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SES # | TOPICS | SUBTOPICS | INSTRUCTORS | KEY DATES |
---|---|---|---|---|
Nuclear Systematics | ||||
1 | The Basics | Nuclear (in)stability, isotopes, particles, forces, cosmic abundances | Bill Jenkins | |
2 | Nucleosynthesis | Primordial, galactic, stellar evolution and nucleosynthesis (r, s, p processes) | Bill Jenkins | |
3 | Radioactive Decay | Mechanisms, systematics, measurement, statistics | Bernhard Peucker-Ehrenbrink | |
4 | Radiometric Dating I | Extinct, simple, parent-daughter, secular (dis)equilibrium and equations | Bernhard Peucker-Ehrenbrink | |
5 | Radiometric Dating II | Open/closed systems, isochrons (IsoPlot), modeling | Bernhard Peucker-Ehrenbrink | |
6 | Problem-Solving Session 1 | A tutorial on problem solving (basic skills) including dimensional analysis | Bernhard Peucker-Ehrenbrink | Problem set 1 assigned |
Earth Formation and Evolution | ||||
7 | Solar System and Planetary Formation | Concepts, isotopic constraints on timing and processes, core and moon formation | Bernhard Peucker-Ehrenbrink | |
8 | Earth Structure and Evolution | Compatibility, melting, parent-daughter fractionation, formation of reservoirs, heat flow geoneutrinos | Bill Jenkins | |
9 | Atmosphere/Ocean Formation | Noble gases (including 3He) and isotopes (degassing), hydrodynamic escape | Bill Jenkins | |
10 | Cosmogenic Isotopes I | Exposure dating, 10Be, 26Al, 36Cl theory, models, and practice | Bill Jenkins | Problem set 1 due |
11 | Cosmogenic Isotopes II | 14C (carbon cycle, paleo) | Bill Jenkins | |
12 | Problem-Solving Session 2 | A tutorial on model building (box-models), radiocarbon and the carbon cycle | Bill Jenkins | Problem set 2 assigned |
Stable Isotopes | ||||
13 | Mass Spectrometry I | Measurement principles and methodology limitations, statistics, error propagation, isotope dilution | Bill Jenkins | |
14 | Mass Spectrometry II | Measurement principles and methodology limitations, statistics, error propagation, isotope dilution (cont.) | Bill Jenkins | |
15 | Isotope Fractionation I | Theoretical basis: harmonic oscillator model, reduced mass (effusion vs. diffusion), systematics | Bill Jenkins | |
16 | Isotope Fractionation II | Kinetic vs. Equilibrium fractionation, inverse isotope effects, mass-independent fractionation | Bill Jenkins | Problem set 2 due |
17 | Problem-Solving Session 3 | Dealing with Rayleigh equation; G-IG seawater δ18O (Emiliani vs. Shackleton) | Bernhard Peucker-Ehrenbrink | Problem set 3 assigned |
Ocean Applications | ||||
18 | Mass-Independent Fractionation | S-isotopes and early atmosphere oxygenation, O-isotopes and primary production | Bernhard Peucker-Ehrenbrink | |
19 | Clumped Isotopes | Concepts, theory, and application, long term seawater changes in δ18O | Bernhard Peucker-Ehrenbrink | |
20 | Water Column I | Particle scavenging, one-dimensional advection-diffusion models, Ra in circulation, subterranean estuaries | Bernhard Peucker-Ehrenbrink | |
21 | Problem-Solving Session 4 | Using one-dimensional advection-diffusion models to estimate deep ocean rates | Bill Jenkins |
Problem set 3 due Problem set 4 assigned |
22 | Water Column II | Sedimentary processes: sediment focusing (Th-Pa, He), chronology | Bernhard Peucker-Ehrenbrink | |
23 | Water Column III | Long term elements budgets (Sr, Nd, Li, He isotopes) | Bernhard Peucker-Ehrenbrink | |
24 | Water Column IV | Redox processes, metal isotopes, and sediment-sea exchange | Bernhard Peucker-Ehrenbrink | |
25 | Water Column V | Air-sea exchange (222Rn, 14C, 3He) | Bill Jenkins | Problem set 4 due |
26 | Final Exam | Final exam |
In this section we introduce what isotope systematics tell us about how our solar system and the earth are formed, and about the timing and nature of the processes involved. We discuss what isotopes tell us about the early history of the earth and its evolution and its structure, and of the formation of the moon, the atmosphere, and the oceans. We then talk about cosmogenic isotopes and how they are used to constrain recent and current processes on the earth’s surface.
