composición del manto-meteoritos
DESCRIPTION
petrografia igneaTRANSCRIPT
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Explorando
El interior
de
Nuestro Planeta
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Figure 1-5. Relative atomic abundances of the seven most common elements that comprise 97% of the Earth's mass. An Introduction to Igneous and Metamorphic Petrology, by John Winter , Prentice Hall.
O50.7%
Mg15.3%
Fe15.2%
Si14.4%
S3.0%
Al1.4%
Ca1.0%
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Capas de la Tierra Capas de la Tierra (basado en evidencias (basado en evidencias
SismolSismolgicas)gicas)
zzOndas SOndas SsmicassmicaszzP (longitudinales o de compresiP (longitudinales o de compresin)n)zzS (transversales o de cizalla)S (transversales o de cizalla)
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Velocidad de la onda P (Primaria) y S (Secundaria) en funcindel modulo k y
kk == modulo modulo dede compresibilidadcompresibilidad;; == modulo modulo de rigidezde rigidez;; == densidaddensidad (g/cm(g/cm33))
OndaOnda P y P y OndaOnda S?S?
en lquido == 00
3/4= kVp
=Vs
OndaOnda SS
OndaOnda PP(onda de compresi(onda de compresin n o longitudianl)o longitudianl)
(onda Transversal (onda Transversal o de cizalla)o de cizalla)
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Ondas P y SOndas P y S
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MovimientoMovimiento de de laslas OndasOndasP y S a P y S a travestraves de un de un sslidolido
Tomado de la Web
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OndaOnda P y P y OndaOnda S?S?
OndaOnda PP
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OndaOnda P y P y OndaOnda S?S?
OndaOnda SS
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Crust
Mantle
OuterCore
Velocity (km/sec)
0 5 10
1000
2000
3000
4000
5000
6000
Depth (km)
S waves
P waves
InnerCore
Lithosphere
Astheno-sphere
Solid
Liquid
Meso-sphere
S waves
Variacin en las velocidades de las ondas P y S con relacin a la profundidad. Las subdivisiones composicionales de la tierra estan a la izquierda, las subdivisiones
reolgicas en la derecha. Modificado de Kearey and Vine (1990), Global Tectonics. Blackwell Scientific. Oxford. (Tomado de la Web)
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Earthslayered structure
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LA DIFERENCIACIN DE NUESTRO PLANETA ES UN CASO NICO?
QUE DICEN LOS METEORITOS?
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En Gill R. (1989). ChemicalFundamentals of Geology
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Leonid meteorshower, 1998 European Fireball Networkimage
Meteoroid
Meteor(fireball)
Meteorite
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1992 Peekskill fireball video clips
(How to turn a $300 car into one worth $10,000.)
Un Un meteoritometeorito((chondritochondrito) de ) de ~12 kg ~12 kg impactimpact sobresobreun Chevrolet un Chevrolet Malibu en Malibu en Peekskill, NY, Peekskill, NY, en 1992.en 1992.
Da: An Introduction to Igneous and Metamorphic Petrology, by John Winter
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Results of ablation: fusion crust, thumbprints, fragmentation
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Meteorites:different types
Designation Proportion of metal & silicate
Stony >> 50 % silicate
Stony-iron ~ 50% metal, ~ 50% silicate)
Iron >> 50% metal alloy
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Meteorite types & parent bodies# parent
Designation Class & rock types bodies*
Stony chondrites: agglomerate > 13Stony achondrites: igneous, breccia > 8
Stony-iron pallasite: igneous > 3Stony-iron mesosiderite: meta-breccia 1 (2)
Iron many groups: igneous 50-80?
* as inferred from chemical & isotopic studies
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Meteorites:different types
Designation Type of rock
Chondrite agglomerate-- never melted(stony)
All else igneous; impact breccias--(stony, stony- melted at least onceiron, iron)
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Chondrites All other rocks
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Undifferentiatedmeteorites:chondrites
I. METEORITOS INDIFERENCIADOS
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Chondrites
Meteorite type most often seen to fall (85.6%)
Earliest-formed rocks(ages: ~4.55 b.y.)
Formed in solar nebula Solar-like bulk composition
(planetary building blocks)
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Chondrites most contain chondrules
mm to sub-mm-sized objectsformed as melted dispersed objects
some contain refractory inclusions (CAIs)mm to cm-sized objectsformed at high temperatures in solar nebula
some contain pre-solar grainsgrains formed around other stars
some contain pre-biotic organic matter
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Chondritic texture: an agglomeration of chondrules and fine-grained matrix
matrix
chondrules
0.2 mm
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CAIs
contains CAIs andpre-solar grains
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CAIs
Carbonaceouschondrite
chondrules
Image: J.A. Wood
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Differentiatedmeteorites
DAG 485 (urelilite)
Gibeon (IVA iron) Millbillillie (eucrite)
II. METEORITOS DIFERENCIADOS
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Achondrite - any stony meteorite NOT a chondrite - samples of crusts and mantles of differentiated asteroids, the Moon, and Mars
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Big! iron meteorite
Irons - samples of the cores of differentiated asteroids
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Iron meteorite:slow-cooling ina metallic core
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Mesosideriteorigin:
collision of astripped metalcore & anotherdifferentiatedasteroid?
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Model of convective Model of convective flow in the mantleflow in the mantle
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Modelo de ONions et al. (1979). Modelos de evolucin geoqumica del manto.
Modelos 1 y 1b se corresponden con el empobrecimiento del totalidad o o la mitad del manto debido a la extraccin de la corteza continental.
Modelos 2 y 2b muestra tipos de evoluciones alternativas: crecimiento progresivode un manto empobrecido constantemente o empobrecimiento progresivode un manto de volumen constante.
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http://www.see.leeds.ac.uk/structure/dynamicearth/convection/transzone.htm
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Phase diagram for aluminous Phase diagram for aluminous 44--phase lherzolite:phase lherzolite:
zz PlagioclasePlagioclase)) shallow (< 50 km)shallow (< 50 km)
zz SpinelSpinel)) 5050--80 km80 km
zz GarnetGarnet)) 8080--400 km400 km
zz Si Si VI VI coordcoord..)) > 400 km> 400 km
AlAl--phase =phase =
Figure 10Figure 10--2 2 Phase diagram of aluminous lherzolite with melting interval (graPhase diagram of aluminous lherzolite with melting interval (gray), suby), sub--solidus solidus reactions, and geothermal gradient. After reactions, and geothermal gradient. After Wyllie, P. J. (1981). Geol. Wyllie, P. J. (1981). Geol. RundschRundsch. 70, 128. 70, 128--153.153.
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Plate Tectonic Plate Tectonic -- Igneous Igneous GenesisGenesis
1.1. MidMid--ocean Ridgesocean Ridges2.2. IntracontinentalIntracontinentalRiftsRifts3. 3. Island ArcsIsland Arcs4.4. Active ContinentalActive Continental
MarginsMargins
5.5. BackBack--arc Basinsarc Basins6.6. Ocean Island BasaltsOcean Island Basalts7.7. Miscellaneous IntraMiscellaneous Intra--
Continental Continental ActivityActivity
kimberliteskimberlites, , carbonatitescarbonatites, , anorthositesanorthosites......
? ??
?600 km
400
200 km
Continental Crust
Oceanic Crust
Lithospheric Mantle
Sub-lithospheric Mantle
Source of Melts
15 3 46 7 2