The Material Earth Solar System Accretion Theory Accreted - - PowerPoint PPT Presentation

The Material Earth

Solar System Accretion Theory

Chondrite –composition roughly equal to that of the

• Earth. This is a slab of NWA

2089 (LL3)

www.arizonaskiesmeteorites.com

Anatomy of a chondrite

CAI’s: Calcium Aluminum-rich inclusions, varying size of material that condensed at T> 1100ºC Chondrules: rounded grains rich in silicon, condensed between 400-900 ºC. Matrix: low temperature silicon and carbon rich phases, condensed below 175 ºC. Accreted components

Chondrites become attracted and attach Growth continues with impacts

• heating, rounding with size

When a body is larger than 100 km diameter and hot, iron and

• ther heavy compounds sink

towards center, silicon-oxygen compounds float towards surface.

Initial bombardment formation of Earth; impact energy transferred into heat Contraction due to increasing gravitational force; compression increases heat Radioactive decay of elements produces energies that heat surroundings

Hot Earth

The earth’s heat results from kinetic (movement) energy: the energy of large (impactors) and small (electromagnetic photons and atomic particles) objects. But space is cold - we are losing this heat

You should know:

• It’s built from

chondrites.

• Center half is largely

made of iron.

• Only the outer core is

mostly liquid

• Outer half is largely

made of oxygen and silicon.

• Our knowledge

diminishes as we move into the planet. How do we learn of

• ur planet’s interior?

KTB

Photo by Hans-Joachim Kümpel

Kola

Journey to the Center?

Heat release moves crustal- upper mantle masses. Surface includes once deeply buried rocks

The Adirondacks Old rocks from the middle continental crust

Volcanoes - heat and mass breach the surface

diamond Mantle fragment

Our understanding of the earth falls off with depth.

6,378 km

Mid Ocean ridge

Piston Cylinder

Solid Media Pressure Apparatus

Faking it - reproducing conditions within a lab setting. Near isostatic pressure and elevated temperatures

An earthquake releases the energy accumulated from stress in the crust of the earth Earthquake (seismic) waves are the result of energy transfer through matter

19-378 Figure 19.16

Seismic shadow

The speed of the waves changes with depth This is a function of material behavior reflecting changes in three things:

• Temperature
• Pressure
• Composition

Source:After W. Hamilton, U.S. Geological Survey

The major plates of the lithosphere

Cold Lithosphere will sink. Slab drags plate downward. Volcanism and rupturing at weak points builds new

• ceanic crust

A deeper mechanism driving it all?

Subduction: Continental Arcs

Example: the Cascades Trenches are the deepest part of the oceans

Divergent Boundary - Continental Rift

NASA STS- 32

Example: the East African Rift

NASA Digital Tectonic Activity Map

Magmas generated by mantle melting can make their way to the

• surface. They

also may induce partial melting in the crust.

Continental collision

Example: the Himalaya

Arbuckle Mountains, Oklahoma Rattlesnake Mountain, Wyoming

The hydrologic cycle

2-458

H-O bonds are bent towards each other. Hydrogen atoms near one end lend a positive charge.

Water appears to be the most crucial compound to life on Earth It merits a closer look:

Examples of very porous rocks

Rocks like these are responsible for storage and transports of large reservoirs of potable water. Sandstones, white area are grains of quartz (SiO2), blue area is a dye to show pore space in rock)

The path of groundwater

• 4.56 billion year old chondrite-derived planet
• Differentiation has resulted in an iron core, a

rocky mantle and crust, a hydrosphere, and an atmosphere.

• Heat loss from its formation drives interior and

surface modification through plate tectonics.

• Heat gain from Sun’s fusion reaction drives

surface modification through hydrologic cycles.

• The change of these energies results in very

complicated systems.