`š. `tOO pm
Transkript
`š. `tOO pm
]\ -!:'i:\E \C,GREGATES 'š. 1O O- _ o 'tOOpm E4 ó3 70 - ] .{n opticď micÍogÍaph showing abnormď grain growth. one grain grew much larger than the others. Large grains resulting from an abnormal grain growth situation always contain many poÍes and often show facets. r : i, A is arat e srnbols are for : ra:er-free conlcs during diffu- sigruficantly úerB'ater-adřB-erporos1ty ť s.ater. rnlundaries, although some of the large grains rlrnmined internal pores. The size of pores inrůxsed with the increase in grain size. The average grain size is plotted as a function :ť dme in Fig. 12. The data fit eqn. (1) wilh n:2 :r 3. The temperature dependence of the grain grorwh rate is shown in Fig. 13, which indicates ňat the activation energy is ca. 520 or 600 kJ /mol ir-rr/r : 2 or 3 respectively. Discussion of the samin Fig. 11. n gÍain size in porosity B-slze distriore homogeSignificant zled at high E durations mll on grain Grain growth commences in the later stage of hot-pressing. While significant pore space remains, grain growth presumably involves mass transport through a fluid phase (water and hydrogen in water-added conditions; see Karato et al., 1986) or along grain surfaces. The grain growth in this stage is much slower than the grain growth in the later stage (i.e., in low-porosity samples) under otherwise identical conditions (Fig. 9). The inferred slow mass transport through water (and hydrogen) can be attributed to the low solubility of olivine in water (Nakamura and Kushiro, T9'74). When porosity becomes small and the contact area between grains increases, more effective grain growth occurs. The pore-rich zones surrounding the pore-free cores (Fig. 3,A')can be interpreted as a result of rapid grain growth soon after the effective densification. During this process, the grain-size distribution changes from a wide (Fig. 1) to a narrower distribution (Figs. 5 and 7). This suggests that fine grains were selectively consumed by this process. The rapid grain growth inferred from pore entrapment can be attributed to the large driving force caused by the presence of fine grarns. The presence of relatively pore-free rims surrounding pore-rich zones (Fig. 3A) indicates a slower grain growth in the later stage. At grain boundaries, pores occur both at triple junctions and at two-grain contacts (Fig. 3A). Pore entrapment still occurs in this stage (Fig. 3B, C) but with a slower rate (Fig. 3A). Therefore the grain growth rate at this stage is not largely controlled by the presence of pores (Brook, \9691' Carpay, 1977), although it is obúous from Fig. 3 that pores do exert a drag force on movins boundaries. i,;!6I .SIocu€ J d pue fue8ury |t,t:;sc -€ s c) reqtle Áq petBurp serod;o esuecel€oc eql q8norql .serod tuor; u€ 01 J31€1Y\;o podsuur1 3 sel€clpul .s8rg ees) q}mort urer8 qlrat' .(0I pu€ SIqJ v€ es€eJcul o] es€aJcep o1 Á1rsuep Jeqlunu JIeq} pu€ eqJ sreaddt serJzpunoq urur8 le serod;o ezrs sáu3punoq .11 .31g .e4111T.0 l" pápáuu€ se1dures1o sqder8o:crurpcpdg .srazue1odeue1d (g) ls:ezue1odpessorc (y) átoN =refr te seJod ulrl Og @ @ & lš {-.