A Contribution to the Sulphur Isotope Geochemistry of the Upper Continental Crust: the KTB Main Hole - a Case Study

  • Autor: Leosson, M.
  • Quelle: ISSN 0943-8599 / Band 12 (1999)

Kurzfassung (Abstract)

This work is a contribution to the sulphur isotope geochemistry of the Upper Continental Crust and focuses on the metamorphic rocks from three main lithological sequences transcected during the German Continental Deep Drilling Project (Kontinentales Tiefbohrprogramm der Bundesrepublik Deutschland) at Windischeschenbach in the Oberpfalz, Bavaria Germany. Although sulphur isotope geochemistry of lithospheric sources such as marine evaporites, sedimentary rocks, igneous rocks, ore deposits and oceanic crust is well documented, little data on sulphur in metamorphic rocks from the lower regions of the upper crust is available. Most of our knowledge on the behaviour of sulphur during metamorphism is based on its occurrence in metamorphosed ore mineralisation. With the realisation of the KTB project, a singular and a very unique opportunity was presented to investigate the distribution and behaviour of sulphur in metamorphic rocks, with the addition of establishing a sulphur isotope profile of the central European crust. The KTB project established between 1987 and 1994 two crustal transsects (pilot- and main hole) into a succession of metamorphic rocks. The KTB pilot hole drilled a sequence of paragneisses and metabasic rocks, reaching a final depth of 4000.1 meters. The KTB main hole reached a final depth of 9101 meters with a bottom hole temperature of about 260°C. The data presented here indicate that the metamorphic rocks have retained their precursor sulphur isotope signature despite a intricate metamorphic history.