I have just completed the data reduction on a low potassium basalt from the Medicine Lake, California, the basalt of Tionesta. The recent development of small volume low-background noble gas extraction systems and low-background high-sensitivity mass spectrometers have improved our ability to more accurately and argon-argon dating technique date geologic events. However, the dating of Quaternary, low potassium rocks continues to test the limits of the argon-argon dating technique because of small quantities of radiogenic argon and large atmospheric argon contamination. In these early studies the vertical succession of sedimentary rocks and structures were used to date geologic units and events relatively.
All good yeah? Unfortunately, not quite. The technique uses a few key assumptions that are not always true.
potassium-argon and argon-argon dating techniques are used on quizlet
In principle, the potassium-argon K-Ar decay system is no different. Of the naturally occurring isotopes of potassium, 40K is radioactive and decays into 40Ar at a precisely known rate, so that the ratio of 40K to 40Ar in minerals is always proportional to the time elapsed since the mineral formed . In theory, therefore, we can estimate the age of the mineral simply by measuring the relative abundances of each isotope. Over the past 60 years, potassium-argon dating has been extremely successful, particularly in dating the ocean floor and volcanic eruptions. K-Ar ages increase away from spreading ridges, just as we might expect, and recent volcanic eruptions yield very young dates, while older volcanic rocks yield very old dates.
Andrew Alden is a geologist who writes extensively about all aspects of geology, and leads research expeditions for professional organizations. Updated January 31, 2019 The potassium-argon K-Ar isotopic dating method is especially useful for determining the age of lavas.
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