PT Unknown
AU Bial, J
TI The Mesoproterozoic evolution of the central Namaqua Metamorphic Complex (South Africa and Namibia) : Petrology, geochemistry and geochronology
PY 2015
PU Christian-Albrechts-Universität zu Kiel
WP https://macau.uni-kiel.de/receive/diss_mods_00016435
LA en
DE Namaqua Metamorphic Complex; HT-metamorphism; back arc basin; HT-Metamorphose; Back Arc Becken
AB The Namaqua Metamorphic Complex (NMC), a Mesoproterozoic orogenic belt in western South Africa and southern Namibia, developed during the amalgamation of the supercontinent Rodinia (1.3 – 1.0 Ga). The metamorphic belt along the western and southern margins of the Kaapvaal Craton is of low-pressure amphibolite to granulite facies. Several authors described since the 1980s two high-grade metamorphic events at ~1200 Ma and ~1000 Ma, which coincide in age with two of three stages of granitoid emplacement at 1220 – 1180 Ma, ~1100 Ma and 1040 – 1020 Ma. The latter of these magmatic stages exits only in western Namaqua. However, the timing of the high-temperature metamorphism reaching > 800 °C is still controversial discussed and the reasons for the unusual high geotherms are unresolved. Collisional settings have often been proposed as geodynamic model for the development of the NMC, although direct evidences, such as mafic rocks that could be interpreted as former ophiolites, high-pressure rocks, alpine-style nappe tectonics, or orogenic suture zones, are missing. This renders the problem of the tectonic setting of the NMC in the Mesoproterozoic largely unresolved. This thesis aims to solve some of the open questions regarding the formation processes of the NMC by using petrography, texturally controlled in situ dating techniques to combine metamorphic textures with age results and geochemistry of rocks from the central NMC (Kakamas Terrane)...
PI Kiel
ER