Reworking of ichthyoliths in eastern tropical Pacific sediments

Deep-Sea Research. 1977, Vol. 24, pp. 181 to 198. Pergamon Press. Printed in Great Britain

Reworking of ichthyoliths in eastern tropical Pacific sediments

P. S. DOYLE,* M. J. DUNSWORTH* and W. R. RIEDEL*

(Received 23 December 1975 ; accepted 1 July 1976)

Abstract--Evaluation of the extent of rewo rking of ichthyoliths (microscopic skeletal debris of fishes ) in Cenozoic sediments of the eastern tropical Pacific indicates that they are less easily put into suspension and transported than are some other solution-resistant microfossils, such as radiolarians. Consequently, they probably tend to be concentrated as lag deposits in some places. On the other hand, ichthyoliths are reworked sufficiently to permit their geographic distribution in relation to the crest of the East Pacific Rise to be used as an indication of their upper stratigraphic limits. In the course of this investigation new information has been accumulated on the stratigraphic ranges of some Tertiary ichthyoliths.

I N T R O D U C T I O N

RECENTLY, in investigations of pelagic sediment sequences obtained by the Deep Sea Drilling Project, ichthyoliths have proved useful in providing approximate age determinations where other microfossil groups are lacking (DOYLE, KENNEDY and RIEDEL, 1974 ; DENGLER, DOYLE and RIEDEL, 1975 ; DUNSWORTH, DOYLE and RIEDEL, 1975). Although practically ubiquitous in pelagic sediments, these microfossils usually occur in low concentrations, and it is therefore difficult to amass convincing evidence on their stratigraphic ranges. In particular, it is important to evaluate whether the sparse occurrences of many ichthyotiths in the upper parts of their ranges (see numerous examples in the cited papers) are truly indicative of their persistence through the period of time concerned, or whether they are due to erosion of forms from older sediments and their incorporation into younger deposits. Such reworking was a substantial hurdle to the development of radiolarian stratigraphy (RIEDEL, 1952, 1957), and it could be equally widespread in the case of these ichthyoliths, which are even more resistant to solution.

In approaching this problem, a promising course seems to be to examine the distribution of ichthyolith taxa in relation to sea-floor ages in an area where the history of Cenozoic sedimentation and the pattern of distribution of reworked radiolarians are well understood. We have chosen an area in the eastern tropical Pacific, between the equator and about 30C'N latitude, and the East Pacific Rise and about 170°W longitude, because these conditions are fulfilled there and the geographic distribution ofichthyoliths in relation to crustal age in that region could provide information on stratigraphic ranges as indicated in Fig. 1. As new crust has continued to be produced at the crest of the East Pacific Rise, older sediments have been carried away from the crest, and the sediment column represents progressively less geologic time toward the crest. Radiolarians representing all of the ages in the sediment column are known to occur at or near the sediment surface at many localities in this region (RIEDEL, 1967, 1971). Thus, for at least some sedimentary components, reworking has been sufficiently

* Scripps Institution of Oceanography, La Jolla, CA 92093, U.S.A.

181

182 P.S. DOYLE, M. J. DUNSWORTH and W. R. RIEDEL

WEST

Eastern l imit of Eastern limit of

EAST

forms ext inct in forms extinct in F a s t P a c i f i c late Eocene ~ late Miocene ~, R i s e C r e s t

At,

- - Quoternor

Oligocene Eocen &C3 OeO'3'~

Fig. 1. Schematic representation of the relations between spreading from the East Pacific Rise crest, reworking of microfossils into surface sediments, and their upper stratigraphic limits as reflected by their geographic distribution. Quaternary sediments at locality A contain autochthonous microfossils plus reworked forms from the Pliocene, Miocene, Oligocene, and Eocene. At locality B, Quaternary sediments contain autochthonous microfossils plus reworked forms from the Pliocene and Miocene. Topographic irregularities (not shown) permit erosion of the oldest sediments. Although the diagram

is labelled only for the latest Eocene and latest Miocene, the situation in nature is a continuum.

pervasive to permit their geographic distribution in relation to the rise crest to be used as an indication of their latest occurrence in the geologic record.

MATERIAL INVESTIGATED AND I C H T H Y O L I T H S PRESENT

From the region selected, we have examined some 80 samples of both known and unknown ages, from the Scripps Institution of Oceanography geological collection and the Deep Sea Drilling Project, chosen to provide geographic and age coverage as well as reasonably large numbers of ichthyoliths. Sampling locations are plotted in Fig. 2, and further details are provided in the Appendix. Ichthyoliths in samples of known age from this region are shown in Table 1, and those in samples of unknown age (other than from ichthyolith interpretation) in Table 2. Ichthyolith occurrences in samples from other localities, useful in determining the stratigraphic ranges of the various taxa, are shown in Table 4 (in the Appendix). Numbers of individuals of each taxon are given under their colloquial names, as well as the total number of tooth-like ichthyoliths in each sample. For the system of formal nomenclature, see DOYLE, KENNEDY and RIEDEL (1974), RAMSEY, DOYLE and RIEDEL (1976) and DUNSWORTH, DOYLE and RIEDEL (1975).

