But a little later he said, “The main handicap of the method has been the necessity to rely solely on the Pb composition, without assistance from U-Pb, thus limiting the ability to evaluate the state of concordance of the analyses.” So what is it, correct or handicapped?
The paper is technical, so detailed evaluation of the contents should be left to geophysicists.
The following quotes give a sense of the kinds of problems Corfu discussed, and their implications.
Corfu described in the Pb, can also be measured.) “These twin decay systems, running at different speeds, allow an immediate verification of the validity of their ages, which must be concordant to be considered valid, although under favorable circumstances, discordant data can be extrapolated to the correct age.” Since uranium is often locked in tightly-bound minerals called zircons, from which parent and daughter product are locked in, the method is thought by modern geologists to provide a reliable clock. Krogh: “Only one answer is the right one, and only that one is good enough.” The progress in developments of the U-Pb method is both a history of technical discoveries and advances, as well as a history of a long struggle toward concordance, toward an understanding of the causes of discordance, and toward ways to eliminate it.
In “A century of U-Pb geochronology: The long quest towards concordance,” Corfu, a geologist at the University of Oslo, described geologists’ frustration at persistent discordance between the two methods. Still, he finds it troubling that there should be discordance if the same physical processes are operating for the same amount of time. Despite the enormous progress achieved in this field, the problems of U-Pb discordance have not yet been completely resolved and will be one of the main hurdles to overcome in the future.
When a bold maverick, Max Planck, decided to focus on the outlier data, he gave birth to quantum mechanics – a revolutionary new paradigm that changed everything.
As a human with biases, a scientist can be prone to cover up the outlier data points when showing a graph to their colleagues that mostly shows a perfect fit. Since some of the known causes of discordance came to light over decades, we have no confidence now that new unknowns yet to be identified will not color or revolutionize the interpretations of age accepted today by the consensus.
Behind the confidence of uranium-lead dates hides worry about numbers that don’t match up.
Uranium-lead (U-Pb) dating is a staple of the billions-of-years claims about igneous and metamorphic rocks and meteorites – giving rise to the consensus age of the solar system at 4.55 billion years.
In this paper, Corfu has done a good job identifying the known factors that can cause discordance. One big factor is built into the interaction between geologist and lab.