Section outline

  • What good are plate boundaries?
    ::板块边界有什么用?

    Plate boundaries  create  natural resources , such as gold. But plate boundaries also create beautiful scenery like  mountains .   at convergent plate boundaries can be beautiful to look at. They can also be beautiful to visit or even climb!
    ::板块边界创造自然资源,如黄金。但板块边界也创造像山一样的美丽景色。在交汇的板块边界上,可以看到美丽的景色。它们也可以美丽地参观甚至攀登!

    Convergent Plate Boundaries
    ::一致的盘点边界

    Converging  plates  can be oceanic, continental, or one of each. If at least one is oceanic, it will subduct. A subducting plate creates volcanoes. Many of the world's volcanoes are the result of  subduction  at a  convergent plate boundary . A   of the world's  active volcanoes  is pictured below ( Figure   ).
    ::聚在一起的板块可以是海洋的,大陆的,也可以是每个板块中的一个。如果至少有一个是海洋的,它就会沉淀下来。一个沉淀的板块会产生火山。世界上许多火山都是在汇合板块边界上沉没的结果。下面是世界活跃火山的图(图 ) 。

    Map showing active volcanoes and tectonic plates, highlighting the 'Ring of Fire' region.
     
    World map of active volcanoes.

    Melting
    ::熔融

    Mantle melting can come about three ways: (1) when the   rises, (2) if the pressure lowers (which lowers the melting point), and (3) if  water  is added, which lowers the melting point. Increasing temperatures and the additon of water occur at convergent plate boundaries; while decreasing pressure occurs at  .  The temperature of the subducting plate at a convergent boundary increases as it sinks into the hot mantle.  Sediments  lying on top of the subducting plate contain water. As the sediments subduct, the water rises into the overlying mantle material. This lowers the melting temperature of the mantle. When the mantle above the subducting plate melts, volcanoes form above it. This leads to volcanoes in an  island arc  or  continental arc .
    ::Mantle熔化可以有三种方式sad1) 涨幅时,(2) 降压(降低熔点),(2) 降压(降低熔点),(3) 增加水,降低熔点。温度升高和水的腹骨在聚板边界上发生;同时压力下降时发生。汇合边界的下层板的温度随着沉入热层而上升。下层板顶部的沉积物含有水。当沉淀物沉淀在沉淀物中时,水会升入覆盖壁材料中。这样会降低地壳的融化温度。当附着板上方的地壳融化时,火山会形成于上面。这会导致岛屿弧或大陆弧的火山。

    Pacific Rim
    ::环太平洋环环环

    Convergent plate boundaries are found around much of the Pacific  Ocean basin .  Trenches  mark  subduction zones . Volcanoes are found in an arc above those subduction zones.
    ::太平洋盆地大部分地区的板块边界相趋一致。Trenches标记下潜带。在这些下潜带之上的弧线中发现了火山。

    The Cascades ( Figure   ) are a chain of volcanoes at a convergent boundary. In this region, an oceanic plate is subducting beneath a continental plate.
    ::岩层(图)是汇合边界上的火山链。 在这一地区,一个海洋板块正沉入一个大陆板块之下。

    Map showing the Cascade Range volcanoes and tectonic plate boundaries along the Pacific coast.
     
    The Cascade Range is formed by volcanoes created from subduction of oceanic crust beneath the North American continent.

    The Cascades have been active for 27 million years. The mountains we see today are no more than 2 million years old. The volcanoes receive a lot of winter  snow , and many are covered by   ( Figure   ).
    ::火山群已经活跃了2,700万年。 我们今天看到的山峰不到200万年。 火山群受到大量冬季雪雪的侵袭,许多火山群被覆盖(图 ) 。

    Snow-capped Mt. Rainier reflects in a calm lake, surrounded by forests.
     
    Mt. Rainier, Washington.

