Download EPSc 446 STABLE ISOTOPE GEOCHEMISTRY Instructor: Bob Criss

EPSc 446 STABLE ISOTOPE GEOCHEMISTRY MWF 9-10
Instructor: Bob Criss (5-7441) Rm 256; lab 252-4 E&P
Office hours: after class or by appt
E&P 102
Text: Criss (1999) Principles of Stable Isotope Distribution
Homework, Lab & Quizzes
EXAMS I & II
Final Project
40%
20% & 20%
20%
Lecture- 3 hours. TAKE NOTES!
Course Level: Advanced Undergraduate & Graduate
Prerequisites: EPS 441 & Math 233 or permission
Application of equilibrium and kinetic fractionation and material balance
principles to the distribution of oxygen and hydrogen isotopes in
natural systems. Topics include geothermometry and
paleotemperatures, mass spectrometry, isotope hydrology and ice
cores, fluid-rock interaction, igneous rocks and meteorites.
EPSc 446: STABLE ISOTOPE GEOCHEMISTRY TOPIC 1: ISOTOPIC ABUNDANCES AND FRACTIONATION
TOPIC 2: ISOTOPIC EXCHANGE & EQUILIBRIUM FRACTIONATION TOPIC 3: ISOTOPE HYDROLOGY
TOPIC 4: NONEQUILIBRIUM FRACTIONATION & ISOTOPE TRANSPORT
TOPIC 5: IGNEOUS ROCKS, METEORITES, & FLUID-ROCK INTERACTIONS
Development of Geochemistry is closely linked to the spectacular developments in physics and chemistry during the last 200 yrs
~ 1800
Compounds vs. elements had been distinguished. About 30 elements had been recognized Discoveries of new elements were occurring rapidly.
John Dalton (ca 1807)
Matter is comprised of atoms which cannot be further subdivided. Atoms of any given element are identical in all respects, including mass. Atoms of a different elements have a different mass.
cf. Greek word atomos = indivisible; Democritus ~ 400 BC
Atomic Weight = Fundamental property
1st table of atomic weights
Law of Multiple Proportions (1808)
compounds = multiples of atomic weights of elements grouped in definite proportions
John Dalton
AIP
Development of Geochemistry is closely linked to the spectacular developments in physics and chemistry during the last 200 yrs
~ 1800
Compounds vs. elements had been distinguished. About 30 elements had been recognized Discoveries of new elements were occurring rapidly.
John Dalton (ca 1807)
Matter is comprised of atoms which cannot be further subdivided. Atoms of any given element are identical in all respects, including mass. Atoms of a different elements have a different mass.
cf. Greek word atomos = indivisible; Democritus ~ 400 BC
Atomic Weight = Fundamental property
1st table of atomic weights
Law of Multiple Proportions (1808)
compounds = multiples of atomic weights of elements grouped in definite proportions
Sounds great, but mostly wrong!
Gay-Lussac (1808) Volumes of reacting gasses occur in ratios of small whole numbers e.g., 2 liter H2 + 1 liter O2 = 2 liter H2O(v)
Avogadro (1811) Equal gas volumes = Equal # of particles
Reconciles Gay-Lussac's experimental data with Dalton's theory
Prout (1815)
Gas densities Elements have atomic weights close to integer multiples of the weight of hydrogen H units
= basic building blocks of atoms
.
120
Elements Known
100
80
Modern
Chemistry
60
40
20
0
1750
1800
1850
YEAR
1900
1950
2000
120
Emission Spectrograph
Elements Known
100
WWII
80
Modern
Chemistry
60
40
Periodic Table
20
0
1750
1800
1850
YEAR
1900
1950
2000
THERMODYNAMICS
1845 James Joule 1865 Rudolf Clausius
EMISSION SPECTROGRAPH
1859 Gustav Kirchhoff & Robert Bunsen Dibner Library
Mendeleev (1870) 65
elements known Made & organized cards for each
Periodic Table
Relationships
between atomic weight and the
physical-chemical properties of elements
Predicted undiscovered elements
Sc = "eka boron Ga = "eka aluminum"
Ge = "eka silicon H=1
Li=7
Be=9,4
B=11
C=12
N=14
O=16
F=19
Na=23
Mg=24
Al =27,4
Si=28
P=31
S=32
Cl =35,5
K=39
Ca=40
?=45
?Er=56
?Yt=60
?In=75,6
Dmitri Mendeleev chart Ti=50
V=51
Cr=52
Mn=55
Fe=56
Ni=Co=59
Cu=63, 4
Zn=65, 2
?=68
?=70
As=75
Se=79, 4
Br=80
Rb=85,4
Sr =87,6
Ce=92
La=94
Di=95
Th=118?
