A review of radiometric dating methods applicable to kimberlites and related rocks

2012 ◽  
pp. 58-104
Author(s):  
Claude J. Allegre ◽  
Christopher Sutcliffe

1996 ◽  
Vol 61 (4) ◽  
pp. 755-771 ◽  
Author(s):  
Vance T. Holliday ◽  
David J. Meltzer

In 1953 human remains and a new type of Paleoindian artifact were discovered eroding from a "blowout" in a small dune field along Monahans Draw, near Midland, Texas, on the Southern High Plains. The projectile points became the type “Midland” collection. Stratigraphy, radiometric dating, paleontology, and geochemistry suggested that the artifacts and bones dated to at least 10,000 B.P. and that the human remains were possibly as old as 20,000 B.P. The researchers believed that the human bones were from below a red sand that in turn was below a Folsom occupation. The dating of the human remains has long been problematic, however, and recent attempts to apply U-series dating further confuse the story. Geoarchaeological investigations were carried out at the site from 1989 to 1992 to reevaluate the geochronology, with particular reference to the age of the skeletal material. We reach several conclusions: (1) there are two Red Sands; (2) the human remains are from below the upper Red Sand, but the Folsom material is from above the lower Red Sand and, therefore, the Red Sand stratigraphy is not relevant to the age of the human remains; (3) the human remains were associated with the valley-margin facies of a lacustrine carbonate that is well dated in the region and rarely is > 10,000 B.P.; and (4) all numerical dating methods applied at the site produced unreliable results. We find no compelling evidence that the human remains from the Midland site are older than Folsom age; they may be contemporary with or younger than the Folsom occupation.


2012 ◽  
Vol 63 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Alexandru Szakács ◽  
Zoltán Pécskay ◽  
Lóránd Silye ◽  
Kadosa Balogh ◽  
Daniela Vlad ◽  
...  

On the age of the Dej Tuff, Transylvanian Basin (Romania)The Dej Tuff is an important stratigraphic marker in the Transylvanian Basin. However, its Early Badenian age is known only on biostratigraphical grounds so far. A number of radiometric dating techniques including K-Ar, Ar-Ar and fission-track have been used in order to constrain more precisely its age, allowing the calibration of the Transylvanian Basin's evolutionary models. Although individual dating methods could not provide a unique, reliable and accurate radiometric age, comparison and evaluation of multiple methods gives 14.8-15.1 Ma as the most likely formation age of the Dej Tuff.


2020 ◽  
Author(s):  
Drew Downs ◽  
et al.

Table S1 (paleomagnetic analysis methods and data); Table S2 (detailed X-ray fluorescence spectrometry and instrumental neutron activation analysis methods and data); Table S3 and Figures S1–S4 (<sup>40</sup>Ar/<sup>39</sup>Ar experimental results, age spectra, and radiometric dating methods); and Figure S5 (location map of basalts plotted in Figure 2B).<br>


1990 ◽  
pp. 51-314
Author(s):  
Mebus A. Geyh ◽  
Helmut Schleicher

2006 ◽  
Vol 12 ◽  
pp. 1-23 ◽  
Author(s):  
Brent V. Miller

Radiometric dating of rocks and minerals to constrain the age of the Earth, timing of geological events and paleobiological histories has its roots in the works of nuclear physicists of the early Nineteenth Century during the period of discovery of radioactivity and investigations into the nature of the atom. The intervening years since have seen great progress in using the long-lived radioactive elements to constrain the origin and evolution of the Earth and to place the rock and fossil record into a consistent, numerically quantifiable temporal framework.U-Th-Pb and40Ar/39Ar dating methods have emerged as the primary tools for calibrating most of Earth history. It is important for all geoscientists to appreciate the physical basis underlying these methods and to have the ability to evaluate dates by means of currently accepted practices of data presentation. This introduction, along with the accompanying chapters, is intended to help the consumers of radiometric dates to understand better the uses and limitations of radiometric dating methods in an effort to tailor methods and techniques to address specific geochronologic needs, including calibration of the geologic time scale.The ultimate goal of a fully calibrated rock record remains an on-going endeavor. The 2004 ICS geologic time scale is the latest compilation of those efforts. The numerical age calibration is constrained by only 213 radiometric dates, the vast majority of which are U-Pb and40Ar/39Ar dates. Radiometric age control is not evenly distributed through geologic time. There are virtually no radiometric dates in the late Cenozoic where magnetostratigraphy and cyclostratigraphic methods are more precise and applicable. Radiometric dating efforts are concentrated on biostratigraphically important segments of the rock record such as the Permian-Triassic and Cretaceous-Paleocene boundary events, and this is reflected in high-precision calibration of these boundaries. Large segments of geologic time, however, are constrained by either a few radiometric dates per chronostratigraphic unit (most of the Paleozoic) or none at all (Upper Triassic). The current status of radiometric age control on the rock record largely reflects real, underlying scientific issues in biostratigraphy and geochronology, and thus can help point the way to fruitful lines of collaboration between paleontologists, stratigraphers, and geochronologists.


Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 305-324 ◽  
Author(s):  
Peter Vrolijk ◽  
David Pevear ◽  
Michael Covey ◽  
Allan LaRiviere

ABSTRACTRadiometric dating of fault gouges has become a useful tool for regional tectonics studies and for exploring and understanding fault and earthquake processes. Methods to define the absolute age of faults achieved a solid scientific foundation almost 25 years ago when the development and application of illite age analysis for investigating sedimentary burial and thermal histories found a new potential application – defining the age of fold-and-thrust development. Since then, the methods have benefitted from further development and incorporation of the 40Ar/39Ar micro-encapsulation method and quantitative clay mineral evaluation to distinguish polytypes (Wildfire). These refinements to the methods have improved their application in fold-and-thrust terrains and have opened up applications in normal and strike-slip fault environments. Another important development is the use of absolute dating methods in retrograde clay gouges in which clays in a fault develop from igneous or metamorphic wall rocks that contain no clays. In addition, the method has also been shown to be useful at dating folds in fold-and-thrust belts. We think the method is now an established part of the geological toolkit, look forward to future fault structural and tectonic studies that incorporate fault ages and hope that researchers continue to probe and discover ways that the method can assist fault process studies, including earthquake fault studies.


2013 ◽  
Vol 75 (4) ◽  
pp. 251-256 ◽  
Author(s):  
Phil Senter

Biology textbooks tend to assert the correctness of evolutionary concepts but mention very little of the evidence that supports them. This gives the impression that evolutionary theory is poorly supported, which discourages acceptance of the theory. A case in point is the age of the Earth. Biology textbooks usually mention that the planet is ~4.6 billion years old but neither tell how that was determined nor give evidence that the method (radiometric dating) is reliable. Students are therefore given insufficient reason to doubt that the Earth is any older than the 6000 years that the Genesis account suggests. Here, therefore, I review the evidence for an old Earth, to provide a concise but thorough reference for teachers who wish to supplement the meager information in textbooks with further details. Earth’s age is relevant to biology because an old Earth is necessary for macroevolution to occur and also because some dating methods (e.g., dendrochronology, varves) use materials of biological origin.


2020 ◽  
Author(s):  
Drew Downs ◽  
et al.

Table S1 (paleomagnetic analysis methods and data); Table S2 (detailed X-ray fluorescence spectrometry and instrumental neutron activation analysis methods and data); Table S3 and Figures S1–S4 (<sup>40</sup>Ar/<sup>39</sup>Ar experimental results, age spectra, and radiometric dating methods); and Figure S5 (location map of basalts plotted in Figure 2B).<br>


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