Projekt/Project |
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Stalagmite growth and palaeo-climate |
Project leader: |
Georg Kaufmann |
Project members: |
Doushko Romanov, FU Berlin, Germany |
Wolfgang Dreybrodt, Bremen, Germany |
Institutions involved: |
Institut für geologische Wissenschaften, FU Berlin, Germany |
Institut für experimentelle Physik, University Bremen, Germany |
Keywords: |
Equilibrium chemistry; stalagmite growth; palaeo-climate; ice ages |
Start: |
2006 |
Funding: |
FU Berlin |
Summary: |
The growth of stalagmites is controlled by climatic conditions such as temperature, vegetational
cover, and precipitation. Hence, a stalagmite stratigraphy reflects fluctuations of palaeo-climate
conditions on various timescales, from annual variations to ice-age cycles.
Often, variations of stable isotopes, e.g.\ oxygen, measured along the growth axis of a stalagmite
are used to reconstruct palaeo-temperature variability. However, no attempt has been made to infer palaeo-climate
fluctuations from the stratigraphy itself.
We describe the complicated growth of a stalagmite with a simple mathematical model, in which both the
growth rate and the equilibrium diameter of stalagmites are functions of palaeo-climate
variables. Hence, inverting a given stalagmite stratigraphy in terms of growth rate and
equilibrium diameter can in principle recover the palaeo-climate signal.
The strongly non-linear dependence of these two geometrical parameters, however, limits the
success of a formal inversion of stratigraphical data.
In this project, we explore the resolving power of both growth rate and equilibrium diameter
data for the palaeo-climate signals temperature, carbon-dioxide concentration, and precipitation.
We use numerically generated stalagmite stratigraphies as observational data, thus we know
beforehand the palaeo-climate signal contained in the stratigraphic record.
Our results indicate that both variations in carbon-dioxide concentrations (as a proxy of soil cover)
and drip interval (as a proxy of precipitation) can be recovered from the stratigraphy.
However, temperature variations are poorly resolved.
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