Marine Geology Data
Univ. of Minnesota, Large Lakes Observatory
Lake Victoria Cruise V95 Cores
Biogenic Silica and Carbon 14 Age Dates
NGDC Data Set G02885
World Data Center for Geophysics & Marine Geology, Boulder
NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THESE DATA
SUMMARY
Biogenic Silica Data and 14C dates from Lake Victoria Sediments
The LLO operates in conjunction with the Limnological Research Center (LRC) in
working towards fulfilling the objectives of the International Decade for the
East African Lakes (IDEAL) to study the East African Lakes. The Lake Victoria
project is funded by NSF. Like Lake Victoria, extensive work is being
continued on Lake Malawi, Lake Turkana, and Lake Edward. In addition to the
East African lakes, the LLO is working on Lake Issyk Kul', Lake Nicaragua, and Lake Superior.
SUMMARY:
The Biogenic Silica Data file contains data for 5 cores taken from various
sites in Lake Victoria. The data include ship, coring date, water depth,
latitude/longitude, sampling device, sampled interval, % biogenic silica, and
14C dates. Cores were sampled at 10 cm intervals for biogenic silica analysis.
Samples taken for 14C dating were prepared at the LRC Laboratory and sent to
an outside AMS Facility for analysis. Pollen, charcoal, and plant
macrofossils were dated.
Method for Biogenic Silica Analysis:
Biogenic Silica analysis was done using a timed, wet extraction technique
adapted from D. J. DeMaster (1979). The analysis was done using 0.5 M NaOH at
85 0C.
These data were produced by the:
Large Lakes Observatory (LLO)
University of Minnesota, Duluth
213 Research Laboratory Building
2205 East 5th Street
Duluth, MN 55812-2401
email: tcj@d.umn.edu
URL: http://www.d.umn.edu/llo/
Related References:
DeMaster, D.J. (1979) , The Marine Budgets of Silica and 32Si. Ph. D. Thesis,
Yale University. pp 246-264.
Johnson, T. C., C. A. Scholz, M. R. Talbot, K. Kelts, R. D. Ricketts, G.
Ngobi, K. Beuning, I. Ssemmanda and J. McGill, 1996. Late Pleistocene
desiccation of Lake Victoria and rapid evolution of cichlid fishes.
Science, v.273, p. 1091-1093...
Beuning, K., K. Kelts and T. C. Johnson, in press. Paleohydrology of Lake
Victoria, East Africa inferred from 18O/16O ratios in sediment cellulose.
Geology.
Johnson, T. C., Y. Chan, K. Beuning, K. Kelts, G. Ngobi and D. Verschuren,
in press. Biogenic silica profiles in Holocene cores from Lake Victoria:
implications for lake level history and initiation of the Victoria Nile.
In:
Lehman, J. T. (Editor), Environmental Change and Response in East African
Lakes. Kluwer Press, Amsterdam.
Verschuren, D., D. N. Edgington, H. J. Kling and T. C. Johnson, in press.
The eutrophication of Lake Victoria: sedimentary signals at offshore
stations. Journal of Gt. Lakes Research.
Scholz, C. A., T. C. Johnson, P. Cattaneo, H. Malinga and S. Shana, in
press. Initial results of 1995 IDEAL seismic reflection survey of Lake
Victoria, Uganda and Tanzania. In: Lehman, J. T. (Editor),
Environmental Change and Response in East African Lakes. Kluwer Press,
Amsterdam.
SEARCHABLE DATA INVENTORY
NGDC/WDC GMG, Boulder archives a wide variety of digital marine geology data collections, paper reports, microfilm, etc. containing sediment and hardrock data. Many of the digital files are available for direct download. Sample-by-sample inventory information for all data, regardless of format available from NGDC are fully searchable through the marine geology inventory (GEOLIN).
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