Title: Radiohalos as an exploration pathfinder

Author: A.A. Snelling

Category: Earth Sciences

Conference Year: 2018

Abstract: It has been proposed that Po radiohalos were formed from Po derived by 238U decay in the radiocenters of nearby 238U radiohalos which was transported by hydrothermal fluids released from granite plutons as they cooled. Thus, since the same hydrothermal fluids have concentrated metals into economic ore veins in some granites, it has also been proposed Po radiohalos could potentially be used as an exploration pathfinder tool for discovering new ore veins associated with granites. This study in the New England Batholith, eastern Australia, found that Mole Granite samples proximal to known hydrothermal ore veins contained extremely high numbers of Po radiohalos, in contrast to a distant sample that contained almost 90% fewer Po radiohalos. However, in the Hillgrove Granite which also hosts hydrothermal ore veins, all samples contained moderate-high numbers of Po radiohalos similar to those in barren granite plutons elsewhere in the batholith. This is because the Hillgrove ore veins were not produced from the hydrothermal fluids expelled from that cooling pluton, but were precipitated from hydrothermal fluids as distant granitoid plutons cooled in a later magmatic event. Thus, the extremely high numbers of Po radiohalos in Mole Granite samples proximal to known ore veins successfully indicated their proximity to those ore veins. Therefore, Po radiohalos proved to be a reliable pathfinder for the hydrothermal ore veins. This strategy applied to the Stanthorpe Granite found two out of six samples with high to very high numbers Po radiohalos, potentially pinpointing areas for follow-up exploration for possible hydrothermal ore veins. Further detailed sampling work is recommended to develop this exploration tool. Nevertheless, since the same hydrothermal fluid flows responsible for the Po radiohalos were responsible for forming the ore veins, then the ore veins must have formed in the same very rapid timescale, within weeks, a timescale fully compatible with the biblical chronology of earth history.