23. PALYNOLOGY OF SELECTED NEOGENE SAMPLES FROM HOLES 594 AND 594A,CHATHAM RISE1

Linda E. Heusser, Lamont-Doherty Geological Observatory2

ABSTRACT

This chapter presents the results of preliminary palynologic analyses of 132 samples from Holes 594 and 594A fromDeep Sea Drilling Project Leg 90. Palynomorph abundance, diversity, and preservation vary, with minimum concentra-tion in the late early to middle Miocene nannofossil chalk. In the upper part of the late Miocene foraminifer-bearingnannofossil ooze, pollen concentration rises close to the maximum amounts ( — 400 grains/cm 3) found in the Pliocene,Pleistocene, and Quaternary hemipelagic silts and clays.

Pollen spectra in all samples are mainly arboreal pollen. Early Miocene pollen assemblages are dominated byNothofagus brassi, with subsidiary podocarpaceous pollen. In mid-Miocene samples, N. fusca is the major type ofbeech pollen present. Late Miocene, Pliocene, and Quaternary pollen assemblages show decreasing representation ofextinct Tertiary pollen types and evidence of climatic fluctuations.

INTRODUCTION

The purpose of this preliminary survey of palyno-morphs in cores recovered from DSDP Holes 594 and594A on the Chatham Rise in the southwest Pacific eastof South Island, New Zealand, is to evaluate the strati-graphic, paleogeographic, and paleoclimatic potential ofthe marine pollen record from Site 594. Although fewpapers discuss pollen in marine sediments near New Zea-land (Koroneva, 1968), pollen analyses of marine sedi-ments in fjords of western South Island (Harris, 1964;Mildenhall, 1978d) demonstrate the stratigraphic and eco-logic usefulness of marine pollen. Elsewhere in the Anti-podes, Kemp (1975, 1981; Kemp and Harris, 1975) usedpollen from deep-sea cores to reconstruct Antarctic andAustralian Tertiary vegetation and climates. Pollen anal-yses of samples from DSDP sites near western NorthAmerican (Fournier, 1981; Heusser, 1982) and in theBlack Sea (Koroneva and Kartashova, 1978; Traverse,1978) provide age determinations, palynostratigraphic zo-nations, and floral and climatic information about near-by land masses.

New Zealand Tertiary and Quaternary pollen stratig-raphy and vegetation/climatic history are well knownfrom pollen analyses of late Cenozoic shallow-water ma-rine and nonmarine deposits, work begun by New Zea-land palynologists such as Cranwell (Cranwell and vonPost, 1936), Couper (1951a, b), and Moar (1958). Ter-tiary pollen zonations are usually related to the excep-tionally complete and well-correlated New Zealand Ter-tiary marine sequence. Paleoclimatic interpretations oflate Cenozoic pollen assemblages are based on detailedstudies of present relationships between pollen and veg-etation distributions in New Zealand (e.g., McGlone,1982; Moar, 1970; Pocknall, 1980).

Keπnett, J. P., von der Borch, C. C , et al., Init. Repts. DSDP, 90: Washington (U.S.Govt. Printing Office).

2 Address: Lamont-Doherty Geological Observatory, Colombia University, Palisades,N.Y. 10964.

SETTING

The plants of New Zealand (South Island and, to alesser extent, North Island) are the primary source ofpollen in sediments of Site 594. Vegetation of these moun-tainous islands can be simplistically divided into two plantformations, forest and tussock grassland, the first wide-ly distributed in both islands, and the second well-devel-oped in South Island east of the forest-covered SouthernAlps (Cockayne and Phillips-Turner, 1967). Two broadcategories of temperate, board-leaved evergreen forestsare recognized: lowland, conifer-broadleaf forest (includ-ing podocarps such as Podocarpus, Dacrydium, and Phyl-locladus, hardwoods such as Weinmannia, and tree fernslike Cyatheá), and subalpine Nothofagus (southern beech)stands (including TV. fusca and TV. solandri; Wardle etal., 1983).

