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Early Holocene water level changes as recorded on the island of Senoren, eastern Blekinge, southeastern Sweden

Gichina, Boniface M. (1995) In Dissertations in Geology at Lund University
Department of Geology
Abstract
Popular scientific summary: This paper presents a study carried out in the fall of 1994 on Senoren, an island of the Karlskrona archipelago. Considering the aim of the study which was to record Early Holocene water level changes in the Baltic Sea, two bays, Sörevik and Norrevik on this island were chosen because they lie in the province of Blekinge in southeastern Sweden. The coastline of Blekinge is characterized by the fairly unique geological feature of being more or less parallel to the land uplift isobases (Berglund & Björck in press). This makes the area very suitable for shoreline studies, because large areas have experienced approximately the same amount of uplift since the last deglaciation, dated to approximately 12,600 14C years... (More)
Popular scientific summary: This paper presents a study carried out in the fall of 1994 on Senoren, an island of the Karlskrona archipelago. Considering the aim of the study which was to record Early Holocene water level changes in the Baltic Sea, two bays, Sörevik and Norrevik on this island were chosen because they lie in the province of Blekinge in southeastern Sweden. The coastline of Blekinge is characterized by the fairly unique geological feature of being more or less parallel to the land uplift isobases (Berglund & Björck in press). This makes the area very suitable for shoreline studies, because large areas have experienced approximately the same amount of uplift since the last deglaciation, dated to approximately 12,600 14C years BP (Björck & Möller 1987). The area has experienced a number of transgressions and regressions ever since. The present Baltic Sea has changed from the Baltic Ice Lake (12,600-10,200 BP) through the Yoldia Sea (10,200-9500 BP), the Ancylus Lake (9500-8000 BP) and finally the Littorina Sea (8000-5000 BP)
(e.g. Eronen 1988, Björck in press). Water level and other environmental changes throughout these geological episodes can be recorded by analyzing sea and lake sediments in this area.
In this study the sediments were cored with a Russian peat sampler in along a 550 m longitudinal section trending between Sörevik and Norrevik and along a 130 m transverse section at Sörevik. Geological mapping was done in the field to include non-organic deposits like till, sandy till and boulder rich till.
The oldest organic sediments collected in this study is a black drift peat which was dated to 9300±160 14C years BP. This drift peat represents the Yoldia Sea to the Ancylus Lake interphase. The clay gyttja and coarse detritus gyttja which follows respectively were deposited during the Ancylus transgression and the regression there after. Opening of the ocean connection took place about 8000 BP and caused the Littorina transgression during which time fine detritus gyttja and clayey gyttja were deposited. The younger strata namely sand and reed peat were deposited after the cease of Littorina transgression.
The results from magnetic, organic content and minerogenic content analysis have been used for the correlation of the cores, determination of the stratigraphy, and recording of water level changes in the area. (Less)
Abstract
Summary: This is an investigation of Early Holocene water level changes based on the sediments in two bays, Sörevik and Norrevik on Senoren, an island in the Karlskrona archipelago in eastern Blekinge southeastern Sweden. This area has experienced a number of transgressions and regressions since the last deglaciation at approximately 12,600 BP. The history of the Baltic is characterized by many dramatic water level changes, although most of them took place in Late Weichselian and Early Holocene times. Only relatively small and gradual changes have taken place during the last 9000 or 8000 years BP.
Land uplift and shore line regression along different parts of the Baltic coast line were very rapid immediately after the last deglaciation.... (More)
Summary: This is an investigation of Early Holocene water level changes based on the sediments in two bays, Sörevik and Norrevik on Senoren, an island in the Karlskrona archipelago in eastern Blekinge southeastern Sweden. This area has experienced a number of transgressions and regressions since the last deglaciation at approximately 12,600 BP. The history of the Baltic is characterized by many dramatic water level changes, although most of them took place in Late Weichselian and Early Holocene times. Only relatively small and gradual changes have taken place during the last 9000 or 8000 years BP.
Land uplift and shore line regression along different parts of the Baltic coast line were very rapid immediately after the last deglaciation. These large crustal deformations resulted in the closing and opening of the various connections or discharge channels from the Baltic to the ocean. These events, in turn were the reason for the drastic changes in the physical, chemical and biological environments of the Baltic during Late Weichselian and Early Holocene times and thus gave rise to the well known phases of development: Baltic Ice Lake (12,600-10,200 BP), Yoldia Sea (10,200-9500 BP), Ancylus Lake (9500-8000 BP) and Littorina Sea (8000-5000 BP). The vigorous isostatic rebound slowed down relatively rapidly between 8500 and 8000 BP. These phases have been followed by relatively small and gradual land uplift down to present (Eronen 1988, Björck in press).
