Pacific Science (1978), vol. 32, no. 2© 1978 by The University Press of Hawaii. All rights reserved

A Stratigraphically Important New Diatom fromthe Pleistocene of the North Pacific!

L. H. BURCKLE,2 S. R. HAMMOND,3 and STEFAN M. SEYB3

ABSTRACT: Rhizosolenia matuyamai, a stratigraphically useful new diatomfrom the Pleistocene of the north Pacific is described. A detailed paleomagneticand biostratigraphic study of three deep-sea cores from the north Pacific andDeep Sea Drilling Project (DSDP) site 173 indicate that this species rangesconsistently from just below the Jaramillo magnetic event to the lower part ofthe Jaramillo.

TABLE I

WATER CORE

CORE DEPTH LENGTH

NUMBER LATITUDE LONGITUDE (meters) (meters)

K75-1 37°22' N 179°36' W 5,383 17.34K75-2 38°36' N 179°20' E 5,748 17.05K75-3 33°22' N 169°05' E 5,695 17.49Site 173 39°57' N 125°21' W 2,927 333.5

MATERIALS AND METHODS

Three oriented (Seyb, Hammond, andGilliard 1977) deep-sea sediment piston coreswere examined along with sediments fromDSDP site 173 (Leg 18). The piston cores wererecovered from the northwest Pacific in thevicinity of the Hess rise and south EmperorBasin (Table 1). All three cores are similar

THE PURPOSE OF THIS PAPER is to describethe temporal and spatial distribution of ashort-ranging diatom from the Pleistoceneof the north Pacific. This form, here calledRhizosolenia matuyamai, was previouslyfigured by Schrader (1973, Plate 9, Figures10, 12, 22, and 33), who identified it asRhizosolenia bergonii Peragallo. Our investi­gation indicates that its differences fromRhizosolenia bergonii are sufficient to des­ignate it as a new taxon. Moreover, itslimited geologic range over the north Pacificwarrants its separation as a separate taxo­nomic unit.

in lithology, consisting essentially of a brownto yellowish-brown diatom- and radiolaria­rich sediment. The three cores were sampledat 1O-cm intervals using 6 cm3 plastic boxes.Paleomagnetic measurements were madewith a cryogenic rock magnetometer. Allthe paleomagnetic measurements were madebefore the samples were allowed to dry.Alternating-field partial demagnetization wasused to eliminate any magnetic componentspartially obscuring the characteristic detritalremanence. Stepwise analyses of severalsamples from each core indicated that theoptimum demagetization intensity was 100oe for core K75-1 and 150 oe for coresK 75-2 and K 75-3. The response of both the

I This study was supported by National Science paleomagnetic intensity and direction todati0n-gFants-0E-E1-5~196z1and-BES9S~-1-8-1-36,;t""o-..p"'a=rtialaemagnetIzatlOn ina-icateatIiat theLamont-Doherty Geological Observatory and grant samples are very stably magnetized. TheNOOOI4-75-C-0209 to the University of Hawaii. This is median destructive field for all three corescontribution number 2687 from the Lamont-DohertyGeological Observatory and number 804 from the was found to be between 300 and 400 oe.Hawaii Institute of Geophysics. Manuscript received 29 Representative total magnetic moments forApril 1977. samples (after partial demagnetization) vary

2 Lamont-Doherty Geological Observatory of Colum- between 1 x 10 - 4 and 1 x 10- 5 G.bia University, Palisades, New York 10964.

3 Hawaii Institute of Geophysics, University of Each core consists almost entirely ofHawaii, Honolulu, Hawaii 96822. brown clays containing generally abundant

209

210 PACIFIC SCIENCE, Volume 32, April 1978

diatoms along with lesser quantities ofradiolarians and sponge spicules. Some inter­vals in the cores are mottled and otherscontain relatively abundant manganesemicronodules. Deep Sea Drilling Project site173 is also located in the north Pacific at39°57.71' N, 125°21.12' W. The paleomag­netic results and magnetostratigraphy forsediments from this site are discussed byHeinrichs (1973).

Permanent strew slides and smear slideswere made for diatom analysis. The usualsampling interval was 20 cm, but smearslides were examined at lO-cm intervals todetermine the upper and lower range ofRhizosolenia matuyamai.

RESULTS

BR curvirostris

TN reinhold/I"

TMelliptico

o

I----+-BP dolialus

:1----+-TA.oculatus

c

.,, «~--..C)

'"~ ::;,<::: .....'ll

C)

~--..

