Low-Grade Metamorphism

321 Pages·1998·52.48 MB·English

Low-Grade Metamorphism
Low-Grade Metamorphism Martin Frey and Doug Robinson
© 1 9 99 Blackwell Science Ltd. ISBN: 978-0-632-04756-7
Low-Grade Metamorphism
Martin Frey
Mineralogisch·Perrographisches,lnstitutderUniversitiitBasel
Bernoullislrasse30, CH·4056Basel, Switztrland
Doug Robinson
DepanmentofEarthSdences, UniversityofBristol
WillsMemorialBuilding, QueensRoad,BristolBst/RJ. UK
b
Blackwell
Science
o
1999by AUrights reserved. Nopanof DISTRIBUTORS
BlackwellSdenceLtd thispublicationmaybereproduced,
Man;tonBookServicesLtd
EditorialOffice~: storedinaretrievalsystem. or
POBox269
OsneyMead. OxfordOX2OEL transmitted. inanyform orbyany
Abingdon. OxonOXI44YN
25JohnStreet.LondonWCIN2BL means,electronic, mechanical,
(Orders:Tel: [phone]
23AinsliePlace.EdinburghEH36AJ photocopying.recordingorothenNise,
Fax:[phone])
350MainStreet. Malden exceptaspermittedbytheUK
MA02148 5018,USA Copyright, DesignsandPatentsAct USA
54Univen;ityStreet.Carlton 1988,withoutthepriorpermission Blackwell Science. Inc.
Victoria 3053. Au~tralia ofthecopylightowner. CommercePlace
10, rueCasimirDelavigne 350MainStreet
75006Paris, France Acataloguerecordfor thistille Malden, MA02148 5018
isavailablefrom theBritishLibrary (Orders:Tel: [phone]
OtherEditorialOffict>S: 7813888250
BlackwellWissenschafts-VerlagGmbH ISBN0-632-04756-9 Fax:[phone])
Kurfun;tendamm 57
Canada
10707 Berlin,Gennany
LibraryofCongress LoginBrothersBook Company
Blackwell ScienceKK Cataloging-in-publicationData 324 SaulteauxCre~cent
MGKodenmachoBuilding Winnipeg.Manitoba R3J312
Low-grademetamorpWsm/[editedby]
7-10KodenmarhoNihombashi (Ordrrs: Tel:[phone])
Martin Frey, DougRobinson.
Chuo-ku.Tokyo 104,Japan
p. em. Australia
Includesbibliographical BlackwellSciencePlyLtd
TherightoftheAmhon;tobe
references. 54University Street
idemifiedastheAuthon;ofthisWork
ISBN0-632-04756-9 Carlton, Victoria 3053
hasbeenassenedinaccordance
L Metamorphism (Geology) (Orders:Tel: [phone]
withtheCopyright,Designsand
I. Frey, Manin. 1940-.II. Robinson. Fax: [phone])
PatentsAct 1988.
Doug.
QE475.A2L668-1998
Firstpublished 1999 Forfurtherinformationon
552'A-dc21 98-18900
BlackwellScience,visitourwebsite:
ClP
SetbySetriteTypesetten;. HongKong www.blackwell-science.com
Primedandboundin
GreatBritainatthe
Univen;ityPress, Cambridge
TheBlackwellSciencelogoisa
trademarkofBlackwellSdenceLtd.
