Tectonics of an extinct ridgetransform intersection, Drake Passage (Antarctica

• Main Authors: Andrés Maldonado, Juan Carlos Balanyá, Antonio Barnolas, Jesús Galindo-zaldívar, Javier Hernández, Antonio Jabaloy, Roy Livermore, José Miguel Martínez-martínez, Carlos Sanz De Galdeano, Luis Somoza, Emma Suriñach
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2000
• Subjects: Drake Passage; Shackleton; Shackleton Fracture Zone; West Scotia Ridge; Antarc*; Antarctica
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.379.6520; http://hera.ugr.es/doi/1501938X.pdf

Key words: Drake Passage, oceanic crust stratigraphy, ridge-transform intersection, tectonics New swath bathymetric, multichannel seismic and magnetic data reveal the complexity of the intersection between the extinct West Scotia Ridge (WSR) and the Shackleton Fracture Zone (SFZ), a first-order NW-SE trending high-relief ridge cutting across the Drake Passage. The SFZ is composed of shallow, ridge segments and depressions, largely parallel to the fracture zone with an ‘en echelon ’ pattern in plan view. These features are bounded by tectonic lineaments, interpreted as faults. The axial valley of the spreading center intersects the fracture zone in a complex area of deformation, where N120 ◦ E lineaments and E–W faults anastomose on both sides of the intersection. The fracture zone developed within an extensional regime, which facilitated the formation of oceanic transverse ridges parallel to the fracture zone and depressions attributed to pull-apart basins, bounded by normal and strike-slip faults. On the multichannel seismic (MCS) profiles, the igneous crust is well stratified, with numerous discontinuous highamplitude reflectors and many irregular diffractions at the top, and a thicker layer below. The latter has sparse and weak reflectors, although it locally contains strong, dipping reflections. A bright, slightly undulating reflector observed below the