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R. M. Stainforth
The Micropaleontologist 1951 – 5:4:30

At a meeting of the Third World Petroleum Congress in The Hague last May, a resolution beginning with the words “It is the consensus of opinion of the palaeontologists here present or represented that by means of the pelagic foraminifera circumglobal correlations can be established in the Upper Cretaceous and Tertiary rocks…”  and concluding with proposals for concerted research into this problem, was presented and tabled.

The future will decide whether the goal of this resolution can be reached, but for the moment it is of interest to trace the development of this specialized branch of micropaleontology. A check of the literature available here in Peru indicates three successive stages. First, the general principle was established that fossils of planktonic organisms make ideal zonal indices, as in the case of graptolites and cephalopods. Then the zonal value of some planktonic foraminifera, such as Globigerina cretacea vars., Globorotalia velascoensis and the Hantkeninas, was established in an empirical manner along with the benthonic suite. In the third and final stage the special facies-free status of the planktonic forms was recognized, and authors began to stress and to demonstrate their high value in long-range correlations.

A surprising feature is that the earliest papers encountered under this third phase are dated 1948. Thus it seems that in three short years the subject has passed from obscurity to general recognition and appreciation. As a matter of record the earliest papers stressing the zonal value of planktonic foraminifera were written by paleontologists with experience in the Tertiary facies-complex of Trinidad. In that island the orthodox type of zonation based on benthonic microfossils proved so difficult to apply that a new method had to be developed. In the late thirties and early forties a group including T. F. Grimsdale, U. Haanstra, P. W. Jarvis, H. H. Renz, K. Schmid, G. P. J. Terpstra and others worked on the problem and solved it by establishing a master-zonation based on the facies-free Globigerinidae and Globorotaliidae.

Interest in the Radiolaria has lagged behind the studies of foraminifera, possibly for lack of a readily accessible systematic treatise. Campbell and Clark have published descriptions of Californian assemblages which greatly resemble the radiolarian faunas of equivalent age in western South America. W. R. Riedel is currently active in this field and it has a promising scope.

These notes are concluded with a few pertinent excerpts from the literature, to illustrate the three phases already mentioned. However, readers will please note that the literature available has included little beyond the readily accessible American journals. It is fully possible that important references may have been overlooked, especially in the European literature. Correspondence on this point would be welcome.

Phase I

1909 - SCOTT, W. B., An introduction to geology. Ed. 2. New York: Macmillan, p. 523.

“There is a great difference in the value of the various classes of organisms for chronological purposes, the most useful being those which have the most efficient means of very wide simultaneous dispersal. Such are the pelagic organisms which live et the surface of the sea and, either alive or dead, are carried for vast distances by the ocean currents.”

1934 - DAVIES, A. H., Tertiary faunas. London: Murby, vol. 2, p. 55.

“The possibility of using particular species as index fossils over wide areas depends upon their range in time and space. The ideal zone-fossil is a species which can spread over the whole earth in a time which is negligible compared with its duration as a species… The nearest approach to this ideal is made by the graptolites, the ammonites and the Mammalia…”

Phase II

Numerous faunal papers in the Journal of Paleontology, Thalmann’s well-known papers on Hantkenina, etc., indicate short life-ranges and wide geographic spread of various planktonic foraminifera but use the same empirical approach for the planktonic as for the benthonic species..

Phase III

1948 - RENZ, H. H., Geol. Soc. Amer., Mem., New York, no. 32, p. 78 (on the age-correlation of foraminiferal faunas).

“…if there are pelagic species of known time significance present in otherwise heterotopic faunas, a correlation will be possible regardless of the faunal facies…”

1948 - STAINFORTH, R. M., Jour. Pal., Tulsa, Okla., vol. 22, p. 114 (On age-significant foraminifera).

“The value of pelagic species lies in their wide lateral distribution consequent upon their drifting mode of life. As they died these organisms sank and eventually became part of the fossil fauna of the underlying sea-floor, whether the local facies happened to be neritic, lagoonal, reefal, or of some other type. In the two principal families of pelagic foraminifera, the Globigerinidae and the Globorotaliidae, the successive advent and extinction of species in Tertiary time is so spaced as to facilitate the erection of a practicable zonation based on their life-ranges. The truly regional value of this zonation is clearly shown by the almost precisely parallel distribution of species in the Middle Tertiary of Ecuador, on the extreme west of northern South America, and of Trinidad on the eastern extremity.”

1948 - LeROY, L. W., Jour. Pal., Tulsa, Okla., vol. 22, pp. 500, 501 (on microfaunsl correlation).

“…little attention has been given to the possible correlative time-value of the less diversified pelagic foraminifera. It is the writer’s conviction that this group of fossils holds the solution for improving and establishing more accurate long-range Tertiary correlations… Pelagic foraminifera, represented by fewer genera and species than the benthonic group, are more or less independent of bottom environment. Their distribution, development and dispersal are controlled by the physical and chemical nature of the upper layers of the sea, wind patterns, type and intensity of currents and inter-connection of sea-ways.”

1951 - GRIMSDALE, T. F., Third World Petroleum Congress, extract from preprint of a paper entitled “Correlation, age determination and the Tertiary pelagic foraminifera.” (Copyright E. J. Brill, Leiden; quoted by permission.)

“...Clearly these pelagic foraminifera have most of the hallmarks of ideal geological zone-fossils—abundance, wide and rapid dispersal, and freedom from what have lately been termed ‘problems of homeotopy and heterotopy which reduce the value of benthonic microfaunas in long-range correlation.’ In fact, their usefulness as guides for world stratigraphy might have been forecast—at least in theory—at any time during the past sixty years or more, certainly since the publication of the Challenger reports…”

Comparable statements have also been made by P. Brönnimann (1951, Micropaleontologist, vol. 5, no. 1, p. 4 ( and by J. Hofker (1950, ibid., vol. 4, no. 2, pp. 16, 17).

A new arrival in Talara is Irving S. Polson, now junior paleontologist with the International Petroleum Company. His past experience has been with Paleozoic ostracodes and fusulines, but he is now busy familiarizing himself with the Tertiary and Cretaceous foraminifera here. Your correspondent is mainly occupied with routine work but was able to attend a stimulating conference of “Jersey” geologists in New Orleans in March.

In connection with their deep test wells, the geologists of the Empresa Petrolera Fiscal have been doing some field work and revision of old wells. From the distribution of the foraminifera, it begins to seem that there has been confusion between conglomeratic sands, basal to the Upper Oligocene Heath formation, and a lithologically similar unit exposed near the village of Mancora. Both units have been called the Mancora formation, but it now seems that the type (surface) Mancora will prove to be an equivalent in age and facies of the late Eocene Mirador formation in the south of the area. The problem has regional implications (cf. the Hannatoma symposium, Jour. Pal., vol. 23, 1949, pp. 145-160), hence it is hoped that a definite solution can be reached.

Who says there’s nothing new under the sun? In over twenty years of operations here we had never encountered Chara in our samples. Now two wells twenty miles apart have disclosed rich charophyte faunas—floras, rather—in the lower Tertiaries, so we must modify our facies maps accordingly.