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埋藏在印度洋下面的古大陆(图)  

2017-04-13 06:54:20|  分类: 探索发现 |  标签: |举报 |字号 订阅

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埋藏在印度洋下面的古大陆(图)


埋藏在印度洋下面的古大陆(图) 

1:地球上的陆地曾经连接在一起,成为一块叫做“罗迪尼亚”的超大陆。图中显示的是,7.5亿年前这块超大陆开始分离时的情况。现在,科学家们认为他们发现了超大陆中的一小块,埋藏在印度洋之下。

埋藏在印度洋下面的古大陆(图)

2:一旦陆地开始漂移到各自目前的位置,长条状陆地“毛里提亚”不复存在。

 Fragments of ancient continent buried under Indian Ocean

By Rebecca Morelle       胡德良 

 

Fragments of an ancient continent are buried beneath the floor of the Indian Ocean, a study suggests.  一项研究表明,一块古大陆的地块被埋藏在印度洋洋底之下。
 Researchers have found evidence for a landmass that would have existed between 2,000 and 85 million years ago. The strip of land, which scientists have called Mauritia, eventually fragmented and vanished beneath the waves as the modern world started to take shape. 研究人员发现的证据表明:一块大陆曾经存在于20亿年至8500万年之前。科学家们把那块长条状的陆地称为“毛里提亚(Mauritia)”。随着当今世界陆地格局的形成,那块陆地最终分裂开来并消失在海洋的波涛之下。
 The study is published in the journal Nature Geoscience. 该研究的成果发表在《自然-地球科学》杂志上。
 Supercontinent 超大陆
 Until about 750 million years ago, the Earth's landmass was gathered into a vast single continent called Rodinia. 在大约7.5亿年之前,地球上的陆地是连在一起的,形成一块被称为“罗迪尼亚(Rodinia)”的巨大陆地。
 And although they are now separated by thousands of kilometres of ocean, India was once located next to Madagascar. 尽管印度和马达加斯加岛被数千公里的海洋隔开,但两者一度是相连的。
 Now researchers believe they have found evidence of a sliver of continent - known as a microcontinent - that was once tucked between the two. The team came to this conclusion after studying grains of sand from the beaches of Mauritius. 现在,研究人员相信他们发现的证据表明:一块被称为微大陆的长条状大陆曾经夹在印度和马达加斯加岛之间。经过研究毛里求斯沙滩上的沙粒,研究小组得出了上述结论。
 While the grains dated back to a volcanic eruption that happened about nine million years ago, they contained minerals that were much older.Professor Trond Torsvik, from the University of Oslo, Norway, said: "We found zircons that we extracted from the beach sands, and these are something you typically find in a continental crust. They are very old in age." The zircon dated to between 1,970 and 600 million years ago, and the team concluded that they were remnants of ancient land that had been dragged up to the surface of the island during a volcanic eruption. 这些沙粒可以追溯到发生于大约900万年前的一次火山爆发,尽管如此,沙粒中所包含的矿物在时间上要久远得多。挪威奥斯陆大学的教授特朗德·托斯维克说:“我们从沙滩沙粒提取物中发现了锆石,而锆石通常是存在于大陆地壳中的矿物,这是一种很古老的矿物。”锆石可以追溯到19.7亿年至6亿年前,因此研究小组得出结论:锆石是古代陆地的遗留物,在火山爆发期间被喷发到岛屿的表面。
 Prof Torsvik said that he believed pieces of Mauritia could be found about 10km down beneath Mauritius and under a swathe of the Indian Ocean. It would have spanned millions years of history, from the Precambrian Era when land was barren and devoid of life to the age when dinosaurs roamed the Earth. 托斯维克教授称:他认为“毛里提亚”可能存在于毛里求斯之下大约10公里处以及印度洋的一片水域之下。从土地荒芜、没有生命的前寒武纪时代到恐龙漫步于地球的时代,那块陆地经历了数百万年的历史。
 But about 85m years ago, as India started to drift away from Madagascar towards its current location, the microcontinent would have broken up, eventually disappearing beneath the waves. However, a small part could have survived. 然而,大约在8500万年之前,随着印度从马达加斯加岛开始漂移到其目前的位置,那块微大陆也开始分崩离析,最终消失在海洋的波涛之下。可是,其中的一小部分可能保存了下来。
 "At the moment the Seychelles is a piece of granite, or continental crust, which is sitting practically in the middle of the Indian Ocean," explained Prof Torsvik. "But once upon a time, it was sitting north of Madagascar. And what we are saying is that maybe this was much bigger, and there are many of these continental fragments that are spread around in the ocean." “目前,塞舌尔群岛是一块花岗岩质地的大陆地壳,几乎坐落在印度洋的中心区,”托斯维克教授解释说,“但是,从前塞舌尔群岛位于马达加斯加岛的北部。我们想说的是,那块微大陆的分布范围也许要大得多,可能有许多这样的古大陆地块散布于印度洋之下。
 Further research is needed to fully investigate what remains of this lost region. 要想对这一失踪地区的遗留之物进行全面的调查,仍需要进一步研究。
 Prof Torsvik explained: "We need seismic data which can image the structure... this would be the ultimate proof. Or you can drill deep, but that would cost a lot of money." 托斯维克教授还解释说:“我们需要反映该地区地质结构的地震资料,这将是我们的根本证据。或者也可以往深处钻探,但那样做将会付出极高的成本。”

 

   译自:英国BBC网站科学环境频道(25 February 2013

原著:Rebecca Morelle

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