Robert Bowen Paleotemperature

ROBERT BOWEN

PALEOTEMPERATURE ANALYSES OF MESOZOIC BELEMNOIDEA FROM AUSTRALIA AND NEW GUINEA

Abstract: Paleotemperature analyses were carried ing from the Jurassic into the Cretaceous and are out on more than 60 Belemnoidea obtained from consistent with the extension of the Albian and Mesozoic strata in West and South Australia and Coniacian-Santonian climatic maxima, previously New Guinea. One set of data records mean rostral demonstrated in Europe, into the Australian area. temperatures, and another derived by analyzing The Cretaceous readings dispose of the idea of an successive increments of powdered carbonate from ice age in South Australia at that time. It appears the rostra shows the variations of temperature dur- that the Belemnoidea were eurythermal through ing ontogenies. The latter probably represent and most of their evolutionary history. The paleotem- in this event would confirm seasonal changes dur- perature results are in accord with a possibly large ing the Mesozoic. The former demonstrate a cool- migration of Australia during the Mesozoic.

Since the preliminary work of Urey (1947; mum delta value obtained was — 0.45%o; 1948) showed that the abundance of the O18 assuming the mean ocean delta in the Jurassic isotope in calcium carbonate is related to the to be 0.00%0, this corresponds to a tempera- temperature of deposition of this compound, ture of 18.5°C. The maximum delta value was measurement by means of sensitive mass -2.72%0 (29.2°C). The average delta value spectrometers has been used to reconstruct past for the entire assemblage was — 1.73%o climates. This paper is concerned with data (24.4°C), and about two-thirds of the belem- derived from such analyses of a number of noids were within 3°C of this figure. A single Mesozoic Belemnoidea from Australia and specimen was obtained from the Kuabgen New Guinea. The original standard gas used group (Upper Jurassic) of the Upper Fly by Urey et al. (1951) was CO 2 obtained from a River, New Guinea. It probably belongs to Belemnitella americana from the Peedee forma- the species Belemnopsis gerardi and gave a delta tion (Upper Cretaceous : Maestrichtian) of value of +0.13%0 (15.9°C). North Carolina, and this is known as PDB-1. 2 : Cretaceous It has no delta value—i.e., its delta can be re- garded as zero. A new standard derived from In Western Australia specimens were de- Jurassic belemnoids from the island of Skye rived from strata of the Alinga formation off the coast of Scotland was used in the present (Albian to Turonian age). Thirteen came from work, and the machine results obtained by the Murchison River area; 8 of these were from comparison of CO 2 samples with it were cor- cliffs west of Murchison House station; these rected so as to relate them to PDB-1. gave delta values ranging from — 0.28%o I : Data Obtained from Analyses (17.7°C) to -2.1%o (26.1°C), the average of Whole Specimens temperature being 20.6°C. Four specimens collected from another locality (cliffs north of These give mean rostral temperatures and an emergency aerodrome on the telegraph line were obtained by cutting a complete cross at Murchison House station) gave an average section representing accumulative growth, temperature close to this figure, namely cleaning it of contaminants, and grinding it to 18.8°C with a delta range from — 0.26%o to a powder; the necessary aliquot for investiga- — 0.74%o. A specimen from a third locality tion was taken from this. in this area gave a delta value of — 0.24%o 1 : Jurassic (17.5°C). Evidence from Europe (Bowen, 1961) indicates a climatic minimum there in Thirty six specimens from the Newmarra- the Cenomanian following an earlier maximum carra Limestone (Middle Jurassic : Bajocian) during Albian time. Possibly these were world- of Bringo Cutting 19 miles east of Geraldton, wide variations; if so, the reading of 17.5°C Western Australia, were analyzed. The mini- may derive from the Cenomanian part of the Geological Society of America Bulletin, v. 72, p. 769-774, 2 figs., May f961 769

