Transcript U4-T2.8-Geology of Newfoundlandx

Earth Systems 3209
Unit: 4
The Forces Within Earth
Reference:
Chapters 4, 15, 16, 19; Appendix A & B
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Unit 4:
Topic 2.8
Geology of Newfoundland
Focus on . . .
 describing the geologic layout of the island of
Newfoundland.
 Core STSE – “The Geology of Newfoundland and
Labrador”
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 About 500 hundred million years ago, the central
portion of North America was under a warm tropical
sea called the Iapetus Ocean. Europe, Africa and
North America bordered this body of water.
Iapetus Ocean
North
American
Plate
African
Plate
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 Over the next 150 million years (350 million years ago),
forces within Earth’s mantle slowly carried these
continents on a collision course. As the continents
drifted together and collided, the ocean floor (a volcanic
island arc) was squeezed and then pushed upward to
form the Appalachian Mountains.
North
American
Plate
Iapetus Ocean
African
Plate
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 The remains of this mountain range now exists throughout
central and western Newfoundland and is the northern most
part of the Appalachians in North America. This range,
continues through most of the British Isles and into Norway.
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 An area called the Tablelands in Gros Morne National Park
has rocks that were once part of Earth’s mantle but were
pushed on top of Earth’s crust during the collision of the
continents 350 million years ago. These sightings called
Ophiolite complexes, represents an ocean floor profile
resting on land and are rarely seen on Earth’s surface.
Ophiolite Complex
Tablelands
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 225 million years ago, the forces in Earth’s mantle that
brought the continents together reversed and slowly
began to pull them apart. The divergent boundary
responsible for the shifting of the plates rifted within the
African plate and caused the plates to drift apart,
leaving a small section of the African plate behind.
North Americam
Plate
New Divergent
Boundary
African Plate
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Plate Tectonics and Newfoundland
 The Geological Formation of Newfoundland
 During this process a small bit of Africa got left behind!
When you stand on Signal Hill in St. John’s, you are
standing on rocks that are identical to ones in the country of
Morocco in Northern Africa! The Eastern part of
Newfoundland was once a part of the African plate.
North Americam
Plate
African Plate Left
Behind
New Divergent
Boundary
African Plate
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Plate Tectonics and Newfoundland
 The Geological Layout of Newfoundland
 Western (Humber) Zone:
 Has been a part of the North American
plate for at least the last billion years.
 Central (Zone) Mobile Belt:
Western Zone
 Remnants of volcanic island arcs and
the ancient Iapetus ocean floor.
 Eastern (Avalon) Zone:
Central Mobile
Belt
 Once part of the African plate which
remained attached as Pangaea split
200 million years ago.
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Eastern Zone
Plate Tectonics and Newfoundland
 The Geology of Newfoundland Labrador
Site of ophiolite
sequence
Western
(Humber)
Platform
Central
Mobile Belt
Eastern
(Avalon)
Platform
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Example 1:
Which area of the island of Newfoundland is
composed of rocks similar to an ancient ocean floor?
(A)
(C)
Eastern
Southern
(B)
(D)
Central
Western
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Example 2:
When the Proto-Atlantic Ocean closed many
years ago, which mountain chain was created
on the East coast of North America?
(A)
(B)
(C)
(D)
Andes Mountains
Appalachian Mountains
Himalaya Mountains
Rocky Mountains
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Your Turn . . .
Take the time and complete the following questions . . .
(Solutions to follow)
Questions:
Use the diagram and your knowledge
of the theory of Plate Tectonics to
explain how the three geologic zones of
the island portion of Newfoundland and
Labrador were formed.
A
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B
C
Solutions . . .
Question:
A
Use the diagram and your knowledge of the theory of Plate
Tectonics to explain how the three geologic zones of the
island portion of Newfoundland and Labrador were formed.
B
C
Answer:
It is thought that the geology of Island Newfoundland resulted long ago
when the Iapetus Ocean was closing. The North American plate
collided with the African plate and as a result a portion of the Iapetus
Ocean floor was sandwiched in between. Zone “A” is referred to as the
Western (Humber) Zone and was part of the North American plate.
Zone “C” is referred to as the Eastern (Avalon) zone and is thought to
part of the African plate. Zone “B” is referred to as the Central Mobile
Belt and is thought to be once part of the ancient Iapetus Ocean.
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Summary . . .
Overview of Points covered:
Newfoundland is divided into THREE geologic zones:
1) Western (Humber) Zone
2) Central (Zone) Mobile Belt
3) Eastern (Avalon) Zone
Note:
Newfoundland formed as a result of plate tectonic activity over the past
500 million years. This activity formed the Appalachian Mountains and
left a part of the African Plate behind as part of Eastern Newfoundland.
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