Modern and late Quaternary pollen spectra of fiord sediments, eastern Baffin Island, Arctic Canada

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1141

Modern and late Quaternary Pollen Spectra ot" Fiord Sediments, eastern Baffin Island, Arctic Canada SU,.qAN 14. SH()R.T ~'~,,J.T. ANDR.EW,q ~':~and W.N. M(:)E)E '~ i lN,~'f'AA R, ~_;tlll'+'r,~ll ~' +I/t'idi~rolJ
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Introduction T h e significance nf st.udies in Quaternary mar.ne palvnoh~t.,w, has been out.lined by Heus ser ( 1985 ). In all regions, the links between t.he t errest.rial and deep sea pollen rain must. be es t ablished. Fiord barons are important interme dmte sediment, t.raps .n t.he land --+deep sea sed iment cascade ( Andrews, 1987 ) hlllen studies in t.he east.ern (?anadian Art' tie have been largely based on Hoh.)cene peaty ,'q A F E

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1985 ). In arctic C a n a d a am.i the w e s t e r n N<)rt, h Atlant,ic, m a r i n e p a l y n o h J ~ was p . m e e r e d by M u d J e ( 1980, 1982 ) and H e u s s e r ( 198;3 ), wnt.h addJt.i(mal cont.rlbuti<)ns by M u d J e a n d Sh<~rt. (198.5), de V e r n a l ( 1 9 8 6 ) a n d tie V e r n a l et. al. ( 1987 ). In this p a p e r we ( 1 ) c o m p a r e t.he p o l l e n t u n t e n t o1' surface s e d i m e n t s in t h r e e B a f l i n Island I]t~rds w i t h t.errest.rial surface (polst.er) pt)llen spectra; and (2) present, the d o w n c t ) r e p a l y n o l

~g'y in a series td'C 14 dat,ed ptsl,on ct~res (Fig l and Table I). Results from the cures are then compared wn/h pollen spectra ~1' nearby terres

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Fiord eireulal, ion and pollen deposil, ion The charaetertsti~.' water etrculatt()n or east ern Canadtan Arctic Iiords us reviewed by Sy vntskn (1986) and S vvit.skn et al. (l,q87). In Ilu vially dominated ti(~rds, such as ()eeur in eastern Bat't] n Island, the spring/summer snowmelt and precipttat.i(m reaches the t'i()rd head and travels seaward as a luw densntv surface layer. T() bal T A P,L,E II I-,'[~rd druil~al2,e I)al,m ,'Jr'~,;le~, art~J I.,,l~Ji'll~r n'z,ed, and ~.,I Irnail~(:l run~ll (all~r ,~V~ tl,,kt (~1 al, I~1~,.I. Table I~ it I-'l~r'~]

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~tl' particles ()CclJrS at, t.he nnt.erl'aue between the surface plume and the underlying marine water. Deposit.ion ol'entranned fine grained sediment, tnchJdtng p()llen grains, ,,.'curs either t.hruugh iI~wculatt~m (~r the pr, Muct,)n (~1' Fecal pellets l'r()m var,,JS marine organisms =n the water c~)lumn. Table II lists pertinent data t',~r the t]()r(ls we discuss. F'()llen can ent.er a t~()rd system ~n several ways, nneluding tluvml, e~)lmn and rnarnne transport, and can represent several st,.trees. Most. pollen pr()bably ~rngnnat.es, as ~n lakes, t'r,~m surfat't~ run(fit' t r()m the drainage hasnn. This represents a ('(mtempt~rant,(~us ('rmzpttrh'nl, derived mainly I'r~)m the local vegetat,.m and a r,,tv,rk~'d c,mpmwnt, derived I'r()m pollen bear nng sediment, and r~,.'k Sngntl'icant quantil nes of rew~lrked I:.)llen, hi' undetected, may cause spu rn(tus tnt.erpretattons Therefore, rec,~gnnt.ton ur the rew(~rked p~)llen I'racti(m ns =mperative. In east.ern Bal'l'nn Island, tw() sources (~1' re w()rked p()llen exnst: ( 1 ) unc~ms(~lndated, Plens t.(,.'ene sednment, and (2) Mes,)z()nc and "Per

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t.iarv sedirnent and sedirnent.arv rock. The f~)rrner are extensive ab~ve and below sea level, but Mesozoic and Tertiary rocks occur only be h)w sea level, with the exception of small out crops ~m eastern Cumberland Peninsula (Clarke and Lipton, 1971). If the reworked c~rnponent ~)l'a p~llen sample includes pre Quaternary t ~ e s , the analyst, is aware of the presence of reworked pollen and tnt.erprets the sample accordingly. But. ~n the absence o1' pre ¢~uaternary types, tt. is difficult to know whether reworked pollen is present., though the degree ~,f det.eri~)rat.,.m ,Jl' pollen gratns, ~r the number ,If' tndet.erminable grains, may be an indication ~)1' rew(~rking (Birks, 1970). L~mg distance aeolian transport, of pollen is an important component of pollen deposition in the Arctic (Nwh~ds et al., 1978; Fredskdd, 1985 ). In our study area, snow is an ~mport.ant trap ~l' h.mg distance pollen (Licht.J Federov ich, 1974, 1975; Bourge~fis et al., 1985; Short. and H~ddswort.h, 1985 ), both on land and upon the sea ice. Because h.)cal pollen product,on is low, exot.tc p~)llen can const.~tut.e a significant pro p~rt.i~m of the sum in modern spectra. In t,er restreal surface samples from Bal'fin Island, the percentage ~1' exutw pollen increases with in creasing alt.ttude Thts ts caused by declining h~cal pollen pn~duction as veget.ati~m c~ver be v~,nes sparser with altitude ( Mode, 1980 ). I:'()l len may als~ be carried ~nt.o fiords by rnartne water ent.ering the fi~rds from the shell'. Thus, the [.)~dlen spectrum in a fiord will be the prod uct. ~)1'the f~)ur mechanisms sh~)wn ~n Fig. 2. The palvnoh~gy of fi~rd sediments will differ from that ~)1'lake sediments because ~)1'the additional ~nput ~)t'p~)llen from the ~)cean. The actual con tr~butmn will depend on current, directions. E n v i r o n m e n t , , c l i m a t e and v e g e t a t i o n The st.udv area has an arctic climate with a mean annual ternperat.ure of - 11" to - 13"C. Average July t.emperature varies between 5" and 8 ' C , although exceptional daily rnax=ma ~)l' 15"(; occur. Snow accumulation ranges t'rorn a