INDICATIONS OF REWORKING AND ITS LIMITS

A few of the samples included in Tables 1 and 2 show clear evidence of older forms reworked into younger assemblages--MSN 7P, 16-33 cm ; JYN V 47P, 124-135 cm ; PROA 168G, 90-102cm; JYN V 42P, 136-142cm; JYN V 23P, 149-155cm. All of those occurrences are at localities at which the crust is Eocene or older.

On the other hand, it appears that ichthyoliths are not reworked so readily as radiolarians. Evidence for this is provided by five samples with ichthyolith assemblages that appear inconsistent in Table 1 - -DSDP 41-1-6, 50-59 cm; JYN V 25P, 427-507 cm; JYN V 10P,

~ ~ QUATERNARY

+otal number of tooth-shaped ichthyoliths

~ite-shaped irregular network

"ive peaks flared base

'lain lanceolate

~all triangle crenate margin

~hombus ~mooth margin

"riangle sigmoid

~iangle pointed margin ends

Isy.~etrical peaks narrow d~ression

~ng triangle thin wall

~iangle short wing

Wide triangle

Triangle medium wing

Triangle transverse line across

Triangle triangular projection

Short kite-sha~ed

Kite-shaped longitudinal line Giant lanceolate

Triangle double flex

Triangle with canals

Curved trian Is ointed ~a in

Flexed triangle 102-112 Triangle with base angle

Rounded apex triangle

Flexed triangle shallow inbase e120

Small dendritic many radiating lines

~all dendritic few radiating lines

~ll circular center

arge with numerous lines

'lexed triangle 115 -118

ec~ula~ serially sawtoothed

'lexed narrow triangle 120-128

~all triangle long striations

'~ular with line across

arge triangle sawtoothed

'hort triangle stepped margin

~tippled triangle

~lliptical with line across

Song triangle stepped margin

~hree tail peaks

Varrow triangle ragged inbase

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Total number of tooth-shaped i chthyo] i ths

Kita-e~ped irPegular nstuork

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870 875 cm and 904-929 cm ; and D O D O 30P, 535 544cm. These samples were originally believed to be Eocene on the basis of their contained radiolarians, but their ichthyoliths are more consistent with a Pliocene or younger age (and they are so placed in Fig. 2). Re- examination of the radiolarians confirmed that none younger than Eocene is present. The conclusion, briefly mentioned in an earlier paper (DuNSWORTH, DOYLE and RIEDEL, 1975), is that radiolarians are present only in Quaternary and Eocene sediments in the vicinity of these four cores, and the age of the samples in question is indeed Pliocene or younger as indicated by the ichthyoliths, while the Eocene radiolarians are the result of reworking. Similarly, many tropical Pacific sediment cores contain only Eocene radiolarians in late Tertiary calcareous oozes, for example the lower part of D W B G 36 described by RIEDEL and FUNNELI, (1964).

The fact that Eocene ichthyoliths do not accompany the reworked radiolarians in the tabulated samples is evidently a result of their greater density causing them to be less readily transported than radiolarians. Ichthyoliths are not absent from Eocene sediments at nearby localities such as DSDP 163, JYN V 28P and, at a somewhat greater distance, MSN 7P. It seems inevitable, therefore, that ichthyoliths must form lag concentrations, when more easily transported components of the sediments are removed and deposited elsewhere. This, rather than an unusually high rate of organic production of ichthyoliths, may explain the high concentrations in some samples.

ICHTHYOLITH STRATIGRAPHY AS RELATED TO REWORKING

Despite the fact that ichthyoliths are not so readily reworked as some other groups of microfossils, the process does occur to a sufficient extent to introduce uncertainty into the upper stratigraphic limits of some taxa. Examples are Triangle pointed margin ends in Tables 1 and 4, and Small triangle crenate in Table 2. These forms occur more sparsely and sporadically in younger than in older assemblages, and it is necessary to find some means to determine whether or not this is due to reworking.

One possible source of information on the upper stratigraphic limits of taxa lies in their geographic distribution in relation to the age of the oceanic crust, as discussed above in connection with Fig. 1. Because ichthyoliths are reworked, the easternmost limits of the occurrence of taxa in the area under investigation should provide clues to the upper limits of their stratigraphic ranges. Even if the extent of their reworking is limited, isolated occurrences over young crust would indicate that the taxon ranged upward to at least that crustal age. Contrariwise, non-occurrence of taxa over areas with young crust could provide evidence that their upper stratigraphic limits are older, so that their occurrences in younger sediments over old crust are due to reworking.

