THE KTB FISSION-TRACK PROJECT - METHODICAL ASPECTS AND GEOLOGICAL IMPLICATIONS

An overview is presented of the apatite fission-track analysis of the 4000 m deep KTB pilot hole drilled in the Variscan crystalline basemen t of the Oberpfalz, Germany. The apatite fission-track age profile bas ed on 41 samples suggests a simple thermal history, i.e. a single even t of uplift-induced cooling during the late Cretaceous-early Tertiary. The length information provided by the confined tracks and the age sp ectra of the surface tracks add complications to this tectonothermal h istory and suggest additional young Cenozoic uplift and faulting toget her with an increase of the geothermal gradient in relatively recent t ime. The validity of this interpretation is, however, inevitably conne cted to the model used to describe track stability in apatite under ge ological conditions.