科学家如何重建前白垩纪大陆如果剩下盘子目前比白垩纪年轻吗?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 10 - t12:30:25z //www.hoelymoley.com/feeds/question/15060 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/15060 5 科学家如何重建前白垩纪大陆如果剩下盘子目前比白垩纪年轻吗? 日航 //www.hoelymoley.com/users/13800 2018 - 09 - 09 - t17:28:03z 2018 - 09 - 14 - t00:57:33z < p >我读了我们今天所看到的最古老的大洋板块来自白垩纪。如果是这样,科学家如何重建板块运动和大陆结构前白垩纪?并不是所有化石在白垩纪之前丢失?< / p >

Why are we able to deduct geology information pre Cretaceous? And what is the oldest period we are able to gain information from?

 //www.hoelymoley.com/questions/15060/-/15065 # 15065 8 斯宾塞的回答科学家如何重建前白垩纪大陆如果剩下盘子目前比白垩纪年轻吗? 斯宾塞 //www.hoelymoley.com/users/6467 2018 - 09 - 10 - t02:16:16z 2018 - 09 - 14 - t00:57:33z < h2 >你忘了大洲< / h2 > < p >首先,有必要指出错误的前提下在你的问题:这是<强>不对< /强>,“所有板块目前比白垩纪年轻”。有一个不间断的记录岩石拉伸一路回< a href = " https://en.wikipedia.org/wiki/Hadean " rel = " nofollow noreferrer " >地狱的< / > Eon 40亿年前。和年长的晶体称为< a href = " https://en.wikipedia.org/wiki/Zircon # Radiometric_Dating”rel = " nofollow noreferrer " >锆石< / > s发现夹杂物在年轻的岩石。< / p > < p >问题是,这些岩石是在陆地上,部分< a href = " https://en.wikipedia.org/wiki/Continental_crust " rel = " nofollow noreferrer " >大陆地壳< / >。你的问题似乎没有意识到大陆地壳的存在。当然,因为你不是现在坐在大海的底部,你现在大陆地壳之上。大部分的大板块是海洋和大陆的一部分。< / p >

Continents have been built up little by little over geological time. Their rocks are a mixed-up jigsaw puzzle of various types and ages. It's the geologist's job to figure out how those pieces fit together.

Here's just a taste, and it doesn't even show the complexity of the puzzle in North America by a long shot:

basement rocks (courtesy of United States Geological Survey, via Wikimedia Commons)

It is true that the oceanic plates are mostly destroyed by subduction, but the oceanic crust has to go beneath something, and that's often a continent. Besides, subduction helps make continents grow:

  • not all of the rock is subducted: some seafloor sediments are scraped off and piled against continental margins

  • The top layers of rock that are subducted melt, and the melted rock bubbles its way up through the overlying crust, producing plutons and volcanic arcs. Sometimes these are on continents (such as the Cascades and Andes) so their rocks directly add mass to them.

  • When the volcanoes are out in the ocean, the subduction process pulls them into continents and they get cemented to the edge. Sometimes they form little mini- continents (such as Japan and New Zealand).

The oldest oceanic crust currently at the seafloor is in the eastern Mediterranean. In an article in Nature Geoscience Roi Granot of Ben-Gurion University of the Negev suggests that the [Herodotus Basin] is a remnant of ancient Tethys Ocean, having formed up to 340 Ma during the Early Carboniferous period. Most oceanic crust is 200 million years old (Jurassic) or younger. They're an important part of putting the puzzle together, but as I stated at the beginning of my answer, the geological record is much older, because of continental rocks.

Finally, there is really old oceanic crust in the form of ophiolites, which are bits of oceanic crust that have been incorporated into continents. Since they're no longer part of the oceanic conveyor belt, some can be quite old. The oldest is about 3.8 billion years old.

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