The lifecycle of mid-ocean ridge seamounts and their prodigious flank collapses
The lifecycle of mid-ocean ridge seamounts and their prodigious flank collapses
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大洋中脊海山的生命周期及其巨大的侧翼塌陷
DOI：
10.1016/j.epsl.2019.115867
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发表时间：
2020
影响因子：
5.3
通讯作者：
Hunt J
中科院分区：
文献类型：
--
作者：
Hunt J
火山海山是一种壮观的水深地貌，代表着“海底山脉”，其大小可与火山岛相媲美。它们往往是活火山活动的地点，代表着主要的海洋栖息地，并含有具有潜在全球意义的痕量金属商品。然而，我们对它们是如何形成的，它们的火山生命周期的程度，以及它们周期性侧翼坍塌带来的风险知之甚少。在这里，我们研究了在东北大西洋的马德拉深海平原上堆积的火山碎屑和钙质碎屑浊积岩的独特广泛的43Myr记录，这些浊积岩来自于邻近的中大西洋海脊侧翼的大流星-巡洋舰海山综合体的大型海底滑坡。这些浊积物首次记录了单一海山复合体在其整个生命周期中海山侧面坍塌的复发、规模和侵位机制。大流星-邮轮海山复合体的滑坡规模与加那利群岛的滑坡相当，平均体积为30-40公里3，但可达130公里，与许多火山岛滑坡相当。这些海山滑坡主要是多阶段崩塌，类似于邻近火山岛的崩塌，但相反，主要发生在海平面较低的时期。我们表明，地幔热柱上方的火山海山具有很长的生命周期，在发展的所有阶段都有可能发生实质性的侧翼破坏。浊积岩成分的时间变化第一次能够重建开始(大约43-45百万年前)、上升(大约20-25百万年)、浮现(30百万年后)和后来的衰退(最后9百万年)、火山活动停止(过去4百万年)和海山下沉(从2百万年以后)。这些位于地幔羽流之上的海山从一开始就花了大约26迈尔的时间才浮出海平面，而它们的火山岛同时代人只花了2到5迈尔。在这里，我们使用来自海山滑坡的浊积岩的历史来展示海山是如何在其生命周期中发展和遭受大量浪费的。
Volcanic seamounts are spectacular bathymetric features representing ‘undersea mountains’ comparable in size to volcanic islands. They are often sites of active volcanism, represent major marine habitats, and contain potentially globally significant commodities of trace metals. However, we know comparatively little about how they form, the extent of their volcanic lifecycle, and what risks they pose from periodic flank collapse. Here, we study a uniquely extensive 43 Myr record of volcaniclastic and calciclastic turbidites accumulated on the Madeira Abyssal Plain in the NE Atlantic, which originate from large submarine landslides from the adjacent Great Meteor-Cruiser seamount complex on the flanks of the Mid-Atlantic Ridge. These turbidites present the first long-term temporal record of the recurrence, magnitude, and emplacement mechanism of seamount flank collapses from a single seamount complex throughout its lifecycle. Landslides from the Great Meteor-Cruiser seamount complex are comparable size to those from the Canary Islands, with average volumes of 30-40 km3but can be as large as 130 km3, comparable to many volcanic island landslides. These seamount landslides were predominantly multi-stage failures similar to those form neighbouring volcanic islands, but in contrast occurred preferentially during sea-level lowstands. We show that volcanic seamounts above mantle plumes have long protracted lifecycles and that substantial flank failures are capable of occurring at all stages of development. Temporal change in turbidite composition has, for the first time, enabled reconstruction of the inception (around 43-45 Myrs ago), ascension (taking around 20-25 Myrs), emergence (after 30 Myrs) and later recession (last 9 Myrs), cessation in volcanism (last 4 Myrs) and subsidence of the seamounts (from 2 Myrs onwards). These seamounts above a mantle plume have taken around 26 Myrs to emergence above sea level from inception, while their volcanic island contemporaries only took 2-to-5 Myrs. Here, we use the history of turbidites derived from landslides from the seamounts to show how the seamounts developed and suffered mass wasting during their life cycles.
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影响因子：
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作者：
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发表时间：
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