LOW-TEMPERATURE THERMOCHRONOLOGY - GBV · Quantitative interpretations of data with numerical models 10 General comments on the future of thermochronology 11 REFERENCES 13 I- Fundamentals

SUB Gottingen217 978 428

2005 A 22809

REVIEWS IN MINERALOGYAND GEOCHEMISTRY

VOLUME 58 2005

LOW-TEMPERATURETHERMOCHRONOLOGY:

TECHNIQUES, INTERPRETATIONS,AND APPLICATIONS

EDITORS:

Peter W. Reiners Yale UniversityNew Haven, Conneticut

Todd A. Ehlers University of MichiganAnn Arbor, Michigan

COVER: Upper left: Apatite crystals from the Bighorn Mountains, Wyoming(scale bar is 300 um). Upper right: Arrhenius plot for step-heating heliumdiffusion experiment on titanite crystal fragments; after Reiners PW, FarleyKA (1999) He diffusion and (U-Th)/He thermochronometry of \titanite.Geochim Cosmochitn Ada 63:3845-3859. Lower left: 3D thermo-kinematicmodel of the Himalayan front and major structures, Central Nepal; courtesyof D. Whipp and T. Ehlers. Lower right: View of the Washington Cascades,from Sahale Arm; photo by Drew Stolar.

Series Editor: Jodi J. Rosso

MINERALOGICAL SOCIETY OF AMERICAGEOCHEMICAL SOCIETY

TABLE OF CONTENTSi Past, Present, and Future of Thermochronology

Peter W. Reiners, ToddA. Ehlers, Peter K. Zeitler

INTRODUCTION 1Geochronology vs. thermochronology 2

HISTORY 21950s and 1960s - development of fundamentals 21970s - a decade of closure 31980s - modern thermochronology is born 41990s and 2000s 4

CURRENT PRACTICE 6PROSPECTS 8

Existing and emerging techniques and approaches 8Kinetics, partitioning, and other fundamentals 9Quantitative interpretations of data with numerical models 10General comments on the future of thermochronology 11

REFERENCES 13

I- Fundamentals of Fission-Track ThermochronologyTakahiro Tagami, Paul B. O 'Sullivan

INTRODUCTION 19FORMATION AND REGISTRATION OF NUCLEAR FISSION TRACKS 20

Spontaneous and induced nuclear fission decay 20Track formation process in solids 20Structure of the latent track 21

CHEMICAL ETCHING AND OPTICAL MICROSCOPE OBSERVATION 22Basic process of track etching 23Etching efficiency and prolonged-etching factor 24Etching criteria and their influences on the observed track density and length 25

DERIVATION OF AGE CALCULATION EQUATION 27STABILITY AND FADING OF TRACKS 28

Basic process of track fading 28Track annealing at geological timescales: procedures and findings 29Laboratory heating experiments: procedures and findings 32

EXPERIMENTAL PROCEDURES 34Methods of analysis 35Sample preparation and track etching 36Neutron irradiation 37Track density determination 37Track length measurement 37

DATA ANALYSIS AND GRAPHICAL DISPLAYS 38Statistical test of single-grain data and error calculation of sample mean age 38Graphical displays of single-grain age distribution 39Graphical displays of track length distribution 40

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Lozv-Temperature Thermochronology - Table of Contents

CONCLUDING REMARKS 41ACKNOWLEDGMENTS 41REFERENCES 41

J Apatite Fission-Track Analysis

Raymond A. Donelick, Paul B. O'SullivanRichard A. Ketcham

INTRODUCTION 49APATITE AS A FISSION-TRACK ANALYSIS MATERIAL 50

General 50Natural occurrence 50Physical properties 51Major and minor element chemistries 51Uranium and thorium as trace elements 51Fission-track retention in the geological environment 53Laboratory analogues to spontaneous fission-track behavior 53

