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Closed Access item A high-resolution study of diatom oxygen isotopes in a Late Pleistocene to Early Holocene laminated record from Lake Chungará (Andean Altiplano, Northern Chile)
Leng, Melanie J.
Barker, Philips A.
Pueyo Mur, Juan José
Moreno Caballud, Ana
Valero-Garcés, Blas L.
Sloane, Hilary J.
|Citation:||Geochimica et Cosmochimica Acta 71(15) Supl. 1: A398 (2007)|
|Abstract:||Lake Chungará (18º15' S, 69º09’ W, 4520 m a.s.l. 22.5
Km2 and 40 m of water depth) is a hydrologically closed lake
located on the Andean Altiplano. The lake is polymictic, meso
to eutrophic and currently primary productivity is mainly
governed by diatoms and chlorophyceans.
Three laminated intervals were selected for detailed
petrographical studies as well as a high resolution diatom
oxygen isotope analysis. These laminated sediments are made
up of bands of white and dark mm-thick laminae and thin
layers of diatomaceous ooze with variable carbonates and
amorphous organic matter.
Assuming no significant changes in the isotopic
compositions of the water sources and according to the diatom
microstratigraphy of the laminae, two alternating
environmental scenarios can be described. Lower-level water
conditions are interpreted during the intervals of white
laminae deposition (high values of delta18O), since those
conditions are more favourable for the massive short-term
deposition of monospecific large centric diatom blooms and
delta18O enrichment. These white laminae are probably the result
of exceptional periods of mixing of the shallow water column
during lowstands, which recycle nutrients from the
hypolimnion. Lower delta18O values, and therefore deeper water
conditions, are more favourable for the development of dark
laminae (normal annual cycle of the lake with alternating
phases of stratification and mixing).
These conditions would lead to the development of a
complex diatom community, among other algal groups.|
|Description:||1 página.-- Awards Ceremony Speeches and Abstract of the 17th Annual V. M. Goldschmidt Conference Cologne, Germany August 2007, 17th Annual V.M. Goldschmidt Conference Cologne, Germany August 2007.|
|Publisher version (URL):||http://dx.doi.org/10.1016/j.gca.2007.06.017|
|Appears in Collections:||(ICTJA) Artículos|
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