-u9 oJvuvx s ílolnhMliii]ll| ] rI1 ]fu:_- \'oLI\ 26',7 INE AGGREGATES o o,'\- "ó; c ť),p I o o o $-^+ 12 log',ot ( h ) "i l o g, o t( h) 11. Time variation of grain size in samples annealed at 0.1 MPa. The data fit the grain gÍowth law Gs" _ Gsď : kl with n:2 3, where GS and GSo are the grain size at time t: t and Í:0 respectively, and k is a rate constant. or Y n-e r o- ^i E ta E i o I o I 21 Lfres at graln cois, 1965) rough the ore coaleun growth ois. 1965) 60 104/r(K) 62 6.4 1o4/T(K) Fig. 13 Temperaturedependenceof grain growth Íateat 0.1 MPa' Ě is a rateconstantdefinedby eqn.(1) in the next:(A) Íotn:2; ( B ) f o r n:3 . lrE ) e^d 1u ÁEreuo ÁJ€punoq urer8 eql leql ueeq s€q u eJeH .(€dc I Jo BdIN 00€ qloq) eql l3 suorlrpuoc ee4-JolB^\ w tLsI IP/N)/G/u) pep *-0I xr, - w puesuorlrpuoc .P.JalB.{{ eql l" (,ut/y{/(s/u) gr_0I x s.Í - W : elEJ qlnorB urer8 pe'rresqo oql tursn peleru -Gse eru serlqrqou fuzpunoq unr8 eql (6) 'uba roJJ '(286I 'lpetqqo;4 pue redoo3 :zu/t t-) ffiraue Árepunoq urur8 eq1 sr l. pue (s96I .treIItH :s.0-) lu?lsuoc leuolsueulp-uou E sI í eJeqd\ (€ ) W LV :1 :(7: u rog) Áq .,;zg.Á1r1rqourÁrepunoq urer8 eql o] pol€ I eJ st (1) .ube ut .7 .lue1suoc elBJ eq1, 'lueuodurt tn a { q q d4 lryt^ nl|Gú|ř aí4 7,nr.ň FFq F1 1 { r lutut traPr 't s tu, .---0t [[suls iT ASEJ plo.É Etrusa )qf lrpuoc r,\Ivuc aq u"c uorlurode,le Jo slceJJe eqt w 'qpeg aql ol Pdl^tr I.0 lB sllnser plueuruedxe eql turÁ1dde ul pesrcJaxe oq lsnIII aJBJ 'JorJelul s.qlJ"a eql ur }uelrodun eq lou III^\pu€ .Sunl álnsseJd q8.rq aql w pe^Josqo se 'sarnssard tururyuoc qtq tu passerddns ásJnoc 1o sr (s)eseqd seB ;o uorsuedxo eql ol enp 1uorudo1e,repÁ1rsoro4 .(9961 .s1oqct51) .utn1 lrodsuerl sseu eseqd rodu,r eql Áq pa11or1uoc .sr qcrq'rr serod 1o uollolu eqt Áq palloJluoc ur sI ?dI^I I.0 1B suolllpuoc eeJJ.Jel€^\ le r{y'ror8 urur8 eql teql palsottns sr lI oroJeJeql '(gt6t ''1r.€c) uorlurode'\a le elueculd i1otll/14 099 Jo 13eq eql ol esolc sr tnq '(686I 'o1uru;1 iyg61 'tpoclg pu" lpels1lo) .aes,tral^eJe rc1ipts/1{ 00'-00€ ) euIAIIo ut uoIsnJJIp cluol Jo luql uuql retre1 Á1luuc -gr.uBls st (1otu/11 oo9-gzs) Átraue uoI1PAIlc? peletrrrlse aL1L'(LL6I'Kedlru3 16961 loorg) eler qlnort urur8 eql sloJluoc serod ;o uorlour eql luql Butlse88ns .(tt .tlg) Seuupunoq urert 1z Ápsour peul€IueJ sero4 .tursserd-1oq 8urrnp (pen1osstp ro) peddu4ue su,t\ l€ql (s)eseqd se8 ;o uorsuedxo uE o1 enp pedo1enep Á1quurnsard s€^\ esec slql uI Álrsorod eqJ .seJnsserd Bumr;uoc qtt.{ te elBJ eql uer{l Je.&ols qcnru sE^\aler qprort urert eql puz paseeJcul Áltsorod .elnsseld Buruquoc Bdl^tr T.0 lB páI€euu? ererrl sa1dtuespasserd.1oq aql ueq^\ .(9961 .uosre1e4)ernsserd uo Á1tuor1sspuedep z1nnb uI Jele.t yo Á1pqn1os eql aculs .ursrueqcaur .usruuqcetu el€ls pqos e Áq paum1dxe eq 11e.,rr,{eru lrodsuerl eseqd prng JoJ ecueplla s€ peJeplsuoc " (zsor) punÁ pu€ sqlnJ qcrq^{ ,z1lenb ur q},rrort urer8 ;o ecuepuedep arnsserd etrel pe^Josqo eqa 'qlrnor8 urert ur pa^lo^u scllaupl el"ls pqos oql socu?qua surur8 zlrcnb ur pellosslp JelB^{oql luqt elqrssod aq o1 sreadde lI 'sele8erEEe zlnnb uI luIIJ snonuuuoc B IuJoJ u€c Je}?1I\Jo luno(u€ .urelsÁs euI^TIo-Je1B^\ il€rus € JI u,t\ou>l1ou sI u agl ur u€ql tueIcIJJe eJolu uralsÁs zlrunb_ralezrr eql ur lrodsuerl sseur eseqd pInIJ oql e4eur Áeru Jel?^\ ur zlnnb yo fiqrqnlos re8rul eql qS.oqtIV .ruelsÁs euIAIIo-Jel3^\ eql ut 1rodsu€Jl sselu eseqd prng Jo eloJ luulrodurrun peJJeJuI eql qlr^\ luelsrsuoc eJB suorlu^Jasqo asaql '(7461 'orrqsn; pue €Jnul"{e5| zirunb Jo luql u3q1 JeIIBtus qcnu sI Jelv,ry\uI auI^ITogo Á1qtqn1os eql leql uÁ\ou>Isr 1r .os1y .(rup; snonutluoc E IuJoJ 01 JelB^\ .o .