That this procedure can provide useful information on the upper stratigraphic limits of ichthyolith taxa is demonstrated by Table 3 and Fig. 3. In the table, ichthyolith taxa are listed in order according to their upper stratigraphic limits, those ranging highest being at the bot tom of the table. Their occurrences are listed according to longitude, which is related to crustal age sufficiently directly for our present purposes, and the upper right-hand corner of the table is blank as expected as a result of the non-occurrence, in areas with young crust, of forms long extinct. Figure 3 shows the stratigraphic ranges of ichthyoliths known from sediments dated on the basis of co-occurring microfossils of other groups, with triangles indicating the age of the youngest crust over which they have been found in the eastern tropical Pacific (from Fig. 1 and Tables 1 and 2) because of uncertainty of crustal age near the rise crest in this region, we have not attempted to place triangles corresponding to crust younger than early Miocene. The triangles are filled in those instances in which we believe

Reworking of ichthyoliths in eastern tropical Pacific sediments 189

~z

Quaternary

Pl iocene

l a t e N2ocene

m~ddle Miocene

e a r l y Miocene

l a t e Ol lgocene

e a r l y Ol igocene

l a t e Eocene

middle Eocene

e a r l y Eocene

• .~ ~

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Fig. 3. Stratigraphic ranges ofichthyoliths as presently known. Sparse occurrences are indicated by dotted lines, and doubtful age assignments by broken lines. Arrows are used to mark forms known to extend into Paleocene or older assemblages. Triangles show the age of the youngest crust over which each form has been found (the evidence being more significant in the case of filled triangles, as

discussed in the text).

that the evidence from crustal age is sufficiently strong to indicate that the occurrences in younger samples may well be due to reworking, whereas open triangles are used for cases in which the evidence is not yet sufficient to indicate upper limits of stratigraphic ranges. Thus the occurrences of Small triangle crenate, Triangle pointed margin ends, and Triangle triangular projection in samples younger than indicated by the filled triangles could well be due to reworking.

It is necessary to exercise caut ion in this interpretation, because of the strong possibility that some ichthyoli th subtypes have different stratigraphic ranges in different biogeographic regions, due to ecological controls. It seems clear that the distribution of Stippled triangle is biogeographically restricted, because it has not been found in sediments west of about 122 ° W in the region under investigation, and similar controls may have affected the distribution of other subtypes, resulting in too low placement of open triangles in relation to solid lines in Fig. 3 (e.g. Long triangle stepped margin, Flexed triangle 115--118, Rectangular serially sawtoothed, etc.).

No t all forms of ichthyoliths are geographically limited to parts of this region, as is evident from the occurrences of Narrow triangle ragged inbase, Small triangle long striations and Triangle sigmoid. The first two range from Pliocene to Quate rnary and Miocene to Quaternary , respectively, and Tables 1 and 3 show that they occur in sediments within those age ranges over the entire region. The distribution of Triangle sigmoid with respect to longitude (Table 3) clearly shows not only the absence of any geographical restriction, but

Tab

le 3

. Ic

hthy

olit

h oc

curr

ence

s in

the

east

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trop

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Pac

ific

arr

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d by

lon

gitu

de (

sum

mar

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in

form

atio

n fr

om T

able

s 1

and

2).

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t are

at

the

bo

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f th

e ta

ble,

tho

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ith

olde

st u

pper

lim

its a

re a

t th

e to

p of

the

tabl

e.

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171-

160

160-

15

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? + +

4"

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Age

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+

+

+

+

+

+

+

+

+

+

+

+

+ ?

+

+

+

+ +

÷

+

+

+

+

+

+

+

+

+

+

÷

+

+

+

+

+

+

+

+1

+

+

Mio

cene

an

d yo

u.g

et

o 0


also an upper stratigraphic limit much higher than previously assumed. For all other ichthyoliths, the evidence from crustal age indicates that the upper stratigraphic limits are either at or below the levels arrived at by investigation of samples dated on the basis of other microfossil groups.

CONCLUSIONS

Two obstacles to developing a stratigraphy of ichthyoliths are their low concentration in most pelagic sediments and their ability to survive reworking because of their resistance to solution. Those obstacles can be overcome, to a limited extent, by combining the results of numerous samples to form a regional picture in which limits to geographic distribution resulting from differing crustal ages can provide evidence on stratigraphic ranges. To compensate further for the low numbers of ichthyoliths, it would be desirable either to separate them from samples much larger than the usual 30 to 50 cm 3 of pelagic sediment, or to group specimens into fewer taxa by developing the capability of recognizing the diversity of forms produced by one and the same organism (fish). This line of investigation cannot, however, provide results having as great a degree of reliability as is attainable with the more abundant types of planktonic microfossils.

The low-latitude Cenozoic stratigraphy of this microfossil group is beginning to be known well enough that it would seem appropriate to initiate studies of their biogeography. Some forms can already be seen to be geographically restricted, and further investigation of their relation to present and past water masses might lead to their application to paleoecological interpretations.

