Figure 4. Some typical examples of the different radiohalos found in granites and metamorphic rocks. All images are in focus, but where the radiohalos appear fuzzy it is due to the intensity of the radiation broadening the outlines and the rings. The scales are provided with the following descriptions. (a) An overexposed 238U radiohalo (Cooma Granodiorite, diameter ~70 μm, center) and a 210Po radiohalo (diameter ~39 μm, right). (b) A well-exposed 238U radiohalo (Shap Granite, diameter ~70 μm). (c) Two faint 218Po radiohalos (Land’s End Granite, diameter ~70 μm, center). (d) 238U (diameter ~70 μm, upper center), 214Po (diameter ~68 μm, lower right) and 210Po (diameter ~39 μm, right) radiohalos together in the same biotite grain (Land’s End Granite). (e) Another 214Po radiohalo (centered on a crack) (Land’s End Granite, diameter ~68 μm, right) and an overexposed 238U radiohalo (diameter ~70 μm, left). (f) Overexposed 238U radiohalos (Vishnu Schist, diameter ~70 μm) and 210Po radiohalos (diameter ~39 μm). SNELLING Radiohalos through earth history 2023 ICC 546
RkJQdWJsaXNoZXIy MTM4ODY=