S K SHI)fC'T',,J 'T' ANDRI?,WS AND W N M()DE

high (if0.5 m near Sunneshine Fiord t.()0. I m in the northwest portion ol'Bafl'in Island. Rainl'all is restricted t.o a few weeks each year and varies between ().1)5 and (). 1() rn. The coastal h,relands (.)f eastern Baffin Is land are part. ()1' Porsild's (1957) high arctic (polar desert, or I'ellfield ) bioclimatic zone ( Fig. 1 ), an area ~1' very. incomplete vegetati~)n cover and few shrubby plants. The ext.ension of this zone southward ah)ng easternm~)st. Bal'fin Is land reflects t.he chilling effect, of the c~)ast.al setting, a fact.or that Polunin (1960) did not. utdlze in his delineathm uf vegetation z~)nes. Inland from t.hts zone, and covering most of Bal'fin Island, is the middle arctic bl~wlimat.ic z~)ne (st,ony sedge-rnoss-lichen tundra). A small p()rtion of s~mt.hern Bafl]n Island, in which dwarf birch spec.ies and other shrubs are common, has a low arctw bi~wlirnate Rannie (1986) showed a strong relationship between ,July temperature and number of vas cular plants in Arctic Canada. In areas c~)vered by this st.udv the t,ot,al vascular Ilora ranges be tween 120 and 140 species (compared t.~)Frobi sher Bay region wit.h 210 species}. However, there is a strong altitudinal gradient (Schwar zenbach, 1975 ) and areas ab~ve 60() m have very. little plant cover. Data collection and preparal.ion The piston c, lres, grab samples, surface p~l st.ers, and a terrestrial sect i~m of peat.y sedi ment.s (Table I, Fig. 1) were collected tn 1982 and 1983 as part. (,1' the Sedi rnent.oh,~t.,.,y of Arctic Fjords Experiment (S.A.F.E.) cruises by the Canadian research vessel CSS HI.IDSON (By vit.ski and Blakeney, 1983; Syv=tski, 1984; By vtt.ski and Schal'er, 1985; Syvit.skl and Praeg, 1987 ). Radt.carb~m chr.vmlngy Twelve radiocarbon dates ( T A M S ) frorn the five cores have been det.errn]ned; three are on shell and nine are ,.,n t.he acid insoluble, fine

I-'l IL, L,EN ~F'Ei "T'RA qIF' F'I()FIE) SEDI M EN'I~

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grained organic fraction ( A I O M ) o1' Iiord sedi ment.. The problem ol' obtaining reliable C 14 dates on the A IOM I'raction ol" man ne sediment. has been discussed by Fillon et. al. ( 1981 ), Mu die and (luilbault (1982) and Andrews et, al. (1985). When dates on the AlUM fraction are compared with dates tin marine shells, they are invariably too old; we have used an empirical equat.i,n (Andrews et. al., 1985) to correct. AlUM dates (Table IV ). There ns adequate radiocarbon chrono[ogv (Table I V ) o n HUB2 CL5 (,lennnngs, 1986), HUB8 MC4.1 (Andrews, unpubl.) and HUB2 SLI5 (Andrews et. al., 1985). These cores span t.he past 600(), 11,600 and 11,000 years, respec tively. Estimated basal dates fur IT3.1 (two dates ) and CA 4.1 (one date ) are 9500 and 4()()() B.P. Three radiocarbon dates (Table IV ) provide age control for HUB2 CL5. Sedimentation rat.es vary. dramatically between the upper t.w~ me t.ers and lower seven meters of Lhe core. The sediment,ulogy and mineralogy of the core are discussed in detail by Jennings (1986). The base of H LI88 MC4.1 has an uncorrected "~(?.age of 16,700 + and a correct.ed age of 11,50() B.P. At. the depth dated only one pre Quaternary pollen grain was recorded whereas 113 TABLE III Mi~diari pl)llerl I;le'reenluge','~ for l h e ('lllTIITlilrl i a x u I'rqlrri |,llt ~ m i d d l e l i n d n(icI,he'rll p(ir'i, li.lnl,i i1[' B a l l in h~hincl [ i a l a Ii~l,~flt lin l.liJl'l'lJt'# r.lllll,lt,ur~ ( i r . m Miic]#, I,gHI)', ,t'21hort, #t ~l,, 1914b) Ni.il,(-, I,l'ial l],'ilTihrl(tl~e" lirlci C l a r k ~ll)rcJf.i lie, m~rlh ill Clyde, ( Pip ;t )

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'AI(.)M = ac.':l m!,,duhh~ .q;i.m.' m a s e r Iraeln.n "'("orTevl,ed date!,~ Irqm'i AricLrews~ el al ( 1!-18h ) All dal.t-'~.iprqwif]ef] by I['ie Lrnlven;.,il yol AI rzona arvelerl.dor IJ.iciJil.v lJ.lee AricLrew!.i PI a l , (19H~i) l'N! dl~,eu.,.lhiim i exv~'pt Ior the ('llnl hrii'lge (CA,.I, I ) , ] a l e

g'rmns were counted in the sum; hence contam inat.i,n by "old" organics, although possible, m not as clear as in HL)77 159 (Andrews et al., 1985; Mudie and Short, 1985) or in HLI82 SI, I5 (this paper). Pollen samples were counted at every. 0.4 m intervals, or about ~me sample/6()0 yea rs. The rariiocarb, n chron~do~w, of HLI82 SI, I5 is based on three dates on small, articulat.ed bl valves (Andrews et. al., 1985). The age of the base of the core is est.imated at. ca. 11,()()() B.P. by ext.rapolati,n of the sedimenLahon rate (().3157 cm y r - ' ) between levels dat.ed at 941() +_400 B.P. (A.A 412) and 10,49() _ 450 B.P. (AA 264 ).