Acknowledgements ---This research was supported partly by National Science Foundation grant no. GA-40158 and partly by the University of California. DAVID J. BUKRY generously provided assignments of some samples to calcareous nannofossil zones---an important factor in developing a coherent biostratigraphy. M. A. HANGER and S. E. HI[.I. MINCHILLI typed and proof-read the manuscript. Samples from the Deep Sea Drilling Project were made available by the National Science Foundation. H. W. MENARD kindly reviewed the manuscript and made suggestions resulting in its improvement.

REFERENCES

DENGLER A. T., P. S. DOYLE and W. R. RIEDEL 0975) Ichthyoliths in some samples from the Philippine Sea, Deep Sea Drilling Project, Leg 31. In: Initial reports of the Deep Sea Drilling Project, D. E. KARIG, J. C. INGLE, JR., A. H. BOUMA, C. H. ELLIS, N. HALLE, I. KOIZUMI, H.-Y. LING, I. MACGREGOR, J. C. MOORE, H. U JilL, T. WATANABE, S. M. WHITE and M. YASU~, U.S. Government Printing Office, 31,821 833.

DOYLE P. S., G. G. KENNEDY and W. R. RIEDEL (1974) Stratignathy. In: Initial reports of the Deep Sea Drilling Project, T. A. DAVIES, B. P. LUYENDYK, K. S. RODOLFO, D. R. C. KEMPE, B. C. MCKELVEY, R. D. LEIDY, G. J. HORVATH, R. D. HYNDMAN, H. R. THIERSTEIN, R. C- HERB, E. BOLTOVSKOY and P. DOYLE, U.S. Government Printing Office, 26, 825 905.

DUNSWORTH M. J., P. S. DOYLE and W. R. RIEDEL (1975) lchthyoliths from some NW Pacific sediments, DSDP Leg 32. In: Initial reports of the Deep Sea Drilling Project, R. L. LARSON, R. M. MOBERLY, J. B. KEENE, Y. LANCELOT, A. MATTER, J. V. GARDNER, H. LUTERBACHER, D. BUKRY, H. P. FOREMAN and M. C. MARSHALL, U.S. Government Printing Office, 32, 853-863.

HAYS J. D., H. E. COOK, III, D. G. JENKINS, F. M. COOK, J. T. FULLER, R. M. GOLL, E. D. MILOW and W. N. ORR (1972) Site 82. In : Initial reports of the Deep Sea Drilling Project, U.S. Government Printing Office, 9, 487-535.

HELMS P. B. and W. R. RIEDEL (1971) Skeletal debris of fishes. In: Initial reports of the Deep Sea Drilling Project, E. L. WINTERER, W. R. RIEDEL, R. M. MOBERLY, JR., J. M. RESIG, L. W. KROENKE, E. L. GEALY, G. R. HEATH, P. BRONNIMAN, E. MARTINI and T. R. WORSLEY, U.S. Government Printing Office, 7(2), 1709-1720.

LAUGHTON A. S., W. A. BERGGREN, R. N. BENSON, T. A. DAVIES, V. FRANZ, L. F. MUSICH, K. PERCH-NIELSEN, A. S. RUFFMAN, J. E. VAN HINTE, R. B. WHITMARSH, H. NELSON, S. A. J. POCOCK, P. A. HAQUEBARD, J. A. JELETSKY, T.


W. BLOXAM, G. KELLING, N. P. JAMES, J. C. HOPKINS, E. A. PESSAGNO, J. K. LANGORIA and D. BUKRY (19"72) Site 111. In: Initial reports of the Deep Sea Drilling Project, U.S. Government Printing OffÉce, 12, 33 159.

MCMANuS D. A., R. E. BURNS, C. VON DER BORCH, R. GOLL, E. D. MILOW, R. K. OLSSON, T. VALLIER and O. WESER (1970) Sites 39 40. In: Initial reports of the Deep Sea Drillin.q Project, U.S. Government Printing Office. 5, 297---367.

PITMAN W. C., III, R. L. LARSON and E. M. HERRON (1974) The a.qe of the ocean basins, Geological Society of America, 2 pp., 2 charts.

RAMSEY C. A., P. S. DOYLE and W. R. RXEDEL (1976) Ichthyoliths in late Mesozoic pelagic sediments, mainly from Italy. Micropaleontolo#y, 22, 129-142.

RIEDEL W. R. (1952) Tertiary radiolaria in western Pacific sediments. G&eborgs Kun#l. vetenskaps- och vitterhetsamhiilles handlin#ar, f61j 7, ser. B, 6(3), 22 pp.

RlEDEL W. R. (1957) Radiolaria: a preliminary stratigraphy. Reports ~!1" the Swedish Deep-Sea Expedition, 6(31, 61 96.

