Tuatara: Volume 16, Issue 1, April 1968
Planktonic Foraminiferida as Indicators of New Zealand Tertiary Paleotemperatures
Planktonic Foraminiferida as Indicators of New Zealand Tertiary Paleotemperatures
Introducing Some Assumptions
Before Attempting to use planktonic Forminiferida as indicators of change in Tertiary paleotemperatures, it is necessary to consider some relevant basic assumptions.
Studies of the present day oceans have revealed that the largest population of living planktonic Foraminiferida occur in the upper 100m. of water, although living specimens have been obtained down to 2000m. It is therefore assumed that the majority of Tertiary species lived in the upper 100m. of water.
Geographic distribution of the Recent 40-50 species of planktonic Foraminiferida is primarily determined by temperature and consequently plots of species distribution indicate a latitudinal belt pattern. The basic assumption of uniformitarianism asserts that the present distribution is an indication of past distribution patterns, but it should be noted that the present is possibly an interglacial and therefore the distribution patterns of biota may be abnormal when compared with the Tertiary distributions. The climate was probably less zonal in the Tertiary and it is postulated that the oceanic Tertiary model had broader latitudinal belts probably lacking the cold and very cold zones for most of the Tertiary, although the model assumed a more modern aspect in the Upper Tertiary with the decline in world temperature.
In the New Zealand area, Kustanowich (1963) was able to divide the region into 3 latitudinal zones based on the occurrence of planktonic Foraminiferida in Recent surface sediment samples.
Of the 163 species and subspecies of planktonic Foraminiferida in the New Zealand Tertiary, about 136 are totally extinct and others became locally extinct in the Upper Tertiary. The totally extinct species are classified as planktonic mainly on comparative test morphology and also on the aspect of their areal distribution.
In the Middle-Upper Tertiary there are a number of species which survive to the present day, but is it scientifically sound to use the knowledge of an animal's present environment to assume that it has remained in the same environment through from the Tertiary? page 33 If such data are used, then the assumption should be noted and not forgotten.
There is a depth zonation of planktonic Foraminiferida in the oceans and given sufficient depth of water a bottom sediment sample will contain both warmer near surface living species as well as the deeper cold water species (see Bé and Hamlin, 1967). In the present study the vertical zonation has been taken into account in order to postulate maximum surface water temperatures, the species to be looked for and recorded are the known warmer water species.
Keeled Recent Globorotalia are characteristic of a water temperature of above 17°C and this knowledge has been used to postulate Tertiary paleotemperatures even in the Lower Tertiary where the Globorotalia species are extinct.
It has not been possible in the present study to consider such factors as diurnal and seasonal temperature variations and oceanic current direction changes in the Tertiary of the New Zealand region.
New Zealand Paleotemperatures
The majority of the world-wide Upper Cretaceous planktonic Foraminiferida became extinct at the Cretaceous-Tertiary boundary, and in New Zealand records indicate that all the species became extinct. In the areas outside New Zealand a new suite of planktonic Foraminiferida exhibit an explosive radiation as they spread and filled a marine environment lacking such animals. In New Zealand, sediments in the lowermost Teurian Stage do not contain such species and the cryptogenic species appear sporadically in the succession, By the end of the Teurian and in the Lower Waipawan, the fauna is cosmopolitan in character.
It is suggested that the lack of species in the lower part of the Teurian Stage indicates a cool water temperature, but it should be noted that their absence could have been due to some other controlling factor.
There are keeled Globorotalia in the upper part of the Teurian and Lower Waipawan Stages suggesting a temperature peak and the presence of the Globorotalia velascoensis fauna suggests tropical to subtropical conditions (Jenkins, 1966). Thereafter there may have been a slight drop in temperature followed by a temperature rise in the Mangaorapan Heretaungan Stages indicated by the Globorotalia crater fauna (Jenkins, 1966). From a comparison of the fauna with faunas from the Lower Eocene of the present day tropical regions it is postulated the temperature was not fully tropical.