€c sI ouIAIIo Jo lunoluu [I€Ius B ro; etrz1 oo1 06 -euhrlo-Jele'u 1e a13ue lPrpewp eqt) serod pe1e1 -osl s? SJncco Jeql?J lnq uIIIJ snonulluoc € IuJoJ lou seop serJppunoq utert aun11o lB Jalu.4aeql l"ql (g 'Erg) uaes sr 11 'atru1 eq lsnu pmg eql uI pllos Jo (Á1prsn;pp eq1 puz) Á1ryqn1oseql .puocas .selJepunoq urer8 le uIIJ snonulluoc € tuJoJ lsnru pmg aql '1srrg 'e'rrlcaJJe aq ol lrodsuurtr sseuJ aseqd pmg B JoJ letu eq lsnru suoulpuoc o^\I 'JelB^\Jo acuosard eql ur qy{oJt urer8 pecueq -ue eql ro; e1qrsuodseJ aq ol peJeplsuoc sI Jel€^\ qtnorqt lrodsuerl sseur .(7361) punÁ puu SII1nI o1 Burproccu 'ereqm zlnnb ur es?c aql ol lsuJluoc uI sI sT-tIJ.(qsor) .IB 1e o1BJe) Áq pa,r:esqo ueeq s€q eurnllo ur .uorsn;;rp pus uollour uollzcolslp s3 qcns .scqeur1 et€ls pl1os turcueque uI Je13^\ pe^Iossp Jo lceJJe eqa .eseqd Je1B^r€ qEnorqt lrodsuerl ss€tu 01 ueql Jeq1BJ ecIllBI outallo eql uI Jel€^\ pe^Iosslp Jo slceJJe eql ol enp eq lsnlu Jol?1y\Jo ecuaserd eql ol enp qltrorE urert ;o lueu -eJu?rTue eqr '(g '3rg ees) solrupunog Bur'rotu uo ecroy Burp ? lJexe ol u/$oqs are serod peIIIJ-JelE^\ eql ecÚS .(Á1rsuepl"clleJooq1 oÁL6<) 1uurs st Á1t -sorod ueq.r 'suorlrpuoc aeJJ-JelBA\lE ueql reqtrq Á1luecrputrs sI suolllpuoc pepp"-Jele^\ Jepun eler qynorE urer8 eql tuqt 6 'Btg ruoJJ uees sr U .(LL6I,.Ie 1e uea) serod ;o ecueserd eql Áq pesodur ezrs urer8 8'p'...'I € l€ pe1€unuJel eq esl^\ -Jeqlo plnoa qcrqrrr 'qplort urert snonurluoc dleq pu€ BeJ€ ecBJJns l€lo1 Jlegl acnpeJ p.tr serod ;o 8uruesreoc .esec Áuu uI .seu€punoq urert q8norqt Á1qeunserd .selod ueeltleq Je13^\ Jo uoIsnJJIp eql ol enp Á1ururu sr serod ;o qyrrorB aql l€ql eroJereql pe1sa88ns q lI '(8 '3rg ees) qlmorE urerE .r,u1-erenbspe^Jesqo eql qll^\ luelsrsuocw sr qcq^\ I-\i OLN-INE r groB.tbf is ůe same as at water-free conditions. grain boundary mobility may also be from the observed abnormal srain {.rf Yund r E\č ua.E{fl y a soLid f,lE lter In qrl!ill m. l98ór rc annealod rru rq ucreasd I sloq'er rlrr The porosít.l :d due to a ntrapped (cr les re6ain6{ ll sugesting Igrarn grouth ibe estimated ll is signinůrn rn olivine (ohlstedt and i close to the L Piacente et ňat the grain 0-1 MPa is rhich is, in rrss transport rt due to the r suppressed cned in the rmportant in exercised in 0-l MPa to rtion can be is related to Íorn :2); (3) rrnt (- 0.5; tdary energy 1982).From ies are estimth rate at re water-ad/s)/(N/rď) 1573K and en assumed water-added sssuming that the driving force in this b ňe grain boundary energy of consumed Erains in the matrix. This gives M - 7 x * 269 AGGREGATES tm7s;76N7rď) at 1573 K (-3x10_14 N,/m') at 1473 K), 300 MPa and water- mďtions. These results are in good agreerith the grain boundary mobility estimated tbe normal grain growth. Since pores are left tbe moving boundaries in abnormal grain ffi (see Fig. 10), this agreement indicates that tFtň boundary mobility at water-added con& -rrain ÚÚfuns in the normal grain growth situation is not nů ďfected by the presence of pores. Therefore Ůc present results in water-added conditions may h applied to the Earth's interior, where the of water is presumably smaller and there-nrnt be the number of pores is much smaller than in '- present study. The observed magnitude of the rnhancement of the grain boundary mobility due n ůe presence of water is similar to the magniwde of the strain rate enhancement in diffusion uerep. both approximately one order of