Inhaltszusammenfassung

New structural data from Elephant Island and adjacent islands are presented with the objective to improve the understanding of subduction kinematics in the area northeast of the Antarctic Peninsula. On the island, a first deformation phase, D1, produced a strong SL fabric with steep stretching and mineral lineations, partly defined by relatively high pressure minerals, such as crossite and glaucophane. D1 is interpreted to record southward subduction along an E–W trench with respect to the pr...New structural data from Elephant Island and adjacent islands are presented with the objective to improve the understanding of subduction kinematics in the area northeast of the Antarctic Peninsula. On the island, a first deformation phase, D1, produced a strong SL fabric with steep stretching and mineral lineations, partly defined by relatively high pressure minerals, such as crossite and glaucophane. D1 is interpreted to record southward subduction along an E–W trench with respect to the present position of the island. A second phase, D2, led to intense folding with steep E–W-trending axial surfaces. The local presence of sinistral C′-type shear bands related to this phase and the oblique inclination of the L2 stretching lineations are the main arguments to interpret this phase as representing oblique sinistral transpressive shear along steep, approximately E–W-trending shear zones, with the northern (Pacific) block going down with respect to the southern (Antarctic Peninsula) block. The sinistral strike-slip component may represent a trench-linked strike-slip movement as a consequence of oblique subduction. Lithostatic pressure decreased and temperature increased to peak values during D2, interpreted to represent the collision of thickened oceanic crust with the active continental margin. The last deformation phase, D3, is characterised by post-metamorphic kink bands, partially forming conjugate sets consistent with E–W shortening and N–S extension. The rock units that underlie the island probably rotated during D3, in Cenozoic times, together with the trench, from an NE–SW to the present ENE–WSW position, during the progressive opening of the Scotia Sea. The similarity between the strain orientation of D3 and that of the sinistral NE–SW Shackleton Fracture Zone is consistent with this interpretation.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
3.31 - Mathematik

DDC Sachgruppe:
Geowissenschaften