Explorando

El interior

de

Nuestro Planeta

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%

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)

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)

Ondas P y SOndas P y S

MovimientoMovimiento de de laslas OndasOndasP y S a P y S a travestraves de un de un sslidolido

Tomado de la Web

OndaOnda P y P y OndaOnda S?S?

OndaOnda PP

OndaOnda P y P y OndaOnda S?S?

OndaOnda SS

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)

Earthslayered structure

LA DIFERENCIACIN DE NUESTRO PLANETA ES UN CASO NICO?

QUE DICEN LOS METEORITOS?

En Gill R. (1989). ChemicalFundamentals of Geology

Leonid meteorshower, 1998 European Fireball Networkimage

Meteoroid

Meteor(fireball)

Meteorite

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

Results of ablation: fusion crust, thumbprints, fragmentation

Meteorites:different types

Designation Proportion of metal & silicate

Stony >> 50 % silicate

Stony-iron ~ 50% metal, ~ 50% silicate)

Iron >> 50% metal alloy

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

Meteorites:different types

Designation Type of rock

Chondrite agglomerate-- never melted(stony)

All else igneous; impact breccias--(stony, stony- melted at least onceiron, iron)

Chondrites All other rocks

Undifferentiatedmeteorites:chondrites

I. METEORITOS INDIFERENCIADOS

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)

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

Chondritic texture: an agglomeration of chondrules and fine-grained matrix

matrix

chondrules

0.2 mm

CAIs

contains CAIs andpre-solar grains

CAIs

Carbonaceouschondrite

chondrules

Image: J.A. Wood

Differentiatedmeteorites

DAG 485 (urelilite)

Gibeon (IVA iron) Millbillillie (eucrite)

II. METEORITOS DIFERENCIADOS

Achondrite - any stony meteorite NOT a chondrite - samples of crusts and mantles of differentiated asteroids, the Moon, and Mars

Big! iron meteorite

Irons - samples of the cores of differentiated asteroids

Iron meteorite:slow-cooling ina metallic core

Mesosideriteorigin:

collision of astripped metalcore & anotherdifferentiatedasteroid?

Model of convective Model of convective flow in the mantleflow in the mantle

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.

http://www.see.leeds.ac.uk/structure/dynamicearth/convection/transzone.htm

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.

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