Back-Arc Extension of the Central Bransfield Basin Induced by Ridge–Trench Collision: Implications From Ambient Noise Tomography and Stress Field Inversion


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Mechita.Schmidt-Aursch [ at ] awi.de

Abstract

The Bransfield Basin is a young (∼4 Ma) back-arc basin related to the remnant subduction of the Phoenix Plate that once existed along the entire Pacific margin of the Antarctic Peninsula. Based on a recently deployed amphibious seismic network, we use ambient noise tomography to obtain the S-wave velocity structure in the Central Bransfield Basin (CBB). Combining with the stress field inverted from focal mechanisms, our images reveal that the CBB suffers a significant extension in the northwest-southeast direction. The extension is strongest in the northeastern CBB with associated mantle exhumation and weakens to the southwest with decoupled deformations between the upper crust and lithospheric mantle. Such an along-strike variation of extension can be explained by slab window formation and forearc rotation, which are associated with the Phoenix Plate detachment during the ridge–trench collisions at the southwest of the Hero Fracture Zone.



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Helmholtz Cross Cutting Activity (2021-2027)
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Peer-reviewed
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Published
Eprint ID
54835
DOI 10.1029/2021GL095032

Cite as
Li, W. , Yuan, X. , Heit, B. , Schmidt-Aursch, M. C. , Almendros, J. , Geissler, W. H. and Chen, Y. (2021): Back-Arc Extension of the Central Bransfield Basin Induced by Ridge–Trench Collision: Implications From Ambient Noise Tomography and Stress Field Inversion , Geophysical Research Letters, 48 (21) . doi: 10.1029/2021GL095032


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