Geology of Afar (East Africa) (Regional Geology Reviews)

This book summarizes the geological knowledge accumulated on Afar in the last 60 years, demonstrating that it is, and will remain, a real “hot spot” for geological and geophysical research. It provides insights into the Earth processes along diverging plate boundaries, the study of both the continental and oceanic lithosphere and underlying asthenosphere, and margins and transitions including magmatic, volcanic, tectonic, sedimentary, hydrothermal and geodynamic processes. The Afar triangle is a geological depression that developed where the Gulf of Aden, Red Sea and East African Rift Valley meet. It is considered to be one of the Earth system’s most important mantle plumes. In 1967, when the first expedition was organized, there was little information on the geology of the area, and even geographic base maps were lacking. However, the first satellite photographs from the Apollo and Gemini space missions offered a complete picture of the Red Sea-Gulf of Aden region, providing a new vision of the Afar triangle. The book describes the unique geological features that make Afar the only place in the world where an oceanic plate boundary with all its successive steps of development can be observed in the open air. It also presents the Afar triangle as one of the cradles of first, now extinct hominids. The Middle Awash area contains sites of several fossil discoveries, such as the well-known Lucy. The hydrothermal processes in Afar provide conditions suitable for the study of the most primitive forms of life (archaebacterial) and it is also one of the few places where significant quantities of telluric energy are available at the surface for geothermal development. Further, the area has economically interesting mineral deposits and illustrates a number of current climate change issues. In addition to providing geological information, the book shows that Afar is an area where an individual human population developed with its own language and culture, and which adapted to the rugged landscape and extremely dry and hot climate. It is a valuable resource for scientists and students, and also serves the needs of the Afar nation, currently split in three different countries as a result of recent historical events. Annotation This book summarizes the geological knowledge accumulated on Afar in the last 60 years, demonstrating that it is, and will remain, a real "hot spot" for geological and geophysical research. It provides insights into the Earth processes along diverging plate boundaries, the study of both the continental and oceanic lithosphere andunderlying asthenosphere, and margins and transitions including magmatic, volcanic, tectonic, sedimentary, hydrothermal and geodynamic processes. The Afar triangle is a geological depression that developed where the Gulf of Aden, Red Sea and East African Rift Valley meet. It is considered to be one of the Earth system's most important mantle plumes. In 1967, when the first expedition was organized, there was little information on the geology of the area, and even geographic base maps were lacking. However, the first satellite photographs from the Apollo and Gemini space missions offered a complete picture of the Red Sea-Gulf of Aden region, providing a new vision of the Afar triangle. The book describes the unique geological features that make Afar the only place in the world where an oceanic plate boundary with all its successive steps of development can be observed in the open air. It also presents the Afar triangle as one of the cradles of first, now extinct hominids. The Middle Awash area contains sites of several fossil discoveries, such as the well-known Lucy. The hydrothermal processes in Afar provide conditions suitable for the study of the most primitive forms of life (archaebacterial) and it is also one of the few places where significant quantities of telluric energy are available at the surface for geothermal development. Further, the area has economically interesting mineral deposits and illustrates a number of current climate change issues. In addition to providing geological information, the book shows that Afar is an area where an individual human population developed with its own language and culture, and which adapted to the rugged landscape and extremely dry and hot climate. It is a valuable resource for scientists and students, and also serves the needs of the Afar nation, currently split in three different countries as a result of recent historical events Front Matter ....Pages i-xviii Front Matter ....Pages 1-1 Global and Regional Geodynamic Context (Jacques Varet)....Pages 3-12 Relief, Climate, People, Languages, Toponymy and Exploration History (Jacques Varet)....Pages 13-38 Geophysical Frame: Mantle Plume(s), Triple Points, Rifting Processes (Jacques Varet)....Pages 39-54 Front Matter ....Pages 55-55 Pre-quaternary Geological Frame (Jacques Varet)....Pages 57-92 First Stage of Oceanisation of the Afar Floor: The Stratoid Series (4–1 Million Years Ago) (Jacques Varet)....Pages 93-104 Front Matter ....Pages 105-105 Axial Volcanic Ranges (Jacques Varet)....Pages 107-204 Recent and Active Units of the Danakil Sea (Dagad Salt Plain) and Afdera Lake (Jacques Varet)....Pages 205-226 Central Silicic Volcanoes of the Afar Margins (Jacques Varet)....Pages 227-239 Transverse Volcanic Alignments Along Afar Margins (Jacques Varet)....Pages 241-251 Southern Afar: The Main Ethiopian Rift (MER) Northern Extremity (Jacques Varet)....Pages 253-281 Front Matter ....Pages 283-283 Afar, a Hot-Spot for Earth’s Geodynamics Studies (Jacques Varet)....Pages 285-293 Geological Resources and Socio-Economic Issues (Jacques Varet)....Pages 295-321 Afar, One Geology, One Culture, Spread in Three Countries, at Present a Melting Pot (Jacques Varet)....Pages 323-324 Back Matter ....Pages 325-336