DATABILITY OF SANIDINE FELDSPARS USING THE NEAR-INFRARED TL EMISSION

TL dating of volcanic feldspars is usually made using TL emissions in the range from UV to 600 nm (red), loosely called the blue range of em ission. This dating is too often handicapped by anomalous fading. Howe ver, volcanic feldspars display a near-infrared (near-IR) emission cen tred around 700 nm, attributed to Fe3+ substituted for Al3+. This IR e mission has several characteristics: the activation energies appear to be similar for the blue and near-IR TL emission and the near-IR TL em ission is sensitive to the light of the sun and bleaches rapidly in a few hours like the blue emission. The variation with dose of the inten sity of TL is very similar for the two bands. In particular, the near- IR TL emission appears much more stable than the blue emission. The sa me IR emission band may be observed in the natural TL (NTL). Dating of sanidine feldspars using the near-IF: emission gives estimated ages i n agreement with the age obtained using other dating methods, such as K/Ar, U/Th and radiocarbon even when any dating using the blue emissio n is prevented by anomalous fading. (C) 1997 Elsevier Science Ltd.