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.

中文翻译：

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由海脊-海沟碰撞引起的中央布兰斯菲尔德盆地的弧后延伸：环境噪声断层扫描和应力场反演的意义

布兰斯菲尔德盆地是一个年轻的（~4 Ma）弧后盆地，与凤凰板块的残余俯冲有关，凤凰板块曾经存在于南极半岛的整个太平洋边缘。基于最近部署的两栖地震网络，我们使用环境噪声层析成像来获得S-中央布兰斯菲尔德盆地 (CBB) 的波速结构。结合从焦点机制反转的应力场，我们的图像显示 CBB 在西北-东南方向上有显着的延伸。在 CBB 的东北部，伴随着地幔剥脱作用最强，随着上地壳和岩石圈地幔之间的解耦变形，向西南方向减弱。这种沿走向的伸展变化可以用板状窗口的形成和弧前旋转来解释，这与英雄断裂带西南部山脊 - 海沟碰撞期间凤凰板块的脱离有关。