RIEDEL W. R. (1967) Radiolarian evidence consistent with spreading of the Pacific floor. Science, 157, 540 542. R~EI)EL W. R. (1971 ) The occurrence of pre-Quaternary Radiolaria in deep-sea sediments. In: The micropalaeon-

tology of oceans, B. M. FUNNELL and W. R. RIEDEt., editors, Cambridge University Press, pp. 567--594. RIEDEL W. R. and B. M. FUNNELL (1964) Tertiary sediment cores and microfossils from the Pacific Ocean floor.

Quarterly Journal (?f the Geological Society oJ London, 120, 305-368. I'RACEY J. I., JR., G. H. SUTTON, W. D. NESTEROFF, J. GALEHOUSE, C. C. VON DER BORCH, T. MOORE, J. LIPPS, U. Z. B.

HAQ and J. P. BECKMANN (1971) Sites 72 and 74. In: Initial reports o['the Deep Sea Drilling Project, L.S. Government Printing Office, 8, 459 534 and 675- 709.

VAN ANDEL T. H., G. R. HEATH, R. H. BENNETT, J. D. BUKRY, S. CHARLESTON, D. S. CRONAN, M. G. DINKELMAN, A. G. KANEPS, K. S. RODOLFO and R. S. YEATS (1973) Sites 159 163. In: Initial reports t?fthe Deep Sea Drilling Project. U.S. Government Printing Office, 16, 265 411.

WINTERER E. L., J. 1. EWING, R. G. DOUGLAS, R. D. JARRARD, V. LANCELOT, R. M. MOBERLY, T. C. MOORE, JR., P. H. ROTH and S O. SCHLANGER (1973) Site 165. In: Initial reports q[' the Deep Sea Drillinq Project, U.S. Government Printing Office, 17, 47-102.

AP P E NDIX

SAMPLES

Samples used in this study and not described in previous papers on ichthyoliths (HELMS and RIEDEL, 1971 ; DOYLE, KENNEDY and RIEDEL, 1974 ; DUNSWORTH, DOYLE and RIEDEL, 1975) are listed below. Those not from the Deep Sea Drilling Project are all from the collections of Scripps Institution of Oceanography. The bases for age assignments are given in parentheses.

A M P H 2P, 300-305 cm ; 19°24'N, 123°41 'W; water depth 4282 m approximately. A M P H 3P, 158-168cm; 15°04'N, 125°05'W; water depth 4440m approximately. A M P H 4G, 103 108 cm; 8°31'N, 127°25'W; water depth 4740 m. BNFC 8P, 270-275cm; 10°58.7'N, 108°32.2'W; water depth 3441m. (Nannofossils are in the Discoaster

pentaradiatus Zone according to P. Roth, personal communicat ion, 1974.) BNFC 9P, 200 205cm; 10°15.5'N, 108°58.1'W; water depth 3377m. (Nannofossils are in the Gephyrocapsa

oceanica Zone or younger according to P. Roth, personal communicat ion, 1974.) BNFC 17P, 155-160 cm ; 11 ° 10.6'N, 109°36.3'W; water depth 3522 m. BNFC 20P, 270-275 cm; 10°33.6'N, 108°23.0'W; water depth 4240 m (Radiolarians are Quaternary according to

J. Westberg, personal communication, 1974.) BNFC 25P, 60-65 cm; 10°22.5'N, 108°38.4'W; water depth 2693 m. BNFC 27P, 500-505cm; 10°34.0'N, 108°43.2'W; water depth 5310m. (Nannofossils are in the Gephyrocapsa

oceanica Zone or younger according to P. Roth, personal communicat ion, 1974.) BNFC 53P, 490 510cm and 515 517cm; 11°52.2'N, l l0°00.1 'W; water depth 3891m. (Nannofossils are late

Pliocene according to D. Bukry, personal communicat ion, 1974.) BNFC 59P, 875-880 cm ; 14°31.8'N, 117 ° 15.5'W ; water depth 4076 m. BNFC 60P, 1000-1005 cm; 14°34.4'N, 117°22.0'W ; water depth 4078 m. BNFC 73P, 800-805cm; 14°33.4'N, 117°18.2'W; water depth 3964m. (Nannofossils are in the Sphenolithus

heteromorphus Zone according to P. Roth, personal communicat ion, 1974.) BNFC 86P, 110 115 cm, 235-240cm, and 610-620cm ; 14°35.1'N, 121°03.7'W ; water depth 4295 m. CAP 49BP, 305-310 cm ; 9°17'N, 124°09'W; water depth 4410 m. D O D O 26P, 186 193 cm; 9°20'N, 169°00'W ; water depth 5138 m. D O D O 30P, 534 544cm; 9 °10'N, 168°50'W; water depth 5166 m. (Radiolarians are in the Thyrsocyrtis bromia

Zone with earlier Eocene admixture.)