Present distribution of plant associations in New Zea-land is related to climatic patterns, controlled by lati-tude, oceanic environment, and relief, as well as to his-torical factors (Wardle et al., 1983). Located between~ 34° and 47°S, the long, narrow (< 300 km) land masslies in the convergence of atmospheric pressure systems(subtropical high and Southern Ocean low) and oceanicwater masses (subantarctic, temperate, and warm sub-tropical) (Griggs, et al., 1983). Precipitation is high, withstrong, circumpolar westerly winds and high relief caus-ing marked differences in average annual rainfall (from6250 mm on the west coast of South Island to < 600 mmin the east). Moderate mean annual temperatures rangefrom 8°C on South Island to 13°C on North Island (Al-lan, 1961; Moar and Suggate, 1979).

METHODS

For this preliminary survey, two to three samples were taken fromeach core from Holes 594 and 594A (Table 1). Sampling intervalsranged from 3 to 10 m. In all, 132 samples were processed, 94 fromHole 594 and 38 from Hole 594A. Sample size ranged from 10 cm3 to20 cm3 wet sediment. Preparations involved mechanical and chemicalextraction techniques described in Heusser and Stock (1984). Palyno-morphs were identified using a reference collection made from plants

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L. E. HEUSSER

Table 1. Samples analyzed for pollen from Holes 594 and 594A. Table 1. (Continued).

Sample(interval in cm)

Hole 594

1-2, 43-471-4, 43-472-2, 43-472-4, 43-472-6, 43-473-1, 43-473-2, 43-473-4, 43-473-5, 43-473-6, 43-474-2, 43-474-4, 43-474-6, 43-475-2, 43-475-4, 43-475-6, 43-476-2, 43-476-4, 43-477-2, 43-479-2, 43-479-4, 43-479-6, 43-4710-2, 43-4711-2,43-4711-4, 43-4711-6, 43-4712-2, 43-4712-4, 43-4713-2, 43-4713-4, 43-4714-2, 43-4714-4, 43-4715-2, 43-4715-4, 43-4715-6, 43-4716-2, 43-4716-4, 43-4718-2, 43-4718-4, 43-4718-6, 43-4719-2, 43-4719-4, 43-4719-6, 43-4720-2, 43-4720-4, 43-4721-2, 43-4721-4, 43-4721-6, 43-4723-2, 43-4723-4, 43-4723-6, 43-4724-2, 43-4724-4, 43-4724-6, 43-4725-2, 43-4725-4, 43-4726-2, 43-4726-4, 43-4727-2, 43-4727-4, 43-4728-2, 43-4728-4, 43-4729-2, 43-4729-4, 43-4729-6, 43-4730-2, 43-4730-4, 43-4730-6, 43-4731-2, 43-4731-4, 43-4731-6, 43-47

Depthbelow

Seafloor(m)

1.954.957.85

10.8513.8516.9517.4520.4521.4523.4527.0530.0533.0536.6539.6542.6546.2549.2555.8575.0578.0581.0584.6594.2597.25

100.25103.85106.85113.45116.45123.05126.05132.65135.65138.65142.25145.25161.45164.45167.45171.05174.05177.05180.65183.65190.25193.25196.25209.45212.45215.45219.05222.05225.05228.65231.65238.25241.25247.05250.85257.45260.45267.05270.05273.05276.65279.65282.65286.25289.25292.25

Lithology

Unit IAlternating bluish gray

foraminifer-bearingnannofossil ooze andgreenish gray nanno-fossil-bearing clayeysilt

Subunit HALight to very light gray

foraminifer-bearingnannofossil ooze tonannofossil ooze

Age

Quaternary

late Pliocene

early Pliocene

late Miocene

Sample(interval in cm)

Hole 594 (Cont.)

34-2, 43-4734-4, 43-4735-2, 43-4735-4, 43-4736-2, 43-4736-4, 43-4738-2, 43-4739-2, 43-4740-2, 43-4740-4, 43-4741-2, 43-4741-4, 43-4742-2, 43-4742-4, 43-4745-2, 43-4746-2, 43-4747-1, 43-4748-2, 43-4749-2, 43-4749-4, 43-4750-2, 43-4751-1, 43-4752-2, 43-47

Hole 594A

1-2, 43-471-4, 43-471-6, 43-472-2, 43-472-4, 43-472-6, 43-473-2, 43-473-4, 43-473-6, 43-474-2, 43-475-2, 43-475-4, 43-475_6, 43-476-2, 43-4710-2, 43-4710-4, 43-4710-6, 43-4711-2, 43-4711-4, 43-47

