2022年经济学人 大陆形成新学说(2)

The team traversed the craton to collect zircon crystals, a mineral with two properties ideally suited to the task.

研究小组穿越古陆核采集锆石晶体，这种矿物有两种特性，非常适合这项任务。

First, their content of radioactive uranium decays to lead at a rate that can be used to calculate their age.

首先，他们的放射性铀含量衰减成铅的速度可以用来计算他们的年龄。

And second, the isotopes¹ of oxygen found within their structure are representative of the environment in which they grew.

其次，在它们的结构中发现的氧同位素代表了它们生长的环境。

Zircons whose ratio of oxygen-18 to oxygen-16 is 0.5% higher than found in seawater, for example, would have originated far below Earth’s surface.

例如，在海水中发现的氧-18和氧-16的比率比高0.5%的锆石可能起源于地球表面以下很远的地方。

Those with values closer to those found in seawater formed much nearer the crust.

那些与海水中发现的值更接近的物质形成于更接近地壳的地方。

Analysis led the researchers to conclude that the oldest crystals on the Pilbara -- those formed around 3.5bn years ago -- must have originated close to the surface.

通过分析，研究人员得出结论，皮尔巴拉上最古老的晶体--大约形成于35亿年前--一定起源于靠近地表的地方。

This favours impact formation, as zircons transported by mantle² plumes³ would have more profound origins.

这有利于撞击的形成，因为地幔热柱搬运的锆石具有更深的起源。

“Giant impacts plus water is a really good way of making a continent,” says Dr Johnson.

约翰逊博士说：“巨型撞击加上水是形成大陆的一种非常好的方式。”

The textbooks will not be rewritten overnight.

教科书不会在一夜之间改写。

Marion Garcon, a geologist⁴ at Clermont-Auvergne University in France, finds the evidence of impact formation plausible⁵ on a local scale, but says more evidence will be needed to extrapolate it planet-wide.

法国克莱蒙特-奥弗涅大学的地质学家马里恩·加尔孔认为，在局部范围内，撞击形成的证据是可信的，但他表示，需要更多证据才能在全球范围内推断这一点。

Fortunately, this can be done.

幸运的是，这是可以做到的。

Ancient continental⁶ fragments exist in other parts of Australia as well as Canada and South Africa.

古老的大陆碎片存在于澳大利亚其他地区、加拿大和南非。

Analyses of their constituent⁷ zircons could well provide valuable supporting evidence that Earth’s continents owe their existence to bodies from outer space.

对其构成的锆石的分析很好地提供有价值的佐证，证明地球大陆的存在应归功于来自外太空的天体。

But the authors will also need to explain why zircons previously⁸ found at other, even older, sites do not display the same telltale signature of impact.

但作者还需要解释，为什么之前在其他更古老的地点发现的锆石没有显示出相同的撞击迹象。

This work could be significant in other ways.

这项工作可能在其他方面具有重要意义。

While the rate of asteroid⁹ collisions experienced by early Earth generally declined over time, it may have spiked¹⁰ some 3.9bn years ago during a postulated¹¹ event known as the Late Heavy Bombardment (lhb).

虽然早期地球经历的小行星碰撞的概率通常会随着时间的推移而下降，但在大约39亿年前的一次假定事件-晚期重轰击(LHB)期间，小行星碰撞的概率可能达到了峰值。

What are taken by some as signs of the lhb pockmark the static surfaces of Mars and the Moon.

一些人认为LHB的迹象在火星和月球的静态表面上留下了凹坑。

Earth’s constant ructions, however, will have destroyed any signs of it.

然而，地球持续不断的骚动将摧毁它的任何迹象。

If Dr Johnson is right, then the formation of the continents could be the first earthly evidence of one of the solar system’s most dramatic moments.

如果约翰逊博士是正确的，那么大陆的形成可能是太阳系最戏剧性时刻之一的第一个地球证据。

1 isotopes   

n.同位素；同位素( isotope的名词复数 )

参考例句：

• the many isotopes of carbon 碳的诸多同位素
• Tritium is one of the mildest radioactive isotopes. 氚是最和缓的放射性同位素之一。 来自《简明英汉词典》

2 mantle   

n.斗篷，覆罩之物，罩子；v.罩住，覆盖，脸红

参考例句：

• The earth had donned her mantle of brightest green.大地披上了苍翠欲滴的绿色斗篷。
• The mountain was covered with a mantle of snow.山上覆盖着一层雪。

3 plumes   

羽毛( plume的名词复数 )； 羽毛饰； 羽毛状物； 升上空中的羽状物

参考例句：

• The dancer wore a headdress of pink ostrich plumes. 那位舞蹈演员戴着粉色鸵鸟毛制作的头饰。
• The plumes on her bonnet barely moved as she nodded. 她点点头，那帽子的羽毛在一个劲儿颤动。

4 geologist   

n.地质学家

参考例句：

• The geologist found many uncovered fossils in the valley.在那山谷里，地质学家发现了许多裸露的化石。
• He was a geologist,rated by his cronies as the best in the business.他是一位地质学家，被他的老朋友们看做是这门行当中最好的一位。

5 plausible   

adj.似真实的，似乎有理的，似乎可信的

参考例句：

• His story sounded plausible.他说的那番话似乎是真实的。
• Her story sounded perfectly plausible.她的说辞听起来言之有理。

6 continental   

adj.大陆的，大陆性的，欧洲大陆的

参考例句：

• A continental climate is different from an insular one.大陆性气候不同于岛屿气候。
• The most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。

7 constituent   

n.选民；成分，组分；adj.组成的，构成的

参考例句：

• Sugar is the main constituent of candy.食糖是糖果的主要成分。
• Fibre is a natural constituent of a healthy diet.纤维是健康饮食的天然组成部分。

8 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

9 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

10 spiked   

adj.有穗的；成锥形的；有尖顶的

参考例句：

• The editor spiked the story. 编辑删去了这篇报道。 来自《简明英汉词典》
• They wondered whether their drinks had been spiked. 他们有些疑惑自己的饮料里是否被偷偷搀了烈性酒。 来自辞典例句

11 postulated   

v.假定，假设( postulate的过去式和过去分词 )

参考例句：

• They postulated a 500-year lifespan for a plastic container. 他们假定塑料容器的寿命为500年。
• Freud postulated that we all have a death instinct as well as a life instinct. 弗洛伊德曾假定我们所有人都有生存本能和死亡本能。 来自辞典例句