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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