Related links are listed below the table. Lecture notes are provided by WHOI and link away from OCW. Select lecture slides are available.
SES # | TOPICS | SUMMARIES | SLIDES |
---|---|---|---|
7 | Solar System and Planetary Formation | We briefly discuss timescales of the universe, stellar nucleosynthesis, and solar system formation, mostly from the perspective of long-lived radionuclides (Problem Set 1). Before we talk about the formation of Earth and Moon, we cover the concept of volatility (half-condensation temperatures) and the partitioning of elements between different phases (lattice strain model), a pre-requisite for understanding the differentiation of our planet. A brief introduction to meteoritics will lead to the discussion of timescales of differentiation, mainly from the perspective of extinct radionuclides (26Al-26Mg, 182Hf-182W) with the use of the 207Pb/206Pb system as an absolute time anchor. We end with the widely accepted scenario for the formation of the moon, and discuss its timing in the context of the 182Hf-182W extinct radionuclide system. | |
8 | Earth Structure and Evolution | Given the timing and nature of the formation of the earth/moon system (especially using extinct radioactivities), we now effects of heat-producing radionuclides on the earth’s evolution and structure (including mantle structure, seafloor spreading, and continent formation), and the more recent constraints on the earth’s composition afforded by isotopes and geoneutrinos. We will learn about parent-daughter fractionation associated with geochemical processes (e.g., melting, metasomatism, crystallization). Finally, we explore how isotopes have shed light on the existence of natural nuclear reactors in the past. | Lecture 8 Notes (PDF) |
9 | Atmosphere-Ocean Formation | The formation of the oceans and atmosphere likely occurred early in the earth’s history. We discuss the isotopic evidence for the timing of these events and on how isotope patterns are reflecting current earth structure, the relationship between the earth and other planets, and possible ongoing terrestrial degassing. We also investigate the fact that for some gas isotopes, the atmosphere is not a closed system, but is still evolving on the mega- to giga-year time-scales. | Lecture 9 Notes (PDF) |
10 | Cosmogenic Isotopes I | The earth has in the past been, and continues to be, bombarded with high-energy cosmic rays. These cosmic rays interact with the atmosphere and surface earth to produce isotopes that in turn prove useful for constraining processes occurring on or near the earth’s surface. We explore the nature of these isotope systems and their application to studying recent and current earth processes. | Lecture 10 Notes (PDF) |
11 | Cosmogenic Isotopes II | One cosmogenic isotope, radiocarbon, holds a special place in isotope geochemistry. Knowing its past abundance in the atmosphere in the ocean is key to (a) establishing chronology over the past ~50,000 years (radiocarbon dating), (b) understanding past changes in cosmogenic production rates, and (c) diagnosing recent past changes in the carbon cycle. We explore all these three aspects in considerable detail here. | Lecture 11 Notes (PDF) |
12 | Problem-Solving Session 2 | Here we embark on a tutorial on model building: a box model of cosmogenic isotope systems, radiocarbon, and the carbon cycle. |
Related Links
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CosmoCalc Website
An Excel Spreadsheet add-in for cosmogenic production rates in time/space including instructions and documentation. -
Moon-forming impact
A simulation (by Robin Canup) of the impact of Mars-size Theia with the proto-Earth (accreted to about 80% of its current size). The formation of the Moon from the debris circling Earth is not shown, but is a well-understood process that took only about a day. -
14 billion years ago
The trailer to “The Big Bang Theory”—watch the first 6 seconds frame by frame—it’s actually quite accurate. The later time axis is pretty distorted (animals emerging from the sea at 11000 BC, dinosaurs roaming the Earth 8000 BC, etc).
