Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics |
| |
| Authors: | Ute Weckmann |
| |
| Institution: | (1) Helmholtz Centre Potsdam, German Research Centre for Geosciences GFZ, Telegrafenberg, 14473, Potsdam, Germany |
| |
| Abstract: | The African continent inherits a long history of continental accretion and breakup. The stage of “making” a continent goes
back to the Archean, when the first continental masses formed cratons which mostly remained stable ever since. Subsequent
collision of weaker continental masses was followed by several extension and compression episodes that resulted in the formation
of super-continents. After the assemblage of Gondwana, a period of predominantly “breaking” , i.e., the breakup of super-continents,
took over. The modern-day African continent exhibits different types of margins; continental rifting occurs side by side with
recent collision. Since the late 1960s, magnetotelluric (MT) experiments have played an important role in studies of the electrical
conductivity structure of Africa. The early results significantly shaped the MT community’s understanding of continental-scale
conductivity belts and basic characteristics of cratons and mobile belts on both crustal and lithospheric mantle scales for
some decades. Modern MT studies in Africa have generally supported earlier results with high resistivities observed on cratons
and low resistivities observed across mobile belts. Advances in instrumentation, data processing and interpretation resulted
in higher-resolution images of the lithosphere, which in consequence induce an improved understanding of tectonic processes
and geological prerequisites for the occurrence of natural resources. The high electrical conductivity of mobile belts and
their relation to reactivated fault and detachment zones were often interpreted to characterize mobile belts as tectonic weak
zones, which can accommodate stress and constitute zones along which continents can break. Recent breaking of the African
continent can be studied on land across the East African rift; however, the lack of amphibian MT experiments across today’s
margins does not allow for good resolution of remnants of continental breakup processes. Naturally, the regions and the focus
of the MT studies in Africa are diverse, but they all contribute to the story of making and breaking a continent. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
