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Plate movement

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Plate movement
Inner core(内地核)
Outer core(外地核)
Mantle(地幔)
Crust(地壳)
Continental Crust 陆壳
Oceanic Crust 洋壳
Thickness
35-40km on average
60-70km under mountain chains
6-10km on average
Age of rocks
Very old, over 1500 million years
Very young, under 200 million years
Weight of rocks
Lighter, average density 2.6 g/cm3
Heavier, average density 3.0g/cm3
Nature of rocks
Light in color, many contain silica and aluminum铝
Dark in color, many contain silica and magnesium镁
Mid-Atlantic Ridge
大西洋中脊
East-Pacific Rise
东太平洋洋隆
Mid-India Ridge
印度洋中脊
亚欧板块
北美洲板块
太平洋板块
非洲板块
南美洲板块
澳大利亚印度板块
南极洲板块
The lithosphere is broken into about two dozen segments of irregular shape and size calls lithospheric plates 板块.
Plate tectonics 板块构造
Plate tectonics is the study of the movement of plates and their resultant landforms. The plates move relative to one
another along plate boundaries. Plate boundaries are classified into three types based on the type of motion occurring
between the adjacent plates.
Boundary
Divergent
离散型
Motion
Results
• Creation of new ocean floor with submarine volcanoes;
Plates move apart
• mid-oceanic ridge;
• small to moderate earthquakes
• Destruction of ocean floor;
Convergent
汇聚型
Plates move towards each other
• creation and growth of mountain range with volcanoes;
subduction zone;
• Earth’s greatest earthquakes and tsunamis
Transform
转换型
Plates move sideways past each other
No creation or destruction of crust;
small to large earthquakes
Oceanic ridges
Oceanic crust
North
America
◼Divergent/constructive plate boundaries
Partial
melting
Asthenosphere
Europe
扩张型板块边界
where two plates move apart, resulting in
Spreading
center
Africa
upwelling and partial melting of hot material
from the mantle to create new crust.
Upwelling
continental
oceanic
◼ Convergent/destructive plate boundaries
汇聚型板块边界—two plates move toward
oceanic
oceanic
each other.
◼ The character of the boundary depends partly
on the types of plates.
continental
continental
Benioff zone
Aerial view of San Andreas Faults
圣安德烈斯断层
◼ Conservative boundary
平错型边界
Two plates move sideways past each other,
land is neither formed nor destroyed.
◼ Transform faults 转换断层 are marked by shallow-focus
earthquakes in a narrow zone for a single fault or a broad zone for a
group of parallel faults
Type of plate boundary
Description of changes
Examples
Constructive boundary
Two plates move away from each other; new oceanic Mid-Atlantic Ridge, Eurasian and African Plates,
crust appears forming mid-ocean ridges with volcanoes East Pacific Rise
Destructive boundary
Andes(Nazca sinks under South American Plate)
Oceanic crust moves towards continental crust but,
Rockies(Juan de Fuca sinks under North
being heavier, sinks and is destroyed forming deep-sea
American Plate)
trenches and island arcs with volcanoes
Island arcs of the West Indies and Aleutians
Collision zones
Conservative boundary
Two continental crusts collide and, as neither can sink,
Himalayas, Alps
are forced up into fold mountains
Two plates move sideways past each other, land is
San Andreas Fault in California
neither formed nor destroyed
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