Distribution of Radioactivity in Granites and Possible Relation to Helium Age Measurement

摘要: Granulated samples of acidic igneous rocks have been found to give a much higher rate emission alpha particles than corresponds the known total contents uranium and thorium. Abnormally large residual ranges suggest surficial distribution radioactive elements on surfaces granules in form secondary mineral coatings. Most alpha-particle activity can be removed by dilute hydrochloric acid, leaving an corresponding low content thorium sandstones arkoses, which essential grains granites rounded cleaned attrition. The proportion appears less for granite taken from considerable depth below surface zone surface-water saturation. Losses acid treatment appear related degree retentivity helium different rock types. Determination age ratio before after suggests that minerals contain as they should commensurate with their quantity radioelements uniformly distributed within them, not removable acid. radioactivity whole may due either loss highly areas are easily affected thus also probably ground waters, or actual supergene enrichment late history rock.