] 94 P.S. DOYLE, M. J. DUNSWORTH and W. R. RIEDEL

DSDP 39-2-6, 50 59 cm; 32°48.28'N, 139°34.29'W; water depth 4929 m (early Eocene; McMANuS, BURNS, VON DER BORCH, GOLL, MILOW, OLSSON, VALLIER and WESER, 1970, p. 307).

DSDP 40-2-2, 50-58cm (late Eocene, p. 319) and 40-2-5, 50 59cm (middle Eocene, p. 319); 19°47.57'N, 139°54.08'W; water depth 5176 m (McMANUS, BURNS, VON DER BORCH, GOLL, MILOW, OLSSON, VALLIER and WESER, 1970).

DSDP 41-1-6, 50-59 cm ; 19°51.25'N, 140°02.88'W ; water depth 5337 m (late Eocene; MCMANUS, BURNS, VON DER BORCH, GOLL, M1LOW, OLSSON, VALLIER and WESER, 1970, p. 359).

DSDP 42-1-4, 50 56cm and 42-2-3, 50 56cm; 13J50.56'N, 140°11.31'W; water depth 4844m (late Oligocene; MCMANUS, BURNS, VON DER BORCH, GOLL, MILOW, OLSSON, VALLIER and WESER, 1970, pp. 379, 383).

DSDP 72-1-6, 44 53 cm (Quaternary, p. 482) and 72-2-3, 48-54 cm (late Miocene, p. 484); 0 26.49'N, 138°52.02'W ; water depth 4326 m (TRACEY, SUTTON, NESTEROFF, GALEHOUSE, VON DER BORCH, MOORE, LIPPS, HAQ and BECKMANN, 1971).

DSDP 82A-2-3, 50-56cm (late Pliocene, p. 520) and 82-6-3, 50--56cm (upper Miocene, p. 530); 2°35.48'N, I06°56.52'W; water depth 3689 m (HAYs, COOK, JENKINS, COOK, FULLER, GOLL, MILOW and Ogg, 1972).

DSDP 111A- 10-4, 72-83 cm; 50°25.57"N, 46°22.05'W; water depth 1797 m (early Eocene; LAUGHTON, BERGGREN, BENSON, DAVIES, FRANZ, MUSICH, PERCH-NIELSEN, RUFFMAN, VAN HINTE, WHITMARSH, NELSON, POCOCK, HAQUEBARD, JELETSKY, BLOXAM, KELLING, JAMES, HOPKINS, PESSAGNO, LANGORIA and BUKRY, 1972, p. 147).

DSDP 159-2-6 (late Miocene?, pp. 159, 241 ) and 159-12-2 (late Oligocene, p. 251 ); 12°19.92'N, 122°17.27'W ; water depth 4484 m (VAN ANDEL, HEATH, BENNETT, BUKRY, CHARLESTON, CRONAN, DINKELMAN, KANEPS, RODOLFO and YEATS, 1973).

DSDP 160-9-3, 70-76 cm (late Oligocene, p. 282) and 160-12-5, 71 77 cm (early Oligocene, p. 272): 11' 42.27'N, 130°52.81'W; water depth 4940m (VAN ANDEL et al., 1973).

DSDP 161A-11-5, 74-80 cm ; 10°14.25qN, 139°57.21'W; water depth 4939 m (late Eocene; VAN ANDEL et al., 1973, p. 337).

DSDP 162-2-3, 73 80cm (early Oligocene, p. 377) and 162-5-4, 75-80cm (late Eocene, p. 380), 14°52.19'N, 140°02.61'W; water depth 4854m (VAN ANDEL et aL, 1973).

DSDP 163-5-3, 70-76 cm (late Eocene, p. 420), 163-11-5, 70-76 cm (middle Eocene, p. 420) and 163-22:5, 72 78 cm (Campanian, p. 422); 11°14.66'N, 150°17.52'W; water depth 5230m (VAN ANDEL et al., 1973).

DSDP 165A-13-4, 45 47cm (middle Eocene, p. 81); 08°10.7"N, 164°51.6'W; water depth 5053m (WINTERER, EWING, DOUGLAS, JARRARD, LANCELOT, MOBERLY, MOORE, ROTH and SCHLANGER, 1973).

