We determine crustal shear wave velocity structure and crustal thickness at recently deployed seismic stations across West Antarctica, using a joint inversion of receiver functions and fundamental mode Rayleigh wave phase velocity dispersion. The stations are from both the UK Antarctic Network (UKANET) and Polar Earth Observing Network/Antarctic Network (POLENET/ANET). The former include, for the first time, four stations along the spine of the Antarctic Peninsula, three in the Ellsworth Land and five stations in the vicinity of the Pine Island Rift. Within the West Antarctic Rift System (WARS) we model a crustal thickness range of 18–28 km, and show that the thinnest crust (∼18 km) is in the vicinity of the Byrd Subglacial Basin and Bentley Subglacial Trench. In these regions we also find the highest ratio of fast (V_s = 4.0–4.3 km s^–1, likely mafic) lower crust to felsic/intermediate upper crust. The thickest mafic lower crust we model is in Ellsworth Land, a critical area for constraining the eastern limits of the WARS. Although we find thinner crust in this region (∼30 km) than in the neighbouring Antarctic Peninsula and Haag-Ellsworth Whitmore block (HEW), the Ellsworth Land crust has not undergone as much extension as the central WARS. This suggests that the WARS does not link with the Weddell Sea Rift System through Ellsworth Land, and instead has progressed during its formation towards the Bellingshausen and Amundsen Sea Embayments. We also find that the thin WARS crust extends towards the Pine Island Rift, suggesting that the boundary between the WARS and the Thurston Island block lies in this region, ∼200 km north of its previously accepted position. The thickest crust (38–40 km) we model in this study is in the Ellsworth Mountain section of the HEW block. We find thinner crust (30–33 km) in the Whitmore Mountains and Haag Nunatak sectors of the HEW, consistent with the composite nature of the block. In the Antarctic Peninsula we find a crustal thickness range of 30–38 km and a likely dominantly felsic/intermediate crustal composition. By forward modelling high frequency receiver functions we also assess if any thick, low velocity subglacial sediment accumulations are present, and find a 0.1–0.8-km-thick layer at 10 stations within the WARS, Thurston Island and Ellsworth Land. We suggest that these units of subglacial sediment could provide a source region for the soft basal till layers found beneath numerous outlet glaciers, and may act to accelerate ice flow.

中文翻译：

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接收器函数和瑞利波相速度色散数据的联合反演以估算南极西部的地壳结构

我们使用接收器函数和基模瑞利波相速度色散的联合反演，确定了南极西部最近部署的地震台站的地壳剪切波速度结构和地壳厚度。这些台站既来自英国南极网（UKANET），也来自极地观测网/南极网（POLENET / ANET）。前者第一次包括沿南极半岛脊柱的四个站点，埃尔斯沃思地带的三个站点和派恩岛裂谷附近的五个站点。在西部南极裂谷系统（WARS）中，我们对地壳厚度范围为18-28 km的模型进行了模拟，结果表明最薄的地壳（约18 km）位于伯德冰河盆地和本特利冰河沟附近。在这些地区，我们还发现最快的速动比率（V_s = 4.0–4.3公里s ^–1，可能是铁镁质）下地壳至长英质/中上地壳。我们模拟的最厚的镁铁质下地壳位于Ellsworth Land，这是限制WARS东边界的关键区域。尽管我们发现该地区的地壳（约30公里）比邻近的南极半岛和Haag-Ellsworth Whitmore区块（HEW）薄，但Ellsworth地壳的扩展程度不如中央WARS。这表明WARS没有通过Ellsworth Land与Weddell Sea Rift系统连接，而是在向Bellingshausen和Amundsen Sea Embayments形成过程中取得了进展。我们还发现，薄的WARS地壳向松岛裂谷延伸，这表明WARS和Thurston岛地块之间的边界位于该区域，距先前接受的位置以北约200公里。我们在这项研究中模拟的最厚的地壳（38–40 km）位于HEW区块的埃尔斯沃思山脉地区。我们在HEW的Whitmore山和Haag Nunatak区段发现了较薄的地壳（30-33 km），这与该区块的复合性质一致。在南极半岛，我们发现地壳厚度范围为30-38 km，并且可能主要是长英质/中性地壳组成。通过对高频接收器功能进行正演模拟，我们还可以评估是否存在任何厚的低速冰下沉积物堆积，并在WARS，瑟斯顿岛和埃尔斯沃思地的10个站点发现一个0.1-0.8公里厚的层。我们认为，这些冰川下的沉积物单元可以为大量出口冰川下方的软基底层提供源区，并可能起到加速冰流的作用。