This section of the course is intended to give the student a firm understanding of the underlying principles that determine the abundance, stability, and nature of the isotopes. We delve into the mechanisms and timing of the creation of the nuclides and the evidence behind our knowledge of these crucial processes. We investigate the mechanics and systematics of radioactive decay and its application to dating methods. We finish with a problem solving session applying these techniques to determining the age of the elements (for our solar system).
Readings and related links are listed below the table. Lecture notes are provided by WHOI and link away from OCW. Select lecture slides are available.
SES # | TOPICS | SUMMARIES | SLIDES |
---|---|---|---|
1 | The Basics | Our starting point is to examine the cosmic abundance of the elements. From this, we embark on a quest to understand the factors underlying the stability of elements and isotopes, and the relation to their cosmic abundances. This also leads to a foundation for explaining the origin of the elements and isotopes (nucleosynthesis). We will outline the nature and relationship of the four fundamental forces, discussing the relativistic and quantum-mechanical principles underlying our understanding of the universe and the factors controlling nuclear stability. We will also briefly discuss the modes of radioactive decay (more on that in Lecture 3). | Lecture 1 Notes (PDF) |
2 | Nucleosynthesis | We aim to understand how the elements and isotopes came to be, within the context of the principles presented in Lecture 1, and how these processes are reflected in the cosmic abundance of the elements and isotopes. We start on a wonderful journey that begins with the big bang (primordial nucleosynthesis), follows through galactic evolution (generations of stars and galactic nucleosynthesis), and arrives at the amazing processes of stellar evolution and nucleosynthesis. We describe how our detailed knowledge of this incredible story is woven into the chart of the nuclides (isotopes) and outline the various nucleosynthetic pathways that lead to very stuff that we (and the earth) are made of. | Lecture 2 Notes (PDF) |
3 | Radioactive Decay | The learning goals for this lecture are the derivation of the isochron equation (simple decay), a basic understanding of how radioactive decay can be used as a dating tool (isochron diagram), and an understanding of some of the pitfalls involved in dating (confusion with mixing lines). We will also cover a special case where two decay systems of a single element leads to two stable isotopes of the same element (238U to 206Pb, 235U to 207Pb), and how these systematics can be used in an isochron diagram (Geochron, growth curves). | |
4 | Radioactive Decay Series | The learning goals for this lecture are to understand the more complex decay schemes that involve a series of coupled decays—so-called “decay series”—the concept of secular equilibrium and disequilibrium, and how decay series can be used to constrain dates in closed vs. open systems. We will introduce the Bateman equations and different equilibrium/disequilibrium diagrams that show the versatility and complexity of decay series dating. The very different half-lives of the nuclides involved imply very different nuclide concentrations at secular equilibrium. As the number of atoms available for analyses strongly influences analytical precision, we will also discuss analytical options (counting vs. mass spectrometry) and their influence of analytical precision. | |
5 | Radioactive Decay - Extinct Radionuclides | We will review simple decay and decay series systematics as an introduction into “extinct radionuclides.” The learning goals for this lecture are an understanding of the utility of nuclear reactions that involve nuclides with such short half-lives that they do not exist anymore (unless newly produced by nuclear reactions) on Earth. Such nuclides provide the foundation for relative dating of processes during the dawn of the Solar System. These systematics will provide the basis for the next lecture(s) on the evolution of the Solar System and our home planet. | |
6 | Problem-Solving Session 1 | We start solving the first problem of Problem Set 1 in class, using strategies for solving problems e.g. carefully reading questions, graphical representation of concepts, simplifying equations, significant figures and uncertainties, dimensional analysis, etc. | Problem Set 1 (PDF) |
Readings
Hester, J. Jeff, Steven J. Desch, et al. “The Cradle of the Solar System.” Science 304, no. 5674 (2004): 1116–7.
A nice descriptive article about what kind of conditions our solar system may have been born in.
