1Sea-floor spreading and deformation processes in the South Atlantic Ocean: An evaluation of the role of mantle hotspots

• Main Authors: Marjorie Wilson, Derek J. Fairhead
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Crest The; Mid-Atlantic Ridge; South Atlantic Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.584.9493; http://www.mantleplumes.org/Penrose/PenPDFAbstracts/Wilson_Marge_abs1.pdf

Recent improvements in our ability to enhance the resolution of satellite-derived marine gravity data (Geosat and ERS1) from 30-40 km down to ~10 km wavelength, has provided a unique opportunity to look in detail at the complex tectono-magmatic processes involved in the opening of the South Atlantic Ocean. This improvement in resolution has been achieved by innovative research and development funded by an oil industry consortium study conducted by the Leeds University spin-off company GETECH [1-3]. Application of new methodologies, developed as part of the above research, can significantly improve our understanding of oceanic crust-forming processes, particularly the role of near-ridge mantle hotspots and intra-plate deformation, hitherto impossible to resolve fully with current datasets. Our current knowledge, based on existing research, indicates that slow-spreading mid-ocean ridges such as the Mid-Atlantic Ridge are strongly segmented along their axes by transform faults (Fig. 1). In the South Atlantic these transform faults are typically spaced some 50-100 km apart, reflect the relative plate motion directions of the newly formed crust and occur at offsets of the normal faulted median rift valley that marks the axis of the ridge. The sites of these active transforms are regions of decreased magma generation, resulting in the transform zone being starved of volcanism and expressed as a deep trough in the oceanic crust. At greater distance from the ridge crest, the transform motion ceases. This change