P, llen ,'.~tract,.m and identl[watmn Preparation tit' fiord sediment was adapted I'r.m techniques o1' MucLie ( 1981 ) and Cwynar et al. (1979), which provide a method for c.n ten|rating pollen and spores in fine grained, mineral rich sediment. This method uses stan dard procedures such as acetolvsis and hydro

IN(;

Ilul)ric actd (Faegrt and Iversen, 1975) and in cludes a s~)diurn pyrophc~sphate wash fi)r disaggregating and removing ('lays and grawt,y filtrati~m t hr,)ugh a 1() micrometer mesh screen. "Absolute" [..~llen c~,Jnt~ng methods were em ph)yed (of ,Iorgensen, 19B7). A known w)lume and weight of sediment was prepared and prior tl~ chemical c~mcentratt~m a tablet ct|ntatntng a known number of ex,,t, tc marker grains (Euca lyptus ) was added ( St llckmarr, 1972 ). P~)llen tder~t~t]cati~)ns were made ustng the I NSTAAR Palvn~h~is,w Lat..)rat~)ry rererence c()llect,m with help trom a number {~t'keys and rh~ras (Kapp, 1969, McAndrews et al., 197:_1; Faegr~ and Iversen, 1975; Moriya, 19714; Moore and Wehb, 197S,; Mudie, 1980). F'lant Itst s and tll)ras f~,Jnd tn Polun~n ( 1959 ), Porsild ( 1957 ), Hult,dn (1968) and l:'i~rstld and (."ody (1980) were used t~) determine clistributi~)ns ~1' plants. ,41nus (ah:ler), Bt'tula ( b=reh ) (see rllSClJSSll.|rl later), Pwea (Sl:)nJce) and Pmus (pine) are all ex~)tte t.~l the st.udv area; m)rt.hern Itmit.s ~)t't.hese genera are shown in Fig. I BetulananaandB glanduh~sa (shrub btrch species) are the only members ~t' t.h=s Ism.|up currently gr~)wing any where on Bafrin Island (Andrews et. al., 1980; Elliot F'isk et. al., 1982; ,lacohs et al., 1985). Other p~llen t.ype~ ex~)t.ic to the study area in elude: I.llmus (elm), Artcm~sm [sage; presently grl~ws =n s~,Jt.hern Baffin Island (Porsih:l and C~)dy, 1980' Map 1(15'7 ) ], Am.br~sia ( ragweed ), and Chem)p~di~neae (goosel'i,)t family; proba bly ~ncludes members of the amarant.h Isq'OUl:)) The distribution ~)1' Lvct~podtum anrmtmum. (bristly cluh moss) ~s of tnt.erest, t.(.) this study. Although P(~rs~ld and C.~dy (198(), Map 38) I~m~t. this t.ax()n t.o southern Bal'fin Island an(:] Hult(-;n's (1962) line ext.encls over northern Cumberland Pentnsula, the vahJes observed in the McBeth Fiord marine core MC4.1, as well as the presence o1' t.hts sp()re tn surface samples rr~)m as far north as Clyde River ( Mode, 198()), indicate t.h=s speetes probably grows s~)me dts tance t.~) t.he m~rth of it.s published limit.. Pollen sums for marine sediment, vary from less t.han 1(1 to greater than 1(1()grains per slide;

,'.~ I~ SI-I()R'I, I'T ANDREWS AND W N M(iDF,

the raw pollen counts are tabulated in Appen dices I, II and III. The sum eJcluded pre Qua ternary p~Jllen and the Dim)llagellate group (labelled [hnollagellate/HystriehlDsphere c)n p~llen diagrams, see Figs. 4, 6, ancl 7 ). The pre quat,ernary g-roup 18 dominat,ed by t,rdete spores ~pl' simple morph~loisw., assignable t~ a br~md time span Spores rererable t(~ Cwatrw,sisp, riles, posstbly of Late ,lurassw t~J Early Creta ce~us age, are als4p ('~tmmon. Prel~mtnary anal yses ~)f the Dinq~llagellates in six I'oss~l m a n n e sa topics suggests the =mporta nce or warrn t~ c~, ~1 temperate Atlantic tl~ras ( P Mudie, pers. c~m mun.). Further analyses are required on both groups. P~dlen gTains that c~)uld n~t he ,lent( fled (Indeterrmnable) were regularly quanti fled ~)nly for the Sunneshine Fi~)rd (.'~re, the last t~ b(-,analyzed (cf. Birks, 197(I)

Modern pollen spectra in fiord sedimenl,s Three aspects of the m~)dern pollen spectra are or interesl,: (1) the average pollen assem blages ~)1'the three fi()rds; (2) the c(~mpar~son of terrestrial versus riord surface spectra; and (3) trends ~n p~)llen percentages along the fi~rd axes (see Ftg. 5B).

F'tdb,n asst,mhlag~'s The m~)dern p~)llen rain was determined us Ing 3() Is'Tab samples fr~m Cambridge, McBet.h and It trbilung Fi~)rds. Median percentages ( Fig. 3) and hinges (Table V) (the hinges include ,5t)% ~)1'the sample dmt rd:)utl~m ) for rnaj~)r taxa in the fiord sediment samples were determined in order to assess t.he relati~)nship between veg etation and p~)llen In Cambridge Fi~)rd, the n~)rthernmost fiord, surl'ace sechrnents cont,atn a Filicales/C, ypera ceae/Gramlneae (fern/sedge/grass) assem blage. Samples rrom McBeth am'l It,irbilung Fiords contain slgntl~cantly higher percent,ages or Bet,da (medians= 14'5, aml 17% respec t ively, versus 3.5% for C,ambrtdge Ftord ). Sam pies from McBeth Fiord c~)ntain a Betula/Gra