magnitude tKarato et ď., 1986). Note that the observed enbncement of the grain boundary mobility may crylain the enhancement of dynamic recrystallizadon due to the presence of water (Chopra and Paterson, 1981, 1984). However, the mechanisms of dynamic recrystallization in these cases have not been studied in detail. The grain boundary mobility may also be estimated from the rate of primary recrystallization (the grain boundary migration driven by ďslocation energy). Using the data of Toriumi (1982) at 0.1 MPa ("dry" conditions), the grain boundary mobility at 15'13 K is estimated to be - 0.8 x 70_1a (m7s)/(N/Í,il, which is in reasonable grain agreement with the boundary mobility estimated from the present results. This is rather surprising since Toriumi (1982) noted a thin melt film in many of the grain boundaries. The agreement, in order of magnitude, of the results of the two studies suggests that the enhancement of the grain boundary mobility by the presence of a melt phase is not very large under these experimental conditions, although significant enhancement of boundary mobility by a melt phase is often reported in other systems (see, e.g., Urai et al., 1986). When pores do not significantly inhibit grain boundary migration, grain boundary mobility may be controlled either by intrinsic mobility or by impurity drag (e.g. Yan et al., 1917). Intrinsic mobility refers to the mobility that is limited by the rearrangement of ions near a grain boundary, including detachment from one side and attachment to the other side of the grain boundary which is not affected by the presence of impurities. The intrinsic mobility is often related to the density of steps of grain boundaries where detachment and/or attachment occurs. Since the density of steps is related to the crystallographic structure on grain boundaries, the intrinsic mobility can be anisotropic and often results in facets (e.g. Yan et a|., 1977; Smith et ď., 1980). In contrast, grďn boundary mobility controlled by impurity drag is less anisotropic and grain boundaries will not show facets (e.g. Yan et a1.,1911).Olivine crystals studied here sometimes show facets (Figs. 6 and 10) and many of the dislocations (presumably screws) are perpendicular to the grain boundaries (Fig. a). These observations suggest that the grain boundary migration in olivine may be controlled by the intrinsic mobility under the experimental conditions. However, more detailed studies on the effects of impurities are needed to clarify the mechanisms of grain boundary migration. Similarly, Tullis and Yund (1982) found that impurities (hematite and calcite) in quartz aggregates have little effect on grain growth, and the quartz crystals in their experiments show facets. They attributed the observed small effects of impurities to their high solubility in water. Thus in this case again, the surface process(es), rather than a fluid phase mass transport, is likely to control the grain boundary mobility. Urai's (1983) observation of faceted grains in the presence of a fluid phase may also be interpreted in a similar way. Geological applications The present study has demonstrated the important roles of temperature, water and pores in Árepunoq urer8 ro; ecro; 8ur,rrrp eql leql P uaeq s?q 1r 'uorssncsrpe^oqBaril uI 'selrlopuad peurJoJep qlznorB urer8 ro; acuap eql eruos ur Jo {em1eu .lr:l pezu€uutns (3161) s"IoJIN .