In other parts of the world keeled Globorotalia continued into the Middle Eocene, as for example in Trinidad (Bolli, 1957). In New Zealand the large keeled Globorotalia became extinct at the end page 34 of the Heretaungan Stage and did not appear again until the Lower Miocene.
There are indications that the New Zealand Middle-Upper Eocene faunas were not fully tropical except possibly for two short periods indicated by invasions of the exotic species of Hantkenina (see fig. 1).
At the end of the Eocene there is a reasonably well marked zone of extinction where the following species became extinct: Globigerapsis index, G. semiinvoluta and Globigerina linaperta (Jenkins, 1966). In order to explain the extinctions, a sharp drop in sea-water temperature has been indicated (fig. 1).
The Oligocene faunas are difficult to interpret because they closely resemble those described from the Oligocene of sub-tropical and tropical areas. The absence of such tropical species and Globigerina oligocaenien and G. tapuriensis indicates a possible sub-tropical surface water temperature.
The planktonic foraminiferal faunas of the Eocene to Lower Miocene suggest warmer conditions in the North Island as compared with the South Island.
There are some species, for example Globigerinoides altiaperturus and Globorotalia kugleri present in the Otaian Stage of the North Island indicating a possible tropical peak. Further warm peaks are postulated for the Clifdenian Stage on the presence of Globigerinatella insueta from the Tuki-Tuki River, and a peak in the Waiauan Stage by the presence of a large heavily keeled Globorotalia menardii from the East Coast of North Island.
By the Pareora and Southland Series, a number of modern species are present in the faunas. The lack or rarity of such Recent tropical and subtropical species as Globigerinoides sacculifer, Globorotalia tumida, Pulleniatina obliquiloculata and Candeina nitida indicate possible warm temperate conditions. The local extinctions of the tropical and subtropical species in the New Zealand area suggests a possible overall decline in temperature in the Upper Southland to Lower Wanganui Series with rare temperature peaks.
I have recently used changes in the coiling ratio of Globorotalia pachyderma to indicate changes in sea water temperature in the Upper Cenozoic rocks of New Zealand (Jenkins, 1967). In the present day seas sinistrally coiled G. pachyderma live in the polar and sub-polar regions, and according to Ericson (1959) sinistrally coiled populations live in water colder than the 7.2°C April surface water isotherm in the Arctic region. In a more recent publication, Bé and Hamlin (1967) recorded sinistrally coiled G. pachyderma living in the North Atlantic within the surface water temperature range of 8.3 - 9.4°C and dextrally coiled populations within the range 11 - 15°C.page 35
In New Zealand, G. pachyderma appears for the first time in the Tongaporutuan Stage and it maintains its sinistral coiling through to the end of the Kapitean. I have preferred to interpret the sinistral coiling of the Taranaki Series as an inherited coiling preference rather than indicating cold sea water temperatures (Jenkins, 1967).
At the base of the Opoitian Stage there is a change to dextral coiling in G. pachyderm a, populations which has been taken to indicate warm water conditions. This was followed by a change to sinistral coiling in the lower Waitotoran Stage (Waipipian) indicating cooler conditions, followed by a return to dextral coiling in the Upper Waitotoran indicating warmer conditions. At the Waitotoran - Hautawan boundary there is a change to sinistral coiling suggesting a further change to cold temperatures which has been correlated with the Pliocene - Pleistocene boundary (Jenkins, 1967).
Dr. N. deB. Hornibrook. I'm wondering just how far back one can take this postulate of keeled Globorotalias only living in waters above 17°C. The present species arose in the Miocene whereas the ones you discussed evolved in the Eocene. It may be quite wrong to suggest that these earlier keeled ones were temperature dependent in the same way as today.
Dr. D. G. Jenkins. I would agree that this is an assumption, but Bandy has used this hypothesis to suggest that the presence of page 36 keeled Globotruncana in the Cretaceous, places a lower limit of 17°C on the water temperature.