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Alinga formation. Four additional specimens variations in climatic conditions . . . there were obtained from Junnawa Hill in the lower differences due to actual climatic fluctuation Murchison River area may also be from the and others due to the considerable variation Alinga formation, but they may come from which one would anticipate in a comparatively the overlying Toolonga Calcilutite (Coniacian- shallow transcontinental sea." Santonian to Maestrichtian). They gave an average temperature of 19.8°C (delta values TABLE 1. ANALYSES OF JURASSIC SPECIMENS ranging from — 0.54%o to — 0.85%0); comparison with Europe would suggest they are Corrected either Cenomanian (if Alinga) or Campanian Specimen Layer delta Temperature (if Toolonga); both were times of climatic number number (%») (°C) minima. Two specimens were collected from 1 1 (Outer) -1.6 23.7 the Gearle Siltstone on Cardabia Creek in the 2 -1.3 22.3 Giralia area. This formation is Albian to 3 -1.2 21.9 Turonian in age, and the specimens gave very 4 — 1.8 24.7 different results, namely 20.3°C and 30.1°C. 5 -1.6 23.7 All the preceding Cretaceous specimens came 6 -1.3 22.3 7 -1.5 23.3 from various parts of Western Australia. Six 8 (Center) — 1.3 22.3 were obtained from South Australia—from 2 1 (Outer) -1.1 21.4 Fossil Creek 35 miles from Oodnadatta—and 2 -1.2 21.9 are Albian in age. They gave delta values rang- 3 -1.2 21.9 4 -1.3 22.3 ing from — 0.85%0 to — 2.45%o, and the 5 -2.1 26.1 average temperature obtained from them is 6 -1.6 23.7 21.9°C. These results are particularly interest- 7 -1.6 23.7 ing because they show that Lowenstam and 8 (Center) -1.3 22.3 Epstein (1954) were in error in assuming that 3 1 (Outer) -1.9 25.2 in Albian time the lowest average temperatures 2 -2.0 25.7 3 -2.1 26.1 were in Australia. They obtained readings of 4 -2.5 28.1 15.2°C and 16.6°C from Australian Upper 5 -2.5 28.1 Albian specimens, but these came from a 6 -2.8 29.6 locality almost 1000 miles from the present one. 7 -2.4 27.6 Dorman and Gill (1959) gave readings ranging 8 (Center) -2.8 29.6 4 1 (Outer) — 1.1 21.4 from 12.2°C to 16.5°C for specimens derived 2 -0.9 20.5 from the Aptian of Lake Eyrie area—close to 3 -0.8 20.0 Oodnadatta. However, they also record seasonal 4 -1.0 20.9 analyses of some of these specimens, and from 5 -1.5 23.3 6 -2.4 27.6 these it can be seen that Aptian temperatures 7 -2.0 25.7 reached a maximum of 21°C. Bowen (1961) 8 (Center) -3.1 31.2 has shown that in Europe Aptian temperatures were substantially lower than those of Albian time. The author concludes that there was considerable temperature fluctuation in South II : Data Obtained from Successive Increments Australia (i.e., in the Cretaceous Tambo Sea of Powdered Carbonate from the Rostra area) from Aptian time through the Albian. Several explanations of these are available. Two points must be borne in mind: (1) the The most likely is that they represent seasonal Tambo Sea became a lake later in the Cretace- changes in temperature in which case the highs ous, hence large ecological and climatic changes may be interpreted as summer maxima and the are to be expected during this period; (2) lows as winter minima. This would give an differences undoubtedly arise from the probable indication of the life span of the animal or at different living habits of the various species least that part of it during which the rostrum of Belemnoidea. In other words, differences in was formed. This hypothesis is accepted by the isotopic composition could result from ecologi- author as being most in accord with the facts. cal differences. This interpretation is in general Another possibility however is that the tem- agreement with the opinion of Gill who stated perature fluctuations represent the results of (personal communication) that "the present migrations. Lowenstam and Epstein (1954) evidence favours your ideas of considerable noted that in some cases the belemnoid tern-

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perature trends parallel those of associated fall. In specimen 1 at least two maxima (prob- benthonic forms—here, the relevant belem- ably summers) and two minima (probably noids (although nektonic in habits) must have winters) can be observed, and thus the animal passed much of their lives in the seasonal probably lived through 2 or more years. Similar climatic ranges of their areas of burial (at least variation analyses were made on some of the the parts of the ontogenies during which the Cretaceous specimens. As with the Jurassic ones, rostra grew). Thus, while no evidence of migra- the range of temperature variation during

TEMP 26 J°C -2-1 -20 -19 -1-8 - -7 - -5 - 4 Z2'5°C - 2 — 1 7I-4°C -10 50 IOO ISO 8 ACCUMULATIVE WEIGHTS OF SUCCESSIVE LAYERS IN MGMS £°') TEMP -2-0 -1-9 — .3 24 7°C - -7 -| 6 23 3°C -1-4 -1-3 — -2 ZI-9°C - -| 5O I0"0 rfp* ACCUMULATIVE WEIGHTS OF SUCCESSIVE LAYERS IN MGMS TEMP -2-9 29-6°C -27 . -2-5 -24 27-6°C -2-3 . -2-2 .