(9161 .reTrlo6 .3.e) sqtr1ouex cIJ€Iu?Jun o1 pereduoc trrB s€IooIN (ssar1s q8q aqt pue) sern1eredure1 Á1e,rr1e1er 'u'o1 pu" uon€ IuJoJ ere Jncco o1 Á1a41 8ur1ueuuu F .se1r1opued adÁ1-eurdp ur 1uaurdo1ea €p qcr.q^\ur .op IBJnlcnJlsoJcIIu eql q e1or 1uu1rodurr ue Áu1d Áuu q1r'rort urur8 eroyereq1 .sseJls 1upr.q q8r-q n/pue sern1eredrua1rrro1Á1e'rr1u1er 1e Áre'rocer uor1 -Bcolstp ueql luepodrur eJorrr sr qlnort uwrt eql .suolllpuoc eeJJ-Jále/Y\aql JoJ esoql lBql uees sI lI Iuo{ lueJeJJtp Á1atre1 oq lou IIII\ suolllpuoc pep -pp-Jet",r\ er{l roJ sqnser eql eJoJeJaql pue '(9961 .t.e) Á:e,rocer uollzcolslp ecuequa ..[B le ol€JB) o1 Á1e1u osp sI Jelzat Jo acueserd eql .JeAe^\oH .poJáplsuoc eJe suolllpuoc aeJJ-Jel?.,n aql Á1uo aJoJeJeqt pue pelpnls uaeq lou suq Ára,rocer uollec ..IB oJule) -olslp uo Jel€ ^ \ Jo lceJJa aql .(086I le ,ezleo9 pue 1pe1s1qo;) uot1ezq1e1sÁrc :vtst qf qÍl -rpuoc eerJ-Jel?A\ pu" pepp?-Jal?^\ Jepun sezs urBr8 eql ^\oqs seu{ ua{orq puB seuq pqos 'pewnss? sl 't1: fs.) - 7s9 'ne1 qlnor8 urerB e.renbs y '(luelsuoc eleJ: I 'azrs urer8 1eqrur :oSC 'rt/!SC <<t) tugpeuue eurl-8uo1 relJu 'S'C 'eumtlo ur ezrs urBr8 go ecuapuadep ernleradural pu? eIrJrJ 'tI 'tld _'..Ť -a Ú '(7961'rurntrol) .suoll Ioul,/f{ 0Tz aq o1 peunss? sr ÁBreue uotl?^Ilc" áql .Á1enr1cedser suorl -Ipuoc ee{-JeluÁ\ lepun eas urBrB eql Joc F i lt (t!Í|)ezls u;e.r60loo; 3 o o t o q, x lioĚc Ntvuo orvuvx s -er crureuÁp pIIB uo4zruJoJep Jo e1u1sÁpee1s eql o1 turpuodseJJoc SenI?A e^Bq ol peunsse eJB ezÍs urer8 pue Á1rsuepuoll"colslp I"DIuI eq1 .uorle1ncpc sTt{1uI .Á1e'tr1cedser.orn1go Jolc?J B Áq ezrs urzr8 esBeJcur ol pepeeu eurl eql pu" o^\1 Jo Jolc"J Áq Á1tsuap uollecolslp eszeJcep ol pepeeu etull oql Áq peulJep eJE SeIuIl cllsuelJeffqc aq1 .91 'ttg ur pe11o1dueoq sBI'Iql^\oJ8 ulerB ;o puu ÁJa^oc -eJ uorlBcolslp Jo seurl crlsuelcBEqc eql '3u1 -I"elrue cr1uls 3urmp ezIS uTPJt puu Á1rsuep uol1uc .suolllpuoc -olslp Jo Á1ryqz1s e^IlBIeJaql Á\oqs oJ pcr8o1oe8 eluos Japun Burpea1srureq Áeu (3161 'su1ocr51 't'a) firsuep uorlucolsrp uuql tuIIBeu -u€ cllBls lsurete elqBls eJolu sI ezls urer8 pazr1 -1u1sfucerleql Jelleq uoluruoc ? 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I974: (MPa) both for water-free conditions. At relatively high tem- initial stresses, dislocation recovery is faster leerures/low m"- o-rain growth, while at relatively low temperatures/high ml.:el stresses, grain growth is faster than dislocation Íecovery. :ron is grain boundary energy. At the early stage .rf static annealing where many dislocations still erist, grain boundary migration driven by dislocadon energy may also occur (primary recrystallizadon; Toriumi, 1982). However, primary recrystallization is a heterogeneous process and the quantitative estimation of its effects is difficult. Second, although dynamic recrystallization might reduce the grain size to something small enough to promote grain-size-sensitive creep, thereby resulting in softening (Twiss, 1976; Karato, 1989), this effect will be ephemeral since grain growth in diffusion creep is very fast. Rapid grain growth will increase the grain size again, and dislocation creep and resultant dynamic recrystallization will occur again. Thus cyclic softening-hardening might occur as a result of grain-size reduction and subsequent grain growth. At preSent clear experimentď evidence is available only for hardening due to