13-2, 43-4713-4, 43-4713-6, 43-4714-2, 43-4714-4, 43-4715-2, 43-4716-2, 43-4716-4, 43-4716-6, 43-4717-2, 43-4717-4, 43-4720-1, 10-1420-2, 43-4721.CC22.CC23-1, 127-13024-1, 110-11225-1, 100-10226-1, 32-34

Depthbelow

Seafloor(m)

314.05317.05323.65326.65333.25336.25352.45362.05371.65374.65382.25385.25391.85394.85420.65430.25438.35449.45459.05462.05468.65476.75487.85

43.2546.2549.2552.8555.8558.8562.4565.4568.4572.0581.6584.6587.6591.25

129.65132.65135.65199.85202.85

507.05510.05513.05516.65519.65526.25535.85538.85540.85545.45548.45572.42574.25584.34592.45602.39611.81621.31630.23

Lithology

Subunit IIBVery light gray nannofossil

chalk with occasionalinterbeds of olive graysilt-bearing clayeynannofossil chalk

Unit IAlternating bluish gray

foraminifer-bearingnannofossil ooze andgreenish gray nanno-fossil bearing clayeysilt

Subunit HALight to very light gray

foraminifer-bearingnannofossil ooze tonannofossil ooze

Subunit IIBVery light gray nannofossil

chalk with occasionalinterbeds of olive graysilt-bearing clayeynannofossil chalk

Age

mid Miocene

Quaternary

late Plioceneearly Pliocene

late Miocene

mid-Miocene

early Miocene

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NEOGENE PALYNOLOGY, CHATHAM RISE

collected in New Zealand by the author, C. J. Heusser, and L. B.Moore; from reference slides and photographs graciously lent by L. M.Cranwell; and from illustrations and descriptions published by Cook-son, 1959; Couper, 1953c; Cranwell, 1938-1963. Hanks and Fairbroth-ers, 1976; Harris, 1955; and Truswell 1982b, 1983. Poor preservationand the presence of numerous opaque (pyrite ?) particles often madeidentification difficult; therefore, many groups were not differentiatedand classifications should be regarded as tentative, pending furtherdetailed study. For example, Dacrydium kirkii-biforme-bidwilli typeswere not differentiated and may be included in the Podocarpus groupor mistakenly assigned to Dacrydium cupressinum (Mildenhall, 1978c).Tertiary bisaccate grains with small sacci placed in the Phyllocladusgroup may include Phyllocladites mawsoni (Couper, 1953c; Tulip, etal., 1982), and some small, trisaccate grains may represent Microcach-rys, Microstrobus (Pherosphaera) species, Microcachryidites, or pos-sibly Acmopylepancheri and A. alba from New Caledonia (Cranwell,1961; personal communication, 1983).

SITE 594 (45°31.41'S; 174°56.88'E)

Site 594 is located in the South Pacific Ocean at adepth of 1204 m on the southern margin of the Chat-ham Rise about 250 km east of South Island, New Zea-land (Fig. 1). The site, downslope from Waitaki Can-yon, is situated in a transitional area between ocean (sub-antarctic waters immediately south of the SubtropicalConvergence) and terrigenous influences, particularly theWaitaki River drainage.

Holocene through lower Miocene sediments were re-covered from three holes cored to a maximum sub-bot-tom depth of 639 m, with four unconformities detected(about 8.3-6.5 Ma, about 5.4-4.5 Ma, about 3.85-2.7Ma, and about 1.6-0.74 Ma). Both the Miocene/Plio-cene boundary and the early/late Pliocene boundary fallwithin disconformities. Two lithostratigraphic units weredefined (Table 1). Unit I (earliest Pliocene to Quater-

38°S

170° 178°E

Figure 1. Location of Site 594 off South Island, New Zealand.

nary age) consists of an alternating sequence of greenishgray hemipelagic and bluish gray pelagic lithofacies sep-arated from the lower units by a gradational contact.Unit II (late early Miocene to earliest Pliocene age) is apelagic facies consisting mainly of light gray foramini-fer-bearing nannofossil ooze (Subunit IIA, middle Mio-cene to earliest Pliocene age), and light gray nannofossilchalk with occasional interbeds of olive gray silt-bearingnannofossil chalk (Subunit IIB, late early to middle Mi-ocene).