registeredattheUnitedKingdom
TradeMarks Registry
Contents
Listofcontributors, viii techniques, 37
2.4.3 CorrelationofX-raydiffractionand
Preface.ix transmissionelectronmicroscope
measurements,47
1 Low-temperature metamorphism: 2.4.4 Retrogression, 49
an overview. 1 2.5 Geothermometryandgeobarometry, 51
D.Robinw/landR.J.Mrrriman 2.5.1 Illite-smectite reaction, 52
1.1 Whatisit?, I 2.5.2 Illiteandchloritecryslallinity, 53
1.2 Adecadeofprogress. 2 2.5.3 Chloritegeothennometers, 53
1.3 Verylow-grademetamorphisminaglobal 2.5.4 Polytypismofchloriteandwhitemica,
selling. 4 54
1.4 Doeslow.temperaturrmetamorphismmatler? 2.5.5 Ph('ncitegt>onarometer, 55
8 2.6 Overviewofconditionsofverylow-grade
1.5 Mineralabbreviations. 9 metamorphism, 56
2.7 Futureresearch, 58
2 Very low-grade metapelite.:
mineralogy, microfabric8 and 3 Patterns of very low-grade
measuring reaction progr••s, 10 metamorphism in metepelitic rocks, 61
R.J.Mem"manandD.R.Peacer R.J.MerrimQIlQlldM.Frry
2.1 MetapeUticrocks. 10 3.1 Introduction,61
2.1.( Introduction. 10 3.2 Samplinganddatainterpretation. 62
2.1.2 Metapeliticzonesandlithology. II 3.2.1 Fieldsampling,62
2.1.3 Metastableequilibriumanddaymineral 3.2.2 Methodsofdisplayingregional
reactionprogress. 13 metapcliticdata,64
2.2 Mineralogical relations. 15 3.2.3 Metapelitesandbasinmaturity. 67
2.2.1 Phyllosilicatereactionseries. 15 3.2.4 Patternrecognition. 71
2.2.2 Smeetite-I1S-illite-muscovitc. 15 3.3 Regionalpatternsofverylow-grade
2.2.3 Smeetite-<:orrensitc-ehlorite.19 metamorphism. 73
2.2.4 Kaolinite-pyrophyllitc.21 3.3.1 Geotectonicsetting, 73
2.2.5 Berthierine, 21 3.3.2 Extensionalseuings,76
2.3 Melapl'liticmicrofabrics, 22 3.3.3 Accretionarysettings. 83
2.3.1 Introduction. 22 3.3.4 Collisionalsettings, 92
2.3.2 MicrofabriCSofthelatediageneticzone. 3.3.5 Highstrainlones, IQI
22 3.4 Low-temperaturecontact metamorphism, 104
2.3.3 Theanchizoneandslatycleavage 3.4.1 AureolespredatillgregiOlJal
development. 25 metamorphism, 104
2.3.4 Theanchizone-epizonetranSilion.28 3.4.2 Aureolespostdatingregiunal
2.4 Measuringreactionprogress. 28 metamorphism, 105
2.4.1 X-raydiUractiontechniques, 28 3.5 Regional comrolson metapeliticpatterns. lOS
242 Transmissioneleoron microscope ~ f.. 'ondll~iom. 107
v
vi Contents
4 Petrological methodsfor the study of 6 Very low-grade hydrothermal
very low-grade metab.sites, 108 metamorphism of basic igneous rocks,
P.SchiffmanandH. W. Day 169
4.1 Imroduaion, 108 J.c.Ait
4.2 Fieldstudyofverylow-grademetabasites, 109 6.1 Introcluaion, 169
4.3 Primaryfeatures, 110 6.2 OceaniccruSt, 169
4.3.1 Glassandpalagonjtc, III 6.2.1 Oceaniccrustalstructure, porosityand
4.3.2 Primaryminerals, III permeabillty. 169
4.3.3 Vesides, IB 6.2.2 Heatsourcesandconvectioninocean
4.4 Secondaryminerals. 113 crust. 171
4.4.1 Maficlayersilicates, 113 6.2.3 Submarineversussubaerial
4.4.2 Pumpellyite,prehniteandepidote, 117 hydrothermalsystems, 173
4.4.3 Otherminerals, 120 6.2.4 SamplingoceancruSL 173
4.5 Elearonmicroprobeanalysisoflow-grade 6.3 Thevolcanicseaion, 175
metabasites, 120 6.3.1 Initiallow-temperaturehydrothermal
4.5.1 Analyticalconditions. 120 processesinthevolcanicsealon. 175
4.5.2 Analyticaldillicultics, 120 6.3.2 Low~temperaturehydrothermal
4.5.3 Standards, 123 seawater-rock interactionsinthe
4.5.4 Analytical unccrtaimks, 123 volcanicsealon, 177
4.5.5 Criteriaforagoodanalysis. 125 6.3.3 Restriaedlow-temperature
4.6 Quantitativeapplicationofelectron microprobe hydrothermal interactionsinthe
