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지질해양학 (Marine Geology)
담당교수: 하호경 ([email protected])
대륙이동설 / 판구조론
• 베거너 (Alfred Wegener)
Alfred Wegener, ca. 1924-‐1930
-‐ 대륙의 기원 (The origin of conAnents): 1912년 1월 발표 -‐ 대륙이 움직이고 있다 (conAnental driD)
-‐ 해안선이 일치 -‐ 고생물학적인 증거
Alfred Wegener InsAtute (독일)
hGp://www.awi.de
• 주요 판의 위치 및 이동방향, 열점(hot spot)의 위치.
• 판 경계부와 지진대가 잘 일치한다.
• 대부분의 지진, 화산활동은 판 경계부를 따라 발행한다.
Plate Tectonics
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• 1977-‐1986년 사이에 발생한 지진.
• 10,000회 이상의 지진이 발생하였다.
• 색깔은 지진의 진원지의 깊이를 나타냄.
Plate Tectonics
The lithospheric plates interact with the neighboring plates in several ways:
(1) Divergent (발산형 판 경계부) (2) Convergent (수렴형 판 경계부) (3) Transform (변환형 판 경계부)
Plate Tectonics
Plate Tectonics
• Plates
• Plate boundaries
• Earthquakes
• Island chains
• Plate moAon
Plates
• A rigid unit of lithosphere that moves as a unit
• Plate =Lithosphere = crust + upper rigid mantle
• Major plates:
Pacific, North American, South American,
Eurasian, Indian, Antarc7c, Australia
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Plates
“Ring of fire”
hGp://www.youtube.com/watch?v=IfAcAxX81tk
Plates
Plates
Plate Boundaries (3 types)
• Divergent
• Convergent
– Ocean/ConAnent – ConAnent/ConAnent – Ocean/Ocean
• Transform
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Divergent Boundary
• Moving apart
• Mid-‐ocean ridges, riD valleys
Divergent Boundary -‐ ocean
Divergent Boundary -‐ conAnent
Tensional Forces
Measured Spreading Across Valley
Convergent Boundary-‐ Ocean/Cont.
• Moving together
• Trenches, mountains, volcanoes
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Convergent Boundary-‐ Ocean/Ocean
• Moving together
• Trenches, island arcs, volcanoes, marginal seas
Convergent Boundary-‐ Cont./Cont.
• Moving together
• Mountains
Transform Boundary
• Plates slide and pass each other
• Usually offset segments of ocean ridges (two divergent boundaries)
Plate Tectonics
There are three types of plate boundaries:
(1) Divergent (발산형 판 경계부)
(2) Convergent (수렴형 판 경계부)
(3) Transform(변환형 판 경계부)
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(1) Divergent Plate Boundary
§ RiDing of the earth’s crust due to tensional forces produced by upwelling magma.
§ Has shallow focus earthquakes.
Divergent plate boundary is along the mid-‐
AtlanAc Ridge.
Iceland is growing bigger because of its existence along the mid-‐AtlanAc Ridge.
The Red Sea and Gulf of Suez are being
created along a divergent plate boundary.
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(2) Convergent Plate Boundary – conAnent-‐conAnent type.
§ UpliD of the Earth’s crust (mountain-‐building) due to less dense conAnental crust subducAng under more dense conAnental crust.
§ Shallow to deep focus earthquakes occur along convergent plate boundary.
Cont-Cont Ocean-Ocean Ocean-Cont
Himalayas are mountains built as the Australian-‐Indian Plate converges with the
Eurasian Plate.
§ Ocean-‐ocean convergent plate boundary creates
shallow to deep focus earthquakes.
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§ Ocean-‐conAnent convergent plate boundary creates shallow to deep focus earthquakes.
Japan is an island arc formed by the converging of the Pacific oceanic plate and the Eurasian conAnent plate.
Example of Ocean-Continent convergence Volcanic Island Arc
§ The Andes mountains are formed by the convergence of the Nazca oceanic plate with the South American conAnental plate.
§ Shallow to deep focus earthquakes occur along this plate boundary.
• Plates move horizontally past each other along strike- slip faults
• Shallow focus earthquakes, especially destructive on continents
Transform Boundaries
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San Andreas
There are three types of plate boundaries:
(1) Divergent-‐
shallow focus earthquake, e.g., Mid-‐AtlanAc Ridge
(2) Convergent-‐
shallow to deep focus earthquake, e.g., Himalayas Mountains
(3) Transform-‐
move parallel to each other e.g., San Andreas Fault
Summary: Plate Boundaries (3 types)
• Narrow, conAnuous bands
• Outline plate boundaries
Earthquakes
• Shallow, intermediate (70-‐300 km) and deep (300-‐700 km) earthquakes outline subducAon zone
• At subducAon zones, deeper earthquakes
Earthquakes
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Earthquakes
• Formed along descending plate
• Benioff Zone:
~45
o(30-‐80
o)
inclined zone
Benioff zone: A dipping planar (flat) zone of earthquakes that is produced by the interacAon of a downgoing oceanic crustal plate with a conAnental plate.
Plate MoCons
Center of plate moves as rigid unit, with deformaAon of weaker conAnental crust in mountain building along edges
Plate speed and direcCon
• Crustal ages
– distance from ridge/age
• Hot spot islands
– distance from hot spot/age
Hot Spots
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Hot Spots
Hawaiian Hot Spot
Spreading rate = distance/age, in cm/yr
대륙경계면의 형태
• 태평양형 (Pacific type, AcAve margin)
대륙경계면의 형태
• 대서양형 (AtlanAc type, Passive margin)
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화산활동 (AcAve margin): 온타케화산 2014. 9
hGp://www.youtube.com/watch?v=Kv2q1Gu_kS8
불의 고리 (Ring of fire)
hGp://www.youtube.com/watch?v=B8AD-‐78ksxA
