Abstract The Sea Point intrusive contact on the Atlantic coast, South Africa, is a site of historical significance that continues to be useful for studying the details of granite–wall rock relationships, some of which have not been properly evaluated yet. At a time when the origin of granites was still controversial, and the concept of contact metamorphism not yet properly developed, Charles Darwin visited the Sea Point contact to make some geologically important observations. He concluded that the granite originated as a magma deep in the Earth, intruded a country rock of sedimentary origin and changed this country rock's appearance owing to the thermal action of the hot granite magma. He also contemplated the long periods of time required to expose the rocks by erosion. Besides its historic value, the Sea Point heritage site exposes unique features giving rare insights into the physical and chemical interaction between intruding granitic magma and a regionally low-grade metamorphosed sedimentary sequence. Questions regarding mechanisms of magmatic emplacement may be answered from this outcrop, including emplacement dynamics and interrelationships of various granitic phases, pre- versus syn-intrusive deformation and metamorphism, assimilation of country rock by a granitic magma and the origin of feldspar phenocrysts seemingly ‘stranded’ in the country rock.

The present contribution synthesizes the main petrographic, mineralogical and chemical features of mantle xenoliths uplifted by Phanerozoic lavas. The collections of mantle xenoliths consist predominantly of peridotites but minor pyroxenites are commonly associated. Two main petrogenetic processes are responsible for the features of mantle xenoliths: partial melting and circulation of melts/fluids and associated metasomatic and magmatic processes. Partial melting processes lead to the formation of residual pieces of upper mantle while two main types of mantle metasomatism could be recognized such as LILE enrichment, the first referring to asthenosphere upwelling settings (essentially mantle plumes, rifting zones and asthenosphere window zones) and the second to mantle wedge settings. The AUZ (asthenospheric upwelling zones) metasomatism is essentially related to the migration of more or less CO 2 -rich alkaline silicate melts and associated fluids while the MWZ (mantle wedge zones) metasomatism is associated with the activity of hydrated liquids (fluids) commonly SiO 2 -rich.