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

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