The oldest organic sediments collected in Sörevik was a black drift peat which was dated 9300±160 14C years BP. This drift peat represents the Yoldia Sea to the Ancylus Lake interphase. This
drift gyttja is overlaid by clay gyttja which was deposited during the Ancylus transgression. The Ancylus Lake had no connection to the ocean and therefore it was a fresh water lake dammed above the sea level (Björck in press). This transgression came to an end when the rising water level reached the crest of the Darss Sill in the southwestern part of the Baltic. According to Kolp (1986) the water masses broke through this ridge and rapidly eroded a channel resulting in a 20 m drop of water level. This took place about 9000 BP and the Ancylus Lake was non-dammed until 8000 BP according to Björck (in press). The coarse detritus gyttja above the clay gyttja in Sörevik was deposited during this low water level stage, which probably lasted until the beginning of the Littorina transgression. The coarse detritus gyttja was dated to about 8200-8500 14C years BP.
Fine detritus gyttja was deposited above the coarse detritus gyttja during the Littorina transgression caused by the opening of the ocean connection. The transgression brought in salt water from the ocean according to earlier diatom studies (Berglund 1964) and brackish water plant (i.e. Zostera marina) identified in this study.
Probably several minor transgressions are recorded in the marine sediments of Sörevik (Berglund 1964), but these have not been possible to trace in detail in this study.
The stratigraphy at Norrevik is in agreement with that of Sörevik.
The methods applied in this study involve sediment description, analysis of organic content, coarse organic and minerogenic content and mineral magnetic analysis. (Less)
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author
Gichina, Boniface M.
supervisor
organization
year
type
H1 - Master's Degree (One Year)
subject
keywords
geography, geology, Early Holocene, water level change, Senoren island, Blekinge, Sweden
publication/series
Dissertations in Geology at Lund University
report number
65
funder
E.F.S. church
funder
Svenska Institutet
language
English
id
2369922
date added to LUP
2012-10-22 14:00:34
date last changed
2015-06-18 14:04:23
@misc{2369922,
  abstract     = {Summary: This is an investigation of Early Holocene water level changes based on the sediments in two bays, Sörevik and Norrevik on Senoren, an island in the Karlskrona archipelago in eastern Blekinge southeastern Sweden. This area has experienced a number of transgressions and regressions since the last deglaciation at approximately 12,600 BP. The history of the Baltic is characterized by many dramatic water level changes, although most of them took place in Late Weichselian and Early Holocene times. Only relatively small and gradual changes have taken place during the last 9000 or 8000 years BP.
Land uplift and shore line regression along different parts of the Baltic coast line were very rapid immediately after the last deglaciation. These large crustal deformations resulted in the closing and opening of the various connections or discharge channels from the Baltic to the ocean. These events, in turn were the reason for the drastic changes in the physical, chemical and biological environments of the Baltic during Late Weichselian and Early Holocene times and thus gave rise to the well known phases of development: Baltic Ice Lake (12,600-10,200 BP), Yoldia Sea (10,200-9500 BP), Ancylus Lake (9500-8000 BP) and Littorina Sea (8000-5000 BP). The vigorous isostatic rebound slowed down relatively rapidly between 8500 and 8000 BP. These phases have been followed by relatively small and gradual land uplift down to present (Eronen 1988, Björck in press).
The oldest organic sediments collected in Sörevik was a black drift peat which was dated 9300±160 14C years BP. This drift peat represents the Yoldia Sea to the Ancylus Lake interphase. This
drift gyttja is overlaid by clay gyttja which was deposited during the Ancylus transgression. The Ancylus Lake had no connection to the ocean and therefore it was a fresh water lake dammed above the sea level (Björck in press). This transgression came to an end when the rising water level reached the crest of the Darss Sill in the southwestern part of the Baltic. According to Kolp (1986) the water masses broke through this ridge and rapidly eroded a channel resulting in a 20 m drop of water level. This took place about 9000 BP and the Ancylus Lake was non-dammed until 8000 BP according to Björck (in press). The coarse detritus gyttja above the clay gyttja in Sörevik was deposited during this low water level stage, which probably lasted until the beginning of the Littorina transgression. The coarse detritus gyttja was dated to about 8200-8500 14C years BP.
Fine detritus gyttja was deposited above the coarse detritus gyttja during the Littorina transgression caused by the opening of the ocean connection. The transgression brought in salt water from the ocean according to earlier diatom studies (Berglund 1964) and brackish water plant (i.e. Zostera marina) identified in this study.
Probably several minor transgressions are recorded in the marine sediments of Sörevik (Berglund 1964), but these have not been possible to trace in detail in this study.
The stratigraphy at Norrevik is in agreement with that of Sörevik.
The methods applied in this study involve sediment description, analysis of organic content, coarse organic and minerogenic content and mineral magnetic analysis.},
  author       = {Gichina, Boniface M.},
  keyword      = {geography,geology,Early Holocene,water level change,Senoren island,Blekinge,Sweden},
  language     = {eng},
  note         = {Student Paper},
  series       = {Dissertations in Geology at Lund University},
  title        = {Early Holocene water level changes as recorded on the island of Senoren, eastern Blekinge, southeastern Sweden},
  year         = {1995},
}