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一个地下海洋？科学家发现地球深处有水_我的网站

一 |     法兰克福歌德大学地球科学研究所的Frank Brenker 教授解释说：“这些矿物的转变极大地阻碍了地幔中岩石的运动。

二 |     LONDON -- A crane on tracks was removing a much-loved tree Thursday from the place near the Roman landmark of Hadrian’s Wall in northeastern England where the sycamore was cut down two weeks ago in an apparent act of vandalism.The National Trust, which seeks to protect England’s heritage and natural landscapes, said the crane will lift the often-photographed and painted tree, which some believe to have been around 300 years old, from where it lies near the delicate and now-damaged wall. Andrew Poad, the site’s general manager for the National Trust, said it was necessary to move the tree “both to preserve the world-famous monument that is Hadrian’s Wall, and to make the site safe again for visitors.”Though the 50-foot (15-meter) tree is too big to move in one piece, experts hope the trunk can be kept in large sections in order to leave future options open on what could be done. The stump, which could generate new shoots, will be kept in place and is currently behind a protective barrier. Seeds have also been collected to see if they could be used to propagate new saplings.“We’ve explored every option for moving the tree and while it isn’t possible to lift it in one go, as the tree is multi-stemmed with a large crown, we have aimed to keep the trunk in as large sections as possible, to give us flexibility on what the tree becomes in future," Poad said.Northumbria Police arrested a 16-year-old boy and a man in his 60s after the tree was felled a fortnight ago. They were released on bail pending further inquiries into what a chief detective described as the “senseless destruction” of the tree.The tree was one of the main landmarks along Hadrian’s Wall, a UNESCO World Heritage Site built nearly 2,000 years ago, when Britain was part of the Roman Empire, to guard its northwestern frontier. For generations, walkers have paused to admire and photograph the tree at Sycamore Gap, which was made famous when it appeared in Kevin Costner’s 1991 film “Robin Hood: Prince Of Thieves.”The tree, which was cut down near the base of its trunk, could grow again, experts said, though they cautioned that it would never be the same.The National Trust has received thousands of messages about the tree, with advice on what to do with the stump and suggestions of what could be done with the felled tree, including making benches from the wood, a sculpture or souvenirs to sell.There will be a public consultation about what happens next at the site.。

三 | 例如，地幔羽流--从深层地幔上升的热岩柱--有时会直接停在过渡带下面。相反方向的质量运动也会停顿下来。俯冲板块往往难以突破整个过渡区。

四 | 因此，在欧洲下面的这个区域，有一整个这样的板块的‘墓地’。”然而，直到现在，人们还不知道“吸入”过渡带的物质对其地球化学成分的长期影响是什么，以及那里是否存在更大量的水。Brenker解释说。“俯冲板块还将深海沉积物捎带着带入地球的内部。这些沉积物可以容纳大量的水和二氧化碳。但是直到现在还不清楚到底有多少以更稳定的水合物矿物和碳酸盐的形式进入过渡带--因此也不清楚大量的水是否真的储存在那里。”目前的情况无疑会有利于此。厚重的矿物瓦茨利石和林伍德石可以容纳大量的水（与较低深度的橄榄石不同），以至于假设过渡带可以吸收我们海洋中六倍的水量。“所以我们知道边界层有巨大的储水能力，”Brenker说。“然而，我们不知道它是否真的这样做了。”现在，一项国际研究已经提供了答案。该研究小组分析了来自非洲博茨瓦纳的一颗钻石。它起源于660公里的深度，直接位于过渡带和下地幔之间的界面，那里的主要矿物是林伍德石。

五 | 来自这一地点的钻石非常罕见，甚至在极其罕见的超深产地的钻石中也是如此，这些钻石只占所有钻石的1%。研究发现，由于存在许多林伍德石内含物，该宝石的含水量很高。研究小组还能够确定该石头的化学成分。

六 | 它几乎与世界上任何地方的玄武岩中发现的几乎所有地幔岩石碎片的化学成分完全相同。这表明该钻石肯定来自于地球地幔的一个正常片段。“在这项研究中，我们证明了过渡区不是一块干燥的海绵，而是拥有相当数量的水，”Brenker说，并补充道。“这也使我们离Jules Verne关于地球内部的海洋的想法又近了一步。

七 | ” 不同的是，那里没有海洋，而是水合岩石，根据Brenker的说法，水合岩石既不会感到潮湿，也不会滴水。早在2014年科学家们就在过渡带的一颗钻石中首次检测到了水合林伍德石。Brenker也参与了这项研究。然而，由于该钻石太小，不可能确定它的精确化学成分。

八 | 因此，仍然不清楚第一项研究对整个地幔的代表性，因为那颗钻石的水含量也可能是由一个奇特的化学环境造成的。

九 | 相比之下，研究小组在本研究中调查的来自博茨瓦纳的1.5厘米（0.6英寸）的钻石中的包裹体足够大，可以确定精确的化学成分，这为2014年的初步结果提供了最终确认。过渡带的高水含量对地球内部的动态情况有着深远的影响。这导致了什么，例如，在来自下面的热地幔羽流中可以看到，这些羽流被困在过渡带。在那里，它们加热了富含水分的过渡带，这反过来又导致了新的较小的地幔羽流的形成，吸收了储存在过渡带的水分。如果这些较小的富水地幔羽流现在进一步向上迁移并突破边界进入上地幔，就会发生以下情况。

十 | 地幔羽流中所包含的水被释放出来，这降低了新出现的物质的熔点。因此，它立即熔化，而不是像通常发生的那样，在到达地表之前就熔化。因此，地球地幔这一部分的岩石块总体上不再那么坚硬，这使质量运动更有活力。

十一 | 过渡带本来是那里的动态的障碍，突然变成了全球物质循环的驱动器。

十二 |

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Published on:11:08:08