The response of sedimentation in three varved lacustrine sequences to air temperature, precipitation and human impact

Itkonen, Arto; Salonen, Veli‐Pekka

doi:10.1007/bf00677992

Cited by 43 publications

(37 citation statements)

References 19 publications

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“…A reduction in both allochthonous organic/clastic sedi ment influx and organic productivity w ithin the lake basin is an alternative means o f producing a m ineral horizon. Scavia et al (1986) and Itkonen and Salonen (1994) have noted that increased lake-ice cover can dramatically affect nutrient avail ability, and consequently productivity, w ithin lake basins.…”

Section: Discussion Deglaciationmentioning

confidence: 99%

Changes in lake-sediment stratigraphy associated with late glacial climate change: examples from western Nova Scotia

Spooner

1998

atgeol

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An investigation of lake-sediment stratigraphy in western Nova Scotia has focused on determining the environmental response to late-glacial climate change. Sediment records from Ave headwater lakes were recovered and sediment stratigraphy from four of the lakes was used to reconstruct late-glacial environments for this region. Results from Sand Lake and Canoran Lake (South Mountain) indicate that the South Mountain was deglaciated by about 11,500 B.P. The North Mountain was deglaciated slightly earlier. All cores contained till (unit 1) which was overlain by a fine-grained diamicton (unit 2) that was deposited after ice had receded. A gyttja with varying mineral sediment concentrations (unit 3) overlies unit 2. Unit 2 is interpreted as sediment that was transferred to the basin as the basin and catchment stabilized. The North Mountain sites are characterized by lack of a Younger Dryas-equivalent loss-on-ignition or mineral oscillation. The South Mountain sites both contain a thin (2 cm) Younger Dryas-equivalent mineral horizon (unit 4) bounded above and below by sandy gyttja (units 3 and 5). Image and grain size analysis of units 3,4 and 5 indicate that these units differ primarily in their amounts of fine silt and clay, as mavimiim grain size is similar in each unit. This result indicates that changes in sediment transfer mechanisms in response to climate change were subtle. The formation of unit 4 (YDimh) was primarily a consequence of intrabasin sediment transfer and reduced productivity; an increase in the extent and/or duration of lake ice cover may have been an important factor. The catchment response to Younger Dryas climate change in western Nova Scotia was probably subdued. Though aufeis and perennial snow cover may have existed at some sites, the presence of Younger Dryas-equivalent glacial ice in western Nova Scotia is unlikely. RÉSUMÉ Une étude stratigraphique des sédiments lacustres dans l'ouest de la Nouvelle-Écosse s'est attachée à déterminer la réaction de l'environnement au changement climatique tardiglaciaire. On a récuperé des échantilions de sédiments de cinq lacs d'amont et on a utilise les données stratigraphiques des sédiments de quatre des lacs pour reconstruire les environnements tardiglaciaires de cette région. Les résultats obtenus du lac Sand et du lac Canoran (mont South) reVelent que la déglaciation du mont South est survenue vers 11 500 avant le présent. La déglaciation du mont North s'est produite légèrement plus tôt. Toutes les carottes contenaient du till (unite 1) recouvert de diamicton à grain fin (unité 2) qui s'était déposé après la disparition de la glace. Un gyttja renfermant des concentrations de sédiments minéraux variables (unité 3) recouvre 1'unité 2. Cette demière est interprétée comme le resultat d'un transfert de sédiments dans le bassin sédimentaire au moment ou le bassin sédimentaire et le bassin hydrographique se sont stabilisés. Les points du mont North se caractérisent par une absence d'oscillation minérale ou de perte au feu équivalente au Dryas récent. Les points du mont South renferment tous deux une mince couche (2 cm) d'horizon minéral équivalent au Dryas récent (unité 4) délimitée au-dessus et au-dessous par un gyttja sableux. Les images et l'analyse de la granulométrie des unités 3,4 et 5 révèlent que ces unités sont différentes, principalement en ce qui concerne leurs teneurs en argile et en silt fins, car la taille maximale des grains est semblable dans chaque unité. Ce résultat témoigne du fait que les changements dans les mécanismes de transfert des sédiments consécutifs au changement climatique ont été subtils. La formation de l'unité 4 (YDimh) a principalement été provoquée par un transfert de sédiments à l'intérieur du bassin et une productivité réduite; l’augmentation de l’étendue ou de la durée de la couverture de glace du lac a peut-être constitue un facteur déterminant. La reaction du bassin hydrographique au changement climatique du Dryas récent dans l'ouest de la Nouvelle-Écosse a probablement été estompée. Même si un aufeis et un tapis de neige pérenne ont pu exister en certains endroits, la présence de glace de l'ère glaciaire équivalente au Dryas récent dans l'ouest de la Nouvelle-Écosse est improbable. Traduit par la rédaction

