Heat Flow-3

Ali [email protected]

Department of Earth SciencesKFUPM

Final Lecture: Heat Flow

Solid Earth Geophysics

Temperature contours and heat flow profile for a subduction zone

Depressing in temperature as the cold slab subducts, leading to low heat flow in the forearc region.

Migrating hot fluids upward from the top of the subducting plate produce magma and high heat flow at the volcanic arc.

Parks and Plates©2005 Robert J. Lillie

Development of Volcanoes as Plate Moves over

Hotspot


Volcanoes are Progressively Lower away

from Hotspot


Volcanoes are Progressively

Older away from Hotspot


Volcanoes Lower away

from Hotspot

Volcanoes Older away

from Hotspot


NATIONAL PARKLANDS

Hawai`i Hotspot Track


Observations Along Hawaiian Island Chain


Observations Along Hawaiian Island Chain

Islands are older

in a northwest direction.


Observations along Hawaiian Island Chain

Islands are more eroded in

a northwest direction.



Islands are shorter in a northwest direction.


Hawai'i Volcanoes

National Park

Haleakalā National Park


These observations are consistent with volcanoes forming as the Pacific Plate moves

northwestward over a hotspot.

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Hawai`i – Emperor Hotspot Track

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80 Million Years Old



Northward Plate Motion


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Forming Today




Northwestward Plate Motion



Rising hotspot plume heats up region, making it expand and rise

upward.

Why are Islands Lower away from a Hotspot?


Why are Islands Lower away from a Hotspot?Drop in pressure on the hot, rising mantle

makes it melt, producing magma. Eruptions build volcanic island on the already elevated seafloor.


Plate motion moves the volcano away from the hotspot. The cooler region contracts, sinking the seafloor and

volcanic island.



Island moves farther away from hotspot and sinks even lower.



Erosion of the extinct volcano also makes it lower.



Elevation of Hawaiian Islands

NATIONAL PARKLANDS


NATIONAL PARKLANDS

Over Hotspot - Highly

Elevated



NATIONAL PARKLANDS


Elevated

Off of Hotspot -

Lower


Parks and Plates©2005 Robert J. LillieNATIONAL PARKLANDS


Elevated

Off of Hotspot -

Lower

Farther from Hotspot and Eroded

- Even Lower


Heat Flow-3

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