'-- ::;,

~'-'C)

"l:

:>

In addition to a coherent paleomagneticreversal record, all the cores examined con­tained the requisite elements from the high­latitude diatom zonation of Koizumi (1975)and the equatorial Indo-Pacific zonation ofBurckle (1972). Figure I shows the resultsof our study of core K75-1. By correlationwith the zonation of Burckle (1972), whichwas previously tied to the magnetic strati­graphy, we can identify the lower normalsection as the Gauss, the long reversed sectionabove this as the Matuyama, and the top­most normal section as the Brunhes. Figure2 demonstrates the paleomagnetic correlationof our three piston cores with this zonalscheme.

« ~~ Hays et al. (1969) and Burckle (1972).,::: ~ reported that the Jaramillo event of the

.~ ~~ Matuyama Reversed Epoch could be identi-, '" TTh. convexo fi d' h . I I d 'fi b hC) ~ e m t e equatona n o-PaCl c y t e~ ~ c::i ~ silicoflagellate, Mesocena elliptica, whose~ B geologic range brackets this event. Addition-~- - ---I----+-FI3-komtschaNca--a Burckle-and-6pdyke-tin-press)-inclieate--

Cl. TN Jouseoe that the range of M. elliptica also brackets0::

FIGURE I. Paleomagnetic and biostratigraphic resultsfor core K75-1. The boundary between the D. seminaezone and the R. curvirostris zone could not be deter­mined. The letter designations in front of the speciesnames on the right side of the chart signify B = base orfirst appearance and T = top or last appearance.

K75 -1EQUATOR IAL NORTH

PACI FIC PALEOMAG- PACIFICDIATOM I NETIC I DIATOMZONES ISTRATIG.I ZONES

211

DSDPK75 -3 HOLE-I73

0-

10-

20-

30-

~

40- I~w0

50-

60-•70-

K75-1 K75-2

//

//

/

\\

\\

/ -----""""'. \/ / \ \/ / \,' \

/ \' \/ // \\ \/ \\ \

\ ,\ ,

\ '/r--"""" \ \\

/ I \ \ 'I I \\ , '

II 0 \/ I \ \

I I \ \/ I \ \

I I \ \I I \ \

I \I

Eo<16-

<

PALEOMAGNETICSTRATIGRAPHY

O-r/)

2- ~::I:1

Z4- ~

(J) ~:3 6- ~f-­W:;;:

I

t14- ~wo

New Diatom from the Pleistocene-BuRCKLE, HAMMOND, AND SEYB

20- '---'---'

FIGURE 2. Paleomagnetic stratigraphy and range of Rhizosolenia matuyamai for three cores from the north Pacific.On the right of each core is the range of this species in DSDP site 173. The basis for the correlation of the paleo­magnetic stratigraphy is given in the text.

the Jaramillo in the north Pacific. Ling (1970) yama in each of three cores studied as thediscussed the problem of the geologic occur- Jaramillo.renee of M. elliptica. He reported it from the In all three cores, Rhizosolenia matuyamaiMiocene of the north Pacific as well as the first appeared just below the base of thePleistocene. Similarly, Bukry and Foster Jaramillo. In two of the cores, this form(1973) reported that this species ranges from last appeared in the lower part of the Jara­the Late Pliocene to the Middle Pleistocene millo. In the third core (K75-3, Figure 2),in the easternmost equatorial Pacific. Burckle the last occurrence was coincidental with(in press) considers these occurrences and the base of the Jaramillo. It seems apparentdemonstrates that the last occurrence of this to us, therefore, that the lowermost part ofspecies is isochronous and is closely related the Jaramillo is missing in this core.

---~('>-the-onset-of-Isotopid5tage-2-z-eShackleton--loLesLtlre-bic>slratigrapnic utIlIty onnis-·and Opdyke 1976). In addition to these data, form, we have reexamined a core fromDonahue (1970) showed that the diatom DSDP hole 173 from off the northern coastActinocyclus oculatus disappears in the north of California (Table 1). In this core the topPacific near the top of the Jaramillo. Koizumi of the A. oculatus zone occurs at approxi­(1975) used this last appearance to identify mately 28 meters, while R. matuyamai rangesthe top of his A. oculatus zone. These two from 37 to 43 meters. These data are atlines of evidence are used to identify the variance with the paleomagnetic results ofuppermost normal event within the Matu- Heinrichs (1973), who recorded the Jara-

:.~ v. ...~'" '. l'

212 PACIFIC SCIENCE, Volume 32, April 1978

34

5

6FIGURES 3-6. Rhizosolenia matuyamai sp. nov. All ma,gnifications are x 2000.

