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BRAVOSEIS: Geophysical investigation of rifting and volcanism in the Bransfield strait, Antarctica
Journal of South American Earth Sciences ( IF 1.8 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.jsames.2020.102834
J. Almendros , W. Wilcock , D. Soule , T. Teixidó , L. Vizcaíno , O. Ardanaz , J.L. Granja-Bruña , D. Martín-Jiménez , X. Yuan , B. Heit , M.C. Schmidt-Aursch , W. Geissler , R. Dziak , F. Carrión , A. Ontiveros , R. Abella , E. Carmona , J.F. Agüí-Fernández , N. Sánchez , I. Serrano , R. Davoli , Z. Krauss , M. Kidiwela , L. Schmahl

Abstract The Bransfield Basin is a back-arc basin located in Western Antarctica between the South Shetland Islands and Antarctic Peninsula. Although the subduction of the Phoenix plate under the South Shetland block has ceased, extension continues through a combination of slab rollback and transtensional motions between the Scotia and Antarctic plates. This process has created a continental rift in the basin, interleaved with volcanic islands and seamounts, which may be near the transition from rifting to seafloor spreading. In the framework of the BRAVOSEIS project (2017–2020), we deployed a dense amphibious seismic network in the Bransfield Strait comprising 15 land stations and 24 ocean-bottom seismometers, as well as a network of 6 moored hydrophones; and acquired marine geophysics data including multibeam bathymetry, sub-bottom profiler, gravity & magnetics, multi-channel seismics, and seismic refraction data. The experiment has collected a unique, high quality, and multifaceted geophysical data set in the Central Bransfield Basin, with a special focus on Orca and Humpback seamounts. Preliminary results confirm that the Bransfield region has slab-related intermediate depth seismicity, with earthquake characteristics suggesting distributed extension across the rift. Gravity and magnetic highs delineate a segmented rift with along-axis variations that are consistent with increased accumulated strain to the northeast. Orca volcano shows evidences of an active caldera and magma accumulation at shallow depths, while Humpback volcano has evolved past the caldera stage and is currently dominated by rifting structures. These differences suggest that volcanic evolution is influenced by the position along the rift. Although a lot of analysis remains, these results provide useful constraints on the structure and dynamics of the Bransfield rift and associated volcanoes.

中文翻译:

BRAVOSEIS:南极布兰斯菲尔德海峡裂谷和火山作用的地球物理调查

摘要 布兰斯菲尔德盆地是一个弧后盆地,位于南设得兰群岛和南极半岛之间的南极洲西部。尽管南设得兰地块下凤凰板块的俯冲已经停止,但通过斯科舍板块和南极板块之间的板块回滚和横张运动的组合,延伸仍在继续。这一过程在盆地内形成了大陆裂谷,与火山岛和海山交错,可能接近裂谷向海底扩张的过渡。在 BRAVOSEIS 项目(2017-2020 年)的框架内,我们在布兰斯菲尔德海峡部署了一个密集的两栖地震网络,包括 15 个陆地站和 24 个海底地震仪,以及一个由 6 个系泊水听器组成的网络;并获得海洋地球物理数据,包括多波束测深、海底剖面仪、重力和磁学、多道地震和地震折射数据。该实验在中央布兰斯菲尔德盆地收集了独特、高质量和多方面的地球物理数据集,特别关注逆戟鲸和座头鲸海山。初步结果证实,布兰斯菲尔德地区具有与板块相关的中深度地震活动,地震特征表明裂谷呈分布延伸。重力和磁高点描绘了一个分段裂谷,沿轴变化与向东北方向增加的累积应变一致。Orca 火山显示了浅层活跃的火山口和岩浆堆积的证据,而驼背火山已经演化过了火山口阶段,目前以裂谷构造为主。这些差异表明火山演化受沿裂谷位置的影响。尽管仍有大量分析,但这些结果为布兰斯菲尔德裂谷和相关火山的结构和动力学提供了有用的约束。
更新日期:2020-12-01
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