科学家发现世界最大钻石的成因
文章来源:未知 文章作者:enread 发布时间:2016-12-19 08:44 字体: [ ]  进入论坛
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Scientists claimed they have figured out how the world's biggest and most-valuable diamonds formed.
 
科学家们表示,他们已经搞清楚世界上最大、最有价值的钻石是如何形成的。
 
In a study published this week in the U.S. journal Science, they said large gem-quality diamonds, like the world-famous Cullinan or Lesotho Promise, may be born in metallic1 liquid deep inside Earth's mantle2.
 
The research team, led by Evan Smith of the Gemological Institute of America, reached the conclusion after examining so-called "offcuts" of massive diamonds, which are the pieces left over after the gem's facets3 are cut for maximum sparkle. 
 
They found tiny metallic grains trapped inside in more than 30 exceptionally large stones, which are made up of a mixture of metallic iron and nickel, along with carbon, sulfur4, methane5, and hydrogen.
 
These inclusions led the researchers to conclude that that these diamonds formed, like all diamonds, in the Earth's mantle, but they did so under conditions in which they were saturated6 by liquid metal.
 
Most diamonds formed at depths of 150 to 200 kilometers under the continents and shoot to the surface in volcanic7 eruptions8. But these large, rare stones formed at extreme depths, likely within 360 to 750 kilometers in the convecting mantle, where rocks are known to be mobile.
 
"Pure carbon crystallized in this mix of molten metallic liquid in Earth's deep mantle to form diamonds," the team explained in a statement.
 
"Small droplets9 of this metallic liquid were occasionally trapped within the diamonds as they grew," offering useful clues that may help "advance our understanding of Earth's deep mantle, hidden beneath tectonic plates and largely inaccessible10 for scientific observation."


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1 metallic LCuxO     
adj.金属的;金属制的;含金属的;产金属的;像金属的
参考例句:
  • A sharp metallic note coming from the outside frightened me.外面传来尖锐铿锵的声音吓了我一跳。
  • He picked up a metallic ring last night.昨夜他捡了一个金属戒指。
2 mantle Y7tzs     
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 facets f954532ea6a2c241dcb9325762a2a145     
n.(宝石或首饰的)小平面( facet的名词复数 );(事物的)面;方面
参考例句:
  • The question had many facets. 这个问题是多方面的。 来自《简明英汉词典》
  • A fully cut brilliant diamond has 68 facets. 经过充分切刻的光彩夺目的钻石有68个小平面。 来自《简明英汉词典》
4 sulfur ps4wC     
n.硫,硫磺(=sulphur)
参考例句:
  • Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
  • Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。
5 methane t1Eyx     
n.甲烷,沼气
参考例句:
  • The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • Methane may have extraterrestrial significance.甲烷具有星际意义。
6 saturated qjEzG3     
a.饱和的,充满的
参考例句:
  • The continuous rain had saturated the soil. 连绵不断的雨把土地淋了个透。
  • a saturated solution of sodium chloride 氯化钠饱和溶液
7 volcanic BLgzQ     
adj.火山的;象火山的;由火山引起的
参考例句:
  • There have been several volcanic eruptions this year.今年火山爆发了好几次。
  • Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
8 eruptions ca60b8eba3620efa5cdd7044f6dd0b66     
n.喷发,爆发( eruption的名词复数 )
参考例句:
  • There have been several volcanic eruptions this year. 今年火山爆发了好几次。 来自《简明英汉词典》
  • Over 200 people have been killed by volcanic eruptions. 火山喷发已导致200多人丧生。 来自辞典例句
9 droplets 3c55b5988da2d40be7a87f6b810732d2     
n.小滴( droplet的名词复数 )
参考例句:
  • Droplets of sweat were welling up on his forehead. 他额头上冒出了滴滴汗珠。 来自辞典例句
  • In constrast, exhaled smoke contains relatively large water droplets and appears white. 相反,从人嘴里呼出的烟则包含相当大的水滴,所以呈白色。 来自辞典例句
10 inaccessible 49Nx8     
adj.达不到的,难接近的
参考例句:
  • This novel seems to me among the most inaccessible.这本书对我来说是最难懂的小说之一。
  • The top of Mount Everest is the most inaccessible place in the world.珠穆朗玛峰是世界上最难到达的地方。
TAG标签: carbon metallic diamonds
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