Table 2. Radiohalos identified and counted in regional metamorphic rocks spanning the geologic record from the Archean to the lower Phanerozoic. Granite Gneiss Minnesota, USA Late Archean 1 (50) 6 0 0 5 0 0.22 0.12 1.2:1 -- -- -- Granite (tonalites) Ilomantsi, Finland Archean 3 (150) 85 0 0 0 0 0.6 0.6 -- -- -- -- Granite Gneiss Minnesota, USA Middle to Lower Archean 1 (50) 48 0 0 28 0 1.52 0.96 1.71:1 -- -- -- Table 1 continued Rock Unit Location “Age” Samples (slides) Radiohalos Number of Radiohalos per slide Number ofPo Radiohalos per slide Ratios 210Po 214Po 218Po 238U 232Th 210Po:238U 210Po:214Po 210Po:218Po 238U:232Th Cooma Metamorphic Complex NSW, Australia 410-433 Ma 7 (350) 3368 76 1 727 0 11.92 9.84 4.63:1 44.3:1 3368:1 -- Migmatite adjacent to Palmer Granite South Australia Ordovician 1(51) 234 8 0 507 3 14.75 4.75 1:2.2 29.3:1 -- 169:1 Biotite Garnet Eclogite Stordal, Norway Upper Proterozoic 1 (50) 7 0 0 0 0 0.14 0.14 -- -- -- -- Thunderhead Sandstone TennesseeNorth Carolina (USA) Upper Proterozoic 10 (500) 522 19 0 0 0 1.08 1.08 -- 24.5:1 -- -- Metamorphic pegmatite Steiggjelselva, Norway Middle to Upper Proterozoic 1 (50) 30 0 0 0 0 0.6 0.6 -- -- -- -- Gneiss (and pegmatite) Hegland, Norway Lower Proterozoic 2 (100) 0 0 0 0 0 0 0 -- -- -- -- Gneiss (and pegmatite) Arendal, Norway Proterozoic 2 (100) 65 33 0 0 0 0.98 0.98 -- 1.97:1 -- -- Gneiss Sandbraten, Norway Proterozoic 1 (50) 78 0 0 0 0 1.56 1.56 -- -- -- -- Gneiss Gravfoss, Norway Proterozoic 1 (50) 0 0 0 0 0 0 0 -- -- -- -- Sundown Group Broken Hill, NSW, Australia 1670-1680 Ma 1 (50) 20 0 0 0 0 0.4 0.4 -- -- -- -- Rasp Ridge Gneiss Broken Hill, NSW, Australia 1683 Ma 6 (300) 1626 0 0 788 0 8.04 5.42 2.06:1 -- -- -- Hores Gneiss Broken Hill, NSW, Australia 1685 Ma 17 (850) 5374 3 2 2459 0 9.22 6.32 2.19:1 1791:1 2687:1 -- Amphibolites in Hores Gneiss Broken Hill, NSW, Australia 1685 Ma 3 (150) 10 0 0 0 0 0.67 0.67 -- -- -- -- Purnamoota Sub-Group (undifferent.) Broken Hill, NSW, Australia 1685-1693 Ma 2 (100) 365 0 0 99 0 4.64 3.65 3.69:1 -- -- -- Amphibolites in Parnell Formation Broken Hill, NSW, Australia 1692-1693 Ma 3 (150) 43 0 0 0 0 0.29 0.29 -- -- -- -- Allendale Metasediments Broken Hill, NSW, Australia 1693 Ma 1 (50) 7 0 0 0 0 0.14 0.14 -- -- -- -- Thackaringa Group Broken Hill, NSW, Australia ~1700 Ma 2 (100) 445 1 0 0 0 4.46 4.46 -- 445:1 -- -- Vishnu Schist Grand Canyon, USA 1730-1750 Ma 30 (1500) 18,523 14 4 11,308 0 19.9 12.36 1.64:1 1323:1 4631:1 -- Rama Schist Grand Canyon, USA 1730-1750 Ma 13 (650) 2398 0 0 1292 0 5.68 3.69 1.86:1 -- -- -- Beartooth Gneiss Montana, USA 2790 Ma 5 (250) 1254 0 0 259 0 6.05 5.02 4.84:1 -- -- -- Biotite Schist Minnesota, USA Late Archean 1 (50) 14 0 0 3 0 0.34 0.28 4.67:1 -- -- -- SNELLING Radiohalos through earth history 2023 ICC 551
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