Bateman, Harry. “The Solution of a System of Differential Equations Occurring in the Theory of Radioactive Transformations.” (PDF) _Proceedings of the Cambridge Philosophical Soc_iety 15, no. pt V (1910): 423–7.
A copy of Bateman’s classic paper with the solutions to the differential equations for unstable daughters of long-lived radionuclides (decay series).
Related Links
-
Basic Nuclear Physics
A straightforward (if non-quantitative) introduction to nuclear physics principles. -
Table of Nuclides
A good starting point learning about the table of nuclides. -
Big Bang Cosmology
A good general summary of the big bang model (from Cambridge University). -
Stellar Nucleosynthesis
A useful entry into all about stellar nucleosynthesis. -
All about SN 1987A
A wiki page on SuperNova 1987A.
In the final section of the course, we apply the theory and techniques we have discussed to the ocean. We delve into two new and promising developments, namely mass-independent fractionation and clumped isotopes. We finish by exploring many geochemical aspects of the water column and sediments including less-conventional stable isotope systems, ocean circulation and ventilation, and air-sea exchange.
Lecture notes are provided by WHOI and link away from OCW. Select lecture slides are available.
SES # | TOPICS | SUMMARIES | SLIDES |
---|---|---|---|
18 | Mass-Independent Fractionation | In this lecture, we will be learning about two applications of mass-independent isotope effects: the use of triple oxygen isotope measurements to decipher gross oxygen production in the surface ocean, and the use of triple sulfur isotopes to understand the history of oxygenation of the atmosphere-ocean system in geologic history. | |
19 | Clumped Isotopes | This lecture is an introduction into the concept of multiple substituted (i.e. two or more rare isotopes) isotopologues and the application of this concept to paleo-temperature determinations. | Lecture 19 Notes (PDF - 3.5MB) |
20 | Water Column I: Non-Conventional Stable Isotopes | In this lecture we explore the use of non-conventional stable isotope systems, particularly Mo and Ca, to better constrain sea-surface temperatures in the geologic past, variations in continental erosion/weathering, and the oxygenation of the ocean/atmosphere systems in the Precambrian. | Lecture 20 Notes (PDF - 4.4MB) |
21 | Problem Session 4 | Dealing with one-dimensional advection-diffusion models (ODADMs): For this assignment, we will use ODADMs to estimate deep ocean rates. | |
22 | Water Column II: Particle Scavenging/Ocean Circulation | This lecture applies concepts learned in the last problem-solving session, particularly the export of particle-reactive radionuclides from the water column, to reconstructing changes in ocean circulation/ventilation between the last glacial maximum and the Holocene. | Lecture 22 Notes (PDF - 3.0MB) |
23 | Water Column III: Marine Isotope Systematics | This lecture is intended to provide an introduction into the many isotope records of seawater that are archived in marine sediments. We will explore the marine strontium isotope record as an example and probe mass balance equations for systems in steady-state those not at steady-state. We will also explore the response of systems to perturbations that can teach us about the resiliency of these systems. | Lecture 23 Notes (PDF - 12.2MB) |
24 | Water Column IV: Sediments | This lecture covers some important issues involving radionuclides in sediments, including the determination of sedimentation/sediment accumulation rates, the role of radionuclides in detecting unusual sources of dissolved (and particulate) matter to the oceans, and the need to properly normalize sediment records to extract paleo-information from such records. | Lecture 24 Notes (PDF - 11.3MB) |
25 | Water Column V: Isotopes and Gases | In this lecture we will explore air-sea exchange with special attention to the following isotopes: 222Rn, 14C, 3He. | Lecture 25 Notes (PDF) |
26 | Final Exam |
So far the emphasis has been on the radioactive isotopes and what they tell us about the timing and nature of processes. We now embark on the topic of stable isotopes and isotope fractionation. We will first learn about how stable (and sometimes unstable) isotope ratios are measured by mass spectrometry. This is important because the isotope geochemist needs to understand the nature of the measurements in order to realize the character and limitations of the data. We then explore the principles, systematics, and mathematics of isotope fractionation.