Zr=90
Nb=94
Mo=96
Rh=104,4
Ru=104,4
Pl=106,6
Ag=108
Cd=112
Ur=116
Sn=118
Sb=122
Te=128?
I=127
Cs=133
Ba=137
?=180
Ta=182
W=186
Pt=197,4
Ir=198
Os=199
Hg=200
Au=197?
Bi=210
Tl=204
Pb=207
Periodic Table = Discovery of new elements
Sc = "eka boron
Ga = "eka aluminum"
Ge = "eka silicon Noble gases
He "helios" Greek for Sun Janssen detected new line w/i solar spectra during 1868 eclipse
Discovered by Ramsay within U mineral in 1895
Ar in air
Rayleigh & Ramsay 1894
Ne Kr Xe
Ramsay & Travers 1898
boiled liquid air; get inert gas residue
By 1900, the periodic table was nearly complete up to U. New problems:
a) Atomic weight Ar > Atomic weight K
Atomic weight Co > Atomic weight Ni
Atomic weight Te > Atomic weight I
b) T.W. Richards discoveries Atomic weights of elements are not simple multiples the H atom mass
Different samples of lead have different Atomic Weights
c)
Discovery of radiation: Indivisibility of the atom violated:
Induced: X-rays (Roentgen, 1895; Geissler 1855; Crookes tube)
Cathode rays (electrons)
J.J. Thomson (1897) q/m (electrical character of matter)
Spontaneous: Continuous emission of radiation of uranium salts (Becquerel, 1896) Different kinds of Th decay at different rates!
16
S 17
32.06
35.453
25 Mn 26
54.938
50
Ar 19
39.948
Fe 27
55.847
Sn 51
118.69
Cl 18
39.098
Co 28
58.933
127.60
20 Ca
40.08
Ni 29 Cu
58.70
Sb 52 Te 53
121.75
K
63.546
I
54 Xe
126.90
131.30
By 1900, the periodic table was nearly complete up to U. New problems:
a) Atomic weight Ar > Atomic weight K
Atomic weight Co > Atomic weight Ni
Atomic weight Te > Atomic weight I
b) T.W. Richards discoveries Atomic weights of elements are not simple multiples the H atom mass
Different samples of lead have different Atomic Weights
c)
Discovery of radiation: Indivisibility of the atom violated:
Induced: X-rays (Roentgen, 1895; Geissler 1855; Crookes tube)
Cathode rays (electrons)
J.J Thomson (1897) q/m (electrical character of matter)
Spontaneous: Continuous emission of radiation of uranium salts (Becquerel, 1896) Different kinds of Th decay at different rates!
masspec.scripps.edu
J.J. Thomson (1897)
Used electrometers to show that particles had negative charge Measured q/m of cathode rays (e-)
Showed that electrons" are corpuscular fragments of atoms
"Plumb pudding" atomic model: Atoms are spheres of uniformly distributed positive electricity with a negatively charged electrons.