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Section: Discussion Deglaciationmentioning

confidence: 99%

Changes in lake-sediment stratigraphy associated with late glacial climate change: examples from western Nova Scotia

Spooner

1998

atgeol

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“…In a boreal climate setting, characterized by snowy winters and mild summers, clastic-organic varves are commonly preserved in the sediment record. Many such records from Scandinavia have been studied in detail (Petterson et al 1993;Itkonen and Salonen 1994;Snowball et al 1999;Tiljander et al 2003;Ojala and Alenius 2005;Haltia-Hovi et al 2007). In these studies, the deposition of the clastic laminae was attributed to catchment erosion caused by snowmelt, whereas there was little discussion of organic laminae.…”

Section: Introductionmentioning

confidence: 99%

Organic lacustrine sediment varves as indicators of past precipitation changes: a 3,000-year climate record from Central Finland

2015

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“…Therefore, a first priority in studies of laminated sediments is to establish the seasonal nature of the layering. The presence of such laminations, as well as specific features of their formation, yields information about past environmental conditions such as climate (Perkins and Sims, 1983;Renberg et al, 1984;Leemann et al, 1991;Itkonen and Salonen, 1994) or trophic state of a lake (Simola et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Varve formation since 1885 and high-resolution varve analyses in hypertrophic Baldeggersee (Switzerland)

et al. 1997

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According to their microstratigraphical composition the laminated sediments of Baldeggersee are true varves. Two varve time-series from freeze cores taken in the deepest part (66 m) of Baldeggersee have been analysed for annual and seasonal layers. The varve time-series covers the period of 1885 to 1993.The two freeze-cores from Baldeggersee can be accurately correlated by means of distinct layers (e.g. marker varves, turbidites), lithological units, and varve measurements. The Baldeggersee varve chronology has been checked by independent high-resolution 137 Cs dating. Mobility of cesium has not been detected in Baldeggersee. A highly positive correlation between phosphorus concentration in the lake water and median grain size of calcite crystals has been observed and allows, together with the results of geochemical analyses, to hindcast the trophic state in Baldeggersee for periods where no limnological data are available.The main features of the Baldeggersee varve time-series can be summarized as follows: before 1885 there are packets of 5 -10 varves interrupted by massive, homogeneous marl beds, indicating oscillating hypolimnetic oxygen levels until the lake ultimately became anoxic in 1885. Between 1885 and 1905 varves are thin, with a high carbonate content. Between 1905 and 1910 the thickness of varves increased steadily, and an increase in calcite grain size suggests a major step in eutrophication. Median grain size values increase again at the end of the 1940s, whereas the thickness of the seasonal layers decreased between the early 1940s and the early 1960s. At the onset of the 1960s, during the time of highest epilimnetic phosphorus concentrations in Baldeggersee, the total phosphorus concentrations in the sediments as well as the varve thickness and the total accumulation rates all increased. At the beginning of the 1980s the median grain size decreased substantially as a result of lower phosphorus concentrations in Baldeggersee.

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The response of sedimentation in three varved lacustrine sequences to air temperature, precipitation and human impact

Cited by 43 publications

References 19 publications

Changes in lake-sediment stratigraphy associated with late glacial climate change: examples from western Nova Scotia

Changes in lake-sediment stratigraphy associated with late glacial climate change: examples from western Nova Scotia

Organic lacustrine sediment varves as indicators of past precipitation changes: a 3,000-year climate record from Central Finland

Varve formation since 1885 and high-resolution varve analyses in hypertrophic Baldeggersee (Switzerland)

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