Abstract
A total of 1.500 km of multichannel seismic reflection profiles recorded aboard B/O Hesperides using a seven gun array and a 96 channel streamer during the austral summer of 1991-1992 were used to study four structural provinces on the Antarctic and Scotia plates. These provinces which differ in structural style and crustal character include:
I. Bransfield Trough, a half-graben in the back of the South Shetland trench/island arc with the master fault on the Antarctic Peninsula side and a chain of volcanic structures along its axis. It was formed either by a combination of continental rifting and back-arc sea-floor spreading and the volcanic chain along its axis represents a poorly organized spreading axis or by continental extension due either to a 110 º bend in the Scotia-Antarctic plate boundary in the vicinity of Clarence Island or to complex plate interactions in the northern Antarctic Peninsula.
II. South Scotia Ridge, a chain of highs and depressions along the boundary between the Scotia and Antarctic plates. It consists of continental crustal fragments transported eastward from their original position along the South America-Antarctic isthmus during the opening of Drake Passage about 29 Ma ago.
III. The Scotia Sea. This structural province, north of the South Scotia Ridge has an oceanic crust. The surface of the crust is quite rough and in places it displays sub-crustal reflections. On two of the three profiles crossing of the South Scotia Ridge boundary there is evidence of compression due to local convergence along the Scotia-Antarctic plate boundary.
IV. Powell Basin. This basin located within the Antarctic plate was formed by back-arc spreading shortly before the collision of a spreading axis with a trench east of Jane Bank about 20 Ma. Except for a few local swells the basement surface lacks the relief typical of oceanic basement which is found in the Scotia Sea. This smooth surface could represent the top of a sequence of volcanics and sediments resting on oceanic crust.
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Vegas, R., Acosta, J., Uchupi, E. (1995). Continental-Oceanic Crustal Transition in the Bransfield Trough and the South Scotia Ridge (Antarctica); Preliminary Results. In: Banda, E., Torné, M., Talwani, M. (eds) Rifted Ocean-Continent Boundaries. NATO ASI Series, vol 463. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-0043-4_15
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DOI: https://doi.org/10.1007/978-94-011-0043-4_15
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