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Stratigraphy of volcanic rock successions of the North Atlantic rifted margin: the offshore record of the Faroe–Shetland and Rockall basins
Earth and Environmental Science Transactions of the Royal Society of Edinburgh ( IF 1.2 ) Pub Date : 2021-05-26 , DOI: 10.1017/s1755691021000037
David W. JOLLEY , John M. MILLETT , Nick SCHOFIELD , Lena BROADLEY , Malcolm J. HOLE

The integration of biostratigraphical, wireline log, geophysical and available geochronological ages has identified two principal periods of volcanism in the Faroe–Shetland and Rockall basins. The first is pre-breakup, upper Danian to lower Thanetian: in the Rockall and Faroe–Shetland basins, isolated volcanic activity from 62 Ma to 58.7 Ma is identified in areas closely linked to the SSW–NNE structural fabric of the continental margin. Volcanic activity was concentrated at basin flank fissures and localised point sources. This rift-flank volcanism led to widespread volcanic ash deposition, localised lava flow fields and the formation of igneous centres. Some of the Hebridean and onshore central complexes (e.g., Rum) were uplifted and rapidly eroded during the later pre-breakup period, while additional accommodation space was developed in the adjacent offshore basins. Onset and termination of pre-breakup volcanism is correlated to intra-plate stress regimes in Europe, following the cessation of convergence of Africa and Europe in the Danian. The second is syn-breakup, upper Thanetian to Ypresian, initiated at ca.57 Ma in the Rockall and Faroe–Shetland basins. Initial high-volume extrusive igneous successions were focussed to the W in the Faroe–Shetland Basin. In the centre and E of the Faroe–Shetland and Rockall basins, separate eruption loci developed along pre-existing lineaments either as fissure or point-sourced lava fields. Short-term cessation of eruption at ~55.8 Ma was followed by resumption of flood basalt eruptions and a shift in focus to the NW. Fluctuations in the syn-breakup eruption tempo are reflected in the formation and subsequent rejuvenation of prominent unconformities, only previously recognised as a single erosive event. The W and northward shift of eruption focus, and the eruption of mid ocean ridge basalt-type lavas in the syn-breakup period reflect the onset of lithospheric thinning in the nascent North Atlantic Rift prior to flooding of the rift and eruption of the widespread lower Ypresian Balder Formation tephras.

中文翻译:

北大西洋裂谷边缘火山岩层序的地层学:法罗-设得兰和洛克尔盆地的近海记录

生物地层、电缆测井、地球物理和可用的地球年代学年龄的整合确定了法罗-设得兰和洛克尔盆地的两个主要火山活动时期。第一个是破裂前,上大尼安到下塔尼提安:在洛克尔和法罗-设得兰盆地,在与大陆边缘的 SSW-NNE 构造结构密切相关的区域发现了 62 Ma 到 58.7 Ma 的孤立火山活动。火山活动集中在盆地侧面裂隙和局部点源。这种裂谷火山活动导致了广泛的火山灰沉积、局部熔岩流场和火成中心的形成。一些赫布里底和陆上中心复合体(例如,朗姆酒)在分裂前后期被抬升并迅速侵蚀,同时在邻近的近海盆地开发了额外的住宿空间。随着非洲和欧洲在达尼安的汇合停止,分裂前火山活动的开始和结束与欧洲的板内应力状态相关。第二个是syn-breakup,从上Thanetian到Ypresian,开始于57 Ma 在 Rockall 和 Faroe-Shetland 盆地。最初的大量喷出火成岩层系集中在法罗-设得兰盆地的 W 方向。在法罗-设得兰和洛克尔盆地的中部和东部,沿着预先存在的线状线发展了单独的喷发地点,无论是裂缝还是点源熔岩场。大约 55.8 Ma 的短期喷发停止,随后恢复了洪水玄武岩喷发,并将焦点转移到 NW。同步破裂喷发速度的波动反映在显着不整合的形成和随后的再生中,以前只被认为是一个单一的侵蚀事件。喷发焦点的W和北移,
更新日期:2021-05-26
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