Varve chronology of the glacial sediments in Blekinge and northeastern Skåne, southeastern Sweden

A clay varve chronology has been established for the Late Weichselian ice recession east of Mt. Billingen in Västergötland, Sweden. In this area the Middle‐Swedish end moraine zone was built up as a consequence of cold climate during the Younger Dryas stadial. A change‐over from rapid to slow retreat as a result of climatic deterioration at the Alleröd/Younger Dryas transition cannot be traced with certainty in the varve sequences, but it seems to have taken place just before 11,600 varve years BP. The following deglaciation was very slow for about 700 years — within the Middle‐Swedish end moraine zone the annual ice‐front retreat was only c. 10 m on average. A considerable time‐lag is to be expected between the Younger Dryas climatic event and this period of slow retreat. The 700 years of slow retreat were succeeded by 200 years of more rapid recession, about 50–75 m annually, and then by a mainly rapid and uncomplicated retreat of the ice‐front by 100–200 m/year or more, characterizing the next 1500 years of deglaciation in south and central Sweden. The change from about 50–75 m to 100–200 m of annual ice‐front retreat may reflect the Younger Dryas/Preboreal transition. Clay‐stratigraph‐ically defined, the transition is dated at c. 10,740 varve years BP, with an error of +100 to ‐250 years. In the countings of ice layers in Greenland ice cores (GRIP and GISP‐2) the end of the Younger Dryas climatic event is 800–900 years older. However, a climatic amelioration after the cold part of the Younger Dryas and in early Preboreal should rapidly be reflected by for example chemical components and dust in Greenland ice cores, and by increasing δ13C content in tree rings. On the other hand, the start of a rapid retreat of the inland ice margin can be delayed by several centuries. This can explain at least a part of the discrepancy between the time‐scales.

Section: B O Mmentioning

confidence: 99%

Younger Dryas deglaciation at Mt. Billingen, and clay varve dating of the Younger Dryas/Preboreal transition

Strömberg

1994

“…l), new measurements have been made (Kristiansson 1982) and the earlier time scale (Nilsson 1968) has been extended by about 250 years. Recently, clay varve measurements have been made in order to connect local time scales in Blekinge (Ringberg 1971(Ringberg , 1979 and in the Kalmar area (Rudmark 1975) -see Ringberg Probably the same event is recorded biostr;itigraphicallv as ;I transition from cold to warm. At Hiigsby "C-datings are lacking.…”

Section: Checks Of the Earlier Revision (Jarnefors 1963)mentioning

confidence: 99%

Revision of the lateglacial Swedish varve chronology

Strömberg

1985

A survey of the revised lateglacial varve chronology is given. Almost all revisions are based on new, independent measurements not yet finished. Compared with the old time scale, the preliminary datings (calendar years ± a margin of error) of the ice margin retreat are ‘older’, mainly due to the fact that the postglacial varve chronology has been extended by 365 years. This implies that the so‐called zero year (sensu De Geer 1940: limit of late glacial and beginning of postglacial varve sedimentation). earlier estimated at 6,923 B.C. (Nilsson 1964), is now dated 7,288 B.C. According to the new time scale, deglaciation from Stockholm to the area of zero‐year formation in Indalsälven's valley lasted about 1,190 ± 40 years, compared with 1,073 years in De Geer's (1940) time scale or 1,092 in Jarnefors' (1963). Preliminary varve graph correlations, which are still very weak concerning the Fennoscandian moraine zone, indicate that the ice receded from Högsby, northwest of Kalmar at approximately 10,700+200−300 B.C. At localities just to the north of the Fennoscandian moraines, deglaciation started about 8,750+50−150 years B.C. according to the new varve measurements, and the ice front receded in southern Stockholm 8,470+40−140 B.C. Varve dating now gives older ages (calendar years) than 14C‐dating; about 200–400 years older regarding some ice margin positions in south Sweden.

“…The study area lies below 80 m above sea level and is characterised by north-northwest-south-southeast river valleys, often deep and narrow, which run from the northern area of uneven topography (generally above 30 m above sea level) through a wide coastal plain into the Blekinge archipelago. Till is the dominant Quaternary deposit in the area and according to Ringberg (1971) is composed mainly of archean bedrock, gneiss and granite. Red and grey porphyries originating from the north contribute to the till in proportions not exceeding 11%.…”

Section: Area Description and Samplingmentioning

confidence: 99%

“…The contribution by sedimentary rocks to the till is negligible, rarely exceeding 0.5% of the fine gravel fraction. Below the highest shore line, approximately 65 m above sea level (Ringberg 1971), the till is thin and usually follows the topography of the underlying bedrock, while above it can be much thicker (up to 10 m) and have an independent form. The texture of the till is usually sandy or slightly silty, with a clay content of between 5 and 15% (Ringberg 1971).…”

Section: Area Description and Samplingmentioning

confidence: 99%

“…Below the highest shore line, approximately 65 m above sea level (Ringberg 1971), the till is thin and usually follows the topography of the underlying bedrock, while above it can be much thicker (up to 10 m) and have an independent form. The texture of the till is usually sandy or slightly silty, with a clay content of between 5 and 15% (Ringberg 1971). Coarse glaciofluvial deposits are mainly restricted to large valleys, and finer deltaic deposits are most commonly found at the valley mouths.…”

Section: Area Description and Samplingmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic susceptibility of Late Weichselian deposits in southeastern Sweden

Björck

Dearing

Jönsson

1982

The magnetic suceptibility of Late Weichselian glacial, late‐glacial and post‐glacial deposits from Blekinge, southeast Sweden, has been measured. The susceptibility variations proved to be dependent upon the particle size distribution of the sample and the type of bedrock from which the deposit is derived. Comparison of susceptibility variations in the Baltic Ice Lake and lacustrine sediments with biological indicators of environmental change suggests that susceptibility can be a useful complement to studies aimed at identifying lake isolation, climatic change or changes in erosion within the catchment. The results also suggest that comparison of susceptibility versus fraction size curves can aid lithostratigraphic division of unconsolidated deposits.