Dr. P. Webb. Would you say a little more as to whether your Teurian/Waipawan result is based on absence or low incidence of warm water planktonic Foraminifera?
Dr. D. G. Jenkins. In the Waipara section the lower 40 feet do not have any planktonic Foraminiferida. Then they start slowly, until above the Waipara Greensand where there is a very good fauna which represent my first peak. We do not have as many species as occur in Trinidad so I postulate that the lower part of the Teurian was cool.
Dr. P. Webb. I think this lack of forams in the lower part could be a facies problem and leaching away of tests is definitely a problem.
Dr. C. A. Fleming. I wonder if Mr. Edwards would comment on the Waipara section.
Mr. A. R. Edwards. In the lower 40 feet there are no nannoplankton.
Dr. D. G. Jenkins. But benthonic Foraminiferida do occur. Therefore calcareous nannoplankton and Foraminiferida would be found if they had originally occurred there.
Mr. A. R. Edwards. The nannoplankton had a complete extinction at the end of the Cretaceous. Their occurrences in the Teurian appear to be a radical evolution giving a lot of new species. I believe this is similar to the Foraminifera.
Dr. D. G. Jenkins. This is so in most parts of the world — there is an explosive evolution but there is this lag in New Zealand which I attribute to cool temperatures.
Mr. A. R. Edwards. There is a marked difference between Europe and Trinidad in the Oligocene. There is a large difference in the nannoplankton between New Zealand and Trinidad in the Landon. Is this the case with the Foraminifera?
Dr. D. G. Jenkins. It is difficult to detect; some species are common to both areas but are rare. I have considered that it is also a temperature effect.
Mr. I. Devereux. Do your peaks in the Southland Series represent incomings of warm water species and then a sudden extinction or just gradually trailing off.
Dr. D. G. Jenkins. There are sudden extinctions superposed on the downward trend.
Dr. C. A. Fleming. You show your peaks in the Eocene as higher than in the Miocene. This is, I think, the first time this has been postulated and affects our basic concept of whether Australasia shows a different climate pattern to that of the Northern Hemisphere. Would anyone like to comment on this.page 37
Dr. D. G. Jenkins. I do not have any evidence that the Otaian is truly tropical but parts of the Eocene seem to be tropical. It is difficult to directly compare the two.
Mr. A. R. Edwards. The nannoplankton suggest that the Eocene peak could be higher than the Southland peak but comparison is difficult.
Professor A. Wilson. Catastrophic extinctions have been shown to occur along the magnetic reversals. What thickness of sediment is associated with these extinctions that have been mentioned?
Dr. D. G. Jenkins. A very abrupt extinction occurs at the Eocene/Oligocene boundary, possibly over only a few inches.
Mr. I. Devereux. Professor Wellman has told me that a distinct colour change occurs in the sediments, at this time also.
Bé, W. A. H.; Hamlin, W. H., 1967. Ecology of Recent planktonic Foraminifera. Micropaleontology 13 (1): 87-106.
Bolli, H., 1957. Planktonic Foraminifera from the Eocene Navet and San Fernando Formations of Trinidad, B.W.I. U.S. Nat. Mus. Bull. 215: 155-72.
Ericson, D. B., 1959. Coiling of Globorotalia pachyderma as a climatic index. Science, 130 (3369): 219-220.
Jenkins, D. G., 1966. Planktonic Foraminiferal Zones and new taxa from the Danian to Lower Miocene of New Zealand. N.Z.J. Geol, Geophys. 8 (6): 1088-1126.
Jenkins, D. G., 1967. Recent Distribution, Origin, and Coiling Ratio Changes in Globorotalia pachyderma (Ehrenberg). Micropaleontology 13 (2): 195-203.
Kustanowich, S., 1963. Distribution of Planktonic Foraminifera in surface sediments of the South-West Pacific Ocean. N.Z. Geol. Geophys. 6 (4): 534-65.