Two major tectonic episodes are recorded in sedimentsof Site 594. The clay turbidites of Subunit IIB provideevidence of an early tectonic pulse about 17 Ma, whichcoincides with strike-slip motion along the Alpine Faultsector of the Indian/Pacific plate boundary (site chap-ter, this volume). At 6 Ma, the first late Neogene influxof hemipelagic sediments dates the beginning of the Kai-koura Orogeny and the emergence of a fairly substan-tial, continuous, northeast-to-southwest-trending land-mass (site chapter, this volume; Nelson, this volume;Suggate, 1978). In the upper 200 m below the seafloor,25 major hemipelagic depositional episodes are recorded.Shipboard investigations indicate that this sequence ofalternating dark hemipelagic and light pelagic biogenicsediments of latest Miocene to Pleistocene age is relatedto climatic change: warm climates (interglacials) and highsea levels are associated with pelagic sediment contain-ing warm planktonic foraminifer faunas, and cold cli-mates (glacials) and low sea levels are associated withpelagic sediments containing much biosiliceous materialand cold planktonic foraminifer faunas (site chapter, thisvolume). High-resolution carbonate and isotope stratig-raphies provide detailed confirmation of the correlationbetween sedimentary parameters and late Quaternary cli-matic changes, and provide a correlation between NewZealand Quaternary records and fluctuations of north-ern hemisphere ice sheets (Nelson, Hendy, et al., thisvolume).

RESULTS

The results presented in this preliminary report can-not do justice to the paleoecological potential of the pol-len record in the sediments of Site 594. Palynomorphs insamples from Holes 594 and 594A (Table 1) are Notho-fagus fusca type, Nothofagus menziesü type, Nothofa-gus brassi type, Podocarpus types, Dacrydium types,Phyllocladus type, Michrocachrys type, inaperturate cu-pressaceous types, Myrtaceae, Coprosma types, Erica-ceae, Gramineae, Cyperaceae, Compositae, Chenopodi-aceae, Polypodiaceae, and Lycopodiaceae. Dinoflagel-lates, micro foraminifers, and recycled pollen and sporesare frequently present. Pollen types identified, but nottabulated, include Haloragacidites (al. Triorites) harrisiiand H. trioratus, extinct species probably belonging tothe Haloragaceae or Betulaceae (Couper, 1953a-c; Mil-denhall and Harris, 1970), Proteacidites, and membersof the Umbelliferae, Rosaceae, Loranthaceae, Cupres-saceae, Proteaceae, and Cunoniaceae (Allan, 1961; Mooreand Edgar, 1970).

Pollen spectra from samples from Sites 594 and 594Aare not correlated with New Zealand stratigraphic unitsbecause rare diagnostic forms (Couper, 1951-1960; Cou-

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L. E. HEUSSER

per and McQueen, 1954; Couper and Harris, 1960; Mil-denhall, 1972-1980. Moar and Suggate, 1979) were notoften identified. Future preparation of larger samplesfrom cores taken at Site 594 to isolate diagnostic pollentypes may prove useful for late Cenozoic correlations;however, Mildenhall and Suggate (1981) suggest that paly-nological subdivision using extinct species may be of on-ly local value in the upper Pliocene and basal Quater-nary. In deep-sea sediments, rare extinct or extant pollentypes must be interpreted with caution because of theincreased possibilities for contamination by long-distancetransport or the addition of recycled pollen.

Palynomorphs were recovered from both lithostrati-graphic units (Unit I, and Subunits IIA and IIB). EarlyPliocene-Quaternary samples from the interbedded hemi-pelagic and pelagic facies of Unit I and late Miocene-early Pliocene Samples 594A-11-2, 43-47 cm and 594-21-6, 43-47 cm through 594-19-2, 43-47 cm from Sub-unit IIA were generally more productive than the nan-nofossil ooze of Subunit IIB, with the exception of tur-bidite samples 594A-17-2, 43-47 cm, 594A-17-4, 43-47cm, and 594A-20-1, 10-14 cm. Pollen concentration islow (<400 pollen grains/cm3), and shows no apparentcorrelation with the detailed changes in sedimentary prop-erties of the Quaternary pelagic and hemipelagic oozesat Site 594 described by Nelson (Nelson et al., this vol-ume). Preservation and pollen diversity vary: more pol-len groups are identified in well-preserved assemblageswith relatively high pollen counts (50 to 100 grains),samples which often, but not always, have high pollendensity.