AFT SAMPLE PREPARATION 54APATITE FISSION-TRACKAGE EQUATIONS 54AFT DATA AND DATA COLLECTION 55

General 55Analyst bias 56Spontaneous fission-track densities 58Relative uranium concentrations 59Confined fission-track lengths 60AFT annealing kinetic parameters 66How many AFT grain ages and lengths should be measured? 72

LABORATORY CALIBRATION OF THE APATITE FISSION-TRACK SYSTEM 73General 73Setting up a calibration procedure 73

DISCUSSION AND FUTURE WORK ., 76General ;. 76Type of data to measure for AFT ages and lengths 77Measurement of kinetic parameter for AFT analysis 77Extrapolation of calibrations to geological time 78Can AFT models be improved? 78

ACKNOWLEDGMENTS 84REFERENCES 84APPENDIX 1: AFT SAMPLE PREPARATION TIPS 87

General 87Tips for apatite mineral separation 87Tips for mounting and polishing apatite grain mounts 89Tips for etching apatite grain mounts 90Tips for 252Cf-derived fission-fragment irradiation of apatite grain mounts 91Tip for preparing apatite grain mounts forEDM age dating 92Tips for preparing apatite mounts for the LA-ICP-MS age dating 92Preparing apatite grain mounts for electron probe microanalysis (EPMA) 92

Low-Temperature Thermochronology - Table of Contents

APPENDIX 2: DATA COLLECTION SCHEMES FORAPATITE FISSION-TRACK ANALYSIS 93

Measurement of grain ages 93Measurement of lengths 93AFT analysis 93

T1 Zircon Fission-Track Thermochronologyand Applications to Fault Studies

Takahiro Tagami

INTRODUCTION 95THERMAL SENSITIVITY OF ZIRCON FISSION-TRACK

THERMOCHRONOMETRY 95Laboratory heating data and annealing models 95Long-term track annealing at geological timescales 100

ANALYTICAL PROCEDURES 103Zircon fission-track dating 103Track length measurement 107

APPLICATION TO THE NOJIMA FAULT ZONE 108Geological setting 109Sample description 110Data and interpretation 110Geological implications 115Summary 118


D Fundamentals of Noble Gas ThermochronometryT. Mark Harrison, Peter K. Zeitler

INTRODUCTION , 123BASICS OF NOBLE-GAS GEOCHRONOLOGY 124

K-Ar and 40Ar/39Ar systematics and analysis 12440Ar/39Ar mineral thermochronometers 127Principal interpretive methods and analytical issues, 40Ar/39Ar 127(U-Th)/He systematics and analysis 129(U-Th)/He mineral thermochronometers 130Principal interpretive methods and analytical issues, (U-Th)/He 130

DIFFUSION 131Background 131Diffusion mechanisms 132The Arrhenius relationship 133Episodic loss 134

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Coupling fractional loss equations with the Arrhenius relationship 135Calculation of age spectra resulting from episodic loss 135Closure temperature 136

EXPERIMENTAL DETERMINATION OF DIFFUSION PARAMETERS 140Calculation of diffusion coefficients from bulk loss experiments 140Calculation of Ar and He diffusion coefficients from step-heating results 141Experimental criteria 142Laboratory diffusion studies - helium '. 142Laboratory diffusion studies - argon 143

INTERPRETATION OF THERMOCHRONOLOGICAL DATA 145Heat transfer 145Sampling considerations 145Constraining power 146Intercomparison and accuracy of thermochronological data 146

CONCLUDING REMARKS 146REFERENCES 147

O Zircon (U-Th)/He ThermochronometryPeter W. Reiners

INTRODUCTION 151Historical perspective 151

HELIUM DIFFUSION IN ZIRCON 153Step-heating experiments 153Radiation damage 155

ANALYTICAL AND AGE DETERMINATION TECHNIQUES 159Analytical methods 159

CASE-STUDY EXAMPLES 166Comparison with K-feldspar 40Ar/39Ar cooling models 166Dike heating 166Exhumed crustal sections 168Orogenic exhumation: Dabie Shan \ 171Detrital zircon dating 171