data. 127 volcanicsection, 181
4.6.1 Projectionsoflow-grademineral 6.3.4 Ageingofthevolcanicseaion: late
assemblages, 128 carbonatesandzeolites. 183
4.6.2 Projeaion from chloritc. 129 6.4 ThetransitionZOlleand uppersheeteddyke
4.6.3 Projectionsfrom caicium-aluminium complex:tbetransition tolow-grade
silicates. BI hydrothermal metamorphism, 185
4.6.4 Algebrakmelhuds, 133 6.5 Thelowersheeteddykecomplex andthe
4.6.5 Petrogeneticgrids.135 plutonicsection:therootsofsubmarine
4.6.6 Thermobaromelry, 139 hydrothermalsystems, 187
4.7 Summary, 141 6.6 Hydrothermal upflowzonesand formation of
seafloorsulphidedeposits, 189
5 Patterns of regional low-grade 6.7 Scawater-crustalchemicalfluxes at
metamorphism in metabasit.s, 143 mid-oceanridgesandcyclingatsubduction
D.RobinsonandR.E.Bevim zones, 190
5.1 Introduction. 143 6.8 Ophiolites, 191
5.2 Rcgionailow-grademetamorphism, 144 6.9 Verylow-grademetamorphismat oceanic
5.2.1 Extensionalsettjngs--WelshBasin, 144 islands, 192
5.2.2 Extensional settings-AndeanBasins. 6.9.1 Iceland,192
150 6.9.2 La Palma, 194
5.3 Subaerial flood basaltsequences, 155 6.10 Islandarcsandback-arcbasins. 194
5.3.1 EasternNorthGreenland, 156 6.10.1 Submarinerocks, 194
5.3.2 North ShoreVolcanicGroup, 6.10.2 Japan. 196
Minnesota, 157 6.11 Examplesofsediment-hostedgeothermal
5.4 Convergent settings. 162 systt'ms. 197
5.4.1 Canadian Shield, Abitibiterrane. 162 6.12 Rhyoli!icvolcanic-hostedgeothermalsystems,
."
5.4.2 Northern Sierra Nevalla, 165
5.5 Conclusions, 168 6.13 Summaryandconclusions. 199
Contents vii
7 Isotopic dating of very low-grade 8.3 Massspectrometry, 228
metasedimentary and metavolcanic 8.4 Sampleextraction techniques, 230
rocks: techniques and methods, 202 8.4.1 Carbonates, 230
N.ClauuandS.Chaudhuri 8.4.2 Silicates, 230
7.1 Introduction, 202 8.4.3 Sulphidesand sulphates, 23\
7.2 Importanceofmineralseparationand 8.4.4 Graphiteandorganicmatter, 232
characterization,204 8.4,5 Hydrogen, 232
7.2.1 Separation,204 8.4.6 Gaschromatography isotoperatiomass
7.2.2 Characterization, 205 spectrometrymethods,232
7.2.3 Summary,206 8.5 Isotopicreservoirs, 233
7.3 Prindplesofisotopedating, 206 8.5.1 Water, 233
7.3.1 Methodologyofisotopicdating, 207 8.5.2 Rocks,235
7.3.2 Somespedficaspectsandapplications. 8.6 Thermometry, 236
210 8,6.\ Basicfractionation eqoations, 236
7.4 Fission-nackdating, 213 8.6.2 Mineral fractionation factors. 236
7.5 Rocklithologiesand isotopichomogenization, 8.7 Volatileloss: dehydration, decarbonation,
216 desulphidationand dehydrogenation, 239
7.5.J Insheetsi!icatesofmetapclitesand 8.8 Mineralpurification, 240
metaarkoses, 216 8.8.\ Chemical purificatiOll, 240
7.5.2 Insheetsilicatesofmetapelitesand 8.8.2 Fine-grained phyllosilicates:clays, 242
metatufls.217 8.8.3 Porphyroblasts, veinsand vugfillings,
7.5.3 Insheetsilicatesofmetapelitesand 243
metabasites.218 8.9 Applicationstorocksofsedimentaryorigin,
7.5.4 Summary, 218 243
7.6 Metamorphicdegreeand extentofisotopic 8.9.\ Diagenesis:generalconsiderations,243
homogeniz.ation,218 8.9.2 Diagenesis:examples, 245
7.6.1 Insheetsilicatesofshales. 218 8.9.3 Low·grademetamorphism, 247
7.6.2 Insheetsilicatesofslates, 219 8.10 Oceanbasalts, 253
7.6.3 Insheetsilicatesofmdagreywackes. 220 8.\0.\ DSDP-ODPresults, 254
7.6.4 Inwholerocks. 221 8.\1 Veins,255
7.7 Amodelforisotopichomogenizationinlow 8.\\.1 Tracingfluid origins: acombinedstable
grademetamorphicconditions. 223 isotope-fluid inclusiOIlstudyofVariscan
7,8 BaSin evolutionbasedoncombinedisotopic crustalfluids, 256