Pteridophyte spores (Filicopsida and Lycopsida) andredeposited pollen and spores occur in all three sedimen-tary units. A few grains identified as Sphagnum appearat the base of Subunit IIA. Dinoflagellates are com-monly present and frequently abundant in samples fromUnit I and Subunit IIA, and are rare in Subunit IIB.Units I and II contain micro foraminifers, ranging fromabundant in Unit I to absent in Subunit IIB. Other com-ponents of the organic residue include fungal spores,blackened and degraded plant fragments, amorphous or-ganic material (<5 µm), and algal fragments.

Early Miocene

In the six early Miocene samples, pollen assemblagesare dominated by Nothofagus, primarily N. brassi withlesser N. menziesii. Nothofagus fusca is present in smallamounts. Podocarp and Microcachryidites-type pollenoccurs throughout. Haloragacidites harrisii and Prote-acidites are present, along with recycled pollen and spores.Herb and shrub pollen is essentially absent (one Grami-neae grain was identified), and no dinoflagellates or mi-croforaminifers were found.

Mid-Miocene

Pollen concentration is very low in most mid-Mio-cene samples. Eight samples are barren and four othersamples have <IO pollen grains. Samples 594A-20-1,43-47 cm, 594A-13-6, 43-47 cm, 594-49-2, 43-47 cm,594-46-2, 43-47 cm, and 594-45-2, 43-47 cm, are veryproductive, with > 50 pollen grains identified from each

sample. Nothofagus fusca is the most important arbore-al pollen type, and replaces N. brassi in prominence. N.menziesii, podocarpaceous pollen, and Microchachryi-dites-types are present, along with representatives of theGramineae, Compositae, Chenopodiaceae, and Cypera-ceae. Pteridophyte spores, including Cyathea-typcs, in-crease in abundance upwards, Dinoflagellates are pres-ent in each sample, and recycled palynomorphs, mi-cro foraminifer cysts, and a few Sphagnum-like grainsoccasionally appear.

Late Miocene

Basal late Miocene Samples 594-38-2, 43-47 cm,through 594-31-4, 43-47 cm are relatively unproductive.Pollen becomes more numerous in Samples 594-31-2,43-47 cm, through 594-28-2, 43-47 cm, with 65 grainsidentified in Samples 594-28-4, 43-47 cm. Podocarpa-ceous pollen types (including Dacrydium cupressinum)are more numerous than Nothofagus types. Fern sporesand dinoflagellate are frequent, microforaminifers ap-pear occasionally, and lycopod spores occur in a fewsamples. Between 250 and 212 m (Samples 594-27-4,43-47 cm through 594-23-6, 43-47 cm), podocarps {Da-crydium cupressinum, Podocarpus dacrydiodes, and tri-saccate types) outnumber Nothofagus types (N. fusca,N. menziesii, and N. brassi, in order of prominence).Fern (polypod) spores and dinoflagellates are consistentlyabundant. Nonarboreal pollen, lycopod spores, and mi-croforaminifers appear occasionally.

The poáocaip/Nothofagus ratio reverses in pollen-rich(> 100 pollen grains/sample), younger late Miocene sam-ples (594-23-4, 43-47 cm, through 594-21-2, 43-47 cm,594A-11-4, 43-47 cm, and 594A-11-2, 43-47 cm), withNothofagus fusca the leading arboreal pollen group. Com-positae pollen is present in each sample, and Coprosma,Chenopodiaceae, Gramineae, and Cyperaceae pollen areoccasional components of these pollen assemblages. Pter-idophyte spores (polypod and lycopod) are more promi-nent than dinoflagellates and microforaminifers. Micro-cachryidites is present. A few grains of Haloragaciditesharrisii and Protaecidites were identified, apparentlymarking the last appearance of these grains.

