Resan till jordens inre
Athanasius Kircher(1665) Mundus Subterraneus
Jules Verne (1864)
Nuvarande schematisk bild av jordens inre
Temperatur i jordens inre
Tryck och densitet profiler i jordens inre
Tryck i jordens inre
350
12
300
10
250
8
200
6
150
4
100
50
outer
core
mantle
0
inner
core
2
0
0
1000
2000
3000
4000
5000
6000
Depth (km)
1 GPa = 100 000 N / cm2
järn
0 GPa
järn
364 GPa
Density (g/cm3)
0.1 GPa
3 GPa
364 GPa
550 GPa
2 TPa
100 TPa
30 000 TPa
Pressure (GPa)
Djupaste hav
Industri
Max. tryck i Jorden
Diamancell
Max. tryck i Jupiter
Explosion av kärnvapen
Solens kärna
14
400
Studier av jordens inre med hjälp av seismiska vågor
Density, pressure and gravity within the Earth
Key questions of the Earth’s deep interior rely on high pressure experiments
fältspat
Silikater
olivin
pyroxen
kvarts
granat
hematit (Fe2O3)
koksalt (NaCl)
pyrit (FeS2)
gips (CaSO4 . 2H2O)
Subduktionszon (neddykningszon)
- en långsmal zon i jordskorpan längs vilken två litosfäriska plattor kolliderar varvid den
ena tvingas ned i manteln
Vad händer med strukturen av en silikat
mineral när tryck och temperatur ökar
vid neddykning i subduktionszonen?
gips
(CaSO4 . 2H2O)
Vatten i jordens inre
Range of water concentrations in mantle-derived samples
clinopyroxene
orthopyroxene
garnet
olivine
0
200
400
600
800
1000
ppm H2 O
Olivine, enstatite, diopside and garnet
make up 95% of the upper mantle.
They all contain water.
1200
1400
•
•
•
Oceans cover 71% of surface
Only 0.025 % of Earth’s mass
Chondrites contain 0.10% H2O
Fasövergångar hos olivin
olivin
quartz
Coesite inclusions in Pyrope. Size
of Pyrope is about 10x7 mm
Coesite inclusion in garnet of eclogite
sample
Coesite is a form of silicon dioxide that is formed when very high pressure (2–3
gigapascals) and moderately high temperature (700 °C) are applied to quartz.
Coesite was first created by in 1953. In 1960, coesite was found by Eugene
Shoemaker to naturally occur in the Barringer Crater, which was evidence that
the crater must have been formed by an impact.
The presence of coesite in unmetamorphosed rocks may be evidence of a
meteorite impact event or of an atomic bomb explosion. In metamorphic rocks,
coesite commonly is one of the best mineral indicators of metamorphism at very
high pressures (UHP, or ultrahigh-pressure metamorphism). Such UHP
metamorphic rocks record subduction or continental collisions in which crustal
rocks are carried to depths of 70 km or more. Coesite also has been identified in
eclogite xenoliths from the mantle of the earth that were carried up by ascending
magmas; kimberlite is the most common host of such xenoliths.
The molecular structure of coesite consists of four silicon dioxide tetrahedra
arranged in a ring. The rings are further arranged into a chain. This structure is
metastable within the stability field of quartz: coesite will eventually decay back
into quartz with a consequent volume increase, although the metamorphic
reaction is very slow at the low temperatures of the Earth's surface.
Stishovite – a high pressure polymorph of SiO2
The structure is dense-packed. Unlike in
quartz, where Si-O are arranged in a tetrahedral
coordination, in stishovite each silicon atom has
6 oxygen neighbours (octahedral coordination)
Tiny (< 1 mm) greyish-white, roundish aggregates
of the high pressure mineral Stishovite on a matrix
of Magadiite-Kenyaite-Coesite. Field of view 3 mm.
The source of 'forming' the Stishovite was extreme
heat by an meteorite impact near Bisbee, Arizona.
The exact location and the year of impact is
unknown.
Examples of some high pressure – high temperature
phase diagrams of minerals determined in laboratory
Phase diagrams depict P-T ranges of stability of various crystallographic
forms of minerals.
Phase diagram of MgSiO3
(At ambient conditions, MgSiO3 represents
mineral enstatite, belonging to the pyroxene
group of silicates)
Examples of some high pressure – high temperature
phase diagrams of minerals determined in laboratory
Phase relationships for SiO2
(quartz at ambient conditions)
Phase diagram of NaAlSi3O8
(feldspar albite at ambient conditions)
Diamantcell – ”öppnar ett fönster” till jordens inre
Tryck = kraft / yta
Prov i diamantcell
Laseruppvärmning av material i diamantcell
Laseruppvärmning av material i diamantcell
iron at high pressure
in diamond anvil cell
Bilder på
glödande
provet
50 microner
Omvandling av grafit till diamant i diamantcell vid högt tryck och temperatur
Fasdiagram av kol
Determination of crystal structure by x-ray diffraction
Fig. 5.06
W. W. Norton
By analyzing diffraction pattern, crystal structure of mineral can be determined
Synkrotron anläggningar används ofta för högtryckstudier.
Synkrotron i Argonne, USA.
Synkrotron i Grenoble, Frankrike.
Discovery of post-perovskite transition in MgSiO3 - A new paradigm for core-mantle boundary
CMB
4500
Murakami et al.,
Science (2004)
4000
Temperature (K)
3500
7.5 MPa/K
3000
2500
2000
1500
1000
Orthorombicperovskite
Post-Pv
500
error ~5 GPa
0
70
80
90
100
110
120
130
140
150
Pressure (GPa)
Valley
bottom
Hill top
~8 GPa
~250 km
D” lager
MgSiO3
perovskite
Post-perovskite
Si
Mg
Kristallstruktur av post-perovskit
Si
Mg
Perovskite
Post-Perovskite
The dominant mineral on the Earth
Forms 150 km thick layer adjacent to the core
Framsteg i forskning om jordens inre
Year-points mark the time and depths, for which
corresponding experimentral pressure-temperature
conditions were reached in the laboratory.
Modern tomographic 3-D image of the Earth.
Colors encode speesd of seismic waves; blue
for faster-than average; red for slower-than average
speeds. These variations are connected to changes
in temperature and/or chemical composition.
