago, namely Tenerife. Because of this oceanographic pattern, we recommend the extrapolation of these results to the remaining islands of the archipelago, i.e. the first value must be used for the eastern islands, while for the central and western islands the acceptable ΔR value is 0 ± 35 14C yr.

scholarly journals Holocene biogeography of Tsuga mertensiana and other conifers in the Kenai Mountains and Prince William Sound, south-central Alaska

The Holocene ◽  
2016 ◽  
Vol 27 (4) ◽  
pp. 485-495 ◽  
Author(s):  
R Scott Anderson ◽  
Darrell S Kaufman ◽  
Edward Berg ◽  
Caleb Schiff ◽  
Thomas Daigle
Keyword(s):  
Climatic Factors ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Early Holocene ◽  
Ice Age ◽  
Prince William Sound ◽  
Conifer Forest ◽  
The Holocene ◽  
South Central ◽  
Tsuga Mertensiana

Several important North American coastal conifers – having immigrated during the Holocene from the southeast – reach their northern and upper elevation limits in south-central Alaska. However, our understanding of the specific timing of migration has been incomplete. Here, we use two new pollen profiles from a coastal and a high-elevation site in the Eastern Kenai Peninsula–Prince William Sound region, along with other published pollen records, to investigate the Holocene biogeography and development history of the modern coastal Picea (spruce)– Tsuga (hemlock) forest. Tsuga mertensiana became established at Mica Lake (100 m elevation, near Prince William Sound) by 6000 cal. BP and at Goat Lake (550 m elevation in the Kenai Mountains) sometime after 3000 years ago. Tsuga heterophylla was the last major conifer to arrive in the region. Although driven partially by climate change, major vegetation changes during much of the Holocene are difficult to interpret exclusively in terms of climate, with periods of slow migration alternating with more rapid movement. T. mertensiana expanded slowly northeastward in the early Holocene, compared with Picea sitchensis or T. heterophylla. Difficulty of invading an already established conifer forest may account for this. We suggest that during the early Holocene, non-climatic factors as well as proximity to refugia, influenced rates of migration. Climate may have been more important after ~2600 cal. BP. Continued expansion of T. mertensiana at Goat Lake at the Medieval Climate Anomaly (MCA)–‘Little Ice Age’ (‘LIA’) transition suggests warm and wet winters. But expansion of T. mertensiana at both sites was arrested during the colder climate of the ‘LIA’. The decline was more extensive at Goat Lake, where climatic conditions may have been severe enough to reduce or eliminate the T. mertensiana population. T. mertensiana continued its expansion around Goat Lake after the ‘LIA’.

14C and Marine Reservoir Effect in Archaeological Samples from the Northeast Gulf of California

Radiocarbon ◽  
2015 ◽  
Vol 57 (5) ◽  
pp. 785-793 ◽  
Author(s):  
David L Dettman ◽  
Douglas R Mitchell ◽  
Gary Huckleberry ◽  
Michael S Foster
Keyword(s):  
Standard Deviation ◽  
Gulf Of California ◽  
Shell Midden ◽  
Reservoir Effect ◽  
Mollusk Shells

Previous studies of live-collected pre-weapons testing mollusk shells in the northern Gulf of California have demonstrated that the local radiocarbon reservoir effect (ΔR) is large and highly variable. To test the validity of this observation for paired charcoal and shell samples from archaeological contexts, we dated samples from four shell midden locations and six midden layers from the eastern shoreline of the Gulf of California near Puerto Peñasco, Sonora, Mexico. Dated charcoal samples were small twigs or brushy plants used to cook shellfish and the shells dated within each midden showed signs of burning. Ages range from approximately 5700 to 1900 cal BP. The offset between the modeled marine 14C age for calibrated ages of the middens and measured shell 14C age (ΔR) averaged 425 yr with a standard deviation of 115 yr.

Charophyte Population Dynamics during the Late Quaternary at Lake Bibersee, Switzerland

1999 ◽  
Vol 47 (3) ◽  
pp. 315 ◽  
Author(s):  
Jean Nicolas Haas
Keyword(s):  
Bronze Age ◽  
Lake Level ◽  
Climatic Factors ◽  
Late Quaternary ◽  
Prehistoric Agriculture ◽  
The Holocene ◽  
Ph Values ◽  
Middle Bronze Age ◽  
The Town ◽  
Boreal Period

Oospores of 11 charophyte species were found in the Late Quaternary gyttja deposits of Lake Bibersee near the town of Zug. Except for the Boreal period rarely more than three different species were growing simultaneously during the Holocene. This compares well to typical Characeae lakes of the same size today, and shows that considerable changes in the hydrophyte diversity have taken place through time. During the first part of the Holocene the lake was oligotrophic and the species composition was mainly regulated by lake-level fluctuations due to climatic factors. During the younger periods of the Holocene the lake became mesotrophic, and pH values were for a longer period slightly alkaline. During the Early to Middle Bronze Age (1900–1400 BC) the considerable alterations in the hydrophyte composition and the simultaneous extensive prehistoric agriculture on the fertile shores of the lake point to human impact as the primary cause for changes in charophyte diversity.

Reconstructing El Ni?o-Southern Oscillation activity and ocean temperature seasonality from short-lived marine mollusk shells from Peru

2013 ◽  
Vol 371 ◽  
pp. 45-53 ◽  
Author(s):  
Matthieu Carr ◽  
Julian P. Sachs ◽  
Andrew J. Schauer ◽  
Walter Elliott Rodrguez ◽  
Fredy Cardenas Ramos
Keyword(s):  
Southern Oscillation ◽  
Ocean Temperature ◽  
Marine Mollusk ◽  
Mollusk Shells ◽  
Temperature Seasonality

scholarly journals ALGAS MARINAS BENTICAS INDICADORAS DE UN AREA AFECTADA POR AGUAS DE SURGENCIA FRENTE A LA COSTA CARIBE DE COLOMBIA

2016 ◽  
Vol 9 ◽  
Author(s):  
Germán Bula Meyer
Keyword(s):  
Coastal Upwelling ◽  
Climatic Factors ◽  
Biological Indicators ◽  
Sea Bottom ◽  
Chemical Factors ◽  
The Caribbean ◽  
Relationship Of ◽  
Physical And Chemical ◽  
Counter Current ◽  
The Relationship

The present paper is the result of a study undertaken to establish the relationship of certain marine envlromental factors and the benthic flora of the Caribbean littoral of Colombia. For the purpose of this study this coastal bands has been divided in two Areas. Area 1 is found between Cabo Tiburón and the mouth of the Río Magdalena, and is characterized by warm waters with very small fluctuations of the surface temperature. Area 2 ranges from the mouth of the Río Magdalena to Castilletes, and its waters are affected by a coastal upwelling with a locality of maximum intensity at the West of Península de Guajira. As a result of the presence of this upwelling there are considerable variations in the physical and chemical factors acting upon the benthic flora, there established for very short periods or all year round, as well as determining the absence of some genera and species typical of these latitudes. The parameters used for detecting this oceanographic phenomenon are given by Díaz-Piferrer (1967 a) for Venezuela. To the biological indicators cited by this author for Venezuela, the present writer adds the brown alga Ectocarpus confervoides (Roth) Le Jolis, which was found in the area of upwelling in Colombia. A comparative study of these indicators plants with those of Venezuela is given in the present paper. Similarities and differences were found to be caused by the over-run of the warm counter current on the Colombian upwelling; by the different forces of the Caribbean Current and Guayana Current, all of which lead to the related oceanographic phenomenon; tfie climatic factors; the topography of the sea bottom and the influence of the continental waters over these upwelling.

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