火星上神秘岩石堆和高原的形成猜想
文章来源:未知 文章作者:meng 发布时间:2010-06-29 02:45 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

When Mars Express set sail for(开船,动身) the crater1(火山口,弹坑) named after Portuguese2 navigator Ferdinand Magellan, it found a windblown(被风吹的) plateau and mysterious rocky mounds3 nearby. Stretching across 190 x 112 km, this region of Mars covers an area of about 21 280 sq km, which is roughly the size of Slovenia. It is located to the southwest of the volcanic4 region Tharsis on the southern highlands of Mars, near the crater Magellan.

Named after the famous Portuguese navigator and explorer Ferdinand Magellan, the impact crater is about 100 km across. Only a small portion of the crater rim5(火山口边缘) is visible in this image, sitting at the lower right, because the Mars Express High-Resolution Stereo Camera (HRSC) has zeroed in on some intriguing6(有趣的,迷人的) features nearby.

In the west of this region (at the upper edge of the main image) there are light-coloured, irregular protrusions(突出) . These features are up to 2 km tall and are probably large rock fragments or mounds(堆,高地) of rock. However, their formation is still debated.

One possibility is that the top layer of rock was shattered(打碎,削弱) by the shockwaves from an impact. Another possible explanation would be from a process called subrosion. On Mars, subrosion is widely observed when rising magma(岩浆,糊剂) heats frozen ground water, which melts and removes subsurface material as it flows away. This leads to a honeycomb of cavities that eventually collapse7 due to the weight of the overlying rock layers, leaving the irregular mounds standing8.

The northern part of the region (to the right of the main image) displays linear(线型的,直线的) features with a preferential(优先的) northwest–southeast orientation9. These eventually lead to deep, well-defined valleys and are likely to be faults, formed during either an impact event or the upsurge(高潮,高涨) of the Tharsis region that created enormous stresses in the planet's crust(外壳) . Examining the geometry(几何学) of fault zones offers clues to the level and the direction of the stress exerted(外露的) on the rock.

A rather smooth, barely fractured plateau is located almost in the centre of the main image. It is possible the plateau is made up of the same material as the highly fractured(断裂的,挫伤的) mounds in the west. Fine trails run from southwest to northeast across here. These could be an indication of erosion(侵蚀,腐蚀) by fine dust particles carried on the wind, sandblasting(喷砂) the plateau smooth.

With a ground resolution(分辨率) of about 25 m per pixel, the data were acquired for the region of Magellan Crater at about 34°S/185°E, during Mars Express's orbit 6547 on 6 February 2009.



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1 crater WofzH     
n.火山口,弹坑
参考例句:
  • With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
  • They came to the lip of a dead crater.他们来到了一个死火山口。
2 Portuguese alRzLs     
n.葡萄牙人;葡萄牙语
参考例句:
  • They styled their house in the Portuguese manner.他们仿照葡萄牙的风格设计自己的房子。
  • Her family is Portuguese in origin.她的家族是葡萄牙血统。
3 mounds dd943890a7780b264a2a6c1fa8d084a3     
土堆,土丘( mound的名词复数 ); 一大堆
参考例句:
  • We had mounds of tasteless rice. 我们有成堆成堆的淡而无味的米饭。
  • Ah! and there's the cemetery' - cemetery, he must have meant. 'You see the mounds? 啊,这就是同墓,”——我想他要说的一定是公墓,“看到那些土墩了吗?
4 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。
5 rim RXSxl     
n.(圆物的)边,轮缘;边界
参考例句:
  • The water was even with the rim of the basin.盆里的水与盆边平齐了。
  • She looked at him over the rim of her glass.她的目光越过玻璃杯的边沿看着他。
6 intriguing vqyzM1     
adj.有趣的;迷人的v.搞阴谋诡计(intrigue的现在分词);激起…的好奇心
参考例句:
  • These discoveries raise intriguing questions. 这些发现带来了非常有趣的问题。
  • It all sounds very intriguing. 这些听起来都很有趣。 来自《简明英汉词典》
7 collapse aWvyE     
vi.累倒;昏倒;倒塌;塌陷
参考例句:
  • The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
  • The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。
8 standing 2hCzgo     
n.持续,地位;adj.永久的,不动的,直立的,不流动的
参考例句:
  • After the earthquake only a few houses were left standing.地震过后只有几幢房屋还立着。
  • They're standing out against any change in the law.他们坚决反对对法律做任何修改。
9 orientation IJ4xo     
n.方向,目标;熟悉,适应,情况介绍
参考例句:
  • Children need some orientation when they go to school.小孩子上学时需要适应。
  • The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。
TAG标签: Mars plateau mounds
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