Geochemical Analysis and Integrated Modelling of Basalt Samples from V-Shaped Ridges of North Atlantic Ocean

北大西洋 V 形海脊玄武岩样品的地球化学分析和综合模拟

• 批准号: NE/W007150/1
• 负责人: Nicholas White
• 金额: $ 3.21万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FW007150%2F1
• 关键词: Geochemical; Analysis; Integrated; Modelling; Basalt

Deep within the Earth's interior underneath Iceland there sits a gigantic hot upwelling or plume. This plume is the biggest on Earth and has been in existence for about sixty million years. It has had a profound effect upon the shape of the seabed beneath the North Atlantic Ocean which is about two kilometres shallower than it should be. The existence of this plume also explains why the British Isles stick up in the air. There is considerable interest in the way these hot plume change over time. Luckily, the North America tectonic plate and the European tectonic plate are spreading apart exactly on top of the Icelandic plume. As a result, we have a really convenient window into the way in which this particular plume evolves over time. Changes within the plume are faithfully recorded by thickened trails of crust along the ocean floor. This summer, a group of scientists will sail into the middle of the Atlantic Ocean south of Iceland and drill holes into these crustal trails. These holes will be about ten centimetres across and hundreds of metres deep. The samples of lava recovered by this complex operation provide an invaluable record of the way temperature has changed through time deep within the plume's interior. In that sense, we will be using the rock samples as plume thermometers. Once the samples are recovered, we will bring them back to the lab and measure concentrations of familiar elements such as iron, potassium, lead and many others. These concentrations will be used to aid computer modeling of deep temperature changes. In the end, we will be able to take the 'pulse' of the Icelandic plume over many millions of years. The final piece of the jigsaw puzzle concerns how plume activity has made the seabed around Iceland bob up and down over long periods of time. This bobbing about has affected how deep water currents flow southwestward from the Greenland-Norwegian Sea into the rest of the Atlantic Ocean. It is a bit like a canal lockgate mechanism where the ridge between Greenland and Scotland that crosses Iceland moves up and down. This motion affects how much deep water escapes into the rest of the Atlantic Ocean. Fossil bugs that once lived on the seabed and which are can be sampled in exactly the same hole that are drilled into lava help us to measure how much deep water flows across the canal lockgate at different times in the past. This trick works because the bugs once lived in deep water and made their shells from the tiny amounts of calcium carbonate dissolved in that deep water. When the flow of deep water shuts on and off, the bugs inadvertently record these changes in the composition of their shells. Hey Presto! Our ultimate goal is to link the bobbing of the seafloor which changes deep water flow with the throbbing pulse of the hot plume.In this way, we hope to show how processes going on deep within the Earth influence ocean currents which in turn control our climate.

冰岛下面的地球内部深处坐着巨大的热上升或羽流。这种羽流是地球上最大的羽流，已经存在约600万年。它对北大西洋下面的海底的形状产生了深远的影响，北大西洋的形状比应有的浅约两公里。这种羽流的存在也解释了为什么不列颠群岛悬在空中。这些热羽流随时间变化的方式引起了极大的兴趣。幸运的是，北美构造板块和欧洲构造板正好散布在冰岛羽流的顶部。结果，我们有一个非常方便的窗口，该窗口随着时间的流逝而演变的方式。羽流内的变化是通过沿海底的地壳增厚的地壳忠实记录的。今年夏天，一群科学家将航行到冰岛南部大西洋中部，并钻进这些地壳小径。这些孔将大约有十厘米的深度。这种复杂操作回收的熔岩样品为温度在羽流的内部深处变化提供了宝贵的记录。从这个意义上讲，我们将使用岩石样品作为羽流温度计。恢复样品后，我们将将它们带回实验室，并测量熟悉的元素的浓度，例如铁，钾，铅等。这些浓度将用于辅助深度温度变化的计算机建模。最后，我们将能够在数百万年内采用冰岛羽流的“脉搏”。拼图游戏的最后一部分涉及羽流活动如何使冰岛周围的海床长时间上下摇摆。这种摇摆不定，从而影响了从格陵兰 - 北北海向西南流动到大西洋其他地区的深水流。这有点像一种运河洛克盖特机构，越过冰岛的格陵兰和苏格兰之间的山脊在上下移动。这一运动影响了多少深水逃到大西洋的其他地方。曾经生活在海床上并可以在熔岩钻入熔岩的完全相同的孔中采样的化石虫子有助于我们在过去的不同时间衡量在运河Lockgate上流过多少深水。这种技巧之所以起作用，是因为这些虫子曾经生活在深水中，并用少量碳酸钙溶解在深水中的碳酸钙。当深水的流动闭合和关闭时，这些虫子无意中记录了这些变化的壳。嘿，普雷斯托！我们的最终目标是将海底的波动与热羽流脉冲的变化脉动联系起来。这样，我们希望展示地球深处的过程如何影响洋流，从而控制我们的气候。