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Petrologic and geochemical investigations of high-T fluid-rock interaction in carbonate-bearing metasediments: the Navachab gold deposit, Namibia.


Team members: A. Dziggel, F.M. Meyer, J.Kolb, K. Wulff.

The Navachab gold deposit in the Southern Central Zone of the Damara Orogen, Namibia, is situated within marbles, calc-silicate rocks and metapelitic schists of the Damara sequence. The mine is currently the only known primary gold deposit in the extensive system of Pan-African orogenic belts in southern Africa. The deposit has experienced multiple episodes of high-T fluid-rock interaction during compressive deformation, that resulted in the formation of massive “replacement style” ore bodies, as well as several generations of quartz-sulfide veins. This study will examine the stable isotope and geochemical effects of superimposed fluid-rock interaction in this unusual gold deposit. An isotopic tracer study on a continuous section from the unaltered host rocks through one of the ore bodies will be undertaken in order to quantify the isotopic exchange between the ore-forming fluids and carbonaceous host rocks. In combination with fluid inclusion work (including in-situ chemical analyses of the fluid content), the results will provide new insights into the controls on hydrothermal fluid compositions, and the dynamics of this metamorphic (and magmatic?) hydrothermal system in a typical high-T, low-P metamorphic terrain.

Publications

Dziggel, A., Wulff, K., Kolb, J., Meyer, F.M. (2009) Processes of high-T fluid-rock interaction during gold mineralization in carbonate-bearing metasediments: the Navachab gold deposit, Namibia. Mineralium Deposita, doi:10.1007/s00126-009-0231-9.

Dziggel, A., Wulff, K., Kolb, J., Meyer, F.M., Lahaye, Y. (2009) Significance of oscillatory and bell-shaped growth zoning in hydrothermal garnet: evidence from the Navachab gold deposit, Namibia. Chemical Geology, doi:10.1016/j.chemgeo.2009.01.027.


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