Geissler (1855)
Crookes Tube HYDROGEN
NEON
Electron
Electron
Sphere of Positive Charge
Sphere of Positive Charge
Thomson s Plum Pudding Model
Electrons embedded in positively-charged fluid after prenhall.com
Ernest Rutherford (1911) Scattering experiments with α particles shot at metal foils. Found that a few α particles were deflected through large angles- up to 180°. It was quite the most incredible event that ever happened to me in my life. It was almost as incredible as if you had fired a 15-inch shell at a piece of tissue paper and it came back and hit you. Result inconsistent with "plumb pudding" model
Alpha Emitter
in lead box
Detector
Au foil
cont1.edunet4u.net
Ernest Rutherford (1911) Scattering experiments with α particles shot at metal foils. Found that a few α particles were deflected through large angles- up to 180°. It was quite the most incredible event that ever happened to me in my life. It was almost as incredible as if you had fired a 15-inch shell at a piece of tissue paper and it came back and hit you. Result inconsistent with "plumb pudding" model NEW ATOMIC MODEL: Atoms have a small (10-14 m) positively-charged nucleus,
surrounded by electrons that orbit in a roughly spherical volume with a radius of 10-10 m (1 Å). Most chemical properties controlled by this electronic shell. Nucleus: 99.95% of atomic mass, but only 1 trillionth of atomic volume. _
_
_
_
+ +
+ +
+
_
#1: Hydrogen
#4: Beryllium
Rutherford Model
_
_
_
_
+ +
+ +
+
_
#1: Hydrogen
At. Wt. 1.0079
#4: Beryllium
At. Wt. 9.012
Rutherford Model
Problem: Disparity between Atomic No. and Atomic Weight
J.J. Thomson (1913)
Geissler (1855)
Crookes Tube Modified his "positive ray apparatus," Found that neon is comprised of atoms with masses of 20 and 22 20Ne
and 22Ne
masspec.scripps.edu
Frederick Soddy (1914)
The place occupied
by a particular element in the periodic table can accommodate more than one kind of atom
"ISOTOPES"
Greek isos topos = same place ISOTOPES = Nuclides of elements with different atomic weights
Differences from Dalton s theory:
Instead of ~103 elements, there are > 2900 known nuclides
Identical masses vs. different masses for atoms of an element
Alleged indivisibility of atom vs. radioactive emissions of most nuclides
No account of old theory for the electrical character of matter
Z Moody et al. (2005)
N
Ch 1 probs
1, 2, 3, 5, 7, 9, 11
Fri 29th
_
_
_
_
+
#1: Hydrogen
At Wt = 1.079
_
+ + +
+ + +
_
_
#6: Carbon
At Wt = 12.011
Rutherford Model
Problem: Disparity between Atomic No. and Atomic Weight
J.J. Thomson (1913)
Geissler (1855)
Crookes Tube Modified his "positive ray apparatus," Found that neon is comprised of atoms with masses of 20 and 22 20Ne
and 22Ne
masspec.scripps.edu
Confirmation of Isotopes
J.J. Thomson (1913) Modified his "positive ray apparatus" Found that neon is comprised of atoms with masses of 20 and 22:
20Ne
F W Aston (ff) Improved Thomson's design- "mass spectrograph Discovered 212 of the 287 naturally-occurring nuclides, inc.
21Ne.
and 22Ne
Cl
35.453
80
70
35
Cl
Mass Spectrum of
Natural Atomic Chlorine
Intensity
60
50
40
30
37
Cl
20
10
0
34
35
36
MASS, amu
37
38
Explanation of Isotopes
Discovery of the Neutron James Chadwick (1932)
Interpreted Bothe & Becker(1930) experiment:
1) Bombarded Be foil with α particles 2) Bombarded paraffin with resulting radiation 3) Generated energetic protons
AIP
9Be
+ 4He => 1n + 12C + 6 MeV
9Be
(α, n)12C PARTICLE
SYMBOL
REST MASS
CHARGE
(amu)
Proton
p
1.0072765
+1
Neutron
n
1.0086649
0
Electron
!-
0.0005486
-1
Positron
!+
0.0005486
+1
"
0
0
H
1.007825
0
H, or D
2.014102
0
He++, or #
4.001475
+2
Gamma ray
1
Protium atom
2
Deuterium atom
Alpha particle
4
H
1.0079
HYDROGEN ISOTOPES
PROTIUM
Protium
1H
1.00782503
99.985 at. %
DEUTERIUM
TRITIUM
Deuterium
Tritium
2H
3H
2.01410178
0.015 at %
3.01605
12.32 yr
80
70
35
Cl
Cl
Mass Spectrum of
Natural Atomic Chlorine
Intensity
60
35.453
50
40
30
37
Cl
20
10
0
34
35
36
37
38
MASS, amu
Isotope
Mass
x Abundance
amu
35
Cl
34.96885 x
0.7577
=
26.4958
37
Cl
36.96590 x
0.2423
=
8.9568
35.453 amu
The atomic weight of an element represents the !
weighted average of the atomic weights of the !
constituent isotopes!
i.e.
