their half-lives are so fleeting (3.1 mins, 164 µsec, and 138 days, respectively), the existence of these Po radiohalos has been “a tiny mystery”, though now explained by the hydrothermal fluid transport model proposed and elaborated by Snelling and Armitage (2003) and Snelling (2005a), and tested successively by Snelling (2008b, c, d, 2014, 2018) and Snelling and Gates (2009). This hydrothermal fluid transport model for the formation of polonium radiohalos involves a pulse of accelerated radioactive decay. Hundreds of millions of years’ worth of 238U decay must have occurred within days so enough daughter Po isotopes were produced rapidly to be transported by hydrothermal fluids to closely adjacent locations within the host crystals to form separate (“orphan”) Po radiohalos (Snelling 2005a). One major objection raised is the huge amount of heat (as well as radiation) that would seem to be generated by the pulse of accelerated 238U decay. However, Laney and Laughlin (1981) have documented that natural annealing of radiohalos occurs at as low as 150°C. Thus, there may not have been a heat problem because the radiohalos have survived to the present, and/or the radiohalos formed as the host crystals cooled after the heat dissipated from the pulse of accelerated 238U decay. The important corollary to that is the radiohalos we observe today had to form after whatever was the last heating event these rocks suffered. Because there is abundant evidence that the last pulse of accelerated 238U decay occurred during the Flood, as indicated by the lines of supporting evidences enumerated above (Vardiman et al. 2005), then the radiohalos we observe today had to form during the Flood. That would thus seem to apply not to just the rocks produced by the Flood, but also to the pre-Flood and Creation Week rocks. The latter rocks would have been affected by both the pulse of accelerated 238U decay during the Flood and the heat that pulse produced. It is thus possible that any previously formed radiohalos in Precambrian rocks (if those are pre-Flood and Creation Week rocks) were annealed during the Flood. Yet, there has been insufficient data on the distribution of all radiohalo types in the vast Precambrian geological record. Indeed, the distribution pattern of all radiohalo types in Precambrian granitic and metamorphic rocks might well be significant, providing clues about the earth’s early history within the Biblical framework. Snelling (2005a) made an initial attempt to survey the radiohalos data collected from granites and metamorphic rocks spanning earth history. However, the data he tabulated and plotted were preliminary and insufficient to draw any major conclusions. Yet, it was evident from his data that Precambrian granites generally have fewer radiohalos than Phanerozoic granites. Those Phanerozoic granites were formed during the Flood because they intruded fossiliferous, Flood-deposited sedimentary strata, and they had generated enough water as they crystallized and cooled to produce a lot more radiohalos. In contrast, the Precambrian granites had already been formed, presumably during the Creation Week, as the basement (or foundation) to the Flood rocks and therefore did not necessarily have much water generated in them during the Flood so were thus less able to produce radiohalos. It was also found that certain suitable Precambrian metamorphic rocks have as many radiohalos within them as some Phanerozoic metamorphic rocks. This suggested that whatever the precursor pre-Flood rocks were, some metamorphism of those pre-Flood basement rocks releasing water may have still radiohalos were alongside U and Th radiohalos in the same Floodrelated granitic rocks, then that would have implications as to the rate of formation and age of these granitic rocks formed during the Flood year within the Biblical timescale. Subsequently, case studies were undertaken to test this hydrothermal fluid transport model for the formation of Po radiohalos. Most remarkable was the fulfilled prediction of many more Po radiohalos at the staurolite isograd in regionally metamorphosed sandstones in the Great Smoky Mountains, Tennessee-North Carolina, where the metamorphic reaction would have released a lot of water (224 water molecules for every 54 units of muscovite reacting with chlorite; Snelling 2008b). Then, in the Cooma regional metamorphic complex of southeastern Australia the numbers of Po radiohalos increased where water was released in the high-grade zone and in the central granodiorite, but decreased sharply in the zone of partial melting where water was dissolved into the melt, just as expected in the model (Snelling 2008c). In granites, increased numbers of Po radiohalos were also found where they were predicted to be based on the release of hydrothermal fluids during granite crystallization and cooling (Snelling 2008a). In the Shap Granite of northern England, prolific Po radiohalos matched the higher volume of hydrothermal fluids associated with that granite’s large K-feldspar phenocrysts (Snelling 2008d, Glazner and Johnson 2013). The nested plutons of the Tuolumne Intrusive Suite, Yosemite, California (Glazner et al. 2022) contain increasing numbers of Po radiohalos proportional to the increased volumes of active hydrothermal fluids within the sequentially emplaced intrusions (Snelling and Gates 2009). High numbers of Po radiohalos and active hydrothermal fluids coincide with the large K-feldspar phenocrysts in the second to last pluton and the connection to explosive volcanism of the last pluton (Bateman and Chappell 1979; Snelling and Gates 2009; Glazner and Johnson 2013; Glazner et al. 2022). The Bathurst Batholith west of Sydney, Australia, consists of an enormous pluton of 1600 km2 (620 sq. mi) (the Bathurst Granite) intruded into fossiliferous sedimentary strata and numerous smaller related satellite plutons and dikes, which field and textural data have established were sequentially intruded while still hot (Snelling 2014). The presence of Po radiohalos in all three sequentiallyintruded granite phases is evidence that all this intrusive activity, and the cooling of all three granite phases, must have occurred within a week or two so that these Po radiohalos in them formed subsequently within days to weeks. And Snelling (2018) successfully tested the use of Po radiohalos as an exploration guide to locate hydrothermal ore deposits associated with granites, higher numbers of Po radiohalos being spatially associated with hydrothermal ore veins within granites in the New England region of northern New South Wales, Australia. II. MATERIALS – THE PRESENT STUDY Radiohalos are thus a physical record of radioactive decay that occurred in granites and metamorphic rocks through earth history. They are the result of damage to the host crystals by α-particles produced in the 238U decay chain (Snelling 2000b). Normally 238U radiohalos are produced. However, there are also radiohalos produced by the three isotopes of Po (218Po, 214Po and 210Po) that are generated towards the end of the 238U decay chain. Because SNELLING Radiohalos through earth history 2023 ICC 544
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