Physical Geology 2003

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Table of Contents:
1.) What is a Superplume?
2.) Geologic Processes
3.) Impacts of Superplumes on the Earth
-Temperature
-Sea Levels
-Ocean Crust
-Magnetic Reversals

4.) When did they occur?
-Cretaceous
-Pennsylvania/Permian
5. Locations of Superplumes today, past and present
6.) Literature Cited / Image Links


Roger L. Larson
formulated the Superplume theory (Image 3)


Image 6: The Earth we live on: Seen by Apollo

Related Links:
- Link to sea the ancient world: http://www.scotese.
com/Default.htm

- Power Point: Superplume Project:Towards a new view of whole Earth dynamics


Image10: Etna, Italy
Photo courtesy: Tom Pfeiffer /
www.decadevolcano.net


Image 12: Pu`u `O`o-Kupaianaha, Kilauea, Hawaii

Peake's Superplume Webpage

Introduction: What is a Superplume?
A superplume occurs when a large mantle upwelling is convected to the Earth's surface. A superplume should not be confused with a hot-spot. Although similar, a superplume forms at the mantle-core boundary while a hot-spot occurs at the mantle-crust layer. Superplumes create cataclysmic events that affect the whole world when they explode. Scientists have found evidence of superplume activity occurring throughout the Earth's history. Roger L. Larson formulated the superplume theory, and since then scientists have been supporting his theory by finding out more and more about superplumes . Below, features an image that shows how a superplume was created.


Image 1: The creation of a superplume

Geologic Processes:
A superplume forms at the core-mantle boundary and confection forces the superplume through entire mantle until the superplume meets the crust. The world changes when the superplume explodes. Superplumes can occur anywhere, even in the middle of continental plates. In order to get a core-mantle upwelling to the Earth's surface, the thrust force of a downwelling must have occurred. The downwelling comes form a subduction zone that has cooled magma that has sunk into the earth. All this movement in the Earth's body causes plate tectinoc to go into full throttle. The Earth's fueling of tectonics forces an increase in oceanic crust formation.


Video 5: Video depicting the "Superplume Formation Beneath an Ancient Slab"

Impacts of Superplumes on the Earth:

Temperature: Superplumes increase world temperatures by the release of CO2 into the atmosphere. This phenonmenon is also called the greenhouse effect. The superplume activity causes carbon to be brought up by the magma from the Earth. A chart is shown below showing temperature levels from the Pre-Cambrian to the present day. Notice the temperature increases during the Cretaceous and the Permian periods.

Image 13: Average Global Temperage


Image 2: Ashplume of Mount Etna in Southern Italy represents how the Earth's processes can add material high into the atmosphere


Image 7: The South-Pacific Superswell (note that a superswell also occurs in Africa)


Image 8: Volcano in Popocatepetl, Mexico



Image 9: Volcano in Arsenal, Costa Rica


Image 11: Volcano Kanaga in the Aleutian Islands, USA

Sea Levels: During superplume activity, sea levels rise. This lessens the total amount of landmass making the world have more oceans. The sea levels
rise partly because the temperature increases due to the greenhouse effect melting the polar ice caps.


Image 14

Formation of Oceanic Crust: Superplume activity causes plate tectonic to go into full motion. Plate spreading rates increase tremendously, much of
which is in the form of oceanic crust. You may have noticed much of the earth's images on this website look a little differently. The earth changes by the
movement of the continents from plate tectonics.
Magnetic Reversals: Magnetic reversals usually occur a few times every million years, but when superplumes activity occurs magnetic reversals stop
for the millions of years they are active. Notice the below left chart: During the Cretaceous no magnetic reversals occured. This is some of the evidence
that superplumes are active. The image to the right shows a scientist's view of how magnetic reversals look when in the process of switching.

Image 15: Temperature curve for past 150 million years ___Image 16: This image shows what a magnetic reversal may look like when in the process
of switching

Products of the Past Geologic Process: When did they occur?
Cretaceous Superplume event: Scientist have the most information to back up a hypothesis for a superplume event during the Cretaceous 120-80
million years ago in the Pacific basin. During this period oceanic crust production increased by 50-75%. Ocean levels were higher than present day levels.
During this period magnetic reversals also stopped for 41 million years.CO2 pressure levels were six to eight times higher than they are today creating
a "super-greenhouse" effect. An increased production of black shale occured primarilt because of the increase in organic productivity and poor basin
ventilation. 60% of the world’s known oil was formed in Albian to Turonian stages (112 to 88 million years ago), a period during the Cretaceous. During
this period the Hess Rise, Line Islands, and the Manihiki Plateaus were all formed or present near the pacific superplume.

