WHAT HAPPENS WHEN PIECES OF THE CRUST ARE FORCED TOGETHER ?

WHAT HAPPENS WHEN PIECES OF THE CRUST ARE

FORCED TOGETHER ?

Extension andinjection of mantle material into crust

CrustalCompression

Extension andinjection of mantle material into crust

CrustalCompression

Consideration of Conservation of Mass:

Mass leaving MantleInjected to Crust.

Unless Crustal material is returned mantle in equal volume the Earth will

grow larger and larger, but also “hollower” and “hollower”.

CRUSTAL COMPRESSION

CrustalThickening

CRUSTAL COMPRESSION

CrustalThickening

CRUSTAL COMPRESSION

CrustalThickening

CrustalFaulting

Denser Crust to Mantle.

Crustal Convergenceand Compression.

HeatHeat and

Pressure

CRUSTAL ROCKS

Block 1 Block 2

Two Origins of Crustal Rocks:1) Continental Crust – Lower density as “floated” to outside of Earth.2) Oceanic Crust – Higher density as origin deeper in the mantle.

ContinentalCrust

Oceanic Crust

CONVERGENT BOUNDARIESTwo types of crustal rocks, thus three possibletypes of convergence:

1. Oceanic vs. Continental:

e.g. Western South America

2. Oceanic vs. Oceanic:

e.g. Japanese Islands

2. Oceanic vs. Oceanic:

e.g. Japanese Islands

3. Continental vs. Continental:

e.g. Himalayas

1. GENERAL SETTING

WESTERN SOUTH AMERICAPacific Ocean Atlantic OceanSouth America

Mid-Atlantic

South American Plate

African Plate

Mid-Atlantic

African Plate

Mid-Atlantic

EastPacific

African Plate

Mid-Atlantic

EastPacific

Nazca Plate

Pacific Plate

African Plate

Mid-Atlantic

EastPacific

Nazca Plate

Pacific Plate

African Plate

Mid-Atlantic

EastPacific

Nazca Plate

Pacific Plate

African Plate

CONVERGENCE AND CRUSTAL COMPRESSION

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

Crustal Thickening

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

Mato GrossoBrazilian HighlandsGuiana Highlands

Compressional Faulting

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

More dense oceanic crustSub-ducted beneath South America

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

Deep oceantrench

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

ShallowEarthquakes

DeepEarthquakes

Heat and pressurecause melting

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

Ocean sediments

Nazca Plate

African Plate

Pacific Plate

EastPacific

Mid-Atlantic

AndesActive Volcanoes

03.05.b1

03.09.a1

2. JAPANESE ISLANDS GENERAL SETTING

Pacific OceanAsia Sea ofJapan

JAPANESE ISLANDS

EastPacific

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

JAPANESE ISLANDS

Eurasia Moved from North Atlantic Mid-ocean Ridge

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

JAPANESE ISLANDS

CONVERGENCE AND CRUSTAL COMPRESSION

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Pacific OceanAsia Sea ofJapan The Pacific Plate composed

entirely of denser oceanic crust, is subducted beneath the oceanic fringe of the dominantly continental Eurasian Plate.

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Ocean trench

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Heat andPressure cause melting

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Heat andPressure cause melting

Shallow and deep earthquakes

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Pacific OceanAsia Sea ofJapan Mountain building breaking

ocean surface as a series of islands or “island arcs”.

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Compressional faulting permits “recycled” oceanic crust to rise to the surface, producing active volcanoes.

JAPANESE ISLANDS

Island Arcs

OceanTrenches

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Pacific OceanAsia Sea ofJapan As the Pacific plate is

subducted it tends to “roll-back” southeastwards, pulling the Japanese Islands further off of Asia.

“Push”

“Pull”

JAPANESE ISLANDS

EastPacific

Nazca Plate

Pacific Plate

Eurasian Plate

Pacific OceanAsia Sea ofJapan Motion of Japanese islands

away from Asia causes split of crust and “back arc spreading” beneath the sea of Japan .

JAPANESE ISLANDS

03.00.a1e

Source: R.A. Kerr., 2011 Science, 332, p.911

Displacement duringEarthquake March 2011.

Source: Simons et al., 2011 Science Express

CREDIT: ADAPTED FROM THE EARTHQUAKE RESEARCH COMMITTEE, NATIONAL SEISMIC HAZARD MAPS FOR JAPAN (2010), HEADQUARTERS FOR EARTHQUAKE RESEARCH PROMOTION

3. HIMALAYAGENERAL SETTING

250 million years ago

Eurasia

Indian sub-continent

EARLY DIVERGENCE ANDCRUSTAL EXTENSIONAfrica India

HIMALAYA MOUNTAINS250 million years ago

Africa and India part of the same continental mass, Gondwanaland, also comprised of present day, South Africa, Australia and Antarctica.

Africa India Eurasia

Eurasian Plate

African Plate

Eurasia (Europe and Asia), part of northern continental landmass including present day North America.

Eurasian Plate

African Plate

Sea of Tethys

Tethys Plate

Eurasian Plate

Tethys Plate

African Plate

HIMALAYA MOUNTAINS250 million years ago CONVERGENCE (Ocean

vs Continent) AND CRUSTAL COMPRESSION

Eurasian Plate

Tethys Plate

African Plate

Tethys Ocean crustsubducted beneath Eurasian continent

Eurasian Plate

Tethys Plate

African Plate

Ocean trench

Eurasian Plate

Tethys Plate

African Plate

Melting underHeat and pressure

Eurasian Plate

Tethys Plate

African Plate

Earthquakes

Eurasian Plate

Tethys Plate

African Plate

Mountainbuilding

Eurasian Plate

Tethys Plate

African Plate

Volcanoes

Africa India EurasiaSea ofTethys

Eurasian Plate

Tethys Plate

African Plate

IndianOcean

Indo-Australian Plate

Africa India EurasiaSea ofTethys

Eurasian Plate

Tethys Plate

African Plate

IndianOcean

Eurasian Plate

Tethys Plate

African Plate

IndianOcean

HimalayaMountains

HIMALAYA MOUNTAINSPresent

Wilhan and Gaur, 2013. Buildings as weapons of mass destruction.www.sciencemag.org SCIENCE VOL 341 9, p618-619

03.00.a1d

INDUS GANGES

PAKISTAN

BANGLADESH

HIMALAYATIBET

PLATEAU

SICHUAN EARTHQUAKECHINA, 2008.

0 20 40 60 80 1006.0

WORLD’S 100 HIGHEST MOUNTAINS

Himalaya and Associated Ranges

03.02.b1

VOLCANOES

WHY NO VOLCANOES?

India Eurasia

Eurasian Plate

Tethys Plate

IndianOcean

HimalayaMountains

WHAT’S HAPPENING NOW?Present

Tibetan Plateau

India Eurasia

Eurasian Plate

Tethys Plate

IndianOcean

HimalayaMountains

WHAT’S HAPPENING NOW?Present

Tibetan Plateau

GLOBAL DISTRIBUTION OF EARTHQUAKES

1. Western South America

2. Japanese Islands

3. Himalaya

GLOBAL DISTRIBUTION OF VOLCANOES

GLOBAL DISTRIBUTION OF VOLCANOES1. Western South America

GLOBAL DISTRIBUTION OF VOLCANOES2. Japanese Islands

GLOBAL DISTRIBUTION OF VOLCANOES3. Himalaya

WHAT HAPPENS WHEN PIECES OF THE CRUST ARE FORCED TOGETHER ?

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