    Divergent Plate Boundaries
    ::差异表边框

    At divergent plate boundaries hot mantle   rises into the space where the plates are moving apart. As the hot mantle rock rises, it goes from higher to lower pressure. This is because there is no longer the weight of all the rock above it. Lower pressure decreases the melting temperature of the rock. This is why there is volcanism at divergent plate boundaries.  Lava  erupts through long cracks in the ground, or  fissures.
    ::在不同的板块边界上,热粪便会升到板块分离的空间。 随着热土岩层升高, 压力会从高到低。 这是因为上面所有岩石的重量不再存在。 低压会降低岩石的熔化温度。 这就是为什么在不同的板块边界上存在火山现象。 岩浆会通过地上的长裂缝或裂缝爆发。

    Mid-Ocean Ridges
    ::中洋海脊

    Volcanoes erupt at mid-ocean ridges, such as the Mid-Atlantic ridge.  Seafloor spreading  creates new seafloor in the rift  valleys . This type of volcanism makes all of the ocean floor! Where a  hotspot  is located along the ridge, such as at Iceland, volcanoes grow high enough to create islands ( Figure   ).
    ::火山在中洋脊,如中大西洋海脊爆发,海底的扩张在裂谷中创造了新的海底。这种火山活动使所有洋底都成形。 在冰岛等海脊沿线的热点地区,火山高得足以创造岛屿(图 )。

    Eruption of a volcano on Iceland, showcasing lava and ash during an explosive eruption.
     
    A volcanic eruption on Iceland, where the Mid-Atlantic Ridge breaches the ocean surface.

    Continental Rifting
    ::大陆裂动

    Eruptions are found at divergent plate boundaries as continents break apart, known as  continental rifting . The Mount Gahinga volcanoes are in the East African Rift between the African and Arabian plates.  Dormant  volcanoes are also present on Baja California ( Figure   ), which is breaking apart from mainland Mexico by continental rifting.
    ::火山喷发发生在不同的板块边界上,因为大陆分崩离析,称为大陆裂裂。 伽辛加山火山位于东非非洲和阿拉伯板块之间的裂谷中。 下加利福尼亚州(Figure ) 也有多曼特火山(Dormant 火山 ) , 下加利福尼亚州因大陆裂裂裂而与墨西哥大陆分裂。

    Satellite view of Baja California, illustrating continental rifting and plate boundary separation.
     
    Baja California exists on the Pacific plate and is slowly separating from the rest of Mexico as the North American and Pacific plate move against each other.

    Summary
     ::摘要

    • Subduction at convergent plate boundaries leads to melting and volcanoes.
      ::聚集板块边界的潜入导致熔化和火山爆发
    • Convergent plate boundaries line the Pacific Ocean basin so that volcanic arcs line the region.
      ::相趋同的板块边界分太平洋盆地线,因此火山弧线划区域。
    • Melting at divergent plate boundaries is due to release of pressure.
      ::不同板块边界的熔化是由于压力的释放。
    • At mid-ocean ridges seafloor is pulled apart and new seafloor is created. Rifting in a continent can create a new ocean eventually.
      ::在洋中脊海底被拆解,新的海底被创造出来。 大陆的裂裂最终可以创造出新的海洋。

    Review
     ::回顾

    1. What are the two sources of melting at convergent plate boundaries?
      ::在聚集板块边界融化的两种来源是什么?
    1. Why are there so many volcanoes around the Pacific Ocean basin?
      ::为什么太平洋盆地周围有这么多火山?
    1. What causes melting at divergent plate boundaries?
      ::是什么导致不同板块边界的融化?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

     

     

    1. Where does the melted mantle rock rise?
      ::熔化的地壳岩在哪里上升?
    1. What does spreading cause?
      ::传播的原因是什么?
    1. What happens where there is plate convergence?
      ::在板块交汇的地方会怎样?
    1. How is carbon dioxide released from the rock?
      ::如何从岩石中释放二氧化碳?
    1. How is carbon dioxide returned to the atmosphere?
      ::二氧化碳如何返回大气层?