The Continental Deep Drilling Project (KTB) in Germany: Overview and Major Result on the Geochemistry of Crustal Fluids and Gases

Abstract

The German Continental Deep Drilling Program (KTB) was designed to study the properties and processes of the deeper continental crust by means of a superdeep borehole in the Oberpfalz (Bavaria, Germany) near the town of Windischeschenbach. Major research themes were (1) the nature of geophysical structures and phenomena, (2) the crustal stress field and the brittle-ductile transition, (3) the thermal structure of the crust, (4) crustal fluids and transport processes, and (5) structure and evolution of the central European Variscan basement. The project was conducted in distinct phases: a preparatory phase (1982-1984), a phase of site selection (1985-1986), and a pilot phase (1987-1990), which included drilling of a pilot borehole (KTB-VB) to 4000 m and a 1- year experimentation program. The main phase (1990-1994) comprised drilling of a superdeep borehole (KTB-HB) which reached a final depth of 9101 m at a temperature of ~265