New Diatom from the Pleistocene-BuRcKLE, HAMMOND, AND SEYB 213

We also acknowledge the Deep Sea DrillingProgram for allowing us access to samplesfrom site 173. The biostratigraphic part ofthis study was carried out while one of us(L.H.B.) was on vacation in Hawaii. Hethanks his wife, Evelyn, for letting him usehis vacation time properly.

APPENDIX: TAXONOMIC NOTE4

4Prepared by Lloyd H. Burckle.

millo event between 25 and 28 meters.However, this is regarded as tentative be­cause of the low intensity of the samples(Heinrichs, personal communication 1976).

CONCLUSIONS

Rhizosolenia matuyamai, a new fossilmarine diatom, is reported from MiddlePleistocene sediments of the north Pacific.This form should help resolve problems inbiostratigraphy and correlation in high north­ern latitudes.

Genus Rhizosolenia Ehrenberg (1841)Rhizosolenia matuyamai sp. nov.

Figures 3-6Description: Valve cylindrical, moderately

robust, widened at the base, and taperingtoward the apex. Rows of radial punctae runfrom base of valve to just below the apicalprocess. Apical process is long, taperingwith a moderate to pronounced bend justabove its base. This bend ranges from 7 to200

• A central canal runs the entire lengthof the apical process. At the base, the canalwidens into a teardrop-shaped cavity (am­pulla). At the apical end a V-shaped slotprojects into the central canal.

Discussion: This species differs fromRhizosolenia bergonii by the pronouncedbend near the base of the apical process.This bend is the single most importantfeature of this new form.

LITERATURE CITED

BUKRY, D., and J. H. FOSTER. 1973. Silico­flagellate and diatom stratigraphy, Leg 16.Pages 815-871 in T. H. Van Andel, G. R.Heath et al. Initial reports of the DeepSea Drilling Project. Vol. 16. U.S. Govern­ment Printing Office, Washington, D.C.

BURCKLE, L. H. 1972. Late Cenozoic plank­tonic diatom zones from the eastern equa­torial Pacific. Bech. zur Nova Hedwegia39:217-246.

---. In press. Pliocene and Pleistocenediatom datum levels from the equatorialPacific.

BURCKLE, L. H., and N. D. OPDYKE. In press.Late Neogene diatom correlations in thecircum-Pacific. Internat. Congr. Pac. Neo­gene Strat., First Tokyo Proc.

DONAHUE, J. G. 1970. Pleistocene diatomsas climatic indicators in north Pacificsediments. Geol. Soc. Am. Mem. 126: 121­138.

HAYS, J. D., T. SAITO, N. D. OPDYKE, andL. H. BURCICLE. 1969. Pliocene-Pleistocenesediments of the equatorial Pacific-theirpaleomagnetic, biostratigraphic andclimatic record. Geol. Soc. Am. Bull.80 : 1481-1514.

HEINRICHS, b. F. 1973. Paleomagnetic studiesof sediments from DSDP site 173. Pages843-846 in L. D. Kulm, R. Von Huene,

ACKNOWLEDGMENTS et al. Initial reports of the Deep Sea DrillingllS study grew out of1li-e-n-e-e-'d---;t-o~i'd-en-t;O-if"y--Pro-ject-;-Vol-;-I-8-;-tJ-;-S-=-ouverrrment-F)rintin-g-

additional datum levels for the Pleistocene Office, Washington, D.C.of the north Pacific. Discussions with a KorZUMI, I. 1975. Late Cenozoic diatomnumber of colleagues have been most helpful biostratigraphy in the circum-Pacific re-in realizing this objective. In particular, we gion. J. Geol. Soc. Japan 81: 11-627.thank Fritz Theyer and Tsunemasa Saito. LING, H. 1970. Silicoflagellates from central

north Pacific core sediment. Bull. Am.Paleont. 58: 85-129.

SCHRADER, H. J. 1973. Cenozoic diatoms

214

from the northeast Pacific, Leg 18. Pages673-698 in L. D. Kulm, R. Von Huene,et al. Initial reports of the Deep SeaDrilling Project. Vol. 18. U.S. GovernmentPrinting Office, Washington, D.C.

SEYB, S. M., S. R. HAMMOND, and T. GIL­LIARD. 1977. A new device for recording

PACIFIC SCIENCE, Volume 32, April 1978

the behavior of a piston corer. Deep-SeaRes. 24(10): 943-950.

SHACKLETON, N. J., and N. D. OPDYKE. 1976.Oxygen isotope and paleomagnetic strati­graphy of Pacific core V28-239, LatePliocene to latest Pliocene. Geol. Soc. Am.Mem. 145: 449-464.

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