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mlneae/Cvperaceae/Fdicales/Ericales (heath) assemblage, and It.lrbilung Fiord samples pos sess a Betula/Gramlneae/Cyperaceae/Fili cabs assemblage. The abundance ()1' Bctula cunt.rast.s with all four of Mudie's ( 1982 ) core t.op samples from the shell' and fiords of thin region of t.he eastern Baffin Island coast, all of which cunt.ained less than 5% Betula. High Fil icales percent.ages are dil'ficult to explain be cause ferns are rare in t.he present, veget.atiorl of Baffin Island. Mudie (L982) noted maximum Filicales percent.ages (5-8%) in core tops from the BaMn shell' and attributed them to locally common ferns ~wowmg in coastal cliffscrees and t() rapid depusit,iun (close t.o shore) of the spores because of their g'reat, weight. Another factor contribut.ing t.o high Filicales percentages may be the relatively ~,weat.er resistance ()1' Fd,cales spores t() bmh)gical and chemical degradat, lon (Havlnga, 1971), alTorchng them a better chance of surviving fluvial transport intact

T h i s mechanism is supported by under repre sent.at,.)n ul'Sali~ (wdh)w) in fiord surface muds because Sah.~ ts ()ne ()t' t.he least, resistant p()llen (Havinga, 1971 ). The surface sample from HU82 SU5 (Sun neshine Fiord ) comes from i -2 cm in the pint.on core (Appendix II ); hence, it, may re)t. be en t.irely represent.atwe ()1' present, p()llen deposi tion. It. cont.ains a Cyperaceae/,.~ahx/(]rami neae/Ericales assemblage. Betula percentage is 9"!;,, well below t.he values in M c B e t h and It lr bihJng Fiord samples, desplt.e the fact thai. dwarf' birch occurs only 55 km t.o the m)rt.hwest (An drews et. al., 198()). Mudie ( 1982 ) reported t.w() cure t.op samples from the shell' near Sunr~e shine Fiord, both ()1' which o m t a i n e d less t.han 5% Betula. Of special Int.erest., because they are an index of old carbon omt.amlnation of radJ()carbon samples (Mudie and (luilbault, 1982), are the h)u, numbers <)1' pre Quaternary pollen in all

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trial surface samples (pqflst.ers) cuntmn a Sa hx/(_;ramineae/Er,cales assemblage that corn pares chJselv wtt.h data I'rom p~)lst.ers in the Clyde area (Fig. 3 ) ( T a b l e III)(M~Me, 1980; Short et al., 198b ) The p~)lst.er assemblages re rlect local and regional vegetat,,.m more accu rat.ely than du the fiord samples. The latter consistently reo,rd much higher percent.ages of Bet,da and Yilicales, t.axa that are absent and rare, respectively, tn t.he plant communities ()n land. Because p<)lst.ers rellect eolian p<)llen in ilux, these differences must be attributable t.o tluvial a n d / o r marine processes

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One o1' t.he most. interest.ing t.axa tn ()ur st.udy is Betula. AIt.hough Betula reaches only () t~) 2% in polst,ers from the mlddie Arc.tic (Table Ill ), it, const.lt.ut,es 3.5%, 14% and 17% on average =n surface muds of the t,hree t]ords (Table V). A plot ()1'Betula percentages versus distance from tiord heads shows high values at t.he fiord heads that decrease toward mid fiord and t.hen in crease somewhat, ~n out,er I'iurd sit.es ( Fig. 5A ). This may indicat.e different, source regions for the Betulo pollen (see Pig. 2). One source re gion, located close t,o the fiord head, could rep resent, eit.her local p~fllen production or reuJnrh mg or older sediment,. The other source region, Iocat.ed near fiord mouths, could represent, local pollen production, reworking, or inllowing water from Baffin Bay carrying pollen from a West. G reenla nd/eolian sou roe. Although Betula is not known t.o occu r within 50 k m of any of the fiords ( Andrews et, aJ., 1981)) ( Fig. l ), ~t Is possible t,hat local p()pulat.ions ex ist, but. have not been observed due t.o the rarit,v of t,horough bot,amcal surveys m t.hm remot.e re gion. No one has systemat.lcally collected vas cular plants in the valleys leading into IUrbi lung and McBet.h Piords, although Andrews saw tm evidence for hitch dunng a single extended foot, traverse in t.he I'~)rmer valley in 1983. Low percentages (0-2%) ()1'Betula in polst,ers from the Clyde foreland, the head o1' Clyde Inlet. and

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surface samples This cunt, rasts wtt h some ()1' the early Holocene rec~)rds (discussed below) and suggests t,hat reworking ~s not. a problem in recent fi~)rd sediments. By cont.rast., Mudie's (1980) surface muds from the BaMn shell'and LJpper cont.inental slope c~mt.ained significant quant.tt.ies of pre Quaternary pollen (9-66%). However, t.hls may be because the shell' has been in a non depositional mode tbr several t.hou sands of years. In addit.ion, pist.on cores rarely sample t.he current sediment, surface because of recovery problems o1' the upper "soupy" layer.

Terrestrial samples Short et al ( 1985, Table 22. I ) presented me dmn pollen percent,ages from surface polsters for eight regions ~1' the eastern Canadian Arc tit'. Table Ill list,s median pollen percentages for the rour northernmost regions which pertain to our study. We also compare polst,er dat,a from Cambridge and McBet.h Fiurds with pollen data I'r~)m the surface fiord muds (Fig. 3). Terres

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BAFFIN FIORD SURFACE SAMPLES PERCENTAGE DIAGRAM w

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and I'OClJS sediment. This stream convergence does not, often occur elsewhere in the fiords. A substant,ial c~,nponent, ~d' rew~rked pollen might also be expected in outer fiord samples because ~1' the adjacent coastal fi)relands where unctmsolidated Plelst,~wene and pre Plelst,~) cene sediments are most extensive and are being rew~rked by coastal eros,re. Some ~1' these de posits include cons=derable Bct,la pqdlen (Mode, 198(), 1985). A high prup~wtt~m of de graded and indet,erminable palym~m~)rphs in a pollen sathple wc)uld indicate the presence ~t' reworked pollen, but except in SUS, these pa rameters were not measured in t.hls study. Inrh~wtng, subsurface wat.er f n , n Bal'fin Bay could be an additu.mal s~)urce of Bclu/o pollen in fi~)rd sediment, a source implied hv Heusser's (1983) classificati~m of the pollen assemblage in Baffin Bay core tops as a Betula and AInus assemblage (see also: de Vernal, 1986). H~)w ever, il' this were the only source . f Betu/a pol len, Alnus percentages would he expected t.~ be h~gher than they are ~n the fiord surface sedi ment samples.