FUTURE DEVELOPMENTS 174ACKNOWLEDGMENTS 176REFERENCES 176

/ 4He/3He Thermochronometry:Theory, Practice, and Potential Complications

David L. Shuster, Kenneth A. Farley

INTRODUCTION 181FUNDAMENTAL CONSIDERATIONS 181

The 4He spatial distribution 182

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Proton-induced 3He 183The 4He/3He ratio evolution diagram 185The effect of -ejection 186The 3He Arrhenius plot 187Constraining thermal histories 1884He/3He age spectra 188

TECHNICAL ASPECTS 192Proton irradiation 192Sample requirements 193Stepwise degassing analysis 193

POTENTIAL COMPLICATIONS 194Mineral surfaces 194Geometry 194Does proton irradiation affect helium diffusion kinetics? 194Diffusive fractionation of helium isotopes? 195Non-uniform U and Th distributions 196

EXAMPLE APPLICATIONS 197Example 1: controlled 4He distributions 197Example 2: natural apatite 199Example 3: natural apatite 200

CONCLUSIONS 201ACKNOWLEDGMENTS 202REFERENCES 202

8 Fission-track Analysis of Detrital Zircon

Matthias Bernet, John I. Garver

INTRODUCTION 205FISSION-TRACK DATING OF DETRITAL ZIRCON 207

Field collection 207Analytical considerations in the lab 209Grain-age analysis and data presentation 213

INTERPRETATION OF FISSION-TRACK GRAIN-AGE DISTRIBUTIONS 213The partial annealing zone and closure of the ZFT system 213Lag time -. 215Types of lag-time changes 216

EXAMPLES AND APPLICATIONS 217Provenance analysis 218Dating strata 222Exhumation studies 224Dating low-temperature thermal events and strata exhumation 22 8Combination with other isotopic dating techniques 231

CONCLUSIONS 233ACKNOWLEDGMENTS 234REFERENCES 234

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s 40Ar/39Ar Thermochronology of Detrital MineralsK. V. Hodges, K. W. Ruhl,

C. W. Wobus, M.S. Pringle

INTRODUCTION 239MOTIVATIONS FOR DETRITAL 40Ar/39Ar STUDIES 239SAMPLING AND SAMPLE PREPARATION 240

The number of analyses necessary for a robust result 241ANALYTICAL TECHNIQUES 241

Data presentation and interpretation 242Inferring population characteristics 243

APPLICATIONS AND EXAMPLES 246Determining sediment source regions 246Constraining minimum depositional ages of ancient sediments 246Estimating the timing of source region exhumation 246Constraining the erosion-transport interval for orogenic detritus 246Elucidating modern erosional patterns 249Estimating erosion rates for modern sedimentary catchments 249Defining the positions of young deformational features 251

FUTURE DIRECTIONS 252REFERENCES 253

10 Forward Modeling and Interpretation of (U-Th)/He AgesTibor J. Dunai

INTRODUCTION 259FORWARD MODELING 259

General remarks 259Effect of shape and surface/volume ratio 261Simultaneous treatment of alpha ejection and diffusion : 263Considering parent nuclide distribution 264FT correction vs. FM an apparent conflict resolved 265A checklist for FM 266

DECOMP - A USER FRIENDLY FM SOFTWARE 266A quick guide to DECOMP 267

EVALUATION OF SAMPLE DATA BY FORWARD MODELING 268Qualitative evaluation of competing hypothesis 268Quantification of process rates and model parameters 270

OUTLOOK FOR FORWARD MODELING 270REFERENCES 272


I I Forward and Inverse Modeling ofLow-Temperature Thermochronometry Data

Richard A. Ketcham

INTRODUCTION 275FORWARD MODELING OF THE FISSION-TRACK SYSTEM 275

Calibrations 276Length distribution calculation 286Age calculation 291Oldest track 292Example FT forward models 292

