Igneous rocks dating


17-Oct-2020 07:35

1) constant rate of decay over supposedly hundreds of millions of years, 2) no loss or gain of parent or daughter isotopes over the supposed many millions of years of earth’s history (that is, there is no mixing of the magma and crustal rocks resulting in loss or gain of isotopes), 3) known amounts of daughter isotopes at the time of cooling.The first assumption is a constant rate of radioactive decay based on uniformity theory—that is, a doctrine which maintains that natural processes have remained constant during earth’s history.If the rate of decay from uranium to lead is constant (with a half-life of 4,470 million years), and if we know the amount of daughter isotopes in the rock at the beginning, and if we can measure how much parent and daughter isotopes are present in a given rock sample, we can supposedly calculate the age of the rock.The isochron method, based on least squares regression, does not address rate of decay, and attempts to address assumptions 2 and 3, but results have been found to be discordant, “commonly fail at some level,” and are essentially meaningless.For example, uranium-238 (parent isotope) decays into thorium-234, which itself is unstable, and the process continues until the atom changes into lead-206 (daughter isotope), which is stable.Advocates of these methods assume that melting or liquid magma at the beginning resets the age clock to zero (that is, there are no daughter isotopes in the rock at the time of cooling or solidification).In the beginning when the universe was expanding and accelerating at inconceivable rates, daughter isotopes (Pb-206 and Ar-40) would have been present.Large concentrations of daughter isotopes were mixed into the upper mantle during the first few days of Creation—and then later mixed into the earth’s crust during the flood.

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The bottom line is this: Ancient and recent lava flows have the same chemistry derived from the earth’s upper mantle.By contrast, Intrusive rocks are formed from magma that cools underground.