Generation and modification of large-scale post-tectonic batholiths (Donkerhuk granite; Namibia): Incremental growth vs in-situ differentiation

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The proposed project deals with the major and trace element and radiogenic isotope (Sr, Nd, Pb; the latter obtained on acid-leached Kfs) composition of a large-scale apparently undeformed post-tectonic granite in Namibia; the Donkerhuk granite. Available data are incomplete but published major and trace element variations suggest that the various subtypes of granite may have originated from distinct sources and evolved through different processes. On the other hand, the possibility exists that the various subtypes resulted from in-situ differentiation of larger isolated magma batches. The new results will place constraints on possible heterogeneities of the crustal structure beneath the adjacent southern and central Damara orogen and can be used to distinguish second-order processes (e.g., crustal contamination with or without fractional crystallization, magma mixing?) from first-order processes (e.g., partial melting of diverse crustal sources, coupled crust-mantle evolution). The project aims at understanding complex crustal processes at a time where pre-existing continental crust is re-organized and re-processed. These igneous processes are fingerprints of the dynamic melting of diverese crustal sources and is therefore ideally suited to add knowledge on crustal dynamics in general.