FORWARD MODELING OF THE (U-Th)/He SYSTEM 292Equations defining the (U-Th)/He dating system 293Calibration 294Finite difference solution 294Example He forward models 298

INVERSE MODELING 299Statistical tests 300Defining and searching candidate thermal histories 303Presentation of inversion results 304

EXECUTION AND INTERPRETATION OF INVERSE MODELING 305AVAILABLE SOFTWARE 310CLOSING THOUGHTS 311ACKNOWLEDGMENTS 311REFERENCES 311

1 JL Crustal Thermal Processes and the Interpretationof Thermochronometer Data

ToddA. Ehlers

INTRODUCTION 315NATURAL VARIABILITY IN TERRESTRIAL HEAT FLOW 316AGE-ELEVATION PLOTS AND SUBSURFACE TEMPERATURES 318GEOLOGIC PROCESSES INFLUENCING THERMOCHRONOMETER AGES 321

Background thermal state of the crust 321Erosion and sedimentation 323Tectonics and faulting 328Magmatism 333Topography 337Fluid flow 337

CONCLUDING REMARKS 341ACKNOWLEDGMENTS 343REFERENCES 344APPENDIX A: THERMOPHYSICAL PROPERTIES OF EARTH MATERIALS 349

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Quantitative Constraints on the Rate of LandformEvolution Derived from Low-Temperature Thermochronology

Jean Braun

INTRODUCTION 351TOPOGRAPHY AND TEMPERATURE 352AGE-ELEVATION DATASETS 354SPECTRAL ANALYSIS 3553D THERMAL MODELING: PECUBE 358EXAMPLE FROM THE SIERRA NEVADA 359

Interpreting the Sierra Nevada data using the spectral method 359Interpreting the Sierra Nevada using Pecube 360

SLOW EROSIONAL SETTINGS 362Isostasy 362

INVERSION OF AGE-ELEVATION DATASETS 364Post-orogenic erosional decay, example from the Dabie Shan 365Rate and nature of passive margin escarpment evolution, example

from SE Australia 368CONCLUSIONS AND FUTURE WORK 371ACKNOWLEDGEMENTS 372REFERENCES 372

I 4 Exploiting 3D Spatial Sampling inInverse Modeling of Thermochronological Data

Kerry Gallagher, John Stephenson,Roderick Brown, Chris Holmes, Pedro Ballester

INTRODUCTION 375What is a good but simple thermal history model? 376ID modeling 3802D modeling 3823D modeling 384

SUMMARY 386REFERENCES 386

1 D Continuous Thermal Histories fromInversion of Closure Profiles

T. Mark Harrison, Marty Grove,Oscar M. Lovera, Peter K. Zeitler

INTRODUCTION 389Background 389An example: the bulk closure temperature of biotite 390


Bulk mineral thermochronometry 390How do we obtain the highest accuracy and resolution thermal histories? 391

IN SITU CLOSURE PROFILES 391The closure profile equation 391

INFERING CLOSURE PROFILES FROM 40Ar/39Ar DATA 39240Ar/39Ar step-heating of K-feldspar 393Fundamental assumptions for recovering thermal history information 394Recognition of problematic behavior in K-feldspar 40Ar/39Ar age spectra 395The multi-diffusion domain model 396Inversion of 40Ar/39Ar results to thermal history data 397Numerical simulation of domain instability during slow-cooling 402Other applications: Th-Pb dating of monazite 404

