230 likes | 340 Vues
Summary from Previous Class. Earth’s Internal Layering - Crust, Mantle and Core Seismology, LVZ, Lithosphere, and Asthenosphere P,T, density variation in the earth’s interior Transition Zone, Two-layered vs. whole mantle convection
E N D
Summary from Previous Class Earth’s Internal Layering - Crust, Mantle and Core Seismology, LVZ, Lithosphere, and Asthenosphere P,T, density variation in the earth’s interior Transition Zone, Two-layered vs. whole mantle convection Plate tectonics, Plumes, Wilson Cycle, and recent hypotheses by Anderson and Larson
Layer Names Inner Core Solid Iron Outer Core Molten Iron Mantle Dense silicates Crust Great variety of minerals in the continental crust but limited in the oceanic crust
Meteorite TypesIrons (Core Equivalent)Stony Irons (Core/Mantle Boundary)Stony meteoritesAchondrites (silicate dominated) Chondrites (silicate) Carbonaceous Chondrites (only type with C & H2O…source of LIFE!)
Meteorite composition and abundance Stony meteorites (92.8%) Chondrites (85.7%) Carbonaceous (5.7%) hydrated mins. (serpentine), organic compounds, 1-9%H2O ordinary (67.6%) pyroxenes, olivines, Fe-Ni metal other (12.5%) similar Achondrites (7.1%) Ca-rich (4.7%) pyroxenes,olivines,plagioclase Ca-poor (2.4%) no plag Stony irons (1.5%) mesosiderites pyrox, plag, Fe-Ni pallasites olivine, Fe-Ni others pyrox, oliv, Fe-Ni Irons (5.7%) octahedrites kamacite, taenite hexahedrites kamacites ataxites taenite, kamacite Source: Emiliani (1990) Planet Earth
Source of Meteorites • Achondrites - from Mars & Moon • Chondrites - stuff terrestrial planets are made of • Irons - Core of the earth • Stony Irons - CMB • The oldest meteorites are 4.5 billion years old
Composition of C chondrites • The average Carbonaceous Chondrite Weight% • Carbon 2.0 • Metals 1.8 • Nitrogen 0.2 • Silicates 83.0 • Water 1- 9.0
Core dT/dz Depth (km)
Some Statistics….. • OF ALL THE METEORITES THAT FALL ON EARTH: • 86% are Chondrites • 7.1% are Achondrites • 5.7% are Irons • And 1.5% are Stony Irons