Atomic Wt. = Σ Abi Wti
where
ΣAbi
= AbaWta + AbbWtb + ....
=1
Formerly atomic weights based on the basis of the weight of oxygen = 16.0000
16O by physicists, which was taken as
and as the mix of all oxygen isotopes by the chemists
Since 1961, atomic weights have been based on the mass of the intrinsic mass of the isotope 12
C = 12.00000 amu
i.e.
1
amu = (1/12)(mass 12C )
1 amu = 1.660 10-27 kg
MODERN VIEW:
Principal components of atoms are protons, neutrons, and electrons
Atomic # = Z
Neutron # = N
Mass # = A
13.00335483
1.10 at.%
6
+
7
13
_
A = Z+N
Notation:
13C
AQ
all integers
_
_
O O +
+ +
O O O
+O+O
+
_
_
_
CHART OF NUCLIDES
! ! !
! ! !
! ! !
Types of Nuclides!
!
!
!
!
!
!
Plot of Z vs. N
!!
!ISOTOPES (same proton #, Z)!
!ISOBARS (same mass #, A)!
!ISOTONES (same neutron#, N)
Radioactive Isotopes:
!
e.g., 40K, 87Rb, 235U !
! !Parent - Daughter @ statistically-predictable rate
! !N = Nie-λt
Rutherford & Soddy (1902)!
Stable Isotopes
(Do not decay) !
!Radiogenic Stable Isotopes:
e.g., 40Ar, 87Sr, 207Pb
! ! !Formed by decay !
! ! ! D* = N(e+λt -1)
Non-radiogenic Stable Isotopes: e.g., 13C, 12C, 18O!
! ! !Variations caused by physiochemical processes!
Utility to Geology:
!!
!Geochronology!
!Isotopic Tracer Studies!
!Studies of physical processes, past conditions!
!
Geologically Most Useful
Stable Isotopes
Approximate Natural Abundance
H : D
99.985 : 0.015
12C
: 13C
98.89 : 1.11
14N
: 15N
99.63 : 0.37
16O
: 17O : 18O
99.759 : 0.037 : 0.204
28Si
: 29Si : 30Si
92.21 : 4.7 : 3.09
: 33S : 34S : 36S
95.0 : 0.76 : 4.22 : 0.014
32S
120
100
80
Z
60
40
20
0
0
20
40
60
80
N
100
120
140
160
120
100
80
Z
60
40
Isotones
20
Isotopes
0
0
20
40
60
80
N
100
120
140
160
Most elements below Bi (#83) have at least two stable nuclides
Exceptions: 9Be
19F
23Na
27Al 31P
45Sc
…
http://wwwndc.tokai.jaeri.go.jp/CN03/CN001.html
SOHO
6768Å Solar & Heliospheric Observatory
Lagrange Point L1
SOHO
SDO/HMI
Solar & Heliospheric Observatory
Lagrange Point L1
Log Abundance
12
H
He
10
C O
8
Solar Photosphere
data in Lodders & Fegley 1998
Mg Si
Fe
6
4
2
0
Tc
0
20
40
Th
U
Pm
60
Atomic Number, Z
80
100
SOLAR ABUNDANCES !
!Solar Photosphere is similar to chondritic meteorites (except for H, He…)!
!Similar to bulk Earth!
!Earth is residue of preexisting stars!
!
1)  !Large amounts of H (>93 atom %) and He (>6 at.%) !
Primordial composition; stellar fuel!
!
2)  !Heavier elements all very rare (Σ ~ 0.1 atom %); trace elements! !
!!
3) Progressive, exponential-like decline w/ A!
4)  Abundance minimum at Li, Be, B!
5)  !Abundance peaks at C, O, Fe. !
High for nuclides with Mass # A of multiples of 4 = α particle mass!
Bulk Earth > 92 wt % Fe, O, Si, Mg {56Fe, 16O, 28Si, 24Mg} !
!
