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1 Institut für Geowissenschaften, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany, and Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany
2 Institut für Geowissenschaften, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
3 Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany
4 School of Mines, University of Zambia, P.O. Box 32379, Lusaka, Zambia
Precambrian eclogites, metagabbros, and gabbros occur in an 
200-km-long by 40-km-wide zone in central Zambia. Pressure-temperature (P-T) estimates of kyanite-bearing eclogites (kyanite eclogites) throughout the zone give temperatures of 590–750 °C at minimum pressures of 20 kbar. Phengite-bearing eclogites equilibrated at 720–755 °C and 26–28 kbar and show evidence for a clockwise P-T path. These P-T conditions imply a low geothermal gradient of 8 °C/km and a subduction depth of 90 km. The eclogites, metagabbros, and gabbros show incompatible element patterns similar to those of recent mid-oceanic-ridge basalts, and thus are interpreted to represent former oceanic crust. The low geothermal gradient indicates a cold subducted oceanic lithosphere, implying long-lived, fast convergence and a relatively large (>1000 km) associated ocean basin. A Sm-Nd isochron defines an age of 595 ± 10 Ma for the eclogite facies metamorphism. These results imply that a Neoproterozoic suture zone exists between the Congo and Kalahari cratons. Suturing occurred during the same orogenic cycle that formed the Zambezi belt and is related to the assembly of Gondwana.
Key Words: eclogites • Gondwana assembly • Neoproterozoic • Rodinia breakup • suture zone
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