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| Titel |
Temperature and precipitation records from stalagmites grown under disequilibrium conditions: A model approach. |
| VerfasserIn |
C. Mühlinghaus, D. Scholz, A. Mangini |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023461
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| Zusammenfassung |
| To reconstruct past variations in Earth’s climate, a variety of climate archives are studied.
During the last decades stalagmites came into focus due to their long, continuous growth and
absolute dating techniques. In this study a numerical model was developed, which
calculates variations in temperature and precipitation during the growth period of
stalagmites grown under isotopic disequilibrium conditions using the isotope profiles both
along the growth axis and individual growth layers as well as the growth depth
relation.
The model is based on the inversion and combination of existing models (Dreybrodt
1999, Kaufmann et al. 2004, Mühlinghaus et al. 2007, Scholz et al. 2008, Mühlinghaus et al.
2008b) and incorporates important parameters describing the cave and the overlying soil.
Beside the dependence on temperature and water supply it depends on the isotopic
composition of the drip water, the pCO2 pressure of the soil and the cave atmosphere as well
as on the mixing coefficient, which describes mixing between the impinging drop and
the existing solution layer. To determine the characteristics of temperature and
precipitation, in a first step all other parameters are assumed to remain constant over
the whole growth period to simplify calculations. This allows to run the model
with only two input variables: the isotopic composition δ13C of the drip water and
a temperature information at any point of time during the growth period of the
stalagmite (e.g. the recent cave temperature). All other parameters are determined by the
model.
The CSM (Combined Stalagmite Model, Mühlinghaus et al. 2008a) was applied to three
stalagmites from the Marcelo Arévalo cave in Southern Patagonia, Chile (Schimpf 2005,
Kilian et al. 2006, Schimpf et al. in prep). These stalagmites grew in a small cave next to each
other during the last 4500 years. However, their isotopic profiles along the growth axis show
different kinetic influences. Despite these conditions, the temperature records of the
stalagmites, which were obtained by three independent model runs, follow a general trend
over the whole growth period and reveal good correlations within certain time-frames. This is
a promising first result of the model. In addition the calculated temperatures are
robust to small variations of the input variables, giving confidence in the algorithm
of the model and for further temperature reconstructions from kinetically grown
stalagmites.
Literature
Dreybrodt, W., 1999. Chemical kinetics, speleothem growth and climate. Boreas 28, 347
-356.
Kaufmann, G., Dreybrodt, W. , 2004. Stalagmite growth and palaeo-climate: an inverse
approach. Earth and Planetary Science Letters 224, 529 - 545.
Kilian, R., Biester, H., Behrmann, J., Baeza, O., Fesq-Martin, M., Hohner, M., Schimpf,
D., Friedmann, A., Mangini, A., 2006: Millennium-scale volcanic impact on a superhumid
and pristine ecosystem, Geology, 34: 609 – 612.
Mühlinghaus, C., Scholz, D., Mangini, A., 2007. Modelling stalagmite growth and δ13C
as a function of drip interval and temperature. Geochimica et Cosmochimica Acta 71, 2780 -
2790.
Mühlinghaus, C.; Scholz, D., Mangini, A., 2008a. Temperature and precipitation records
from stalagmites grown under disequilibrium conditions: A first approach. Advances in
speleothem research, PAGES News, 16
Mühlinghaus, C., Scholz, D., Mangini, A., 2008b. Fractionation of stable isotopes in
stalagmites under disequilibrium conditions. Geochimica et Cosmochimica Acta,
Submitted.
Schimpf, D., 2005. Datierung und Interpretation der Kohlenstoff- und Sauerstoffsotopie
zweier holozäner Stalagmiten aus dem Süden Chiles (Patagonien). Master’s thesis,
Ruprecht-Karls- University, Heidelberg.
Schimpf, D., Kilian, R., Mangini, A., Spötl, C., Kronz, A., in prep. Evaluation of
chemical, isotopic and detrital proxies of a high-resolution stalagmite record from the
southernmost Chilean Andes (53Ë S)
Scholz, D., Mühlinghaus, C., Mangini, A., 2008. Modelling the evolution of δ13C and
δ18O in the solution layer on stalagmite surfaces. Geochimica et Cosmochimica Acta,
Submitted. |
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