6)  Tc (Z=43) and Pm (z=61) missing- all nuclides radioactive w short half lives
! ! ! ! 4.2 Ma for 98Tc; but Tc is known in stellar spectra => active nucleosynthesis!
!
7)  !No stable nuclides for Z > 83 (Bi)!
8)  !Even/Odd effect: Harkin's rule.!
Elements w/ even atomic # s are more abundant than those w/ odd at. # s!
!
Log Abundance
12
H
He
10
C O
8
Solar Photosphere
data in Lodders & Fegley 1998
Mg Si
Fe
6
4
2
0
Tc
0
20
40
Th
U
Pm
60
Atomic Number, Z
80
100
SOHO
6768Å Solar & Heliospheric Observatory
Lagrange Point L1
Allende carbonaceous chondrite
asu.edu
8
SMg
i
Fe
S
Abundance in C1 Meteorites
7
Al
Ca
Na
Ni
6
K
CoT i
5
Cu
4
Zn
F
V
Li
3
B
2
1
0
Cr
Mn
P
Cl
Tb
Tm
0
Ho Eu
Re
Kr
Ga Sc
Sr
Ge
Se
Z rr
B
As Rb
Te
Xe
Y
Ba
Sn
Pb
Mo
Ru
PdCd
Ce Pt
INd
I Nb
rOs
Ag La
Dy
Be
Hg
Cs
Gd
Rh
ESb
Sm
rYb
In
P rT lAu
B i Hf W
data from
Lodders & Fegley 1998
Lu
1
2
3
4
5
6
7
12
Solar Photosphere Abundances rel H =10
8
EVEN / ODD EFFECT
True for chemical elements
Confirms work of F.W. Clarke (Chief Chemist) & H.S. Washington (1889 -1930's) on the relative abundance of the elements in the Earth's crust. Data of Geochemistry USGS Bull 330
Harkin's Rule: Elements with even atomic numbers are more abundant in nature than those with odd numbers. 0.7
CI Meteorites
Concentration, ppm
Ce
0.6
data from Loders & Fegley 1998
0.5
Nd
0.4
0.3
Dy
Gd
La
0.2
0.1
0
Pr
Pm
56
Er
Sm
58
60
Eu
62
Tb
64
Ho
66
Atomic Number, Z
Tm
68
Yb
Lu
70
72
Abundance, Atom %
0.12
0.011
40
41
42
43 44 45
Mass Number A
46
47
0.187%
4.5 days
0
0.001
0.004%
2.086%
13
162.7 days
0.135%
0.647%
103,000 years
104
96.941%
1005
Calcium
48
30
Sn Isotopes
data from Walker et al 1989
25
20
15
110
2.1h
115d
105
9.6d
105a
0
5
129d
55a
10
18m
4.1h
35m
Abundance, Atom %
35
115
120
125
Mass Number A
130
EVEN / ODD EFFECT
True for chemical elements
Confirms work of F.W. Clarke (Chief Chemist) & H.S. Washington (1889 -1930's) on the relative abundance of the elements in the Earth's crust. Data of Geochemistry USGS Bull 330
Harkin's Rule:
Elements with even atomic numbers are more abundant in
nature than those with odd numbers. Isotope Abundance Even-odd effects also apply to the isotopes of a single element. Even-odd phenomenon is a nuclear effect, not a chemical effect.
A
Z
Even
Odd
Odd
Even
Even
Even
Odd
Odd
Total
N
Even
Odd
Even
Odd
# Stable Nuclides
157
53
50
4
Nuclear Spin
0
1/2; 3/2; 5/2; 7/2
1/2; 3/2; 5/2; 7/2
1; 3
264
Mattauch's rule: For each odd mass number, there exists ≤1 stable nuclide.
Al
OTHER 1.4%
5.4%
Mg
14.9%
SILICON
OXYGEN
14.6%
31.7%
IRON
32.0%
Bulk Earth
Estimate of
Kargel & Lewis 1993
Al
OTHER 1.4%
5.4%
24Mg
Mg
= 78.99 %
14.9%
16O
= 99.76 %
28Si
= 92.23 %
SILICON OXYGEN
14.6%
31.7%
IRON
32.0%
56Fe
= 91.72 %
Bulk Earth
Estimate of
Kargel & Lewis 1993