[(Title)]Scientists discover 'quadrillion tons of diamond' beneath Earth's surface

The diamonds were found by analysing seismic records - essentially sound waves travelling through the Earth triggered by ground-shaking forces.Dr Ulrich Faul, a research scientist at MIT, explained that one of diamond's many special properties is the speed at which sound waves travel through the material.

这些钻石是通过分析地震记录发现的 - 基本上是由地面震动力引发的通过地球传播的声波。麻省理工学院研究科学家乌尔里希·福尔解释说，钻石的许多特殊属性之一就是声波在其中通过的速度。 

"Diamond in many ways is special," Dr Faul said.

福尔博士说：“钻石在许多方面都是特殊的。”

"One of its special properties is that the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.

“它的一个特殊属性是，钻石中的声波传递的速度比上地幔岩石中的主要矿物的速度快两倍。

"Unfortunately for diamond hunters, the minerals are buried more than 160km (100 miles) beneath the Earth's surface - far deeper than any human drills have ever reached.Dr Faul and his team discovered that sound was moving much faster than it could have been expected to within sections of rock known as cratonic roots.Cratons are the oldest sections of rock beneath that usually lie beneath continental tectonic plates, and their roots - shaped like inverted mountains - stretch up to 200 miles beneath the Earth's surface.The new study suggests that up to 2% of these roots may be composed of diamond, which they say would mean there could be about a quadrillion tons (that's 15 zeroes) of diamond scattered up to 150 miles below the surface.This makes it very unlikely that the diamond could be retrieved with current technology.The deepest drill ever made by humanity is the Kola Superdeep Borehole in Russia, which took 20 years to reach a depth of 12km (7.5 miles) before being abandoned with the collapse of the Soviet Union.The research from MIT and other universities published in the journal Geochemistry, Geophysics, Geosystems explains how the scientists reached their conclusion.Dr Faul explained: "[Cratons] are like pieces of wood, floating on water.

“不幸的是，这些矿物埋在地球表面下160多公里( 100英里)的地方——比人类的任何一次钻探都要深得多。福尔博士和他的研究小组发现，在被称为克拉通根的岩石区域内，声音的移动速度比预期的要快得多。

克拉通是最古老的岩石段，通常位于大陆构造板块之下，其根部形状像倒置的山脉，延伸到地表以下200英里。

新的研究表明，这些岩石中中有2 %可能由钻石组成，他们说，这意味着地表下150英里处可能有大约1000万吨(即15个零)的钻石。

这使得用目前的技术很难采集这些钻石。人类有史以来最深的一次钻探是俄罗斯的科拉超深钻孔，它用了20年才达到12公里( 7.5英里)的深度，并在苏联解体后被遗弃。

麻省理工学院和其他大学发表在地球化学、地球物理学、地球系统杂志上的这项研究解释了科学家们是如何得出结论的。福尔博士解释说:“克拉通就像一块木头，漂浮在水面上。”

Cratons are a tiny bit less dense than their surroundings, so they don't get subducted back into the Earth but stay floating on the surface.

“克拉通的密度比周围环境要小一些，所以它们不会进入到地球里面，而是漂浮在表面上。”

"This is how they preserve the oldest rocks.

“这就是他们保存最古老的岩块的方法。”

So we found that you just need 1% to 2% diamond for cratons to be stable and not sink.

我们发现，仅仅需要1%到2%的钻石就能保证克拉通稳定而不会沉没。

"It's circumstantial evidence, but we've pieced it all together.

“这是间接的证据，但我们已经拼凑在一起了。”

"We went through all the different possibilities, from every angle, and this is the only one that's left as a reasonable explanation."

“我们从每个角度都经历了所有的不同可能性，而这是唯一作为合理解释的。”