then the amount of intermediate daughter isotopes remaining in the sample is directly controlled by parent decays since the longer halflife parent is the rate-limiting factor in growth of the intermediates. If secular equilibrium has been established by the time of measurement, then the ratios of the isotopes in the chain reach a steady-state, and dating can be done under the assumption that parent decays directly to the ultimate daughter isotope at the decay rate of the parent. Secular equilibrium is established after several half-lives of the intermediate daughter products have passed, sufficient for any initial excess to have decayed away. Secular equilibrium is an observable condition, but in most cases, it is assumed to be true rather than measured. Prior studies have shown that secular equilibrium is established in at least some cases (Deschamps et al., 2004). One caveat to consider is that the half-lives of long-lived intermediate daughter products are typically measured by first assuming that secular equilibrium has been reached, though it is possible to measure them directly without that assumption and achieve a generally similar value (Varga et al., 2016). The vast majority of radioisotopes in the U/Pb system have sufficiently short half-lives to have established secular equilibrium in the time since the Flood, with four notable exceptions. In the radium series, 234U has a half-life of 245,500 years, 230Th has a half-life of 75,400 years, and 226Ra has a half-life of 1,600 years. In the actinium series, 231Pa has a half-life of 32,760 years (National Nuclear Data Center, 2008). It is possible that following the AND epoch, that samples would have an excess of these daughter products, causing the radiometric system to tick at an anomalously high rate until these isotopes were depleted. Several studies have documented significant excesses of 231Pa in a wide variety of geodynamic settings (Asmerom et al., 2000, p. 293). Rioux et al. (2015, p. 144) acknowledge that their observed excess 231Pa is likely the cause of the discordance in high precision U-Pb dates of mid ocean ridge zircons. They proposed preferential incorporation of Pa into zircon crystals during formation. The expected departure from secular equilibrium following AND depends on the chemical affinities of each of the elements (Kelemen et al., 2004, p. 629), as well as the relative change in the decay constants of parent and intermediate daughter during the epoch. This provides a unique window into how AND affected different isotopes. Standard radiometric analyses do not include measurements of these intermediate isotopes, and so the measurements are not common. These additional measurements should be prioritized to better constrain the nature of the underlying mechanism for AND and the amount of decay acceleration experienced. Similarly, discordance between different radioisotopes systems provide constraints on the relative decay acceleration between the two isotopes. This information may also elucidate geophysical conditions that effect reservoir relaxation, establishing a basis to consider dates to be relatively comparable. Other geochronometers such as fission track dating and He diffusion provide evidence on in situ nuclear decay, so can constrain the impact of secondary processes. With variable decay acceleration, symmetric analytical uncertainties will generally be asymmetric when corrected to absolute times via the inverse decay history function. B. Broad outline of potential models There is a diversity of opinion on how to correlate the Global Uniformitarian Chronostratigraphic Time Scale with the Flood year. However, most agree that at least Cambrian (541Ma) thru Cretaceous (66Ma) are Flood equivalent, yielding a minimum Flood radiometric range of 475 million years. Assuming this minimal consensus Flood radiometric range for the Flood leaves 4026 million radiometric years for the Antediluvian period and 66 million years for the modern period. Dividing each of these accumulated radiometric ages by Ussher’s durations for each respective period of history (Ussher, 2003) gives the following time averaged nuclear decay accelerations: Even though there is more than 8 times as much accumulated radiometric age before the consensus Flood range, there is a much larger time period that this acceleration is averaged over, so the average acceleration is smaller. A portion of this earlier apparent acceleration could be due to a primordial signature as well. This leads to the conclusion that to first order, decay acceleration during the Flood must be pulse-like. This pulse would be even more significant if additional accumulated radiometric age is attributable to the Flood above the consensus Flood range. Even though there may be differences between models during the Flood, they are only going to be interesting at second order or lower, so it is natural to differentiate models primarily by how the extra radiometric range is distributed both during Antediluvian time, and the termination behavior. A potential model could be Flood-only, accounting for all the Precambrian accumulated decay during the time of the Flood. Other models may be Flood anticipatory, where AND is proposed to occur before the Flood, but only in direct association (lead-up) with it. Other potential model categories propose a significant primordial signature, or two pulses of AND at different times in history e.g., Creation/Flood. Models can also be described by their termination behavior as mid-Flood, endFlood, or post-Flood. C. Possible case study for reservoir relaxation If the reservoir relaxation mechanism following AND described in this report has occurred in earth history, then one of the most apparent unique features that could potentially be observed is the behavior of geographically proximal, but chemically distinct post-Flood volcanic centers which would undergo differing rates of decay product release. If the stratigraphy of numerous distinct flows could be determined without reference to radiometric dates, then the nonlinear behavior of the reservoir relaxation might be determined. This would be manifest as dates decreasing opposite to stratigraphic position, and perhaps a transition point where one system measures younger for later times, and then begins to measure older for equivalent earlier times. See figure 5 for a contrived example. The benefit of studying a heterogeneous system like this is that rocks from both magma sources have been subject to the same decay history, and the reservoir relaxation can be determined without having established the decay history beforehand to correct eruption timelines. It may be possible to jointly solve for the relaxation parameters of both reservoirs simultaneously. MOGK Disequilibrium Relaxation Following Accelerated Nuclear Decay 2023 ICC 339
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