Uranium lead dating method

06 Feb

A Pb-Pb isochron plots U, with both normalized to 204Pb.The in situ U-Pb technique involves laser ablation to remove minute particles of the fossil which then undergo isotopic analysis.The results have now been published in Geology, the journal of the Geological Society of America.Lead isotopes are commonly used in dating rocks and provide some of the best evidence for the Earth's age.In order to be used as a natural clock to calculate the age of the earth, the processes generating lead isotopes must meet the four conditions of a natural clock: an irreversible process, a uniform rate, an initial condition, and a final condition.

Dalrymple (2004) cites examples of lead isotope dating that give an age for the earth of about 4.5 billion years.Lead isotopes are important because two different lead isotopes (U).The possibility that dinosaur eggs might survive extreme climatic conditions is also a possible avenue to be explored.If the new U-Pb dating technique is borne out by more fossil samples, then the KT extinction paradigm and the end of the dinosaurs will have to be revised, Heaman and his colleagues believe.Second, using two isotopes of the same element makes the sample immune to chemical fractionation during a post-crystallization disturbance (Dalrymple 208). This model ultimately led to the development of isochrons, in which two isotopes are plotted against each other to calculate an age for the mineral or rock.The commonly accepted 4.5 billion year age of the earth is derived from radiometric dating of lunar rocks and meteorites in addition to dating methods based on the Gerling-Holmes-Houtermans model. Those who developed the method utilized Pb, lead isotopes that are the product of radioactive decay, normalized to 204Pb.The results from Heaman's team show that the sauropod in question was alive 64.8 million years ago, 700,000 years after the mass extinction, bringing into question the fate of the dinosaurs after the KT extinction.There could be several reasons why the New Mexico dinosaur and its ancestors survived the KT extinction.