Modern pollen concentralmns

!

I~)=,domle (kin) Ftg hA Var ml i~=n~, m lhe p~-,rrenl.al.:es i~f H,'h.~/o uh ml.,, ("am hr ~dl_.',~,M~' R~I h and II ~rt-Hlung f , m.:b~ a~., mPasurPd I'n m= I he Il~aiJ ( = I} kin) ,dl-,arh ll,~rIJ F'~I:, :~I~ Fhdlon acciJmLIlat.m vahJPs (l_.,qatli!,i/cm"/vr) pl¢~l tPd Ir~uTi I'i~rr] head I,, li~mJ m,~ulh I'l)r (~amhr ndl.~e. M c B e l h ;Jlld 11 nri~lhJrll.~, I'tl~rlll,

the q t w t u Ii~reland tndicat.e that. shruh birch ~s absent from t,hat region (Mode, 19N0). How ever, our data may indicate that stands of dwarf birch exist north of the mapped limit. An alternatwe hypothesis is that the birch p~fllen is reworked from middle Holocene or last, interglacml seditnents which conta=n high percent,ages ~)1' birch (of. Terasmae et al., 1966; Mode, 1985). Betula deposit,ed near the fiord heads could =nclude a significant reworked c~)mponent because large streams converge here

P~llen concentrati~ms (grains/gram cLrv weight =g/gdw) vary. rn)m 4`) g/gdw t.q~701 g/ gdw (excluding pre Quaternary and Dmotla gellate palynomorphs). P~)llen concent.rati.n was converted t,~ pollen accumulation (grains/ cm': per year) by using data ~n se&ment den sity and the rate.l'sediment accumulaticm (e.g., Jennings, 1986; Andrews and ,.lenn~ngs, 1987 ) Based on a series of Lehigh cores (in: Syvitski, 1984 ), the denmt, y of surface sediments was de t,ermined on board CSS Hudstm. Redimenta t,ion rat,es were est, imat,ed based on " ' ? b and un extrapolatitm from ~4C dated o~res. Sedlmen ration rates dechne exponentially t'nml , ().(11 m/yr, in basms close t.~)the fiord heads, h)(H)O()2 m/yr in the outer fiord basins, where cores CL5, MC4.1 and S1,I5 were taken. Cores IT3.1 and C,a4.1 were obt.alned in middle fiord locations (Ftg. I ). All three fiords show the same trend

I'I )1 1 ,[?,N SF'l~ll "T'FIA I IF' F'll IR[I ,_4El H M I~',N"[',~;

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1)l'p~dlen inllux ( Fig. 5B ). Within '__8 km (fithe fiord heads, p()llen inllux Is relat.~velv h~gh, be tween ca 911 and 1()(';1)grmns/cm?/yr. H()wever, I:.)llen inl'hJx declines rapidly between 11)and 21) km I'r()m the fiord head and remains at. a rel at.tvelv c~,nsl.ant value of ," 3() t,~ains/cm':/yr t~warcl the fiord m()uths. The decrease in ~n fhJx ~s rapid and ~)cclJrs (wer ca. ,5 kin. F o s s i l p o l l e n spect, ra f r o m f i o r d c o r e s

In this section we Iirst. descrtbe the pollen stratigraphy of the c()res (from n()rth t~) south ) and then examine the significance of these data. Percentage pollen diagrams for McBeth and Sunneshine F,)rds (Figs. ,5 and 7), the best dated and q)ldest data sets, are inchJded. The raw r.,,llen count data for all sites are listed in Appendix II.

H1.I83 CA4 / (Cambridge Fwrd) Five samples

(Appendix

II)

have been

t'(~tJnt,ed at a sampltng interval ranging I'r()m

perhaps 4()() t() 1()()() years. The pollen spectra are d(~minat.ed by Gramlneae (11)-20%), Cy peraceae (1(I-20%), and Fdwales (20-411%), except t.he 147-152 cm level (ca. 1400 B.P.?) where a large Betula percentage q~l'23% is reg tst.ered. Otherwme Betula percentages are h)w, as they are in t.he surface muds from t.hm fiord. N() exotic grains were rec~)vered below the 147152 cm level. Pre Quat.ernary pollen were rarely rec()vered in t.hts c()re but percentages of [)im~ flagellates (outside the sum) increase wlt.h depth t()vahJes , 10(1%. H1_I82 t'L5 tClark Ftord) Etght levels have been processed fi)r pollen (Appendix II). The pollen spectra are domi nated by Filicales, Gramineae, Cvperaceae and Betula This assemblage is similar to that. of the surface sample from Cambridge Fiord, 1(111km tt, the n~)rth, but. dtl'fers from the three fiords

discussed belt)w, which lie t.q, t.he s()ut.h ()1'Clyde River (Fig 11. Twq~ broad p~)llen zones can be delimited. Be cause of high dep()stt.,.,n rates (Table IV ), the lowermost z(me may only represent a few hundred years ('57110-Blll() B P.'~ ). It ~s char act.enzed by high Betulu percenlage (ca. 2(1% ), 10-21)% pre Quaternary pollen, large F~licales vahJes (311'I'~, } and minimum values uf Grami neae and Cyperaceae. Local pt,llen types such as Gram~neae, C,y peraceae and Filwales beck)me ml)re important in the upper zone (perhaps , 4()()()B.P.);sig nificant.lv, Bctu/a dr()ps t.i) ca. 1()%. Large num bers ()1' Dinoflagellat.es occur heg=nmng at the 1()7-114 cm level, with a peak ¢)t' 168% (out.side the sum) rec(~rded between 151)-1'5'5 cm.