Readings are listed below the table. Lecture notes are provided by WHOI and link away from OCW.
SES # | TOPICS | SUMMARIES | SLIDES |
---|---|---|---|
13 & 14 | Isotope Measurements | Since you need to understand the limits and character of your data in order to use it effectively, we spend the next two lectures discussing isotope ratio measurements. The tool of choice for these measurements is the mass spectrometer, so we concentrate on the mechanics of how these instruments work. This involves a discussion of the underlying principles of mass spectrometry and a broad survey of the various types of mass spectrometers, ranging from “traditional” stable isotope mass spectrometers through ICPMS and AMS systems. We investigate some of the analytical challenges involved in the various methods. The isotope dilution methodology and mathematics are explored. Then we discuss some basic concepts of data treatment and review error propagation one more time. Finally, we explore how half-lives can be determined using mass spectrometers. | |
15 & 16 | Isotope Fractionation Systematics | Here we learn about the underlying physical principles about isotope fractionation, the basic mathematics and calculations, and some of the generalities associated with using stable isotopes as probes of biogeochemical processes. We finish by exploring mass independent isotope fractionation. | |
17 | Problem Session 3 |
Dealing with the Rayleigh equation. G‐IG seawater δ18O (Emiliani vs. Shackleton) |
Problem Set 3 (PDF) |
Readings
Intro to Isotopic Calculations (PDF)
A nice introduction written by John Hayes on isotopic calculations. Courtesy of John Hayes. Used with permission.
Stable Isotopes Review (PDF)
A recent review article from Biogeosciences on using stable isotopes to trace plant carbon and water relations across scales.
Werner, Christiane, H. Schnyder, et al. “Progress and Challenges in Using Stable Isotopes to Trace Plant Carbon and Water Relations Across Scales.” Biogeosciences 9 (2012): 3083–111. This work is distributed under the Creative Commons Attribution 3.0 License.
Teaching assistant Kyrstin Fornace created cartoons to depict key concepts from the course. These cartoons were used during the weekly recitation sections.
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Extras |
![]() Normal Kinetic Isotope Effect (PDF) ![]() |
Course Meeting Times
Lectures: 2 sessions / week, 1.5 hours / session
Recitations: 1 session / week, 1 hour / session
Prerequisite
12.748 Introduction to Isotope Chemistry or permission of the instructor.
Course Description
The objective of this course is to develop a conceptual, quantitative, and thorough understanding of principles of marine isotope geochemistry, its systematics and its application to the study of the behavior and history of the oceans within the earth system. The emphasis is on developing the underlying concepts and theory as well as proficiency in working with practical isotope systems. This will not be a comprehensive survey of isotope geochemistry literature but rather the building of foundational knowledge and skills in working with isotope systems. Reference will be made to recent theories, developments, and key papers.
The course is divided into four sections:
- Nuclear systematics
- Earth formation and evolution
- Stable isotopes
- Applications to the ocean system
We will start our journey with the basics of nuclear systematics that control the cosmic abundances of the elements and isotopes, nucleosynthesis, and nuclear stability. We will go into quantitative details about the mechanics and systematics of radioactive decay and how they apply to radioactive dating. Next, we will show how isotope distributions can constrain the nature and timing of formation of the solar system, the earth, and its atmosphere and oceans. We discuss what isotopes reveal about the structure and evolution of the earth. Stable isotopes, their measurement, fractionation, and systematics will be investigated, including recent developments in and applications of mass-independent fraction and clumped isotope systems. In the final section of the course we investigate applications of isotope systems to numerous processes in the ocean, including particle scavenging, sedimentary processes, long term elemental balances, redox processes, and air-sea exchange.
Grading
In addition to 21 lectures, there will be 4 problem-solving sessions aimed at hands-on development of key skills. Each session begins a problem set assignment due ~10 days after. A final exam will be given.
ACTIVITY | PERCENTAGE |
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Assignments | 40% |
Final exam | 40% |
Class participation | 20% |