Pliocene-Quaternary

Plio-Pleistocene samples are characterized by large fluc-tuations in pollen density, changing from 400 to 5 grains/cm3 in one sample interval. Nothofagus fusca is the lead-ing pollen type, and Nothofagus types usually occur morefrequently than podocarps, although some levels do havelarger numbers of conifer pollen. Nonarboreal pollen isalways less numerous than arboreal pollen; only 2 sam-ples (594-5-6, 43-47 cm and 594A-2-6, 43-47 cm) have>25% herb pollen. As in older samples, fern spores aremore abundant than lycopod spores. Dinoflagellatesand microforaminifers vary in relative frequency of totalpalynomorphs, the latter increasing in the upper 36 mbelow the seafloor. Characteristic older Tertiary types,N. brassi and trisaccate conifers, gradually decrease inyounger sediment. Sample 594-18-2, 43-47 cm (161 msub-bottom depth) marks the last fairly continuous ap-pearance of N. brassi, although (?recycled) pollen grains

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NEOGENE PALYNOLOGY, CHATHAM RISE

which appear to be N. brassi occur occasionally in youn-ger sediments up to 43 m sub-bottom depth (Sample594-1-2, 43-47 cm).

DISCUSSION

Pollen concentration (<400/cm3) in all samples ana-lyzed from Site 594 is unexpectedly low, although largerthan concentration values of marine pollen in pistoncores taken off North Island, New Zealand (Koroneva,1968). In similar marine sedimentary environments ad-jacent to North America and Japan (continental slopeat ~ 40° latitude near large river systems draining tem-perate vegetation), pollen concentrations are 2 to 20 timesgreater than in sediments east of New Zealand (Heusser,1983; Heusser and Balsam, 1977; Heusser, L. E., un-published data). Perhaps the relatively small area fromwhich pollen is derived (both the present surface area ofNorth and South Island and the even smaller area ca-pable of supporting vegetation in the Tertiary; Walcott,1984) accounts for the low amount of pollen in coresfrom Holes 594 and 594A. Sedimentation and preserva-tion are also important determinants in pollen concen-tration in sediments from Chatham Rise. Dilution byterrigenous and pelagic sedimentary components may ac-count for the scarcity of pollen at Site 594. Oxidationand winnowing related to vigorous current action mayhave differentially destroyed or removed pollen (Heusserand Balsam, 1977), and oxidizing depositional environ-ments are noted for poor pollen preservation (Tschudyand Scott, 1969). Pollen concentration is broadly corre-lated with intervals of terrigenous influx, with greatestpollen influx in the Plio-Pleistocene hemipelagic sequence(Samples 594-1-2, 43-47 cm through 594-11-2, 43-47 cm,and 594A-1-2, 43-47 cm through 594A-6-2, 43-47 cm),and in basal Miocene turbidites (Samples 594A-20-1,10-14 cm and 594A-25-1, 100-102 cm). Lowest polleninflux, in middle Miocene nannofossil oozes (Sample594-49-4, 43-47 cm through 594-28-2, 43-47 cm) is as-sociated with pelagic carbonates and virtual lack of ter-rigenous input (site chapter, this volume). The sparse-ness of pollen in these mid-Miocene samples may alsobe related to the increased corrosiveness of Pacific Oceanbottom waters associated with Antarctic glaciation andthe formation of Antarctic Bottom Water (Shackletonand Kennett, 1975).

Broad changes in marine plankton in the pollen con-centrate of samples analyzed from Sites 594 and 594A,an absence of dinoflagellate and microforaminifer cystsin the lower Miocene, and abundance variations in youn-ger sediments probably relate to the paleoceanographicchanges (i.e., changes in sea surface temperature and sa-linity, sediment supply, current velocity, and glacioeu-static sea level). Increased numbers of dinoflagellates inthe upper Miocene may be associated with developmentof the Subtropical Convergence at this time (site chap-ter, this volume). In the northeast Pacific Ocean, lateMiocene dinoflagellate abundance and diversity indicatechanges in surface waters of the California Current (Bal-log and Malloy, 1981). Further south off Mexico, Four-nier (1981) related dinoflagellate abundance to water depthand turbulence: high dinoflagellate density is associatedwith low sea level in shallow depositional sites.

