Roeser, Patricia A; Franz, Sven-Oliver; Litt, Thomas (2016): Carbonates and selected geochemistry composition for sediments from Lake Iznik for the past 31 ka cal BP [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.863235, Supplement to: Roeser, Patricia A; Franz, Sven-Oliver; Litt, Thomas; Ariztegui, Daniel (2016): Aragonite and calcite preservation in sediments from Lake Iznik related to bottom lake oxygenation and water column depth. Sedimentology, 63(7), 2253-2277, https://doi.org/10.1111/sed.12306
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Abstract:
This study examines the forcing mechanisms driving long-term carbonate accumulation and preservation in lacustrine sediments in Lake Iznik (northwestern Turkey) since the last glacial. Currently, carbonates precipitate during summer from the alkaline water column, and the sediments preserve aragonite and calcite. Based on X-ray diffraction data, carbonate accumulation has changed significantly and striking reversals in the abundance of the two carbonate polymorphs have occurred on a decadal time scale, during the last 31 ka cal BP. Different lines of evidence, such as grain size, organic matter and redox sensitive elements, indicate that reversals in carbonate polymorph abundance arise due to physical changes in the lacustrine setting, for example, water column depth and lake mixing. The aragonite concentrations are remarkably sensitive to climate, and exhibit millennial-scale oscillations. Extending observations from modern lakes, the Iznik record shows that the aerobic decomposition of organic matter and sulphate reduction are also substantial factors in carbonate preservation over long time periods. Lower lake levels favour aragonite precipitation from supersaturated waters. Prolonged periods of stratification and consequently enhanced sulphate reduction favour aragonite preservation. In contrast, prolonged or repeated exposure of the sediment-water interface to oxygen results in in situ aerobic organic matter decomposition, eventually leading to carbonate dissolution. Notably, the Iznik sediment profile raises the hypothesis that different states of lacustrine mixing lead to selective preservation of different carbonate polymorphs. Thus, a change in the entire lake water chemistry is not strictly necessary to favour the preservation of one polymorph over another.
Coverage:
Latitude: 40.433300 * Longitude: 29.541700
Minimum Elevation: -50.0 m * Maximum Elevation: -50.0 m
Event(s):
IZN09/LC2+LC3 * Latitude: 40.433300 * Longitude: 29.541700 * Elevation: -50.0 m * Recovery: 45 m * Location: Turkey * Method/Device: Composite Core (COMPCORE) * Comment: Core IZN09/LC2: 14 meters piston core in succesive 2 meter sections at (40° 26.57' N, 29° 32.35' E), 50 meter water depth
Core IZN09/LC3: 14 meters piston core in succesive 2 meter sections at (40° 26.92' N, 29° 32.61' E), 50 meters water depth
Core IZN09/LC3: 14 meters piston core in succesive 2 meter sections at (40° 26.92' N, 29° 32.61' E), 50 meters water depth
Parameter(s):
# | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
---|---|---|---|---|---|---|
1 | Sample code/label | Sample label | Roeser, Patricia A | sample id from the geochemistry laboratory of uni bonn | ||
2 | Depth, composite | Depth comp | mcd | Roeser, Patricia A | Intercore correlation | depth given in meters of composite depth. Details on the composite profile see Roeser et al. 2012 |
3 | AGE | Age | ka BP | Roeser, Patricia A | Age, calibrated | Geocode – ka cal BP |
4 | Calcite | Cal | % | Roeser, Patricia A | weight % | |
5 | Calcite, standard deviation | Cal std dev | ± | Roeser, Patricia A | ||
6 | Aragonite | Arg | % | Roeser, Patricia A | weight % | |
7 | Aragonite, standard deviation | Arg std dev | ± | Roeser, Patricia A | ||
8 | Calcite, lattice parameter a | Calcite a | Å | Roeser, Patricia A | Latice parameters for Calcite concentrations smaller than 2% are not given | |
9 | Standard deviation | Std dev | ± | Roeser, Patricia A | Calcite a | |
10 | Calcite, lattice parameter c | Calcite c | Å | Roeser, Patricia A | Latice parameters for Calcite concentrations smaller than 2% are not given | |
11 | Standard deviation | Std dev | ± | Roeser, Patricia A | Calcite c | |
12 | Manganese | Mn | % | Roeser, Patricia A | ||
13 | Manganese | Mn | % | Roeser, Patricia A | <63 µm, concentrations for the fraction smaller than 63 micron were obtained only for unit IV | |
14 | Iron | Fe | % | Roeser, Patricia A | <63 µm, concentrations for the fraction smaller than 63 micron were obtained only for unit IV | |
15 | Carbon, organic, total | TOC | % | Roeser, Patricia A | ||
16 | Nitrogen, total | TN | % | Roeser, Patricia A |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
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