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Answers in Genesis
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Hebron, KY 41048
Andrew A. Snelling obtained a PhD in geology from the University of Sydney, Australia, then worked a few years in the exploration and mining industry and in mineral deposit research, before working in full-time creation ministry and research since late 1983, first with the Australian ministry, then with the Institute for Creation Research, and now with Answers in Genesis (USA). He was the founding editor of what is now the Journal of Creation, was involved in the RATE project as a principal researcher and editor, was the 6th ICC editor, and is founding editor of the Answers Research Journal.
Full Paper Presentation
Radiohalos are 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 2000). 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 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”.
The current 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 2005). This model was used to make predictions that were verified as to where the most Po radiohalos would occur in two regional metamorphic complexes based on the water generated in the respective metamorphic reactions (Snelling 2008a, b).
One major objection raised is the huge amount of heat 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, and/or the radiohalos formed as the host crystals cooled after the heat dissipated from the pulse of accelerated 238U decay. The 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, then the radiohalos we observe today had to form during the Flood. That would thus seem to apply not to just the Phanerozoic rocks produced by the Flood, but also to the pre-Flood and Creation Week Precambrian 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 were annealed during the Flood.
With these guidelines established, this paper will survey the radiohalos data collected from granites and metamorphic rocks spanning earth history, reported by Snelling (2005) and obtained in yet-to-be published case studies. It is evident that Precambrian granites generally have fewer radiohalos than Phanerozoic granites. The latter granites being formed during the Flood generated enough water as they crystallized and cooled to produce a lot more radiohalos. In contrast, the Precambrian granites has already formed as the basement to the Flood rocks and therefore not having water generated in them during the Flood were thus less able to produce radiohalos. However, certain suitable Precambrian metamorphic rocks have as many radiohalos within them as some Phanerozoic metamorphic rocks. This suggests that whatever the precursor pre-Flood rocks were, some metamorphism of those pre-Flood basement rocks releasing water may have still occurred during the Flood to generate so many radiohalos.
This paper will further present the details and implications of these observations. These implications are also relevant to an explanation for the supposed vast radioactive ages conventionally assigned to rocks through earth history, which is exceedingly important and much needed for the creationist community.
radiohalos, granites, metamorphic rocks, accelerated decay, annealing, pre-Flood, Flood, post-Flood
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Snelling, Andrew A.
"Radiohalos Through Earth History – What Clues Can They Provide Us?,"
Proceedings of the International Conference on Creationism: Vol. 9, Article 5.
Available at: https://digitalcommons.cedarville.edu/icc_proceedings/vol9/iss1/5