H1,I82 M('4. I (McBeth Fmrd) P~)llen samples (Appendix I I ) w e r e c()unted at. every 0.4 m intervals, ~lr about ()ne sample/ 600 years. The percentage pollen dmffram ( Fig. 6) can be divided into three pollen z~)nes. Zurw I (500- 782 cm) (8000- I 1,500 B. P ): this section of the c()re is dominated by Bt, tula pol len ( . 45'I;, ). Must ot.her p()llen types register mtntmum vahJes during this interval and other exot.w p(~llen types, Alnus, Picea and Pin us, are ran' Zone II (200-500 cm) ( 40007-,~000 B P ): the middle zq)ne cuntatns maximum Cvperaceae values (31)-40'.';,). Filwales percentages are varmble but average around 15'!;, and Grami neae percentages are somewhat higher than ~n Z()ne I Betula percent.ages decline, ranging generally fr~)m 5 to 21)% (36% at 221 cm ). Pi nus percentages reach maximum values ~)1'51()% and Pwea pollen is conststently present. Pre Quaternary pollen reach maximum val ues within Zone II with 8/51 grains at 341)-342 cm. A peak Din~)llagellate percentage (out.side the sum ) of 196% occurs at. 361)-362 cm. Zone III (0-200 cm.) (. 4000 B P ): the up permost sediment c(mt.mns maximum (~ram~ neae percentages ( 15-2()% ) and minimum Bt,

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Fig 6. Percentage pollen diagram. MC4 1 McBeth Fiord Baffin Island Pollen sum excludes pre-Quaterna~- and Dm.-.flageiiate palyn..morphs Vert-_,cai hnes represent _<1%. Reduced dat~ set.

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PERCENTAGE DtAGRAM

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SUNNESHINE FIORD- 5 PERCENTAGE DIAGRAM

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faw~rably w~th that det.ermmed I'~)r the surface muds.

The p()llen c,)nt.ent ot'a " p e a t " ( Appendix III ) collected by Andrews in 198:3 I'r~)m t.he large valley mirth of t.he s~t.e ~)1' H1.188 MC,4.1 was analyzed t~)compare to the p=sttm c()re dat.a. The base ~lt' the ,)rganic rich sect i()n has a ~q.2, age of 12:31.) + 11() B.P. ((3X 1(r374 ), corresponding tn part with the upper sect ion ~1' Zone I I I in H 1.183 MC4.1. T h e alterat.i~)n between SaliJ and Gra mineae d o m i n a t e d intervals may reflect h)cal changes =n moisture availabd=ty. T h e max= mum in Er~cales (ca. (';()()-11)( )() B . P ) c~rre spends wit.h the period ~t' l(~west p~)llen concen t rat t~)ns und may represent, a hwal e x p a n s , m ~)f (lry heath tundra. T h e t errestrtal sediment & ffers I'r~,n the lizard sediment because it. c~)ntains much lower per centages qll' B~,tulo and Filicales and much htgher percentages at ,. ah ~, (., ram~neae and C.y peraceae, all tmp()rtant t.axa Jn the h)cal vege tart(in. T h t s parallels the differences in t.he sur face fi~rd and t errestrml sediments discussed prev~)uslv.

HI.IS:I I'F,'t I (Ihrhdtmg Ftord)(. 9,50n B.P ) The p~dlen spectra (Appendix II) are d~.)rn~ hated by Br,tula (45-6t)+ %), with less t,han 1()% each Gramtneae, Ertcales, Filicales and L.w'op,dium annotirium Percentages i~t' [)im~ flagellates are h)w. Alnus p~)llen is c(msist.ent.lv represent ecl but [','~'a ~s rare. Alt h~ugh Betula ~s an ~mportant c~)mp~)nent ~1' surface muds tn th~s Iq~)rd (Fig. 4), the t'oss~l spectra present a st rqmg c~mtrast t(i the ~)ther fossil c~)res. It is [.)sstble that the ptst~m core bypassed the up per sedtments ~t' they were especially "soft". T(.) test t h~s p~)ssibilily, a sample was submit.ted for datJng from 1()() cm dept.h ~n this core (Table IV). T h i s date, plus an analys~s of the pale~) magnetic reci~rd I'r~)m that core (Andrews, un publ.), support.s t hts ~nterpret.ati~)n and Jnd~ cares that. the top of the piston core dates fr(~m ca h()()()+_ 11)1)1)B P

T h e p~)llen diagram (Fig 7) is divtded int,i two zones separated by the 'q? date [)1'9411) B.P.; h~)wever, the precise b(.~undary is nq~l km)wn be cause ~,t'a gap in sampling betweerl 227 and 3(";() cm,

T h e sampling tnterval in the h~wer z()ne ranges between 811 and 1!41)years. Pro Quater narv palym)morphs d~)rntnale I he hlwer zone w~t.h percentages (~ut.side the sum ) ranging be tween 82 and 16,-I%. Other ~mp~)rtant taxa in the h)wer zone are Indet.ermlnable palvml m~rphs (~)utside the sum: 6~;-1,4'7%; n(ll ilhJs trat.ed ) and B,,hlla ( 15-39%, except for one level w d h 2%). Ex~)tic [','~'o and Plnus c~mstdute 25% ~Jl't.he ave rage polle n su m, m~ire t ha n twtce their average percentage (12%) ~n the upper zlIne,

T h e sediment at 10re rate in the upper pqdlen zone (().()3()7 cm yr - ~) is an i~rder q~t' magnlt.ude slower t.han in the I()wer zone. T h e sampling in t erval in the upper z , n e ranges between 590 and 1271) years. (?yperaceae dumirmtes lhis z . n e with 25-4W!7,, tidlowed by E)im~llagellates (out. sH:le t.he sum: 3-81;% ). Indeterminable palym~ m~)rphs and B~,tulo are much reduced in t.he up per c.mparecl t~) the h)wer z~me, and pre Quat.ernarv p a l y n o m u r p h s are virt.ually absent. T h e Bf'tula rec~rd in the upper z~me lacks evidence I't~r a B~'tula tnaxirrlurn at. 51)I)I) B.P. which has been m)t,ed in the Iglut.allk Lake (near Pangnirt,ung) p~dlen dtagram (Daws, 19811; Sh(~rt. et. al., 1985 ), between 451)1)and 251)() B.P. in the Hikwa Lake (near Fr~)btsher Bay) pldlen cbagrarn (Mode and ,lac~bs, 1985), and be tween ca. 4Bill)and ~7()1) B.P. ~n the p~st.on c(~re H1.I'7'7 159, Frobisher Bay (Mudie and Sh~)rl., 1985, fig. 11).9)

