Isochron date of young Grand Canyon lava is excessively old (Talk.Origins)

Claim CD014.1:


 * The hawaiite lava flows from the Uinkaret Plateau of the Grand Canyon are dated by K-Ar at about 1.2 million years old, an age consistent with the lava flow being younger than the canyon itself. However, a Rb/Sr isochron plot of samples from the lava flow gives an age of 1.34 billion years old, which is older even than the Cardenas Basalt, some of the oldest rock in the Canyon. The data points are colinear, which is supposed to indicate a valid isochron. This result shows that the isochron method is invalid.

Source: Austin, Steven A., 1992. Excessively old "ages" for Grand Canyon lava flows. Impact 224 (Feb.).

CreationWiki response:

There seems to be no basis for Talk.Origins' claim here. Austin makes it clear that he chose samples that should have been isotopically homogeneous.

This assumes that Talk.Origins' claim #1 is correct, but there is empirical evidence that contradicts that claim.

Ages of Uinkaret Plateau Rocks in Millions of Years. Data from: Radioactive Dating Explained - Part 2

The K-Ar and straight Rb-Sr dates strongly disagree with each other. Yet, the straight Rb-Sr dates have a good degree of agreement with each other and the Rb-Sr Isochron, showing that the Isochron is not a result of non-cogenetic samples as Talk Origins claims. This is further supported by the fact that the Pb-Pb Isochron disagrees with the Rb-Sr Isochron date by a billion years.

The fact only works against Talk.Origins' claim that the samples were non-cogenetic. Adding this to the additional dating data above show that Talk.Origins' claim is wrong and that the samples were cogenetic.

It seems more likely that it is Talk.Origins that is doing the misstating here.

A data isocrônica da lava jovem do Grand Canyon é excessivamente velha (Talk.Origins)