andfission-track data. 224 8.\1.2 Acombined structural-oxygen
7.9 Conclusions, 226 isotopethermometrystudyofnappe
7.10 Acknowledgemems,226 formation: anexamplefrom the
HelveticAlps. 257
8.12 Retrogrademetamorphism. 257
8 Application of stable isotope 8.13 Summary, 259
geochemistry to low-grade
metamorphic rocks, 227 References, 261
Z D, Slwrp
8.1 Intruductiun.227 Index, 303
8.2 Terminology. 228
List of contributors
J. C. Att R.J. Merriman
IHpantnrntafGtologiullSdmas. Uni~'rT'SityofMid/igan, BritishGtologiCiJISUrvt)'.K~",nh. Nr:ttringhamNGll
AnnArbor:Ml48109-I06J, USA SGG, UK
R. E. Bevins D. R. Pe.cor
lXparrmm/ofGtology.NationalM~uma[Waln,CIlthys DtpanmmtofGtologiallSdmcn. UnivrrsityofMichigan.
Park,QJrdi/fCFlJNp,UK AnnA.rbor.MJ48109-106J. USA
S. Chaudhuri D. Robinson
DtpanmrntofGtology.IVIIUosStll~ Unil'fTSity. IXpartmmtofEanhSdmcn. UnivrrsiryofBristol, Wills
Manhattan, KS66506, USA. MtmDriaiBuilding. Quml5Road. BristolBSSJRJ. UK
N. CI.uer P.Schiffman
emtrtdtGtrxhimitdtlaSurfau(CNRS-L1LP). Univrrsiti ~partmmlofGtology.Utli1lfffityofCAlifornia.Davis.
LouisPQj/lur. I rut Blmig,67084Slrtubourgerda. CA 95616. USA
Frana
Z. D. Sharp
H. W. Day DfpanmttltofEanhandP{atlttarySrittlcts. Nonhrup
Departmtnf"fGtology. UnivtrSityo[California.Davis. Hall, ThtUtliwrsityofNtwMtxico, Albuqutrqut,NM
CA95616. USA 81131-11/6. USA
M. Frey
Mintral09isch·Pmographischrs. fnstitutdrrUniversitat
Basel.Btmou/liSlrasSlJO, CH-4056Bastl,Swi/urland
viii
Preface
Metamorphism is broadly a process of solid-state exciting and challenging topics as at higher grades
changeinthemineralogy, textureandchemislryof of metamorphism. We see research in this field as
rocks in the Earth's crust. It provides a powerful having reacheda threshold at which several ofthe
recordofchangein theEarth's most active settings broad qualitative questionsabout the nature ofthe
wheremelamorphismhasproceededinresponseto transformation and related processes have been
global tectonics. Metamorphic rocks are defined in successfullyaddressedoverthelaSIdecade.Thishas
most petrological textsas having mineralogies and proVidedasolidbasisformovingforwardtotestthese
textures that arc a consequence 01 recrystallization latest ideas and 10 provide for a more quantitative
under P-T regimes different from the diagenetic assessmentoftheseprocesses, ashastakenplace in
realm. Metamorphism 'proper can thus be dearly the mainstream of the subject. Low-temperature
recognizedwhererockshavebeenfullyrecrystallized metamorphism is a widespread phenomenon as
and no direci evidence of the protolith remains. sociated wilh major processes of crustal growth
II is in such rocks that the principles ofequilibrium and destruction, whose implications are perhaps
thermodynamics have allowed, over lhe past tWO underappreciated in terms ofmajor Eanh systems,
decadesorso,anincreasinglyquantilaoveassessment such as arc volcanism and recycling of crustal
ofmetamorphicprocesses. materials into the mantle. Also. at the tum of the
In reality, however, there is no clear or sharp millennium, Earth Science is increasingly concen
break between the diagenetic and metamorphic tratingonprocessesatshallowerlevelsintheEarth's
fields; instead there is a continuum of increasing crust, including low-temperature metamorphism,
recrystallizationinthebodyoftheprotolith.Indeed, withtheirrelevancetomasstransferandfluid-rock
theextentofanytransitionzonewillvarydepending interaction aimed al better utilization of Earth
