U-Th isotope systematics from the Soreq cave, Israel and climatic correlations
- Permanent Link:
- U-Th isotope systematics from the Soreq cave, Israel and climatic correlations
- Series Title:
- Earth and planetary science letters
- Kaufman, A.
- Publication Date:
- March 30, 1998
- Physical Description:
- 1 online resource
- Subjects / Keywords:
- Uranium-thorium dating ( lcsh )
Climate change ( lcsh )
- serial ( sobekcm )
- Asia -- Israel
- Precise230Th234U ages were obtained on thirty-one growth laminae in speleothem samples which are self-consistent with the detailed layer stratigraphy. Samples with low232Th238U ratios give ages with analytical uncertainties of 40 years at 2 ky and 1000 years at 90 ky. Some growth zones with high but variable232Th238U were dated by intermal isochrons. This permits the determination of the initial230Th232Th assuming equilibrium of232Th and238U series in the source of the high232Th component. This shows initial (230Th232Th) (in activity units) of from 1.3 to 2.9. The calculated atomic ratios of232Th238U for the high232Th component range from 1.08 to 2.4 which is well below the average crustal value. Speleothem materials with high232Th238U are found to exhibit clear correlations of232Th with Si, Al and Fe, while238U correlates with Sr and Ba. Analyses of Soreq cave drip waters show that the particulates in the waters have high232Th concentrations and a232Th238U ratio much lower than that found in the high232Th component in speleothems but with230Th232Th) = 1.0 to 2.4. We infer that the trapped high-Th component in speleothems is from particulate matter in water with a large concentration of adsorbed U and not simply from detrital material. The speleothems have only small234U excess The initial234U238U)0 show a range of 1.02 to 1.14 that was found to correlate with age over the past 25 ky. The youngest samples have values in the same range as the modern drip waters. There appears to be a correlation of234U238U)0 with the Î´18O values. There is a drop of Î´18O in the time interval 20 to 15 ky which then remains relatively constant to recent times. As the high Î´18O values have been related to rainfall and associated climatic conditions, we suggest that the234U238U in the speleothem reflects the effects of rainfall and soil weathering conditions on drip-water composition and may provide a proxy for climate change.
- Original Version:
- Volume 156, Issues 3-4
- Source Institution:
- University of South Florida
- Holding Location:
- University of South Florida
- Rights Management:
- All applicable rights reserved by the source institution and holding location.
- Resource Identifier:
- K26-05453 ( USFLDC DOI )
k26.5453 ( USFLDC Handle )
Download Options [CUSTOM IMAGE]close
No images are available for this item.
Cras ut cursus ante, a fringilla nunc. Mauris lorem nunc, cursus sit amet enim ac, vehicula vestibulum mi. Mauris viverra nisl vel enim faucibus porta. Praesent sit amet ornare diam, non finibus nulla.
Cras efficitur magna et sapien varius, luctus ullamcorper dolor convallis. Orci varius natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Fusce sit amet justo ut erat laoreet congue sed a ante.
Phasellus ornare in augue eu imperdiet. Donec malesuada sapien ante, at vehicula orci tempor molestie. Proin vitae urna elit. Pellentesque vitae nisi et diam euismod malesuada aliquet non erat.
Nunc fringilla dolor ut dictum placerat. Proin ac neque rutrum, consectetur ligula id, laoreet ligula. Nulla lorem massa, consectetur vitae consequat in, lobortis at dolor. Nunc sed leo odio.