Pollen spectra from marine sediments of Site 594 canbe interpreted only in relation to late Cenozoic pollenassemblages found on land (New Zealand) because thereare no comprehensive studies relating New Zealand veg-etation and pollen deposition in marine environmentsoffshore. In comparing marine pollen assemblages fromDSDP cores taken on Chatham Rise with pollen assem-blages from South and North Island, differences in pol-len source and sedimentation should be noted. Pollenfrom most peats, lignites, or nonmarine sediment is largelywind-transported short distances from small plant com-munities and rapidly deposited in lakes and bogs, envi-ronments with excellent pollen preservation. Pollen fromshallow-water marine sediments (the fjords of South Is-land, or the mudstones and siltstones of the WanganuiSeries) is derived from large vegetation formations, andshows effects of differential sorting and preservation dur-ing aerial and fluviomarine transport before final depo-sition in high-energy environments. Pollen and spores indeep-water marine sediments reflect vegetation of broadregions, as well as eolian and fluviomarine transport anddeposition (Heusser, 1983; Heusser and Balsam, 1977).

Late Cenozoic pollen assemblages from Site 594 aredominated by arboreal pollen: Nothofagus (southernbeech), the most common Cretaceous and Tertiary pol-len type of New Zealand (Couper, 1951a), and repre-sentatives of the Podocarpaceae (conifers), including Da-crydium, Podocarpus, and Phyllocladus species (Allan,1961). Pollen and macrofossils from these wind-polli-nated trees are prominent in Tertiary marine and non-marine sediments in the southern hemisphere, and rela-tive differences in representation of beech and coniferpollen are criteria for stratigraphic assignments and cli-matologic interpretations of Tertiary and Quaternary pol-liniferous sediments from New Zealand, Australia, andAntarctica (Couper, 1951-60; Cranwell, 1969; Kemp,1975; Mildenhall, 1978a, b).

Despite differences in source and sedimentation, lateCenozoic pollen spectra in samples analyzed from Site594 are broadly correlative with pollen obtained frommarine and nonmarine sediments on New Zealand. Ear-ly Miocene floras are characterized by the presence ofnumerous extinct pollen and spore types. The mid-Mio-cene marks a transition, with some older pollen types(N. brassi, Haloragacidites harrisii) continuing in a mi-nor role and others (N. fused) playing a major role. Ason North and South islands, new groups (Compositaeand Chenopodiaceae) appear in greater numbers. UpperMiocene and Pliocene marine samples show a gradualdecline in extinct species, and no abrupt changes in flo-ral assemblage appear between —2.47 and -5 .5 Ma.On New Zealand, no evidence exists of exceptional cli-matic changes (Suggate et al., 1978), or of abrupt floralextinctions at the Miocene/Pliocene boundary or in lat-est Miocene (Kapitean) pollen sequences. Pliocene-Qua-ternary pollen assemblages also record an apparent grad-ual loss of extinct taxa, although a substantial numberof extinct species make their last appearance in the Plio-cene Taranaki Series (Suggate et al., 1978; Mildenhalland Suggate, 1981). The progressive extinction of Ter-tiary groups includes forms with interrupted ranges, suchas the Nothofagus brassi group which appears in inter-

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glacial deposits after absence in earlier glacial periods(Suggate et al., 1978).

In New Zealand, Quaternary pollen stratigraphic unitsare defined by climatic criteria supported by physiogra-phy, lithostratigraphy, and radioisotope and tephrochro-nology (Fleming, 1970; 1975; Moar, 1982). Generally,nonarboreal pollen assemblages are present in glacial in-tervals, and arboreal-dominated pollen assemblages aremore prominent in interstadial or interglacial intervals.All Quaternary spectra in samples analyzed from Site594 are dominated by arboreal pollen. Arboreal pollendominates interglacial as well as glacial intervals, as de-fined by oxygen isotope stratigraphy of samples fromthe last -400,000 yr. (Nelson, Hendy, et al., this vol-ume). Samples 594-1-2, 43-47 cm and 594-1-4, 43-47 cmdeposited during isotope Stage 2, the last glacial maxi-mum, have a prominence of cool-temperate forest pol-len.3 Interstadial intervals are characterized by podocarppollen in sediments from Site 594 and on North Island(Otamangakau interstadial; McGlone and Topping, 1983).

