LA-ICPMS for In Situ U-Th Dating of Holocene Stalagmites
Journal
Analytical Chemistry
Journal Volume
96
Journal Issue
31
Start Page
12640
End Page
12648
ISSN
0003-2700
1520-6882
Date Issued
2024-07-23
Author(s)
Abstract
Here, we present an in situ U-Th dating approach of carbonate speleothems using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) with a detection efficiency of 1-2%. By online addition of a 229Th-233U-236U isotope triple spike to the laser-generated aerosol, instrumental mass discrimination and U/Th elemental fractionation could be monitored and corrected. With this approach, the 234U/238U and 230Th/238U activity ratios of a flowstone sample in secular equilibrium could be accurately reproduced as unity with two-sigma uncertainties ±0.053 and ±0.050, respectively. The method was used for the determination of the formation ages of individual layers in natural stalagmites ranging between 210 and 1 thousand years ago (ka). The determined ages corresponded well with those obtained using conventional solution multi collector-ICPMS techniques after isotope separation. Particularly, Holocene stalagmites, as young as 1 ka, could be accurately dated with 2 standard error of ±76 years. This developed microdomain U-Th dating approach thus can be applicable for diverse research areas, such as paleoclimatology, oceanography, geomagnetism, and archeology.
Subjects
Binary alloys
Geomagnetism
Inductively coupled plasma mass spectrometry
Laser ablation
Mass spectrometers
Thorium alloys
Uranium alloys
SDGs
Publisher
American Chemical Society (ACS)
Type
journal article