— 1-9 25-ZC -1-B 20 40 60 SO IOO 120 ACCUMULATIVE WEIGHTS OF SUCCESSIVE LAYERS IN MGMS Figure 1. Variation analyses. Three of the four analyses made on Middle Jurassic (Bajocian) specimens from the Geraldton area of Western Australia to show changes in temperature during rostral growth (interpreted as seasonal in char- acter by the author). Details are recorded in Table 1, and the graphs represent specimens 2 (top), 1, and 3.

tion can be advanced, some evidence against ontogeny was small—of the order of 2°-5°C. it can; hence it is inadvisable to accept this Clearly, the climates of many parts of the interpretation. A third possibility is that the world have altered considerably since the delta fluctuations represent not alternations Mesozoic. Widespread evidence indicates that between warmer and cooler conditions, but the Jurassic and Cretaceous equator ran through salinity changes. However, again there is no the southern United States and Europe. No evidence to support this idea. longer is this the case, and the reason may be Four specimens of Jurassic age from the polar wandering, continental drift, etc. Paleo- Newmarracarra Limestone of Bringo Cutting magnetic investigations summarized by Cox near Geraldton, Western Australia were ana- and Doell (1960) yield a number of Jurassic and lyzed (Table l;Fig. 1). Cretaceous virtual geomagnetic poles which Some of these results, e.g., those for specimen (if, as most workers believe, the average geo- 1, show very well a probable seasonal rise and centric dipole is always directed along the axis

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of rotation) closely approximate or coincide sistent with the Australian results. The world with the geographic poles. In the Jurassic, some Jurassic shows even greater consistency. Un- are located in Asia, and some in North America, published data show this very clearly; e.g., in while in the Cretaceous some are in the Pacific Argentina temperatures of 23.7°C and 25.6°C and Alaska, and others are located elsewhere. average 24.6°C (very close to the average from Obviously, the utility of this work in recon- Western Australia); in Europe, temperatures structing climatic belts of the Mesozoic is of from 20°C to 25°C are common, and this is limited. As Cox and Doell (1960) remark: "the true also in North America. Low temperatures geomagnetic pole positions from the Mesozoic were recorded from Alaska and India, however, . . . are quite scattered (and) no conclusive and also, as was seen earlier, in New Guinea.

PAPUAN GEOSYNCLINE

PRE - CAMBRIAN

SHIELD GERALDTi AREA

DARLING FAULT ZONE

W.ESTRALIANI GEOSYNCLINE I JURASSIC TASMAN GEOSYNCLINE Figure 2. Geology of Australia Left: Paleogeography of Australia during the late Cretaceous. The intercon- nection of the Westralian geosyncline with the Papuan is evident, and through this link contact was made with the Tethys. The Walloon Lake succeeded the Tambo Sea (referred to in the text). Right: Map of southwest Australia showing Jurassic outcrops and their re- lation to the town of Geraldton. The Darling fault zone separates the Jurassic from the great Precambrian shield to the east.

statements concerning drift or wandering can Some inferences may be drawn from the be made." paleotemperature results. At present, the variation of temperature with (1) They show that the belemnoids (known latitude attains a maximum of about 60 °C, and to have been nektonic in their habits) were there still exist polar ice caps. In the Jurassic eurythermal during most of their evolutionary certainly and probably in the Cretaceous also, history. They were successful in colonizing cool there were no appreciable bodies of ice any- and hot bodies of water—the Australasian data where. Seasons existed (Fig. 1). A cooling from record a minimum of 15.9°C and a maximum the Jurassic to the Cretaceous is apparent in the of 31.2°C (a range of more than 15°C). The Australian area. The temperatures recorded in South Australian Cretaceous readings dispose this note are closely comparable with those of of the idea of an ice age at that time in this Western Europe (Bowen, unpublished anal- area. yses): e.g., cf. the Albian of England—20°C, (2) The Australian data are consistent with 21.1°C, 23.3°C; of France—22.7°C, 24.7°C, the world climatic picture derived from ana- 25.1°C. This means that the Albian and lyses made on specimens from many other Coniacian-Santonian climatic maxima spread countries. Comparison with these specimens over most of the planet (except for Japan shows that the Westralian geosyncline (Fig. 2), where the Albian gave a reading of only although warm, was cooler than the Tethys 16.8°C). Neocomian and Cenomanian minima in Jurassic time. The Cretaceous emerges as a recorded in Europe and elsewhere are con- more diversified climatic period, and the

