Morphostructure and evolution of the central and eastern Bransfield basins (NW Antartic Peninsula).

GRACIA, E.; CANALS, M.; FARRÁN, M.; PRIETO, M. J.; SORRIBAS, J.; ACOSTA, J.; BARAZA, J.; BART, P.; CALAFAT, A.; CASAMOR, J. L.; DE BATIST, M.; ERCILLA, G.; FRANCES, G.; RAMOS, E.; SANZ, J. L.; TASSONE, A

MARINE GEOPHYSICAL RESEARCHES

SPRINGER

Año: 1996 vol. 18 p. 429 - 448

0025-3235

The Bransfield Basin is a narrow and elongated active rift basin located between the Antarctic Península and the South Shetland Islands. The Bransfield Basin is composed of three small basins, and two of them, the Central and Eastern Bransfield Basins, were surveyed during a recent cruise (GEBRA 93). The full swath bathymetry coverage as well as the single-channel seismic reflection and magnetic profiles that have been acquired, help us to better understand the morphostructure and recent evolution of the Brans­field Basin. Six large volcanic edifices aligned with the basin axis stick out of the sedimented seafloor of the Central Bransfield Basin. ln contrast, the Eastern Bransfield Basin is characterised by four deep troughs displaying a rhombic-shape, and small, scattered vol­canic cones located in the southwestern half basin. Seamount volcan-ism plays an important role in the formation of new crust in the Bransfield Basin. The larger seamounts of the Central Bransfield Basin are located at the intersection of the two main orthogonal setsoffaults (longitudinal ENE-WSW and transversal NNW-SSE). Morphological analysis of the seamounts indicates a multi-staged volcano-tectonic construction. The distribution and shape of these edifices suggests that both volcanism and extensión are concentrated at the same preferential áreas through time. This might be related to the fracturation style of the continental crust. The Central and Eastern Bransfield Basins are very different in morphostructure, volcanism, and sedimentary cover. The Central Bransfield Basin shows evidence of NW-SE extensional faulting and focused active MORB-volcanism interpreted as result of incipient seafloor spreading. The Eastern Bransfield Basin is still in a rifting stage, mainly dominated by a NW-SE extensión and some left-lateral strike-slip component probably related to the South Scotia Ridge