(Renne et al., 1997). These observations provide several features that should be accounted for in a radiometric dating framework: 1. Extraneous daughter isotopes are common components of the magma sources of modern lava flows. 2. Most modern flows date correctly to near zero age. 3. Some modern volcanic systems consistently measure with anomalously old ages. 4. Behavior of extraneous daughter isotopes is dependent on the volcanic system. C. Magma reservoir radiogenic daughter loss pathways Magma bodies are chemically connected to their immediate surroundings and ultimately the surface via magma/lava convection, diffusion, and dissolution of volcanic fluids and gases (Watkins et al., 2017; Rust et al., 2004). Because radioisotope decay products like Pb and Ar with partition coefficients <1 are preferentially partitioned into fluids and melts, these escaping fluids have the effect of depleting the inventory of daughter products of the magma body over time. If the magma body could be sampled directly, an initial excess would be observed as a steady decrease in the apparent age of the magma over time. Eventually, this would achieve an equilibrium where the rate of removal of decay products is balanced by the production of daughter products via nuclear decay. Decay products are generally trace components of the overall volatile composition and include He and Ar (Cheng et al., 2021). Even lead, as the final decay product of the U and Th decay chains, partitions into volcanic gases, and so will be released to the environment from the magma reservoir over time (Zelenski et al., 2021). Extreme radiogenic excesses of 40Ar that are above the ability of the local radioisotope inventory to produce have been observed (Torgersen et al., 1989), and the production and release of radiogenic Ar has affected the modern atmospheric element ratio with respect to the ancient atmosphere (Renne et al., 2009). Measurements of fumarole gasses are easy to make and abundantly collected at modern volcanoes, however other processes in the magma system are also relevant for reducing large excess of radiogenic daughter products including partial melting and crystal fractionation. Noble gasses are believed to be reliable tracers of source reservoirs because it is thought that the original inventory of the earth contained very little, and the concentration of each is linked to radioactive decay, either as a direct product of common or extinct radionuclides or by interaction with decay induced thermal neutrons (Graham, 2002; Ballentine and Burnard, 2002; Ballentine et al., 2002). Noble gas studies are often undertaken at active volcanic fumaroles to fingerprint the magmatic source and to identify changes which might lead to an eruption. These studies have shown pervasive mixing of sources and their reconfiguration during the course of seismic or magmatic events (Bini et al., 2022). The apparent age of a magma reservoir when at equilibrium depends on the efficiency of decay product removal compared to the production rate. It would be expected to vary by volcano and over time but remain generally low for a long-lived magma body under today’s slow decay rates. However, during the AND epoch, the ability of magma bodies to achieve equilibrium would be severely restricted, and apparent ages would be significantly above the equilibrium values. Over time, these would relax back to the expected equilibrium values. Volatile content of the magma, along with depth, overall volume, and cooling rate all determine the overall fluid flux. Intrusion geometry determines the location of fluid release (Lamy-Chappuis et al., 2020; Kawaguchi et al., 2021). In each case, the controlling parameter is specific to the chemistry and geometry of the specific magma body. The pathways that magma and fluids travel to reach the surface can also have a “filtering” impact on the volatile content of the erupted lava (Ubide et al., 2021). Isotopes in fluids will also be fractionated as they travel through and interact with varying geological contexts (Hoang et al., 2021). D. Prior decay history models In 2005, the Radioisotopes and the Age of the Earth (RATE) research initiative published multiple lines of evidence that decay rates of radioactive isotopes used in radiometric dating were accelerated with respect to current rates in the past (Vardiman et al., 2005). The same lines of evidence were subsequently used to successfully predict field observations of radiohalos in metamorphic terranes (Snelling, 2008). The RATE authors did not provide tight numerical constraints but indicated that rates were likely accelerated by at least a factor of 108 At these great accumulation rates, the amount of daughter products would quickly overwhelm the ability of the magmatic plumbing to keep concentrations at equilibrium values, and they would be inherited by solidifying minerals at anomalously increased rates, commensurate with the relative magnitudes of the decay acceleration and the partition coefficients. Previous modeling of possible decay histories was first done in the RATE report (Vardiman et al., 2005). The authors proposed a twopulse model of AND with a single pulse during the Flood accounting for approximately 500 Ma worth of decay, with a gradual rampdown to modern decay rates in the centuries after the Flood. This was coupled with another, even greater, pulse during the first portion of Creation week, accounting for the remaining 4 Ga worth of decay products, with the Antediluvian period having more or less the same decay rates as modern ones. This model in its essentials is still commonly used by the authors today, as well as others, though some of the original authors have since proposed alternate models. The minor AND ramp-down was proposed to account for the remaining elevated radiometric dates obtained during the post-Flood period. No mechanisms related to the recovery of magmatic systems from the AND epoch were considered (Baumgardner, 2012). In the same volume, Chaffin (2005) took a theoretical approach to mechanisms which might produce the hypothesized accelerations. Some of the possible mechanisms that he identified generally were characterized by discontinuous jumps of many orders of magnitude as the parameters crossed critical thresholds. Humphreys (2014) produced an alternate model based on the remnant magnetizations of lunar rock samples obtained during the Apollo program and his model for the free decay of the lunar magnetic field. His updated model retains the single pulse during the Flood of the same magnitude and gradual ramp-down, but replaces the first pulse by a significantly lower level of AND which persists from the Fall throughout the Antediluvian period. MOGK Disequilibrium Relaxation Following Accelerated Nuclear Decay 2023 ICC 329
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