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PALEOLIMNOLOGY

A magnetic mineral record of Late Quaternary tropical climate variability from Lake Bosumtwi, Ghana
Map of data site
Peck, J.A., R.R. Green, T. Shanahan, J.W. King, J.T. Overpeck, C.A. Scholz. 2004. A magnetic mineral record of Late Quaternary tropical climate variability from Lake Bosumtwi, Ghana. Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 215, pp. 37- 57
Data Coverage North: 6.5 * South: 6.5
West: -1.4167 * East: -1.4167
Altitude: 99 m

Start Year: 26655 cal yr BP * End Year: 152 cal yr BP

Data:     Please Cite Data Contributors!
  Text: africa/bosumtwi2004.txt
  Excel: africa/bosumtwi2004.xls

Summary:

We report magnetic hysteresis results from sediment cores obtained from Lake Bosumtwi, Ghana. As a hydrologically closed basin, the water budget of Lake Bosumtwi is extremely sensitive to changes in the precipitation/ evapotranspiration balance. Lake Bosumtwi lies in the path of the seasonal migration of the intertropical convergence zone (ITCZ); hence, the lake is ideally situated to study monsoon variability in West Africa. Five distinctive magnetic mineral zones (A-E) were identified in the 11-m-long sediment cores that span the last 26,000 calendar years. Prior to 12 calendar (cal) ka, low concentrations of multidomain, high-coercivity magnetic minerals are present. Three prominent shifts towards very high concentrations of high-coercivity iron sulfide (greigite) magnetic minerals are centered at 12,470, 17,290, and 22,600 calendar years during the last glacial period (magnetic zones D1-3). Between 12 and 3.2 cal ka, there is an abrupt shift to moderately high concentrations of mixed multidomain and single-domain, low-coercivity minerals and an organic-rich sapropel lithology. Since 3.2 cal ka, the magnetic mineral parameters reveal a shift to increased amounts of high-coercivity magnetic minerals.
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noaa-lake-5454  (Last Revised: 2009-02-11 )

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