CONCLUSIONS ..407REFERENCES 407

16 Application of Low-Temperature Thermochronometryto Extensional Tectonic Settings

Daniel F. Stockli

INTRODUCTION 411PROCESSES OF EXTENSIONAL UNROOFING AND EXHUMATION 412LOW-TEMPERATURE THERMOCHRONOMETRIC TECHNIQUES 415

40 Ar/39Ar thermochronometry 415Fission-track thermochronometry 416(U-Th)/He thermochronometry 417

THERMOCHRONOMETRY AND EXTENSIONAL TECTONICS 417Timing of extensional faulting and exhumation 418Estimation of fault slip rates 424Thermochronometric constraints on fault dip angles 429Estimation of crustal tilting and footwall rotation 431Estimation of normal fault offset magnitude 432Geothermal gradient estimates 433Spatial and temporal distribution of extension 434

CONCLUSIONS AND FUTURE DIRECTIONS 438ACKNOWLEDGMENTS 439REFERENCES 439

I / Applications of Low-Temperature Thermochronometry toQuantification of Recent Exhumation in Mountain Belts

James Spotila

INTRODUCTION 449DENUDATIONAL MATURITY 450CASE I: ANCIENT OROGENS AND PALEODENUDATION 453


CASE II: EARLY DENUDATION 455CASE III: INTERMEDIATE DENUDATION 457CASE IV: STEADY-STATE 460DISCUSSION AND CONCLUSIONS 461ACKNOWLEDGMENTS 463REFERENCES 463

18 Application of Thermochronology toHydrothermal Ore Deposits

Brent I. A. Mclnnes, Noreen J. Evans,Frank Q. Fu, Steve Garwin

INTRODUCTION 467THERMOCHRONOLOGY AND MINERALIZED SYSTEMS -

AN INTRODUCTION 467(U-Th)/He thermochronology 468Fission track 47040Ar/39Ar 470Using thermochronometry in thermal history studies 471

APPLICATIONS OF THERMOCHRONOMETRY TOGOLD MINERALIZATION 475

Carlin-type gold deposits 475Epithermal gold deposits 475Archean lode gold deposits 476Shale-hosted lode gold deposits 476

APPLICATION OF THERMOCHRONOMETRY TO PORPHYRY COPPER-MOLYBDENUM-GOLD MINERALIZATION 476

Selected porphyry deposits 478Duration of hypogene ore formation: measured vs. modeled 482Emplacement depth 482Hypogene copper grade as a function of cooling rate 486Preservation potential of hypogene ores and potential formation of

supergene ores 486CURRENT TRENDS, FUTURE DIRECTIONS 487ACKNOWLEDGMENTS 488REFERENCES 488APPENDIX I: U/Pb AND (U-Th)/He ANALYTICAL PROCEDURES 494APPENDIX II: EXPLANATIONS AND CALCULATIONS OF

MODELED PARAMETERS 4951. Sample position, eroded thickness of the porphyry, and initial sample depth 4952. Determination of emplacement depth 4953. Calculation of exhumation rates 4964. Example: determination of emplacement depth and exhumation

rate for the Batu Hijau Porphyry 4975. Limitations and future improvements 498

19Low-Temperature Thermochronology - Table of Contents

Thermochronometers in Sedimentary BasinsPhillip A. Armstrong

INTRODUCTION 499PROCESSES THAT AFFECT BASIN TEMPERATURES - THE HEAT BUDGET 499PRESENT-DAY THERMAL FIELD 500BUILDING A BURIAL AND THERMAL HISTORY 501THERMOCHRONOMETERS USED IN SEDIMENTARY BASINS 503

Apatite fission-track dating 503Apatite (U-Th)/He dating 507Combining apatite fission-track and other thermal indicators 508Higher temperature thermochronometers 509

EXAMPLES OF THERMOCHRONOMETER USE IN SEDIMENTARY BASINS 509Example of a sedimentary basin thermal history - the Williston Basin 509Example integrating burial history with AFT data in an active-margin basin 512A complex history example - constraining structures with outcrop and well data ..514Additional illustrative examples of AFT analysis in sedimentary basins 516Higher-temperature thermochronometers in sedimentary basins 517

CONCLUSIONS AND FUTURE DIRECTIONS 519ACKNOWLEDGMENTS 520REFERENCES 520

Z U Visualizing Thermotectonic and DenudationHistories Using Apatite Fission Track Thermochronology

