Potassium dating accuracy
But not always -- contamination of both types is common.To falsify K-Ar dating, as the claim is attempting to do, one must not only show that the predictions of K-Ar measurements lead to incorrect years, but that both assumptions (1) and (2) hold.I haven't heard of this being done, however if you have some evidence to this effect please share it. I have very little knowledge in the field of radioactive dating, and I'm not even sure if 1 is a true statement.However if it is, then wouldnt this invalidate any results made using K-Ar dating?) who obtained some samples of rocks from a lava flow from Mt Ngauruhoe in New Zealand.They claim that the rocks they obtained were from a lava flow which came out of the volcano in 1945.Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Radiometric dating would predict that, if the assumptions (1) and (2) hold, samples from the same flow would have the same age. Excess argon produced apparent ages ranging from 160 million to 2.96 billion years." (Kofahl and Segraves, 1975, p.200) These authors cite a study by Funkhouser and Naughton (1968) on xenolithic inclusions in the 1801 flow from Hualalei Volcano on the Island of Hawaii.Therefore this data cannot be used to falsify K-Ar dating, because it does not violate a prediction of radiometric dating. They come from deep within the mantle and were carried upward to the surface by the lava.Instead, the hypothetical contamination scenarios proposed by other answers/comments gain support. In the field, they look like large raisins in a pudding, and even occur in beds piled one on top of the other, glued together by the lava.Funkhouser and Naughton were able to determine that the excess gas resides primarily in fluid bubbles in the minerals of the xenoliths, where it cannot escape upon reaching the surface.
Studies such as the one by Funkhouser and Naughton (1968) are done to determine which materials are suitable for dating and which are not, and to determine the cause of sometimes strange results. There have been two extensive K-Ar studies on historic lava flows (Dalrymple, 1969; Krummenacher, 1970) that showed that excess argon is not a serious problem for dating lava flows.An exception is the lava from the 1801 Hualalei flow, which is so badly contaminated by the xenoliths that it is not possible to obtain a completely inclusion-free sample.