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  • General

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  • 板内活动

    Why does some geological activity take place away from plate boundaries?
    ::为什么有些地质活动会远离板块边界?

    The geological activity in these photos is not at  plate boundaries . Is  plate tectonics  wrong? Of course not! This activity can also be explained. It's the result of  hotspots . Two hotspot locations are Hawaii and Yellowstone.
    ::这些照片中的地质活动不是在板块边界上。 板块构造是否错了? 当然不是! 这个活动也可以解释。 这是热点的结果。 两个热点地点是夏威夷和黄石公园。

    Intraplate Activity
    ::内板活动

    Most geological activity takes place at plate boundaries. But some activity does not. Much of this  intraplate activity  is found at hot spots.  Hotspots  are plumes of hot material that rise through the mantle. Hotspot   erupt when the hot material melts to create  magma .
    ::大多数地质活动是在板块边界进行的,但有些活动并非如此。这种板内活动大多在热点发现。热点是热材料的羽流,热材料通过地壳上升。热点在热物质熔化产生岩浆时爆发。

    Many hotspots appear to be fixed in the mantle. This means that they do not move relative to each other.  Plates  move above the hotspots, but the hotspots stay in the same spot. This feature is a very useful tool for scientists.
    ::许多热点似乎都固定在地皮上。 这意味着它们不相对移动。 平板移动在热点之上, 但热点停留在同一地点 。 这个特征对于科学家来说是一个非常有用的工具 。

    Hotspots in the Oceans
    ::海洋热点点

    A chain of volcanoes form as an oceanic plate moves over a hotspot. This is how it happens. A volcano forms over the hotspot. Since the plate is moving, the volcano moves off of the hotspot. When the hotspot erupts again, a new volcano forms over it. This volcano is next to the first. Over time, there is a line of volcanoes. The youngest is directly above the hotspot. The oldest is the farthest away ( Figure   ).
    ::火山链形成时, 海洋板块会移动到一个热点上。 这就是它的发生方式。 火山圈会在热点上形成。 自从热点上出现火山, 火山会从热点上移开。 当热点再次爆发时, 火山会从热点上移开。 火山会形成新的火山。 火山会在第一个火山点上方形成。 随着时间的推移, 火山线会一直存在。 最小的火山会直接在热点上方。 最老的火山会最远( 图示 ) 。

    Map illustrating the Hawaiian Islands' formation from volcanoes over a hotspot, indicating ages.

     

    This view of the Hawaiian islands shows the youngest islands in the southeast and the oldest in the northwest. Kilauea volcano, which makes up the southeastern side of the Big Island of Hawaii, is located above the Hawaiian hotspot.
    ::夏威夷群岛的这种景象显示了东南最年轻的岛屿和西北最古老的岛屿,夏威夷大岛东南端的基拉乌亚火山位于夏威夷热点之上。

    The Hawaii-Emperor chain of volcanoes formed over the Hawaiian Hotspot. The Hawaiian Islands formed most recently. Kilauea volcano is currently erupting. It is over the hotspot. The Emperor  Seamounts  are so old they no longer reach above  sea level . The oldest existing of the Emperor Seamounts is about to subduct into the Aleutian  trench  off of Alaska. Older ones may already be in the trench. Geologists can get age dates from the  volcanic rocks  that erupt at these hotspots. So they use hotspot chains to tell the direction and the speed a plate is moving.
    ::夏威夷- Emperor火山链由夏威夷热点形成。 夏威夷群岛最近才形成。 Kilauea火山目前正在喷发。 它在热点上空。 皇帝海山年老, 已经无法再达到海平面以上。 皇帝海山中最古老的海山即将沉入阿拉斯加的阿利乌提海沟中。 年长的海山可能已经进入海沟中。 地质学家们可以从这些热点爆发的火山岩中获取年老的日期。 因此他们用热点链来说明一个板块移动的方向和速度 。

    Hotspots Beneath Continents
    ::位于各大洲以下的热点点

    Satellite view of Yellowstone Lake and West Thumb geyser basin, highlighting natural features.

     

    Yellowstone Lake lies at the center of a giant caldera. This hole in the ground was created by enormous eruptions at the Yellowstone hotspot. The hotspot lies beneath Yellowstone National Park.
    ::黄石公园湖位于一个巨型卡路德拉的中心。这个洞是黄石公园热点的巨大喷发造成的。热点位于黄石公园下方。

    Hotspots are also found under the  continental crust . Since it is more difficult for magma to make it through the thick  crust , they are much less common. One exception is the Yellowstone hotspot ( Figure   ). This hotspot is very active. In the past, the hotspot produced enormous volcanic eruptions. Now its activity is best seen in the region’s famous  geysers .
    ::在大陆地壳下也发现了热点。 由于岩浆更难通过厚厚的地壳,热点就更少了。 黄石公园热点是一个例外。 这个热点非常活跃。 过去,热点引发了巨大的火山爆发。 如今,其活动最能见于该地区著名的热点。

     

    Summary
    ::摘要

    • Not all geological activity is found at plate boundaries. Activity within a plate is called intraplate activity. Most intraplate activity occurs at hotspots.
      ::并非所有地质活动都位于板块边界,板块内的活动称为板块内活动,大部分板块内活动发生在热点。
    • Hotspot volcanoes erupt mostly on oceanic crust. A few hotspots erupt on continental crust. The difference is due to the thickness of the crust.
      ::热点火山主要在大洋地壳上爆发,一些热点在大陆地壳上爆发,区别在于地壳厚度。
    • Hotspots can be used to tell the speed and direction that a plate is moving.
      ::热点可用于显示一个板块移动的速度和方向。

    Review
    ::回顾

    1. What is a hotspot?
      ::什么是热点?
    1. How do scientists use hotspot volcanism to tell the direction and speed of a plate?
      ::科学家如何利用热点火山 来判断一个板块的方向和速度?
    1. Compare and contrast hotspots in the oceans and on continents.
      ::海洋和大陆的热点比较和对比。