板块分裂时断层控制着海水流量
文章来源:未知 文章作者:enread 发布时间:2016-03-08 06:29 字体: [ ]  进入论坛
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New light has been shed on the processes by which ocean water enters the solid Earth during continental1 breakup. Research led by geoscientists at the University of Southampton, and published in Nature Geoscience this week, is the first to show a direct link on geological timescales between fault activity and the amount of water entering the Earth's mantle2 along faults. 
 
When water and carbon is transferred from the ocean to the mantle it reacts with a dry rock called peridotite, which makes up most of the mantle beneath the crust, to form serpentinite. 
 
Dr Gaye Bayrakci, Research Fellow in Geophysics, and Professor Tim Minshull, from Ocean and Earth Science, with colleagues at the University of Southampton and six other institutions, measured the amount of water that had entered the Earth by using sound waves to map the distribution of serpentinite.
 
The sound waves travel through the crust and mantle and can be detected by sensitive instruments placed on the ocean floor. The time taken for the signals to travel from an acoustic3 seismic4 source to the seafloor instruments reveals how fast sound travels in the rocks, and the amount of serpentinite present can be determined5 from this speed.
 
The four-month experiment, which involved two research ships (the R/V Marcus Langseth and the F/S Poseidon), mapped an 80 by 20 km area of seafloor west of Spain called the Deep Galicia Margin6 where the fault structures were formed when North America broke away from Europe about 120 million years ago. 
 
The results showed that the amount of serpentinite formed at the bottom of each fault was directly proportional to the displacement7 on that fault, which in turn is closely related to the duration of fault activity.
 
Dr Bayracki said: "One of the aims of our survey was to explore the relationship between the faults, which we knew already were there, and the presence of serpentinite, which we also knew was there but knew little about its distribution. The link between fault activity and formation of serpentinite was something we might have hoped for but did not really expect to see so clearly. 
 
"This implies that seawater reaches the mantle only when the faults are active and that brittle8 processes in the crust may ultimately control the global amount of seawater entering the solid Earth."


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1 continental Zazyk     
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。
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 acoustic KJ7y8     
adj.听觉的,声音的;(乐器)原声的
参考例句:
  • The hall has a fine acoustic.这个大厅的传音效果很好。
  • Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。
4 seismic SskyM     
a.地震的,地震强度的
参考例句:
  • Earthquakes produce two types of seismic waves.地震产生两种地震波。
  • The latest seismic activity was also felt in northern Kenya.肯尼亚北部也感觉到了最近的地震活动。
5 determined duszmP     
adj.坚定的;有决心的
参考例句:
  • I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
  • He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。
6 margin 67Mzp     
n.页边空白;差额;余地,余裕;边,边缘
参考例句:
  • We allowed a margin of 20 minutes in catching the train.我们有20分钟的余地赶火车。
  • The village is situated at the margin of a forest.村子位于森林的边缘。
7 displacement T98yU     
n.移置,取代,位移,排水量
参考例句:
  • They said that time is the feeling of spatial displacement.他们说时间是空间位移的感觉。
  • The displacement of all my energy into caring for the baby.我所有精力都放在了照顾宝宝上。
8 brittle IWizN     
adj.易碎的;脆弱的;冷淡的;(声音)尖利的
参考例句:
  • The pond was covered in a brittle layer of ice.池塘覆盖了一层易碎的冰。
  • She gave a brittle laugh.她冷淡地笑了笑。
TAG标签: water ocean earth
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