grain growth during diffusion creep (Karato et aI.,7986; Karato, 1989). No convincing demonstration has been made for softening due to grain-size reduction during dynamic recrystallization (see, e.g., Twiss, 1976; Zeuch, 1982; Karato, 1989). A possible complex rheological behavior associated with grain-size changes during deformation will be an important subject for further study. In all of the above discussion, the role of pores or secondary phase particles and the possible effects of differences in the nature of impurities between experimental samples and natural rocks are neglected, although fluid-filled pores and impurities are common in grain boundaries of natural rocks (e.g. Waff and Holdren, 1981). The effects of pores or secondary phase particles depend on their mobility and distribution (e.g. Yan et al., 1977). Their effects in retarding or inhibiting grain growth are a maximum when they are immobile and finely dispersed. The present study has shown that the size of water-filled pores increases with grain growth, and that they do not have a significant effect on grain growth when their amount is limited (ca. > 9'7Votheoretical density). Also, the effects of impurities appear not to be very important under experimental conditions in which grain size is small and the driúng force for grain boundary migration is large. However, the effects of secondary particles or impurities can be important in some geological situations in which grain size is large and the driving force for grain r boundary migration is relatively small. Acknowledgments I thank M.S. Paterson and K. Kogure for the use of the Paterson-gas apparatus and the Elzon Particle Counter respectively. This paper was completed during my visit to University of Colorado, which was supported by CIRES and NSF. I thank H.A. Spetzler for his hospitality during my visit. Careful reading of the first draft and the detailed comments by M.S. Paterson were useful in improving the paper. M.R. Drury offered a comment on the possible role of fluid-phase mass transport. \o .986I ..s.c .JálsIT pu? .o.1r\ .suPeI^I...I'f .Ť?Jo .ssÁqdouo1caa oolrzrlplsÁ.rcor L9Í-9zI .ellloqJslq auqp1sÁrcÁ1od ur Burua1zairr crureuÁp polsrss? 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In: B.E. Hobbs Mileral and H.C. and Rock Deformation: Labora- I sIZe rd Holdren. G.R. Jr.. 1981. The nature of srain in dunite and lherzolite xenoliths: } tl'oá. vqp fu Kimberb n \l'eshingn mof eas phag lnst. B'eÓ- ř I porous cmra] stuďes il ir- I-ond., Serntion of anir- In: K. Fucbs $ructure, and r Srstem. AmL Plasticity and liler'. London. 'rcond-phase Eem, Soc.,69: r pressure apH- Min. Sci., I€Í rn quirrtz. do. V., 1975. l raporization * 1980. Grain ftor), GrainDíetals Park, in olivine at r- 30: 26-35. I bnetics of L -318. er úscosity , 3 3: 88-100. Í€crystďlized nphys., 115: illi'ation and rryhysics,96: 86. Dynamic M.F., Cannon, R.M. and Bowen, H.K., 197'1. Grain boundary migration in ceramics. In: R.M. Fulrath and J.A. Pask (Editors), Ceramic Microstructures '76. Westview, C olo. , p p . 2'76-30'1. Í}-Fe.o= I rbe ot Yan, rc|r" qm tÍÍlllsport in refractory implications upper upper J. Geophys. Res., 8ó: 367.7_3683. mantle Zeuch, D.H., 1982. Ductile faulting, dynamic recrystallization, and grain-size sensitive flow of dunite. Tectonophysics, 83: 293-308.
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