| PALEOLIMNOLOGY |
A Late Quaternary diatom record of tropical climatic history from Lake Titicaca (Peru and Bolivia)
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Fritz, S.C., P.A. Baker, G.O. Seltzer. 2003. A Late Quaternary diatom record of tropical climatic history from Lake Titicaca
(Peru and Bolivia). Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 194, Issues 1-3, pp. 139-164, 15 May 2003
| Data Coverage |
North: -16.13 * South: -16.13 |
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West: -69.25 * East: -69.25 |
Start Year: 31000 cal yr BP * End Year: 0 cal yr BP
Data: Please Cite Data Contributors!
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Summary: A composite high-resolution diatom stratigraphy from three piston cores and one box-core in the deep sub-basin of Lake Titicaca
reveals large moisture variations during the past 30 kyr in the Altiplano region. Diatom sequences indicate orbital and
millennial-scale variability in water level and salinity. The pelagic freshwater diatom species Cyclotella andina and Cyclotella
stelligera dominate Glacial-age sediments, suggesting that the lake was above its present outlet. Generally, wet conditions
continued until 11000 cal yr BP, as indicated by high percentages of freshwater planktonic diatoms. Large pulses of benthic
diatom species between about 11000 and 10000 cal yr BP suggest brief intervals of large-amplitude declines in lake level.
During the early Holocene (10000-8500 cal yr BP), a freshwater diatom assemblage suggests overflowing conditions. Pelagic
freshwater diatoms are replaced ca. 8500 cal yr BP by the salinity-indifferent species Cyclotella meneghiniana and by benthic
taxa, indicating the beginning of lake regression. During the mid-Holocene (6000-3500 cal yr BP), the abundance of the saline
taxon Chaetoceros muelleri, coupled with high abundances of epiphytic and epipelic diatoms, indicates maximum salinity and
lowest lake levels in the entire 30000 year record. Lake transgression began ca. 4000 cal yr BP, and the lake achieved modern
levels by about 1500 cal yr BP. These water-level changes imply changes in effective moisture, most likely resulting from
large precipitation changes. Precipitation was high throughout the Last Glacial Maximum (21000-18000 cal yr BP), likely
due to an enhanced South American Summer Monsoon during peak summer insolation in the Southern Hemisphere. In contrast,
the mid-Holocene transition was dryer than today in association with an austral summer insolation minimum and the subsequent
weakening of the summer monsoon.
More Info on Paleolimnology |
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Complete XML Record: noaa-lake-5485
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