on features suchasthetypeofearthmaterial inves resourcesandassessmentofenvironmentalimpact.
tigated. ortheresolutionofinvestigativetechnique. In the light ofthese considerations we believe that
Forexample,Vitreousandorganicmaterialsundergo the field of low-temperature metamorphism has
change at much lower temperature than silicate much of interest to offer to a broad audience and
materials. while Transmission Electron Microscopy thatthehighlightsofthesefeatures are tobe found
provides greater resolution 01 the finest grained in the contentsofthisbook.
layersilicatesthan docsX-raydiUraction. Although Thebookdoesnotofferacomprehensivecoverage
there is good coverage of the mainstream parts of ofallaspectsofthesubject; features suchasorganic
the subject in a varietyof textbooks, there is often maturation and fluid inclusions are not covered.
only passing treatment of this transitional zone. Concentrationisgiventotopics thatwebelieve are
suggesting that it is of only marginal interest 10 most relevant to a wider audience and in which
the subject as a wholt:. This book came 10 fruition majoradvanceshavebeenmadeinrecentyears.The
with an aim of dispelling any such view by giving buok slarlS with an overview of low-temperature
a specific analysis of the low-temperature pan of metamorphism, highlightingadvances made in the
the metamorphic spectrum. We believe that this lastdecadeandoutliningitscontext10glohalsettings
field of metamorphism offers somewhat different and its rdevance to other Earth systems. This is
perspectives on metamorphic processes. for which followed by detailed analysis in Chapters 2 and 3
therearescientificquestionsthatprovideequallyas of low-temperature metamorphism of mctapelitic
x Preface
rocks. Chapter 2 assesses the remarkable advan~ metamorphismatocean ridgesellings,andidentifies
made in our understanding of the continuum of characteristics thatdistinguish its stylefrom that of
prograde processes that occur in layer silicale otherscllings.
mineralsduring the transformation from diagenesis Chaplers 7 and 8 cover isotopic aspects of low
to metamorphism, in particular those that have temperature metamorphism. the problemsand po
been provided by Electron Microscopy techniques. tentialofradiogenicandstableisotopesforresolVing
Chapler3examine5regional patternsin mctapcHric various problemsand quesllons.
rocks from a global tectonic selling recognizing The Editors thank all authors for their efforts in
characteristic Styles associated with contrasting producing their contributions to meet the deadline
requirementsandalsofor th~1:' rl:'viewingchaptl:'rs
scllinKS·
Metabasitcs fonn the subject of Chaplers 4, 5 otherIhan theirown. DrS. Tn. Schmidtis thanked
and6, commencingwithanassessmentand review for reading and valuable comments on Chaplers 4
of petrological methods that can be applied 10 and S. Chapters 2 and 3 have benefited from the
low-grade metabasites of the styit' widely used at field and laboratory observations of Dr B. Robcns
highergradcsofmetamorphism.Chapter5examines andtheemhusiasmthathe hasgeneratedovermany
regionalpatternsoflow-grademetamorphismtackled, years of fieldwork and discussion. R. J. Merriman
as with rnetapeliticrocks. in lermsofglobal (ecronic publishes with permission of the Director, British
settings. Chapler 6covers lhe most widespread 0( Gcological Survey.
currenceofklw-temperaturt'mctamorphism,namely
IhatintheoceancruSt, resultingfromhydrothermal D.R.