Climatic interpretations of pollen in samples analyzedfrom Site 594 are restricted to broad observations by thepreliminary nature of the data. Early Miocene pollen as-semblages from Chatham Rise probably represent sub-tropical (frost-intolerant) vegetation (trees similar to thosenow growing in New Guinea and New Caledonia—N.brassi group), as well as temperate and cool-temperatevegetation (trees now growing in lowland and montaneparts of New Zealand). Rainfall estimates, based on re-quirements of modern species, range from 1800 mm/yr.(inferred from N. brassi) to as low as 400 mm/yr. (in-ferred from TV. fused) (Truswell, 1982a). Miocene pollenassemblages from Site 594 appear transitional betweenwarm-temperate to subtropical early Cenozoic vegeta-tion (Wardle et al., 1983) and temperate vegetation ofthe late Cenozoic glacial mode. Variations in key pollentypes suggest that climate was not static during the Mio-cene. Using the prominence of conifers (podocarps) andsouthern beech (Nothofagus groups) as a general guide4

to climate suggests that in the late Miocene, a warm,moist interval preceeded cooler, drier conditions in whichherbs and shrubs (vegetation of more open forests orshrublands and grasslands) developed. Miocene New Zea-land apparently was ecologically and topographically di-verse, with local montane and arid habitats (Wardle,1978).

Pollen and spores deposited on Chatham Rise duringthe last 5 m.y. document the gradual disappearance ofsubtropical environments supporting N. brassi, and theexpansion of temperate forests on both South and NorthIsland. Changing climatic modes are suggested by varia-tions in arboreal pollen in the upper 200 m taken from

The absence of herb-dominated pollen spectra from glacial sediments in Site 594 sug-gests that Nothofagus persisted in favorable sites on South Island during Plio-Pleistocene gla-ciations. This agrees with previous observations that scattered clumps of trees now present inSouth Island forests grew on the east coast of South Island during the last glaciation (Wardle,1963, 1978; Wardle et al., 1983).

^ High values in the Podocarpus/Tvo/Ao/agiw ratio are interpreted as warm intervals andlow values as cold intervals (Mildenhall, 1976). Although the ratio of conifers (Podocarpa-ceae) and southern beech (Nothofagus) pollen and macrofossils is used extensively in NewZealand Tertiary and Quaternary paleoclimatic reconstructions to indicate warmer and coolerconditions, recent ecological work in New Zealand stressing the variability of modern NewZealand forests questions the validity of such interpretations (Moar, 1973).

Site 594. Climatic interpretations of the broadly spacedpollen data appear to correlate with similar levels inthe high-resolution sedimentary and geochemical datafrom the upper 80 meters of Site 594 (Nelson, Hendy, etal., this volume). Cool-temperature (glacial) pollen as-semblages occur in hemipelagic ooze enriched in silt,with low carbonate content, high δ 1 8 θ values and lowδ13C values. Warm-temperate (interstadial and intergla-cial) pollen assemblages occur in pelagic oozes high insand and clay, with high carbonate content, low δ 1 8 θvalues, and high δ13C values (Nelson et al., this volume).

CONCLUSIONS

Preparation and preliminary analyses of 132 samplesfrom Holes 594 and 594A produce the following results:

1. Pollen is present in low concentration (< 400 pol-len grains/cm3 wet sediment) in both pelagic and hemi-pelagic facies. Preparation of large samples (on the or-der of 20 cm3 is recommended for future pollen analy-ses.

2. Early Miocene samples are dominated by Notho-fagus brassi type pollen, along with other extinct Ter-tiary pollen types.

3. In mid-Miocene samples, pollen is scarce and N.fusca becomes more important than N. brassi.

4. Pollen concentration increases in late Miocene sam-ples, which show fluctuations in the importance of coni-fers (podocarps) and beech (Nothofagus), suggesting veg-etational and climatic changes on New Zealand.

5. Extinct Tertiary pollen types appear gradually todrop out of the record. Evidence for abrupt, major cli-matic change from late Miocene pollen assemblages inthe samples analyzed from Site 594 is not apparent.

6. Pliocene/Quaternary samples show fluctuations inpollen concentration and in arboreal-dominated pollenassemblages. Climatic interpretations of changes in thesearboreal pollen types appear to correlate with climaticchanges indicated by oxygen isotope analyses of sam-ples from Site 594.

7. Detailed analyses of pollen from Holes 594 and594A will produce high-frequency stratigraphic and cli-matic information.

ACKNOWLEDGMENTS

Thanks are extended to L. Burckle, L., Cranwell, J. Morley, E,Stern, and to the shipboard and editorial staffs of the Deep Sea Drill-ing Project. This research was partially supported by NSF GrantATM82-13609.

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Date of Initial Receipt: 2 July 1984Date of Acceptance: 30 October 1984

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