Annually laminated sequences in the internal structure of some Belgian stalagmites -- Importance for paleoclimatology
- Univ. de Paris-Sud, Orsay (France). Lab. d`Hydrologie et de Geochimie Isotopique
- Faculte Polytechnique de Mons (Belgium). Centre d`Etude et de Recherches Appliquees au Karst
Fifteen stalagmites from four caves and one sealed tunnel in southern Belgium are composed of alternations of annually deposited white-porous and dark-compact laminae. This is demonstrated by comparing the number of laminae with the local history of the site for modern stalagmites and with radioisotopic ages for Late Glacial and Holocene stalagmites. Annual cyclicity in the internal structure of these speleothems is explained by the highly seasonal variations of the water excess, which influences underground water flow. Comparison between climatic data and modern stalagmites of a closed tunnel shows that growth laminae can record climatic variations: (1) there is a good correlation (R = 0.84) between lamina thickness in a stalagmite and water excess; (2) during years with a high water excess, dark-compact laminae are more developed, which makes the speleothem darker. Vertical successions of several laminae represent microsequences that may have recorded climatic variations with a time resolution of 1/2 year. In a Late Glacial stalagmite, successive laminae microsequences form very regular cycles of 11 years separated by a thick dark-compact lamina. It is supported that, as for modern stalagmites, the thick dark-compact lamina corresponds to a period of high water excess. Hence, this 11-year cycle may reflect a climatic cycle.
- OSTI ID:
- 207882
- Journal Information:
- Journal of Sedimentary Research, Section A: Sedimentary Petrology and Processes, Vol. 66, Issue 1; Other Information: PBD: Jan 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Final Technical Report for "High-resolution temporal variations in groundwater chemistry: Tracing the links between climate, hydrology, and element mobility in the vadose zone"
Past fires and post-fire impacts reconstructed from a southwest Australian stalagmite