Notice “Alpha-recoil track dating: problems and prospects”
Please be aware that pubs. During this time, you may not be able to log-in to access your subscribed content, purchase single articles, or modify your e-Alert preferences. We appreciate your patience as we continue to improve the ACS Publications platform. These metrics are regularly updated to reflect usage leading up to the last few days.
Key words: U/Th dating, speleothems, U-leaching, paleoclimate. Parole chiave: into water by α-recoil mechanisms and requires sub- stantial Th mobility in.
Uranium-thorium dating potential of the marine bivalve Lithophaga lithophaga
for gross alpha-particle activity, excluding radon and uranium, of 15 pCi/L in public of the same collected samples at a later date and consequent alpha counting However, due to alpha-recoil process, Ra/Ra activity ratios of over.
Romer, R. Include files Advanced Search Browse. View item. Genre : Journal Article. Files show Files. Locators show.
Fossil alpha-particle recoil tracks: a new method of age determination.
Grant-in-Aid for Challenging Exploratory Research. The number of fission tracks FT is counted under an optical microscope after etching. However, as FT density per unit area rises, it becomes difficult to count the number of tracks because tracks overlap one another and are unable to be readily distinguished.
Use of thin collodion films to prevent recoil-ion contamination of alpha-spectrometry detectors. Journal of Radioanalytical and Nuclear.
Always quote above citation when using data! You can download the citation in several formats below. Radiocarbon and uranium-thorium dating results are presented from a genus of calcitic Antarctic cold-water octocorals family Coralliidae , which were collected from the Marie Byrd Seamounts in the Amundsen Sea Pacific sector of the Southern Ocean and which to date have not been investigated geochemically.
Octocoral radiocarbon ages on living corals are in excellent agreement with modern ambient deep-water D14C, while multiple samples of individual fossil coral specimens yielded reproducible radiocarbon ages. Provided that local radiocarbon reservoir ages can be derived for a given time, fossil Amundsen Sea octocorals should be reliably dateable by means of radiocarbon.
In contrast to the encouraging radiocarbon findings, the uranium-series data are more difficult to interpret. The uranium concentration of these calcitic octocorals is an order of magnitude lower than in the aragonitic hexacorals that are conventionally used for geochronological investigations. While modern and Late Holocene octocorals yield initial dU in good agreement with modern seawater, our results reveal preferential inward diffusion of dissolved alpha-recoiled U and its impact on fossil coral dU.
Besides alpha-recoil related U diffusion, high-resolution sampling of two fossil octocorals further demonstrates that diagenetic uranium mobility has offset apparent coral U-series ages.
Annealing behavior of alpha recoil tracks in phlogopite
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Yuan and R. Ketcham and S. Gao and J.
Similarly, experimental chemical etching of alpha-recoil tracks (Figure 4) caused by the radioactive decay of U and Th (e.g., in alpha-recoil track dating studies of.
Abstract Radiocarbon and uranium-thorium dating results are presented from a genus of calcitic Antarctic cold-water octocorals family Coralliidae , which were collected from the Marie Byrd Seamounts in the Amundsen Sea Pacific sector of the Southern Ocean and which to date have not been investigated geochemically. Provided that local radiocarbon reservoir ages can be derived for a given time, fossil Amundsen Sea octocorals should be reliably dateable by means of radiocarbon.
In contrast to the encouraging radiocarbon findings, the uranium-series data are more difficult to interpret. The uranium concentration of these calcitic octocorals is an order of magnitude lower than in the aragonitic hexacorals that are conventionally used for geochronological investigations. Besides alpha-recoil related U diffusion, high-resolution sampling of two fossil octocorals further demonstrates that diagenetic uranium mobility has offset apparent coral U-series ages.
Combined with the preferential alpha-recoil U diffusion, this process has prevented fossil octocorals from preserving a closed system U-series calendar age for longer than a few thousand years. Our results demonstrate that calcitic cold-water corals are unsuitable for reliable U-series dating. Calcitic octocorals could still be useful for trace element and some isotopic studies, such as reconstruction of ambient deep water neodymium isotope composition or pH, via boron isotopic measurements.
Browse Search About Login. Browse Search About.
The system can’t perform the operation now. Try again later. Citations per year.
Chronology based on excess Pb analysis allows dating up to years Similarly, the method of alpha recoil tracks is based on emissions of.
William G. Thompson Woods Hole Oceanographic Institution. The delicate and open structure of the coral skeleton, and the small size of the aragonite crystals make corals particularly susceptible to the movement of the U-series isotopes used in dating. As a result, many corals behave as open-systems, a problem that gets worse with increasing coral age. There are two fundamental processes that can affect coral isotope systematics: the gain or loss of daughter products during radioactive decay related to alpha recoil and the gain or loss of U or Th due to diagenetic processes.
Age correction approaches do not take into account U or Th gain or loss and typical screening criteria are also not very sensitive to this process, so that reported ages scatter around the true age. The combined impact of these effects on coral-based sea level reconstructions is to make sea level events appear to be older and of greater duration than they actually are. Problems or questions about the site, please contact webdev whoi.
In Section 2. However, certain natural processes can disturb this equilibrium situation, such as chemical weathering, precipitation from a solution, re- crystallisation etc. The leads to two new types of chronometric systems: An intermediate daughter isotope in the decay series is separated from its parent nuclide incorporated into a rock or sediment, and decays according to its own half life. A parent nuclide has separated itself from its previous decay products and it takes some time for secular equilibrium to be re-established.
This idea is most frequently applied to the U-decay series, notably Th and U. The first type of disequilibrium dating forms the basis of the U- U and Th methods Sections 9. The second forms the basis of the Th- U method Section 9. Once the oceanic U is incorporated into the crystal structure of marine carbonates, the radioactive equilibrium gradually restores itself with time.
Then: 9. This causes chemical fractionation and disturbs the secular equilibrium of the U decay series in young volcanic rocks. The total Th activity is given by: 9. Thus, the first term of Equation 9.
Elastic recoil detection analysis with alpha-particles
Jason E. French, David F. Here, we reevaluate the origin of these enigmatic microtextures from a strictly nonbiological standpoint, using a case study on submarine glasses from the western North Atlantic Ocean DSDP A. Our findings have important implications for geomicrobiology, astrobiological exploration of Mars, and understanding of the long-term breakdown of nuclear waste glass.
Thus, uranium series disequilibria dating methods are based on uranium Due to the relatively high difference between alpha particles and recoil nuclei a thin.
The Institute of Physical and Chemical Research. During the past few years, considerable attention has been given to the possibility of dating by fission tracks and alpha-particle recoil tracks. In this paper, it was described the principle and application for Quaternary period. Ages of a few obsidians and old man made glasses were measured by the fission track method. The volcanic glass which was extracted from the deep sea core V , was determined of its age and it was compared with the paleomagnetic result.
According to the experimental result of this method, the difficulty and the usefulness wcre discussed. Already have an account? Login in here. The Quaternary Research Daiyonki-Kenkyu. Journal home Journal issue About the journal.
To browse Academia. Skip to main content. Log In Sign Up.
14 DATE OF REPORT (Year, Month, Day) eous fission fragments, alpha particles, and recoil nuclei provides the means of radon escape.
Richard A. Ketcham, William R. Guenthner, Peter W. Alpha recoil track damage percolates at doses from 2. However, fission tracks percolate at a dose of approximately 1. Consideration of the undamaged regions between damage zones indicates that c-axis-parallel channels are frequently interrupted, at the micrometer scale at very low doses and tens of nanometers at usual doses in natural zircon, with the probable effect of decreasing diffusivity anisotropy.