Discussion and conclusions B a M n Island fiords funct.i()n as sedtment.arv basins, trapping Iluvially transported sedlmenl. and st.arving t.he t'ontinent.al shell' ,ff the hulk of this se&ment.. T h i s is rellected in the de

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creas~ ng sed] men t.at.~)n rate ( Andrews, nn press ) and a 1(1() t.o 1()()() fold decrease in pollen ~nl'lux thai ~ccur between t.he fi(.)rd head and mouth. Th~s decline tn p~)llen influx reflects t.he domi nant role played by fhJvial transport ~)1'p~llen t,~ the marine environment and nndicat.es a mi n~)r cunt, r=but.~(.m I'r~)m eolian t.ransp~rt. P~)llen spectra from surface fiord muds are s(~mewhat represent.at.we of h)cal or reg,)nal veget.at.m. However, Betula and Filicales are ~wer represent.ed and Salix, Cyperaceae and Rrncales are under represented. The cause ~d' this anumaly ts unknown hut. is prubably inher ent in t.he tluwal pr(~cesses that furnish t.he bulk ~)t' p~llen inl]ux t~ the fi(.)rds. Two possible causes are: ( 1 ) fluvml rew(.)rking c~f older sedi ment that contains abundant. Betulo and Fill tales; and (2) great.er resistance of these taxa h) c~rr(~st(.)n and dek~adat.i~m during tluvial t ransp~)rt. Lack (ff pre Quat.ernary p(.)llen types in I'i~rd surface muds indicat.es t.hat rew~rknng by waves and currents ts insignificant un t.he fiords, es pecially by cumparmon t.(.)the degree (.)f rework nng uccurring un the shell' where pre Quater nary palyn(.)m~rphs are c(.~mm~m ( Mudie, 1980). H~wever, rewurknng event.s in t.he past. are tn dicat.ed by d~)wncore increases of these paly n(~m(~rphs in the fi(.)rds. In t.he c~res I'r~)m s~uthern Bat'fin Island (HI.182 ,.ql.15and HLI77 159), hugh pre Quaternary pollen percentages I'ri~m ca. 1').,()()()t.~) 7()()() B.P. rerlect, rew(.)rk~ng durnng glacial advance and ret.reat of the Bal' finland glacial st.ade (Andrews and Miller, 19/44 ) Deglaciat.t(.)n of midst, fiords occurred be tween 6()()() and 9()()() B.P. and caused an ~nt.er val uf rapnd sediment.atiun (ef. Andrews et al., 1985; Andrews, 198'7 ). The numbers ~1' pre Quat,ernarv palynl) m~)rphs ~n our cores, and in HUT7 159 (MudJe and Shurt, 1985), are associated in t.ime w~th the final rapid deglacmt.non ~t' Arctic Canada (11),1.)1)1)-61)1)1) B.P. ). The basal ('(.)re sediments nn H1.177 I,:)9, H1.182 SLI5, HLI83 MC4.1 and H1.183 CL5 all contain large numbers of pre quaternary pollen, although t.he estJmat.ed uc

currence ¢)J' t,his phen(.)men(m, on ()iJr t,tme scales, is time t,ransgressive. The fact, t.hat the B~,tula curve f()r SLI,r) mimws the pre qual.er nary curve furl.her suggest.s that "Quat,ernarv" pollen t.ypes probably alsu represent, sume re worked units. These dat.a ~t' themselves suggest very. strongly t.hat t.here was a sn~mtl'icant ex change (ff wat.er bet.ween the fi(~rds and the (~cean durnng deglactat.i()n There are n~ s~urces I'~r pre Quat.ernarv p~llen in the hnnt.erlands ~~1' the fiords and they must., t.herel'~re, represent er¢~sn(.)n (.ff bedrock either on the Baffin Island shelf(~r I'rom rocks in the High Cana&an Arctic Islands. Pollen zones nn t.he Iqve t'i~rd t'~)res along wit.h t h~)se ~1' core H1.17'7 159 in Frobnsher Bay (ca. 6'2" N ), Bafrnn Islancl ( Mu&e and ,.qh(.)rt, 1985 ) ure summarized in Fig. 8. The upper pollen z(.mes, duminated by C.vperaceae and Gram~ (i:r)r es

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F'II~ H ,%_'lJrTimsry (JlU~-~rLIITI t'~Pmr.larlnl_., , Ihe live !.,ludy !.;11o!., and Ihe I:_~uhh~herl palvn, d, bm,'al rori)rd I'rc~rrl HI.77 Ib!-t, Frid:Jl.,.~her Bay, Balllrl Hand ( Muclle and Shi,rl, I!~IHIp )

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neae in all but. t.he It.irbilung core, are reason ably represent at, we of the regional pollen rain, except, for over.represent.at, ion of Filicales. Represent,ation of t.he regional vegetat.ion in the I~ord cores is much more direct, than in the Frobisher Bay core (I-ILI77 159) where t,he up per pollen zone is d~minat.ed by exotic Picca, Pinus and AInt,s (Mudie and Short., 1985, fig. 1(I.9) Similarly, t.he Late Pleistocene assem blages of t,he Baffi n Bay deep sea cores are dora inated by t.he arboreal taxa Pwea and Pro,is (de Vernal et. al., 1987). The upper zones of t.he fiord c~res are br~adiy sim.lar t.o the upper z~mes of pollen drag'rams from Patrica Bay Lake and Ig lutalik Lake, BaMn Island (Short et. al., 1985, figs. 22.4a and 22.6a ), but. for differences in Fil icales (higher percent.ages in I'i~rd cores) and Sah,t ( higher percentages in lake cores ). In both the above lake sediment, c~res, Sah.t has been a codominant, pollen t..vpe since ca. 50()() B.P An increase in Salix occurs in the upper parts ~1' the McBeth and Sunneshine I~ord cores, but it. dates t~, . 4(.)()() B.P. and ca. 8000 B.P., respectively Deep sea cores from the eastern and west.ern Labrador Sea (de Vernal, 1986) also allow direct correlat.ion t.o the pub hshed t.errest.rial pal.vnost.rat.igtaphy (Short and Nich~ls, 1977; Lamb, 1980; Richard, 1981 ), re Ilect.ing the t.rar|sition I'r~m shrub t.undra t.o bo real I'~rest veget.ation tn the source area at ca. ,'-I()00 B.P The estimated date I~r the t.ranstt.ion t'r,~m herb dominated t,undra t.o shrub domi nat.ed t.undra at ca. 11,()()() B.P. tn t.he deep sea ~.'~res is t.~..| early by several m~llenia, h~wever. The lowest pollen zones ~l'Clark, McBet.h and Sunneshine cores are dominat.ed by Betula, as are t.he st.rface I~rd mud spectra. In t.he latter t w~ cores, the Betula zones date t.o 8()0() t.o 11,5()() B.P., and correlat.e wit.h the lower pollen zone ~n HU77 159 which also contains substan t.ial Betula percent.ages. The age of this zone is pr,,r t~ the time when birch tundra began t.~ Ilounsh ~n Baftln Island (Mode and ,lacobs, 1985 ), northern Labrador (Short and Nichols, 1977), ~r West Greenland (Fredskild, 1985). Hence, the source of the Betu/o p~,llen was re