DWBG 6, 97--101 cm ; 9°36"N, 130°41'W; water depth 5003 m. FAN BP 2, 372 378 cm ; 28°32.5'N, 117°20'W ; water depth 3580 m. JYN V 8G, 29 32cm; 13°26'N, 152°17'W; water depth 5746m. JYN V 10P, 870-875 cm ; 12°43"N, 152°06'W ; water depth 5549 m. (Radiolarians are in the Theocyrtis tuberosa

Zone, with overwhelming Eocene admixture.) JYN V 23P, 149 155 cm; 10°09'N, 147°33'W; water depth 5241 m. JYN V 25P, 427 507 cm; 13°05'N, 147°19'W; water depth 5455 m. (Radiolarians indicate Podocyrtis goetheana

Zone.) JYN V 27P, 80 85 cm; 15°29'N, 147°04'W ; water depth 5424 m. JYN V 28P, 396-399 cm; 14°13'N, 146°24'W ; water depth 4952 m. JYN V 42P, 136 142cm; 9°00'N, 139°51'W; water depth 5000m. JYN V 47P, 124-135cm; 14°39'N, 135°04'W; water depth 4813 m. LSDH 93P, 310-321 cm; 9°49rN, 170°59'W; water depth 4875 m. LSDH 96P, 400 411 cm ; 15 ° 10'N, 164°39'W ; water depth 5523 m. LSDH 99G, 65-75 cm ; 20°07'N, 145°16'W ; water depth 5370 m. MP 3, 401 438 cm; 20°51rN, 127°16'W; water depth 4702m. MSN 2P, 839 846cm; 23°15'N, 130°46'W; water depth 4950m. MSN 7P, 16---33 cm (radiolarians are probably upper Miocene or younger with reworked Eocene; J. Westberg,

personal communication, 1974); and 850 860 cm; 14°09'N, 161°08'W; water depth 5652 m. MSN 154P, 383-406 cm and 556-582 cm (radiolarians at 556 582 cm are in the Calocycletta virginis Zone with

some Eocene reworking; J. Westberg, personal communication, 1974); 15°01'N, 137°01'W; water depth 4920 m.

PAPA 120G, 160--168 cm; 20°56'N, 112°03'W; water depth 3379 m. (Radiolarians are probably Quaternary; J. Westberg, personal communication, 1974.)

PROA 168G, 90-102 cm; 14°56'N, 167°34'W; water depth 4315 m. PROA 174G, 120-131 cm ; 18°26~N, 162 °32'W ; water depth 5420 m. (Radiolarians are probably Quaternary ;

J. Westberg, personal communication, 1974.) RIS 4P, 606-611 cm; 22°17'N, 117°24'W ; water depth 3890 m. RIS 6G, 46-60 cm ; 18°45'N, 117°09'W ; water depth 4060 m. RIS 8P, 650-655 cm and 705-717 cm ; 14°26'N, 117°12'W ; water depth 4065 m. RIS 114P, 404-409 cm ; 21°33'N, 132°54'W; water depth 5040 m. RIS 120P, 224 229 cm, 480-490 cm, and 760 767 cm ; 28°19'N, 133°20'W ; water depth 4420 m.


TET 3G, 50-56 cm ; 13°14'N, 127°06'W; water depth 4758 m. TRI 5P, 192-202cm, 210-215 cm and 470 475 cm; 15°38'N, 112°12'W; water depth 3929 m. (Radiolarians are

Quaternary; J. Westberg, personal communication, 1974.) TRI 7P, 150-155 cm and 460~465 cm ; 17°30'N, 113°00'W; water depth 3697 m. ZTS VII 33G, 130 140cm; 20°47'N, 152°01'W; water depth 5118 m. ZTS VII 39G, 122-130 cm ; 28°40'N, 144°35'W ; water depth 5048 m.

ADDITIONAL STRATIGRAPHIC INFORMATION During the course of this work it has been necessary to investigate the stratigraphic distribution of some

ichthyoliths in greater detail than had been done previously. The results add substantially to our understanding of the stratigraphy of these microfossils and are presented in Table 4. Many of the samples have been used in previous ichthyolith publications, but the list of forms recorded here is more comprehensive.

Calcareous

nann

ofos

si)

Age

zone

s

D.

b~'o

uwer

¢

,. \\

\\~

<

] R

. ps

eudo

- u~

bi ~i

oa

D.

qu

in-

que~

,am

uB

:o

Tab

le 4

. Ic

hthy

olit

hs i

n sa

mpl

es o

f kn

own

ages

(nu

mbe

rs o

f sp

ecim

ens

foun

d).

Tax

a ar

e or

dere

d ac

cord

ing

to t

heir

str

atig

raph

ic r

ange

s. E

xcla

mat

ion

mar

ks (

!) i

ndic

ate

spec

imen

s be

liev

ed t

o be

re

wor

ked

or c

aved

. S

even

add

itio

nal

sam

ples

exa

min

ed a

nd f

ound

not

to

cont

ain

icht

hyol

iths

of t

he

subt

ypes

ta

bula

ted

are-

-DS

DP

29

B-4

-2,

90-9

6cm

; D

SD

P

14-3

-3,

50

56cm

; D

SD

P

75-4

-4,

75

80 c

m;

DS

DP

75-

5-4,

67

71 c

m;

DS

DP

19-

4-3,

50-

56 c

m;

DS

DP

19-

8-3,

50-

56 c

m;

DS

DP

119

- 21

-2, 5

0 56

cm

.

