Start Flaws in radiometric dating

Flaws in radiometric dating

If the rock was reheated at any point, the method no longer provides a straightforward interpretation of the cooling age (hence all dates are termed "apparent ages").

I was originally quite convinced by the discrepancy that radiometric dating methods were fundamentally flawed: "If radiometric dating methods are so wrong when the age is known, how can we trust them when the age is unknown?

" Now, my concern is that to the non-scientist (or even to the experienced scientist that doesn't regularly work with geochronology) this reasoning may seem plausible and end the debate without warrant.

After another 1.25 billion years, you should find 1/4 grams of 40K and 3/4 grams of 40Ar/40Ca.

Therefore, one can use the measured ratio of potassium to argon in a given mineral to infer the time at which the mineral crystallized and began to accumulate argon (note: 40Ca is not considered in the equation, because it is a common isotope that is already abundant in the rock).

My hope is to convince you this is the case through the following example, and that Ai G had prematurely discredited the K-Ar dating method. Doolan provides a convincing case against the credibility of K-Ar dating.

I remember reading similar reports years ago, which cited numerous cases of historical lava flows (note: historical meaning humans witnessed it) that were dated radiometrically to be a few hundred thousand to millions of years old.

Therefore, any mineral that contains potassium (K) will contain a mixture of all its isotopes (39, 40, and 41).

When 40K decays radioactively, it produces both 40Ar (argon) and 40Ca (calcium), with a half-life of 1.25 billion years.

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Chances are, you learned a simplified version of the technique at one point—if you remember your chemistry teacher discussing isotopes, half-lives, hourglasses, well, that was it—but have since removed the lesson to a box labeled "High School Amnesia" in some dark corner of your brain.

As you can imagine, the chaos of Earth systems can produce both scenarios, so geochronologists have developed techniques to verify (test) each assumption. Most people (geologists included) think of radiometric dating methods as a means to assign absolute ages to rocks/minerals.