Novel dating method for speleothems with microscopic fluorescent annual layers

Area of Science:

• Geochemistry
• Paleoclimatology
• Speleothem Science

Background:

• Terrestrial carbonate deposits, like stalagmites, possess banded structures valuable for paleoclimate reconstruction.
• Accurate absolute age dating is crucial for establishing environmental chronologies from these deposits.
• Existing dating methods can be challenging for young speleothem samples.

Purpose of the Study:

• To present a convenient and effective method for the absolute age dating of stalagmites.
• To explore the application of fluorescent annual bandings for dating young speleothems.
• To discuss optimal conditions for spectrofluorometric measurements of stalagmite bandings.

Main Methods:

• Utilized a microscopic spectrofluorometer with an XY-stage to measure fluorescent annual bandings in stalagmites.
• Employed personal computer analysis for objective counting of annual bands.
• Investigated seasonal variations in fulvic acid concentrations as the cause of banding.

Main Results:

• Demonstrated that fluorescent annual bandings in stalagmites can be objectively counted.
• Showcased the effectiveness of this method for dating young stalagmites where other techniques are difficult.
• Identified seasonal differences in fulvic acid concentrations in drip water as the cause of annual banding.

Conclusions:

• Spectrofluorometric measurement of fluorescent annual bandings provides a convenient dating method for stalagmites.
• This technique is particularly effective for determining the absolute age of young speleothem samples.
• The method facilitates the extraction of past environmental information from terrestrial carbonate deposits.