Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Journal of the Geological Society

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by MILLER, J. A. Articles by MANCKTELOW, N. S. GeoRef GeoRef Citation

Oxygen, carbon and strontium isotope constraints on the mechanisms of nappe emplacement and fluid–rock interaction along the subhorizontal Naukluft Thrust, central Namibia

¹ Department of Geology, University of Stellenbosch, Matieland, 7602, Stellenbosch, Republic of South Africa (e-mail: jmiller{at}sun.ac.za)
² Geological Survey of Norway, N 7491, Trondheim, Norway
³ Geological Institute, ETH Zurich, CH-8092 Zurich, Switzerland

The Naukluft Thrust forms the floor thrust to the Naukluft Nappe Complex, a far-travelled, nappe stack of the Pan-African Damara belt in Namibia. The thrust tectonostratigraphy comprises three dolomitic components, a calc-mylonite horizon, and a discrete brittle fault. Stable isotope data indicate that the leading edge is characterized by positive ¹³C values, whereas the trailing edge is characterized by negative ¹³C values. There is a significant range in the ¹⁸O values, over 15 in different sections, with the leading edge showing a larger range than the trailing edge. ¹⁸O values are characteristic of burial dolomites and secondary dolomitization is indicated by the presence of networks above and below the Naukluft Thrust zone. The large range in ¹⁸O values and variations in ¹³C vs. ¹⁸O patterns are interpreted to be the result of interaction between the precursor to the Naukluft Thrust zone dolomites and fluids derived from different footwall lithologies. ⁸⁷Sr/⁸⁶Sr isotope ratios indicate that some fluids were derived from the basement. The data presented in this study suggest that an original carbonate-dominated horizon existed prior to thrusting and that the basal thrust of the nappe complex exploited this horizon.