193 research outputs found
Editorial
No full textThis issue of Quaternary Geochronology is the last one where I am the Editor-in-Chief. Quaternary Geochronology(QG) was born during a conversation when Giff Miller, John Chappell and John Magee and I were sitting around a camp fire in the Simpson Desert in Australia. I took the idea to David Bowen, the Editor-in-Chief of Quaternary Science Reviews (QSR) and Peter Henn, the Production Manager of QSR at Pergamon Press. Both agreed that it was a good idea, however, rather than starting a new journal it was decided to have special issues in QSR. The first issue of Quaternary Geochronology was published in 1994 as QSR 13 (2). In the early 2000s, Jim Rose, then the Editor-in-Chief of QSR, suggested that QG should become a stand-alone-journal. I have to admit that I was quite reluctant to go alone. QSR had impact factors of more than 4, and I thought that QG would struggle to reach 1. Jim suggested to start with a special issue on Cosmogenic Isotopes, as these papers did well in QSR. This was brilliant advice, as QG published some of the most influential papers on this topic over the years. The dreaded impact factor of less than 1 never materialised. QG did much better. The factor has been oscillating widely in a range between 2 and 4, which is typical for a relatively small journal.Full Tex
Editorial-LED 2017
No full textThis special Quaternary Geochronology volume of the Proceedings of the 15th International Conference on Luminescence and Electron Spin Resonance Dating is dedicated to the memory of Martin Aitken, one of the great pioneers in luminescence dating, who passed away on 13 June 2017, aged 95. We are pleased that Ann Wintle, herself the great Dame of luminescence dating, wrote a fitting tribute to Martin, which follows this editorial.Full Tex
Laser ablation depth profiling of U-series and Sr isotopes in human fossils
No full textWe have explored laser depth profiling to obtain data sets for U-series as well as Sr analyses. Laser probing with an 81 gm spot size allows for the exploration of low uranium domains of up to 400 gm below the outer surface in tooth enamel. These low U domains will contain Sr isotope compositions of the individual, that are least affected by diagenetic Sr overprints. The small holes drilled for U surveying are not visible to the naked eye. Using larger spot sizes of around 233 gm, laser drilling can be used to obtain reliable U-series isotope data to a depth of approximately 1000 gm in enamel and around 1300 gm in bone. Furthermore, meaningful Sr-87/Sr-86 isotope data can also be obtained with this spot size. Using our sampling strategy, the overall damage to a human tooth is minute, as demonstrated on a Neanderthal tooth from Moula-Guercy. We expect that laser ablation depth profiling will become routine for gaining insights into the age of human fossils and the migrations of ancient humans. (C) 2013 Elsevier Ltd. All rights reserved
ESR thermochronometry of Al and Ti centres in quartz: A case study of the Fergusons Hill-1 borehole from the Otway Basin, Australia
No full textElectron spin resonance (ESR) thermochronometry can in principle be used for reconstructing thermal histories of the upper ~ 2 km of the Earth's crust. We have analysed the ESR ages of Al and Ti centres in quartz from Fergusons Hill-1 borehole in the Otway Basin, Australia, to assess their trap parameters under natural conditions. The apparent ESR ages of both centres decrease with increasing temperature (42.9-56.2°C)). A feasible sequential quadratic programming optimisation algorithm was applied to determine the optimal trap parameters based on the assumption of first order kinetics and thermally static condition. The estimated activation energy and frequency factor of the Al centre in quartz were 1.5 eV and 1.11011 s−1, respectively. This was in excellent agreement with a re-analysis of samples from the Eldzhurtinskiy granite, a highly dynamic geologic system, for which we obtained 1.5 eV and 1.01011 s−1. The trap parameters of the Ti centre could not be obtained from first order kinetics for the Fergusons Hill samples, but the samples from the Eldzhurtinskiy yielded 1.6 eV and 2.41011 s−1. Further studies on trap kinetics under better controlled laboratory conditions are required for ESR thermochronometry.This work was funded by an ANU-CSC Scholarship to FF. The authors
are grateful to Prof. Barry Kohn for providing FH1 borehole samples and
valuable discussions. We acknowledge Dr. P. Morthekai for helpful
discussion on kinetic model and Mr. Shijie Shu for coding the model. We
also thank Mr. Shane Paxton for sample preparation, Prof. Shenghua Li
and Dr. Shuangli Tang for their help with HF etching, Dr. Mathieu Duval
for Gamma irradiation, Ms. Debbie Howard for her help with the X-ray
dose rate calibration and irradiation. Prof. Ian Williams is thanked for
his comments and corrections. The authors are grateful to two anonymous reviewers for their constructive comments
Confirmation of a late middle Pleistocene age for the Omo Kibish 1 cranium by direct uranium-series dating
No full textWhile it is generally accepted that modern humans evolved in Africa, the specific physical evidence for that origin remains disputed. The modern-looking Omo 1 skeleton, discovered in the Kibish region of Ethiopia in 1967, was controversially dated at ?130 ka (thousands of years ago) by U-series dating on associated Mollusca, and it was not until 2005 that Ar–Ar dating on associated feldspar crystals in pumice clasts provided evidence for an even older age of ?195 ka. However, questions continue to be raised about the age and stratigraphic position of this crucial fossil specimen. Here we present direct U-series determinations on the Omo 1 cranium. In spite of significant methodological complications, which are discussed in detail, the results indicate that the human remains do not belong to a later intrusive burial and are the earliest representative of anatomically modern humans. Given the more archaic morphology shown by the apparently contemporaneous Omo 2 calvaria, we suggest that direct U-series dating is applied to this fossil as well, to confirm its age in relation to Omo 1
The DATA program for the calculation of ESR age estimates on tooth enamel
No full textThe supplementary ZIP file of this paper contains the DATA program, which can be used for ESR age calculations of tooth enamel. This paper outlines the use and limitations of this program
ESR dose estimation on fossil tooth enamel by fitting the natural spectrum into the irradiated spectra
No full textFitting the natural, derivative ESR spectrum into the irradiated spectra has been tested as a method for the estimation of the dose value of powdered fossil tooth enamel, which is the basis of ESR dating. It was found that this method has significant advantages over traditional peak-to-peak assessments, dose versus magnetic field plots as well as deconvolution of the absorption spectrum, because it is less dependent on a range of interferences. Furthermore, the fitting procedure is computationally trivial and the dose results are not dependent on random noise. It is concluded that fitting the natural spectrum ought to provide the most reliable dose estimations for most fossil teeth which have been exposed to doses of more than 5-10 Gy
- …