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climatic maxima and minima, although not region has rotated southward away from the certainly identified in Western Australia (be- equator since the Jurassic. During early Jurassic cause of poor stratigraphical control of the time, therefore, Australia could have occupied relevant specimens), very probably took place this position and later migrated. During later at the same time there as elsewhere. Climatic Jurassic time and in part of the Cretaceous, it maxima and minima do of course occur between may have been near South Africa, and New the Albian and Turonian, and until there is any Guinea may have been a separate unit with evidence to the contrary it is logical to locate locally cool-water conditions. India, also, is them in accordance with more exact data ob- believed to have migrated over a considerable tained from Europe, etc. distance at about the same time. (3) The positions of the poles must be con- sidered. Work to be published later shows that Acknowledgments the north pole probably lay in the general area The author is grateful to Dr. Harold C. Urey of the Bering Sea, and the south pole in the for his advice and encouragement, to Dr. Peter general area of South Africa. Irving (1958) X. Eberhardt for his assistance, and to Dr. .suggested that "from Carboniferous to Eocene Cesare Emiliani for his suggestions. M. F. times Australia was situated in what is nowa- Glaessner, B. F. Glenister, and N. H. Fisher days the position of southern South America supplied specimens. The author is indebted to and has subsequently moved to its present Dr. G. W. Bain, Mr. B. E. Balme, Dr. E. D. position." Irving and Green (1958) gave the Gill, Dr. B. F. Glenister, and Dr. E. Irving for Mesozoic (probably Jurassic) pole position as: their comments. The author also wishes to Lat. 50 S. and Long. 157 E. The latitude is thank the Atomic Energy Commission for sup- possible, but the author believes the true posi- port of the project, through grant number tion is much west of this. The paleotemperature AT(ll-l)-34, and the National Science Foun- data show high temperatures in the Upper dation for support of the project through grant Jurassic of Argentina and suggest that this number G-10220.

References Cited Bowen, Robert, 1961, Paleotemperature analyses of Mesozoic Belemnoidea from Germany and Poland: Jour. Geology, v. 69, p. 75-83 Cox, Allan, and Doell, Richard R., 1960, Review of paleomagnetism: Geol. Soc. America Bull., v. 71. p. 645-768 Dorman, F. H., and Gill, E. D., 1959, Oxygen isotope paleotemperature measurements on Australian fossils: Roy. Soc. Victoria Proc., n. ser., v. 71, pt. 1, p. 73-98 Irving, E., 1958, Paleogeographic reconstruction from paleomagnetism: Geophys. Jour. Royal Astron. Soc., v. 1, p. 224-237 Irving, E., and Green, R., 1958, Polar movement relative to Australia: Geophys. Jour. Royal Astron. Soc., v. 1, p. 64-72 Lowenstam, H. A., and Epstein, S., 1954, Paleotemperatures of the post-Aptian Cretaceous as de- termined by the oxygen isotope method: Jour. Geology, v. 62, p. 207-248 Urey, H. C., 1947, The thertnodynamic properties of isotopic substances: Jour. Chem. Soc., p. 562-581 1948, Oxygen isotopes in nature and in the laboratory: Science, v. 108, no. 2810, p. 489-496 Urey, H. C., Lowenstam, H. A., Epstein, S., and McKinney, C. R., 1951, Measurement of paleotemperatures of the Upper Cretaceous of England, Denmark, and the south-eastern United States: Geol. Soc. America Bull., v. 62, p. 399-416

SCHOOL OF SCIENCE AND ENGINEERING, UNIVERSITY OF CALIFORNIA, LA JOLLA, CALIF. MANUSCRIPT RECEIVED BY THE SECRETARY OF THE SOCIETY, DECEMBER 17, 1959

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