1 Low-temperature metamorphism:
an overview
D. Robinson and R. J. Merriman
controls that had the potential to be explored and
1.1 What is it?
understood. The mainstay of this approach was in
Metamorphism is a process of change at elevated the application of equilibrium thermodynamics to
temperalUres and pressures in rocks occupying define the controlling features of the metamorphic
the outer skin of the Earth. The challenge fadng process.
the metamorphic petrologist is 10 understand and In termsoflow-temperature metamorphism, the
interpret the record of changes that are imprinted recrystallization is often not immediately obvious
in the texturt:, mineralogy and chemistry uf tbe because of the fine-grained s('ale of the products.
metamorphicrock.withrelevance10understanding Also, the apparent lack of regularity in the meta~
the evolution of Earth systems. In this book we morphicdevelopmentandthepanialrecrystallization
investigatechan~csintermsofmetamorphicphase intherockswithmanyrelictfeaturesoftheprolOlith
transformations and the processes driving these preserved.point10non-equilibratedsystemswithout
changes in the broad pressure-temperature field obvious overall controls. Thus the likelihood of
that lies at subgrecnschist and subblueschist facies understanding such metamorphic evolution and
conditions.Thiscoversthetemperatureandpressure predicting outcomes appeared to be low. However,
rangesup10C.400°Candc.4-5kbar. Rocksaffected the first sign that such a view was over-pessimistic
bysuchconditionsoccupylargetractsofthe Earth's was from the work of Coombs (1960). He showed
upper continental and oceanic crust, and on this a regularity in the distribution of zeolite minerals
basisitmustbeexpectedthattheprocessesinvolved in South Island, New Zealand from which he
in their formation arc varied and diverse. Despite proposed the establishment of the zeolite facies of
the widespread occurrence of such rocks, much metamorphismandsincethen,subgreenschistfades
about the actual mineralogical transitions and the metamorphism has been recognized in many parts
processesinvolvedarepoorly understoodcompared of the world. Documentation of subgreenschist
to metamorphism at higher pressure-temperature facies metamorphism, however, still remains of a
conditions. cursory nature ill most traditional textbooks of
What is the reason for the relative lack of metamorphic petrology that typically envisage the
understanding of lower grade metamorphic rocks metamorphicprocessproperasonecommencingat
compared10theirhighertemperaturecounterparts? the greenschistfblueschist boundaries. It is one of
One reason is that most metamorphic petrologists thegoalsofthisbook toshowthat low-temperature
have traditionally concentrated their attention on metamorphicprocessesarcamainstreampartofthe
the changes taking place at devated temperature subject withexcitingscientificchallengesand scope
(+ c. 300°C) and pressures (+c. 3kbar). reflecting 10advance the understanding of the metamorphic
changes in deeper pans of the Earth's crust and process in an equal manner as at higher grade
upper mamle. This has occurred because from the conditions. Indeed, the features examined in this
earliest days of the study of metamorphic rocks book relating prillcipally 10 t1tetap..:lite and mela
it was realized that regularity, recognized initially basite rocks arc reprcsemative of the very great
in these rocks in terms of their mineralogies at m;ljority of rocks ;It or neM \Cl th(' EMth'~ ~lIrfJcf",
the hand specimen and retro~raphi(' s('a]('~. in (lnd their ('levanc.... \0 ann implication for many
time and space, meant that there were systematic othereanh systemsare probablyunderestlmated.
Low-Grade Metamorphism Martin Frey and Doug Robinson
© 1 9 99 Blackwell Science Ltd. ISBN: 978-0-632-04756-7