Diatom surface sediment assemblages around Iceland and their relationships to oceanic environmental variables

Jiang, Hui; Seidenkrantz, Marit‐Solveig; Knudsen, Karen Luise; Eiríksson, Jón

doi:10.1016/s0377-8398(00)00053-0

Cited by 101 publications

(143 citation statements)

References 20 publications

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“…A recent study of the modern distribution of diatoms in surface sediments around Iceland demonstrated a close relationship between diatom assemblages and the modern distribution of water masses (Jiang et al, 2001). These results, coupled with previous diatom research in the North Atlantic form the basis of the environmental interpretation of the diatom results presented in Fig.…”

Section: Diatomsmentioning

confidence: 96%

“…A strong influence of the Irminger Current on the North Icelandic shelf is indicated by Thalassiosira oestrupii, which is the main diatom species of the Atlantic assemblage in the modern warm North Atlantic water mass with salinities higher than 35.3 and sea surface temperatures above 3°C (Koç Karpuz and Schrader, 1990). In modern assemblages around Iceland, it is mainly found in the surface sediments south and west of Iceland, where the warm Irminger Current has a strong impact today ( Jiang et al, 2001). The presence of the Irminger Current is also indicated by Thalassionema nitzschioides and Paralia sulcata, which constitute the main species of the Norwegian-Atlantic Current assemblage in the Greenland-Iceland-Norwegian seas (Koç Karpuz and Schrader, 1990).…”

Section: Diatomsmentioning

confidence: 99%

“…Both species are associated with the Atlantic waters flowing into the Skagerrak-Kattegat in the eastern North Atlantic ( Jiang, 1996). They are mainly found in the modern surface sediments south and west of Iceland, where the Irminger Current has a strong impact ( Jiang et al, 2001). …”

Section: Diatomsmentioning

confidence: 99%

“…One of the most important taxa in the cold-water diatom assemblage associated with the cold, low-salinity East Icelandic Current is Thalassiosira antarctica resting spores (Jiang et al, 2001). It is one of the main taxa of the Arctic water assemblage, which at present coincides geographically with the seasonally sea-ice covered Iceland Plateau with salinity between 34.7 and 34.9 and temperatures ranging from freezing to 8°C ( Koç Karpuz and Jansen, 1992).…”

Section: Diatomsmentioning

confidence: 99%

“…Both species are the main components of the sea-ice diatom assemblage in surface sediments from the seafloor around Iceland ( Jiang et al, 2001). An assemblage containing F. cylindrus, F. oceanica and Thalassiosira nordenskioeldii was considered to be indicator of the spring bloom associated with melting ice in modern Bering Sea assemblages (Sancetta, 1981).…”

Section: Diatomsmentioning

confidence: 99%

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Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Knudsen

Jiang

Jansen

et al. 2004

Marine Micropaleontology

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A combined study of foraminifera, diatoms and stable isotopes in marine sediments off North Iceland records major changes in sea surface conditions since about 15800 cal years (yr) BP. Results are presented from two gravity cores obtained at about 400 m water depth from two separate sedimentary basins on each side of the submarine Kolbeinsey Ridge. The chronology of the sedimentary record is based partly on AMS 14 C dates, partly on the Vedde and the Saksunarvatn tephra markers, as well as the historical Hekla AD 1104 tephra. During the regional deglaciation, the planktonic foraminiferal assemblages are characterised by consistently high percentages of sinistrally coiled Neogloboquadrina pachyderma. However, major environmental variability is reflected by changes in stable isotope values and diatom assemblages. Low 18 O values indicate a strong freshwater peak as well as possible brine formation by sea-ice freezing during a pre-Bølling interval (Greenland Stadial 2), corresponding to the Heinrich 1 event. The foraminifera suggest a strong concurrent influence of relatively warm and saline Atlantic water, and both the foraminifera and the diatoms suggest mixing of cold and warm water masses. Similar but weaker environmental signals are observed during the Younger Dryas (Greenland Stadial 1) around the level of the Vedde Ash. Each freshwater peak is succeeded by an interval of severe cooling both at the beginning of the Bølling-Allerød Interstadial Complex (Greenland Interstadial 1) and during the Preboreal, presumably associated with the onset of intense deep water formatiom in the Nordic Seas. The Holocene thermal optimum, between 10200 and about 7000 cal years (yr) BP, is interrupted by a marked cooling of the surface waters around 8200 cal yr BP. This cold event is clearly expressed by a pronounced increase in the percentages of sinistrally coiled N. pachyderma, corresponding to a temperature decrease of about 3°C. A general cooling in the area is indicated after 7000-6000 cal yr BP, both by the diatom data and by the planktonic foraminiferal data. After a severe cooling around 6000 cal yr BP, the planktonic foraminiferal assemblages suggest a warmer interval between 5500 and 4500 cal yr BP. Minor temperature fluctuations are reflected both in the foraminiferal and in the diatom data in the upper part of the record, but the time resolution of the present data is not high enough to pick up details in environmental changes through the late Holocene.

