(单词翻译:单击)
听力文本
New Details on Asteroid Strike That Killed Off the Dinosaurs
Researchers say they have discovered new details about the day an asteroid hit Earth and killed off the dinosaurs.
Scientists believe the asteroid struck the Earth about 65 million years ago near what is today Mexico's Yucatán Peninsula.
The force of the massive asteroid crash is estimated to have been equal to the strength of about 10 billion nuclear bombs. The U.S. Space Agency NASA has estimated the strike created a huge crater about 180 kilometers wide and 900 meters deep.
The event is believed to have caused widespread wildfires, earthquakes and ocean waves, or tsunamis. It also released chemicals into the atmosphere, leading to severe cooling that harmed many living things.
Scientists blame this climate-changing event for causing the extinction of more than 70 percent of plant and animal life. In addition, all dinosaurs, that were not bird-like, died out.
The crater remained hidden until the late 1970s, when it was first discovered beneath the ocean by a team searching for petroleum. The theory about an asteroid causing the extinction of the dinosaurs was first presented by two American scientists in 1980.
Studies based on materials collected over the years from off the coast of the Yucatán Peninsula led most scientists to agree that an asteroid struck in that place. In 2016, a team went to the area to drill down into the ground beneath the crater to bring up rock samples.
One of the leaders of that team was Sean Gulick, a research professor at the University of Texas Institute for Geophysics. He also led a new study that researchers say provides more evidence and details about the destruction caused by the asteroid.
The study involved the examination of more than 130 meters of rock believed to have built up in the seconds and hours after the asteroid strike. The findings were recently published in the Proceedings of the National Academy of Sciences.
"It's an expanded record of events that we were able to recover from within ground zero," Gulick said in a statement. "It tells us about impact processes from an eyewitness location." He added that the rock record "offers the most detailed look yet" into the period immediately after the asteroid impact.
The researchers noted that the buildup of material was one of the largest in Earth's history. The materials and formations in the rocks provide evidence of what was happening in the environment right after the event.
By examining the rocks, the team found evidence that most of the material that filled the crater after the strike was produced where the impact happened. This included materials that were vaporized from the blast. Some of the material was carried in by seawater pouring back into the crater from the surrounding Gulf of Mexico.
The researchers also found evidence of burned material, sulfur and dust. They believe these substances were vaporized and entered into the atmosphere. They said that these substances blocked the sun's heat and caused the Earth to cool.
The team also found material they believe came from the fungal breakdown of wood within or just above layers of sand. This also showed signs of trees and plant life being drawn into the crater by resurging waters, likely caused by a huge wave, or tsunami.
Sean Gulick said the evidence suggests that a large heat blast, followed by a period of intense cooling killed off the dinosaurs. "We fried them and then we froze them," he said.
Gulick noted that the study provides clear evidence that the dinosaurs did not die from the asteroid impact. Instead, the research suggests they did not survive the resulting climate conditions.
"The real killer has got to be atmospheric," Gulick said. "The only way you get a global mass extinction like this is an atmospheric effect."
I'm Bryan Lynn.
重点解析
重点讲解：
1. kill off 被全部杀死；被灭绝；
Their natural predators have been killed off.
它们的天敌被全部杀死。
2. be equal to （大小、数量、价值等）相同的，同样的；相等的；
Any number to the power of nought is equal to one.
任何数的0次方等于1。
3. die out 逐渐消亡；灭绝；绝种；
How did the dinosaurs die out?
恐龙是如何灭绝的？
4. build up （使）积聚；（使）逐渐增加；
Slowly a thick layer of fat builds up on the pan's surface.
慢慢地，平底锅表面积起了一层厚厚的油脂。
参考译文
小行星袭击致恐龙灭绝的说法添加新证据
研究人员表示，他们发现了小行星袭击地球那天致恐龙灭绝的新证据。
科学家认为，一颗小行星在约6500万年前袭击了地球，遇袭地位于今天的墨西哥尤坦半岛附近。
据估计，这颗巨型小行星的撞击威力相当于100亿颗核弹。美国太空机构美国国家航空航天局（简称NASA）估计，这次撞击产生了一个180千米宽、900米深的巨坑。
人们认为这起事件引发了大规模山火、地震和海浪波或海啸。同时，这起事件还使化学物质被释放到大气层，由此引发的严重降温导致许多生物受到伤害。
科学家认为这起气候变化事件导致超过70%的动植物灭绝。除此之外，这起事件还致非鸟类恐龙灭绝。
撞击坑直到上世纪70年代末期才被发现，一个探索石油的小组最先在海底发现了这个巨坑。小行星导致恐龙灭绝这一说法最先由两名美国科学家在1980年提出。
研究人员利用多年来从尤坦半岛沿岸收集的材料进行了研究，这些研究使大多数科学家一致认为，一颗小行星袭击了这一地区。2016年，一个小组前往该地区钻入巨坑下面的土地，以提取岩石样本。
该团队的其中一名负责人是肖恩·古利克，他是得克萨斯大学地球物理研究所的研究教授。他还领导了一项新研究，研究人员称这项研究为小行星导致毁灭这一说法提供了更多证据和详细信息。
这项新研究对超过130米的岩石进行了检查，据悉这是在小行星撞击后数小时内堆积形成的。这项研究结果于近期发表在《美国国家科学院院刊》上。
古利克在声明中表示，“这是我们可以从袭击地收集的延伸记录。它告诉了我们目击地点的冲击过程。”他补充说，岩石记录提供了小行星袭击之后那段时间的“最详细信息”。
研究人员指出，这是地球有史以来规模最大的物质堆积之一。这些物质和地层岩石提供的证据说明了那起事件之后的环境变化。
该团队在检查岩石后发现，撞击发生后巨坑里堆积的大多数物质是撞击发生地产生的。这包括爆炸后被汽化的物质。一些物质由从墨西哥湾附近回流到巨坑中的海水所携带。
研究人员还发现了燃烧过的物质、硫磺和灰尘等证据。他们认为这些物质遭到汽化后进入了大气层。他们表示，这些物质阻挡了太阳的热量并导致地球降温。
该团队还发现了一种物质，他们认为这种物质来自砂层或以上林地的真菌分解。这同时表明，树木和植物被翻腾的海水卷入了巨坑中，而这很可能是巨浪或海啸引发的。
肖恩·古利克表示，这一证据表明，一起大热爆炸后发生了持续一段时间的激冷，导致恐龙灭绝。他说，“我们先炸了它们，随后又冰冻了它们。”
古利克表示，这项研究提供了明确的证据，证明恐龙并不是死于小行星撞击。相反，研究表明恐龙没能在撞击引发的气候状况下存活。
古利克表示，“真正的凶手肯定是大气。只有大气效应才能导致这种全球性大规模灭绝事件。”
布莱恩·林恩报道。
译文为可可英语翻译，未经授权请勿转载！