Barry P. Kohn, Andrew J. W. Gleadow,Roderick W. Brown, Kerry Gallagher,

Matevz Lorencak, Wayne P. Noble

INTRODUCTION 527APATITE FISSION TRACK THERMOCHRONOLOGY 528THERMAL HISTORY MODELING 529REGIONAL APATITE FISSION TRACK DATA ARRAYS 529QUANTIFYING LONG-TERM DENUDATION 531

Assumptions and uncertainties 531Regional-scale imaging 534Denudation chronologies 536

REGIONAL APATITE FISSION TRACK DATA ARRAYS 537Southern Canadian Shield - record of a foreland basin across a craton 537Southern Africa - formation and evolution of a continental interior 545Eastern Africa - development of an intracontinental rift system 547Southeastern Australia - evolution of a complex rifted passive margin 552


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21Low-Temperature Thermochronology - Table of Contents

Low-Temperature Thermochronometry of MeteoritesKyoungwon Min

INTRODUCTION 567(U-Th)/He METHOD 568

Fundamentals 568History 569Sample preparation 570Age corrections 570Diffusion properties 576(U-Th)/He ages 577Limitations 579

244Pu FISSION TRACK METHOD 579Fundamentals 579History 579Age correction '. 580Annealing properties 582244Pu fission track data 582Limitations 584

CONCLUDING REMARKS 584ACKNOWLEDGMENTS 584REFERENCES 584APPENDIX: SAMPLE PREPARATION AND ANALYTICAL PROCEDURES 588

Computational Tools for Low-TemperatureThermochronometer Interpretation

ToddA. Ehlers, Tehmasp Chaudhri, Santosh Kumar,Chris W. Fuller, Sean D. Willett, Richard A. Ketcham,

Mark T. Brandon, David X. Belton, Barry P. Kohn,Andrew J. W. Gleadow, Tibor J. Dunai, Frank Q. Fu

INTRODUCTION 589TERRA: FORWARD MODELING EXHUMATION HISTORIES

AND THERMOCHRONOMETER AGES 590TERRA - ID and 2D thermal history calculations 591TERRA - thermochronometer age prediction 594

HEFTY: FORWARD AND INVERSE MODELINGTHERMOCHRONOMETER SYSTEMS 596

FTINDEX: INDEX TEMPERATURES FROM FISSION TRACK DATA 597FTIndex program operation 599

BINOMFIT: A WINDOWS® PROGRAM FOR ESTIMATINGFISSION-TRACKAGES FOR CONCORDANT ANDMIXED GRAIN AGE DISTRIBUTIONS 600

Introduction to BINOMFIT 600Using BINOMFIT 601

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PROGRAMS FOR ILLUSTRATING CLOSURE, PARTIAL RETENTION,AND THE RESPONSE OF COOLING AGES TO EROSION:CLOSURE, AGE2EDOT, AND RESPTIME 602

Methods for CLOSURE 603Methods for AGE2EDOT 608Methods for RESPTIME 610

TASC: COOLING ONSET AGES AND EVENT TIMING IN NATURALSAMPLES FROM FISSION TRACK LENGTH DATA 610

Background to the TASC program 610Applications of the TASC program 612Using the TASC program 614TASC controls 614TASC inputs 614TASC outputs 614

DECOMP: FORWARD MODELING AGE EVOLUTION OF (U-Th)/He AGES 615How to use DECOMP 615Temperature history plot 616Age evolution plot 616

4DTHERM: THERMAL AND EXHUMATION HISTORY OF INTRUSIONS 6164DTHERM applications 6174DTHERM inputs 6184DTHERM outputs 618


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LOW-TEMPERATURE THERMOCHRONOLOGY - GBV · Quantitative interpretations of data with numerical models 10 General comments on the future of thermochronology 11 REFERENCES 13 I- Fundamentals