The Material Earth

Solar System Accretion Theory

Chondrite –composition roughly equal to that of the Earth. This is a slab of NWA 2089 (LL3) 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 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 other 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 our 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 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

19-378Figure 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 oceanic 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: 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 (SiO 2 ), 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 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.