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Section: Diatomsmentioning

confidence: 96%

Section: Diatomsmentioning

confidence: 99%

Section: Diatomsmentioning

confidence: 99%

Section: Diatomsmentioning

confidence: 99%

Section: Diatomsmentioning

confidence: 99%

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Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Knudsen

Jiang

Jansen

et al. 2004

Marine Micropaleontology

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Exceptional ocean surface conditions on the SE Greenland shelf during the Medieval Climate Anomaly

et al. 2015

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Diatom inferred 2900 year long records of August sea surface temperature (aSST) and April sea ice concentration (aSIC) are generated from a marine sediment core from the SE Greenland shelf with a special focus on the interval ca. 870-1910 Common Era (C.E.) reconstructed in subdecadal temporal resolution. The Medieval Climate Anomaly (MCA) between 1000 and 1200 C.E. represents the warmest ocean surface conditions of the SE Greenland shelf over the late Holocene (880 B.C.E. (before the Common Era) to 1910 C.E.). It was characterized by abrupt, decadal to multidecadal changes, such as an abrupt warming of 2.4°C in 55 years around 1000 C.E. Temperature changes of these magnitudes are rare on the North Atlantic proxy data. Compared to regional air temperature reconstructions, our results indicate a lag of about 50 years in ocean surface warming either due to increased freshwater discharge from the Greenland ice sheet or intensified sea ice export from the Arctic as a response to atmospheric warming at the beginning of the MCA. A cool phase, from 1200-1890 C.E., associated with the Little Ice Age, ends with the rapid warming of aSST and diminished aSIC in the early twentieth century. The results show that the periods of warm aSST and aSIC minima are coupled with solar minima suggesting that solar forcing possibly amplified by atmospheric forcing have been behind the variability of surface conditions on the SE Greenland over the last millennium.The results indicate that the SE Greenland shelf is a climatologically sensitive area where extremely rapid changes are possible and highlights the importance of the area under the present warming conditions.

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Quantitative reconstruction of Holocene sea ice and sea surface temperature off West Greenland from the first regional diatom data set

et al. 2017

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Holocene oceanographic conditions in Disko Bay, West Greenland, were reconstructed from high‐resolution diatom records derived from two marine sediment cores. A modern data set composed of 35 dated surface sediment samples collected along the West Greenland coast accompanied by remote sensing data was used to develop a diatom transfer function to reconstruct April sea ice concentration (SIC) supported by July sea surface temperature (SST) in the area. Our quantitative reconstruction shows that oceanographic changes recorded throughout the last ~11,000 years reflect seasonal interplay between spring (April SIC) and summer (July SST) conditions. Our records show clear correlation with climate patterns identified from ice core data from GISP2 and Agassiz‐Renland for the early to middle Holocene. The early Holocene deglaciation of western Greenland Ice Sheet was characterized in Disko Bay by initial strong centennial‐scale fluctuations in April SIC with amplitude of over 40%, followed by high April SIC and July SST. These conditions correspond to a general warming of the climate in the Northern Hemisphere. A decrease in April SIC and July SST was recorded during the Holocene Thermal Optimum reflecting more stable spring‐summer conditions in Disko Bay. During the late Holocene, high April SIC characterized the Medieval Climate Anomaly, while high July SST prevailed during the Little Ice Age, supporting previously identified antiphase relationship between surface waters in West Greenland and climate in NW Europe. This antiphase pattern might reflect seasonal variations in regional oceanographic conditions and large‐scale fluctuations within the North Atlantic Oscillation and Atlantic Meridional Overturning Circulation.

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Diatom surface sediment assemblages around Iceland and their relationships to oceanic environmental variables

Cited by 101 publications

References 20 publications

Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Environmental changes off North Iceland during the deglaciation and the Holocene: foraminifera, diatoms and stable isotopes

Exceptional ocean surface conditions on the SE Greenland shelf during the Medieval Climate Anomaly

Quantitative reconstruction of Holocene sea ice and sea surface temperature off West Greenland from the first regional diatom data set

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