Volcanism and Evolution of the African Lithosphere (GSA Special Paper 478)

The distribution of volcanism in the African plate is the surface expression of a variety of processes, many of which are poorly understood, involving interaction between the lithosphere and the underlying convective mantle. Despite the maturity of the plate tectonic paradigm, our knowledge of the processes involved in the breakup of continents and the formation of new ocean basins remains limited. The African Rift system provides a unique natural laboratory to study the transition from continental breakup to seafloor spreading. Thus, it is important to explore the similarities among the volcanic provinces of the Saharan zone, Cameroon volcanic line, Angola and Namibia, and the East African Rift system. The aim of this volume is to bring together recent and updated contributions on African volcanism (and associated mantle xenoliths), providing multidisciplinary contexts that include volcanology, geochemistry, petrology, geophysics, and structural geology, for a better understanding of the geological evolution of the African lithosphere. Volcanism and Evolution of the African Lithosphere......Page 1 Front matter......Page 2 ISBN 978-0-8137-2478-2......Page 3 Contents......Page 4 Preface and Acknowledgments......Page 6 01- Late Mesozoic to Quaternary intraplate magmatism and its relation to the Neoproterozoic lithosphere in NE Africa— New data from lower-crustal and mantle xenoliths from the Bayuda volcanic field, Sudan......Page 8 02- Holocene opening directions along the axes of the Red Sea (Afar) and Main Ethiopian Rifts: An overview......Page 32 03- The upper-mantle low-velocity anomaly beneath Ethiopia, Kenya, and Tanzania: Constraints on the origin of the African superswell in eastern Africa and plate versus plume models of mantle dynamics......Page 44 04- The Ethiopia Afar Geoscientifi c Lithospheric Experiment (EAGLE): Probing the transition from continental rifting to incipient seafloor spreading......Page 58 05- Peridotite xenoliths from Ethiopia: Inferences about mantle processes from plume to rift settings......Page 84 06- Evolution of the lithospheric mantle beneath the East African Rift in Tanzania and its potential signatures in rift magmas......Page 112 07- Petrology and geochemistry of alkaline lava series, Kilimanjaro, Tanzania: New constraints on petrogenetic processes......Page 134 08- Trace-element distribution between coexisting aqueous fumarole condensates and natrocarbonatite lavas at Oldoinyo Lengai volcano, Tanzania......Page 166 09- Cameroon Line alkaline magmatism (central Africa): A reappraisal......Page 180 10- Mineralogical and geochemical fingerprints of mantle metasomatism beneath Nyos volcano (Cameroon volcanic line)......Page 200 11- Dolomitic volcanism in Zambia: Cr and K signatures and comparisons with other dolomitic melts from the mantle......Page 218 12- Post-Paleozoic magmatism in Angola and Namibia: A review......Page 230 13- Is the African cratonic lithosphere wet or dry?......Page 256 14- New 40Ar-39Ar ages and petrogenesis of the Massif d’Ambre volcano, northern Madagascar......Page 264 15- Metasomatism versus host magma infiltration: A case study of Sal mantle xenoliths, Cape Verde Archipelago......Page 290 16- Magmatic evidence for African mantle propagation into the southern Tyrrhenian backarc region......Page 314 Back cover......Page 340