Image 17: Late-Creataceous Earth. Notice how the sea levels are high and little land mass is visible.

Image18: Above shows the climate of the late-Cretaceous. Notice most of the Earth consists of either arid, warm temperate, or tropical
climates. Only the far north and south are cool temperates.

Pennsylvania/Permian Superplume: More of a controversy exists over the existence of the Pennsylvania/Permian superplume.Some evidence does,
however, exists that supports the existence of this superplume. It is believed that magnetism was reversed during this period. The temperature
explains the climate of this time period of swampy, tropical, wet conditions in the northern hemisphere, and the glaciation in the southern hemisphere
or Gondwanaland. The magnetic reversal may play a role in the warmer climates in the north and the cooler climates in the south by the magnetic poles
being switched. Sea levels and gas accumulations both rose during this period. Much of the coal that we mine today in Northern Europe, Pennsylvania,
Russia, and China formed during the Permian. Magnetic reversals did not occur during the 75 million years the Pennsylvanian/Permian superplume was active.

Image 19: Above shows the late-Permain earth. Notice how much the sea levels have risen and how little land mass is visible.

Locations of Superplumes today, past and present:

Much of the past superplume activity is theorized from from looking at fossil and rock (basaltic lavas especially) records. Scientists have
hypothesized that past plates like Farallan Plate, à Hess Rise, Line Islands, and Manihiki Plateau all formed at the Pacific/Farallan boundary
during superplume activity. Some of these occurred or were present during the Cretaceous period of 90-150 million years ago and were part
of the Polynesian superswell. The presence of the superswell can still be visible when monitoring the magma activity inside the Earth. Some
scientists believe that a superswell today feeds many of the volcanic activity in the Pacific basin.


Image 20: Above shows much of the volcanic activity today. When looking at the "Ring of Fire" notice how much of the volcanic activity occurs
around the pacific ocean. Some scientists have hypothesized that much of this activity is fed from the superswell below.


Image 21 and Image 22


When looking at the images above show a superswell in the middle of the Pacific. Both these images show the vocanic activity at certain depths inside
the Earth. Notice on the images that there is definite activity in the Pacific and Africa.

Literature Cited:
- Latest pulse of Earth; evidence for a Mid-Cretaceous super plume, Larson, R. L. In: Geology, June 1991, Vol. 19, Issue 6, pp.547-550

- Geological consequences of superplumes, Larson, Roger L. In: Geology, October 1991, Vol. 19, Issue 10, pp.963-966

- Geochemical evidence for a Mid-Cretaceous superplume, Tatsumi, Yoshiyuki In: Geology, February 1998, Vol. 26, Issue 2, pp.151-154

- The Mid-Cretaceous superplume episode, Larson, Roger L. In: Scientific American, February 1995, Vol. 272, Issue 2, pp.82-86

- Superplumes from the core-mantle boundary to the lithosphere; implications for heat flux, Romanowicz, Barbara In: Science, April 19, 2002,
Vol. 296, Issue 5567, pp.513-516

- Impact dust not the cause of the Cretaceous-Tertiary mass extinction, Pope, Kevin O. In: Geology, February 2002, Vol. 30, Issue 2, pp.99-102

-Catastrophic events in the mantle and episodic growth of continents, Condie, Kent C. In: Abstracts with Programs - Geological Society
of America, 1998, Vol. 30, Issue 7, pp.345-346

- Power Point: Superplume Project:Towards a new view of whole Earth dynamics

- http://www.scotese.com/Default.htm

- http://www.seismo.berkeley.edu/seismo/annual_report/ar01_02/node37.html

- http://www.gps.caltech.edu/~gurnis/Movies/Science_Captions/caption_slab-plume.html

- http://brysonburke.com/mag_index.html

- http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html

Image Citations: Click on the Image for the link

Image 1, Image 2, Image 3, Image 4, Video 5, Image 6, Image 7, Image 8, Image 9, Image 10, Image 11, Image 12 , Image 13,
Image 14, Image 15, Image 16, Image 17, Image 18, Image 19, Image 20 (altered), Image 21, Image 22

 

Author: David Wainwright Peake III
Creation/last revision date: 07.February. 2003 / 08.April.2003

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This website is part of a Geology 211 class project on Processes in Physical Geology.

Earlham · Geosciences Department · Geociences 211: Physical Geology

Copyright © 2003 Earlham College. Revised 08.April.2003. Send corrections or comments toDavid Wainwright Peake III