S K SHOR'T',,IT ANDRE',WSAND W N MI)DE',

working and/or very long cl.ist,anee transport at, a t,ime of minimum local and regi~mal p~llen product.ion. The age of t,he basal Betulo zones in McBet.h and Sunneshine I'ic~rds falls wtt.hin t.he BaMnland glacial st.ade (Andrews and Miller, 1984 ), a period of ext.enswe glaciatmn on Bal'l~n Island. Climatic conditions favorable for glaciation may have been unfavorable for vegetation brrowth and pollen producti~m, al lowing dominance ~1' ezot, ic Betulu. A striking feature of the upper pollen zones ol' all five cores is t.he peak in [hn~llagellat.es that occurs ca. 4000 to 5()()() B.F'. (Fig. 8) and appears t,o have pr~mise as a regi,Jnal b.ost.ra t.igraphic marker. The reason for this appar ent.lv synchronous event is not. known because the ecolol.,.w ~,1't.hls group is not well underst.o~M (of. Mudie and Short., 1985 ), but as n~t.ed above, the preliminary analyses ~,l's~x marine samples seem to indicate Atlant.ic wat.ers (P. Mudie, pers. commun., 1989 ). Perhaps t.he Dinollagel late abundance was caused by warming of t.he surface ocean, as t.his event co~nc,des wiLh t.he postglacial marine climat.ic opt.imum (5()()() t.o 30()() B.P. ) in t.he eastern Canad.an A rot.it (An drews, 1972). This is an ~nterval when subarc tic molluscs and dril:t.wu~M achieved their most ext.ensive penet.rat.ion into the Arct.~c and when well developed sh~relines formed in many Iocalthes. The nat.ure ~1' the pollen records of t.he Ba ffin Island fiord cores is t w~ffold. The lower pollen z~mes are dominat.ed by exotic p~llen t.vpes (es pecmlly Betula ) and t.he upper z~mes are dom~ r|at.ed by regional pollen types. The lower zones were deposited when Bal'fin Island was mmnly glacier covered and e~ot.ic pollen influx was nearly the sole source of p~~llen ~nlo an enw r~m ment of minimum pollen prcMuct.ion. The up per zones were deposit.ed during a period of es tablished vegetation cover q~n Baffin Island; their similarit.y t.o the upper p~llen zones of lake sediment cores from the same region ~nd]cat.es t.hat, fiords have t:unct.ioned as sedimentary ba sins comparable t.o lakes throughout t.he post. glacial. In cont.rast., pollen records from deep

For Appendix

IIP.T.0.

197.198

1,4 il .I ,},?,,,JI.;P Fi',("T'R A q )F' F'I( )RD k;F',DI M RN'I'S

sea cures in Frobisher Bay and BaMn Bay con fain much hugher proport, tons of ex()t,w pollen from the sout.h ( MudJe and Short, 1985; de Ver nal et al., I987) and are not, so clearly relat,ed t~ regiunal vegetation development on Baffin Island Acknowledgements

This paper is a contribution to NSF grants DPP 83 I)6581 and DPP ~6 19315. The maj()r it.v of the dates were pr()vlded by the University

uf Arizona accelerat.or facility. Roll' K~hl, IN STA A R Sech men t,oh.)t.,.,y Lah~)rat,(.)ry, prepa red samples for radiocarb
('anad~an ,~lr~'l w Arcl Alp H.P.~;, 13 ,J I -t-;4 Anlhewl.,, ,I 'P arid Miller, (; H , 19N4 I,~lJaletrlal-~ i.,,larmal arid l,l,ml.:l.,, ,al <'+,rre, lalmn,,+ fur l h e ~-,astern l'al,ladmn Ar~'ll( I n [~ ,l, Pult,m ( ~ d d i ~ r ) , (JPl~l ~ u ~ ('arlalla Pa[i,Ni4 li) I()I 116 Andl,ew~, ,I 'T', ,hJll, ,I 'T', Eiurmhue, E),I , ~l'i~irl, ,~ i~. arid ( )NlPl,'ITiari, I, E, I!+N:, ,~l~dllTierit,a[lllri l'a~eN iri B a i i l n I~,_, land Illlrd i iire!4 Ir'<)rn ~'llmpar'atlVe radl(+l'afhlln ilalPP,, ('all ,J ~arl}-i +_~(.'1 I3'] IN'.+'7 - IN34 Al,u:lrew,.,, ,I T and ,hmnnnl.~, A E , 1!4W7 Inllueru'e .I m~di ,

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lulu flhanduh~,,,a al lh~, Ilmll qfl I.,~W Arclll' IUl,ldra Irl +,;<.Jlhern Bail'in I:dand, N.W 'T', Carlacla At~'l Alp Re+,, 1'7 '2'7~+- 'JN';

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I h ihJrl I n. N , 191;i t I ril r( ti"hJr I ii )rl I { ) lJla rl114(-,i Jl..Tapl I,, and ,.,qIrnl-, r'eI,H~-,d :'.,{'1t"[1('{~ ,, Lilnl.rnall=,, I,iJrldim. (;.-I()pp [-',lr~+lht, A E , IIJ)i;7 IlhJMraled Fh~r'.', ,hi II'le ( 'aJILI