原文已被隐藏，你可用 快捷键 - 或点击 显示原文 按钮来查看原文
第1段
1 .This is Scientific American 60-Second Science. I'm Julia Rosen.
该句暂无译文！
2 .Other rocky planets in our solar system show a common feature: within giant craters caused by impacts there's evidence of volcanic activity.
该句暂无译文！
3 .Which made scientists wonder-can big impacts actually cause volcanic eruptions?
该句暂无译文！
4 .And has that scenario ever happened here?
该句暂无译文！
5 .To find out, scientists went to one of the few massive craters on Earth not erased by plate tectonics: the Sudbury crater in Canada.
该句暂无译文！
6 ."Sudbury is a 1.85-billion-year-old impact structure."
该句暂无译文！
7 .Teresa Ubide, a geochemist at the University of Queensland in Australia.
该句暂无译文！
8 ."Sudbury was generated when a bolide of 10 to 15 kilometers in diameter hit Earth...and what happened was it obviously generated a large basin and also it melted the...crust on top of the Earth at that time.
该句暂无译文！
9 .And generated a massive melt pool, 2.5 kilometers in depth."
该句暂无译文！
10 .But Ubide and her colleagues found that the impact did more than that: it also seems to have triggered eruptions of magma that came from deep in the mantle.
该句暂无译文！
11 .The evidence lies in the fact that the chemistry of the lava that erupted at Sudbury changed over time.
该句暂无译文！
12 .At first, it matched the surface rocks, suggesting it was just from local melting.
该句暂无译文！
13 .But as the eruptions continued, the lava appeared to come from deep in the mantle, suggesting the impact stirred things up inside the Earth.
该句暂无译文！
14 .No one knows yet exactly how the impact could have sparked a prolonged episode of volcanism.
该句暂无译文！
15 .One possible explanation is that after the object smashed into the surface, the crust would have rebounded upward, temporarily decompressing the mostly solid mantle and causing it to melt and produce magma.
该句暂无译文！
16 .The results are in the Journal of Geophysical Research: Planets.
该句暂无译文！
17 .It's hard to know if the same thing happened on other planets, Ubide says.
该句暂无译文！
18 .In many spots in the solar system it looks like volcanism happened much longer after the impact than what she saw at Sudbury.
该句暂无译文！
19 .But without material to examine directly, we can't be sure.
该句暂无译文！
20 .Nevertheless, these results do help explain a mysterious chapter in Earth's own history.
该句暂无译文！
21 .Most major impacts on our planet happened about four billion years ago, when the solar system was still settling down.
该句暂无译文！
22 .But there's no crust around from that time, suggesting the entire planet got a makeover soon after.
该句暂无译文！
23 ."We're suggesting that impacts are able to not only generate the crater, but also, generate melting deeper, say, in the mantle, and bring to the surface material from depth.
该句暂无译文！
24 .So actually, recycle and resurface."
该句暂无译文！
25 .It seems the pummeling that Earth endured in the beginning may have triggered volcanic activity that helped wipe away the evidence of those early impacts.
该句暂无译文！
26 .In other words, our planet took a beating that may have accelerated its own recovery.
该句暂无译文！
27 .Thanks for listening, for Scientific American 60-Second Science. I'm Julia Rosen.
该句暂无译文！