Taxa

~'~

DSD

P 15

-1-3

, 54

-60c

m

15

DSD

P 1

5-2

-I,

20-2

6cm

19

PRO

A 12

8G, 6

7-70

cm

122

DSD

P 3

13

-I-2

, 50

-54c

m

37

DSD

P 3

13

-i-4

, 30

-34c

m

176

DSD

P 3

13

-1-4

, 90

-93c

m

131

DSD

P 3

13

-1-5

, 40

-43c

m

124

AMPH

.98P

, 50

0-50

3cm

31

DSD

P 15

-2-5

, 44

-50c

m

18

DSD

P 2

9-2

-3,

56-6

0cm

30

DSD

P 11

9-3-

2,

50-5

6cm

21

DSD

P 11

9-3-

2,

68-7

2cm

22

DODO

11

7,

216-

232c

m

52

AM

PIt

130G

, 90-

93cm

30

DSD

P 2

9-4

-3,

110-

114¢

m

26

MSN

5~

P,

i09-

113c

m

129

DSD

P 15

-4-6

, 54

-60c

m

16

DSD

P 15

-5-3

30

-34c

m

43

PRO

A iO

3P,

297-

300c

m

64

PRO

A I0

3P,

300-

320c

m

358

DSD

P 30

4-2-

CC

60

USD

P 3

13

-I-b

, bU

-bbc

m

l 14

3

DSD

P 31

3-I-

CC

I

190

DSD

P 2

9B

-I-6

, 85

-89c

m

34

DSD

P 11

9-4-

2,

40-4

4cm

73

MSN

146

P,

354-

375c

m

315

[° I

• ~

~ ~

,~ 2

I 1 1

1 2

1 1 ?

1

1

1

2 2 2[

1

4

2 1

11

1:

1

1

3 1

.~

~

1 1

2i3

1 ,1 5 1

3 1

4 1

6 1

I

I 2

! I

2 5

i'.

I 2

1 1

2

2 1

3 2

2 3]

2 7

4

i I I

1

i 10

3

6 i

9

2 i

3 1

2

3 5

I 1

2 1

I

2 i

2 7

4!

7 3

6 I I

3 i i

1 2

I 3

1

i i

1 1 I

4 1

2 i 7 5 i

4 4 15

2

i

1 4

I

?

T~

,..<

Z

©

,'r

ru

D.

ha,r,

a ~a

\\\\

\\"

~ p.

~

el/.

ie

'E-

,',,

,\\\

\\

S.

h.e t

ero-

~o

rphu

s

H,

~li

- ap

ert.a

S. be~mmoe

T.

om

4.n

a~

s

s.

e@er

o-

ensi

s

\\\\

\\\

S.

dget

~n~u

8

I°I

I U~u

P Z

gB-Z

-3,

5U-5

6cm

DSO

P 29

B-2

-3,

69-7

3cm

DSD

P 29

B-3

-2,

S3-

87cm

PRO

A 96

P,

297-

300c

m

DSD

P 11

9-5-

2,

50-5

6cm

DSD

P 11

9-5-

2,

58-6

2cm

PRO

A 96

P,

480-

483c

m

DSD

P 15

-6-3

, 44

-50c

m

OSD

P 1

5-6

-3,

65-6

9cm

DSD

P 1

5-7

-3,

56-6

0cm

DSD

P 15

-7-3

, 60

-66c

m

DSD

P 29

-7-1

, 12

3-12

7cm

DSD

P 29

B-4

-3,

84-8

8cm

OSD

P 29

B-5

-4,

97-1

01cm

M

SN 1

35P

, 70-

73cm

~i

PH

10

9P,

325-

328c

m

DO

00 3

7P,

356-

370c

m

OO

DO 3

7P,

490-

500c

m

DO

00 3

8P,

132-

152c

m

9SD

P 1

4-1A

-3,

80-8

4cm

0000

38P

, 43

0-45

0cm

MSN

135

P,

702-

705¢

m

DSD

P 14

-2-2

, 33

-37c

m

DSO

P 14

-2-3

, 50

-56c

m

DSD

P 15

-8-3

, 56

-60c

m

DSD

P 15

-8-5

, 77

-81c

m

DSD

P 75

-1-2

, 50

-56c

m

DSD

P 75

-2-2

, 35

-40c

m

DSD

P 75

-2-5

, 50

-56c

m

DSD

P 75

-3-5

, 40

-45c

m

DSD

P 11

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P 14

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DSD

P 75

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m

OSD

P 19

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, 40

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m

DSD

P 14

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, 74

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m

DSD

P 75

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, 40

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m

DSD

P 31

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m

DSD

P 3

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P 14

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P 14

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-39c

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170

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330

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72

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Reworking of ichthyoliths in eastern tropical Pacific sediments

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Transcript of Reworking of ichthyoliths in eastern tropical Pacific sediments