Calcareous Nannoplacton.pdf

Disc Contents© IPA, 2006 - 1st Annual Convention Proceedings, 1972 Contents PROCEEDINGS INDONESIAN PETROLEUM ASSOCIATION First Annual Convention, June 1972 Search 43 CALCAREOUS NANNOPLANKTON A NEW BIOSTRATIGRAPHIC TOOL IN THE OIL INDUSTRY (WITH EMPHASIS ON INDONESIA) P. PRIJOSOESILO ’) Abstract Calcareous nannoplankton. a group of ments contain 10,000,OOQ .OOQ.specimens per cc. microfossils that evolved rapidly during the late Fine sandy inner shelf sedimenrs will commonMesozoic and the Cenozoic eras, is a new and very reliable biostratigraphical tool. Its usefulness has been ly have thousands or tens of thousands specitested successfully during the drilling of the JOIDES* mens per cc Deep Sea Drillim Project and by some of the oil In addition, these ultra-microfossils* offer companies operating in the Gulf Coast Area, USA. same other advantages compared t o the plankStandard Calcareous Nannonplankton Zonations for the Paleogene and for the Neogene are tonic foraminifera : now available. These zonations have been proposed by 1 . short vertical range Martini & Worsley (1970), Martini (1970) and 2 . wide geographical distribution respectively. The study of calcareous nannoplankton 3. ease of preparation in Indonesia as a new biostratigraphic tool has only 4. ease of identification been started recently, however, some very encouraging results have been obtained in Central SuniaThese last two advantages are of prime tra. If similar results can be obtained from other parts interest t o the oil industry since one of the of the country, the prospect of this study in Indonesia will certainly be very bright. The role of the oil most important responsibilities confronting the industry in developing this field of study is very oil company paleontologist is the rapid identiimportant, since the oil companies have direct access fication of fossils encountered in routine to the basic data. examination of well samples. It is believed that establishing a standard zonation for Indonesia is not impossible. Once this is established, it will be beneficial to both the oil industry ACKNOWLEDGEMENTS and the academic institutions, and more imuortant it will be a major contribution to the study on the The author thanks P.T. Caltex Pacific Indostratigraphy of Indonesia. * Joint Oceanographic Institutions for Deep Earth Sampling. nesia for permitting this presentation and his colleagues in the Exploration Division in Rumbai for the constructive review of the manuscript. INTRODUCTION CALCAREOUS NANNOPLANKTON Until the late fifties little was known about calcareous nannoplankton. However, sonie paleontologists have envisioned that “when better understood, these coinparatively unknown organisms may show promise of becoming important in biostratigrauhic studies” (Hoffmeister, 1958, p.207) Since then a number of publications have stressed the usefulness of fossil calcareous nannoplankton as biostratigraphical indicators and several useful zonations have been established. At present the calcareous nannoplank t o n zonations are as good as the standard planktonic foraminifera1 zonations. The calcareous nannoplankton occur abundantly in marine pelagic and shelf environments. According to Hay and Mohler (1967) oceanic oozes may contain 10,000,000,000,000 specimens per cc., and shallower marine sediCalcarous nannoplankton consist predominantly of coccolithcphorids. Other fossil forms of unknown affinities such as discoasters, nannoconids, etc. are also included. All these organisms belong to the algal phylum (or division) Ctirysophyta, because of its golden brown plastid s, The cell is usually biflagellate, but in any cases it includes a haptomena (coiled organelle resembling flagella used for temporary attachment). Reference 1s made to Text Figure No, 1. Usually it consists of two large plastids, with pigments chlorophyl a anu c, color from fucoxanthin (a xanthophyll) and is uninucleate. * $Usually 1) P.T. Caltex Pacific Indonesia, Rumbai less than 30 microns 1969) .44 INTERNA f ( A f t e r : PIENAAR . either a pelagic cyst of a benthic filament. 3. North America and North Africa. Because of complications of more than one type of coccoliths on a single cell. e. 1964). defined as the body of strata characterized by a certain assemblage of fossils without regard t o their ranges. or palmella. many groups have evolved very rapidly since the Lower Jurassic. The Concurrent Range Zone. The oldest nannofossils that have ever been found were recovered from Lower Liassic (Jurassic) strata of Wurttemberg. Within the Jurassic strata Stradner has further recognized four nannofossils associations. classification isin a state of flux.punctulata and P. namely Schizosphaera punctulata Deflandre and Parhabdolithus liasicus Deflandre. Evidence of a great change in calcareous nannoplankton communities has been recorded between Maestrichtian and Danian (Bramlette. & Martini. : 1. These include : 1. In this respect most authors follow the definition provided by t h e American Commission o n Stratigraphic Nomenclature (1961). A fourth type of zone.geologic periods until the present time. 2 . Some workers have a very complex classification. Bigoti association. Characterized by the development of some new forms. it is necessary t o define exactly the nature of the zone proposed. 3. one for the isolated coccoliths and another for those in which the entire cell is known. o r packet of cells. essent ially there are three kinds of biostratigraphic zones: 1 . discoids or modified calcite platelets of characteristic form and microstructure. liasicus. The Kange Zone. 2 . E‘s and U’s. Germany. 1963). Dominated by double rimmed coccoliths. BIOSTRATIGRAPHY As stated by Hay & Mohler ( 1967) calcareous nannofossils have several peculiarities which make them uniquely suitable for use as biostratigraphic indicators. The Assemblage Zone. Those studied thus far have a complex life cycle. including Rhabdolithus aff dekorus Deflandre ( a dou ble rimmed coccolith with trumpet-like apical stem and central crossbars). making age determinations and establishing regional dS well as intercontinental correlations.45 The cell may be covered with coccoliths. Characterized by the firs$ appearance of Discolithus crassus Deflandre and Coccolithus opacus Stradner (first COCCOlith with a double rim). 197 1>. including guide fossil Stephandithion bigoti Deflandre which Itas delicate hollow starshaped elements that easily break into parts resembling certain letters of the alphabet. Thus far studied nannofossils have not been found in the Triassic or Paleozoic sediments. with one stage non-motile. they are extremely abundant in many samples. or at different stages in the life cycle.”. which is a combination between range and assemblage zones k recognized b y Hay (in press. 3.This zone is designated as “partial range zont:. and Discolithus rugosas Noel (with numerous pores). 2. Decorus association. Liasicus association. Coccolithus bri tannicus Stradner (with a typical transversal bridge). The application of nannofossils t o solve biostratigraphical problems has been emphasized by Bramlette and Riedel (1954). a large number of species haiie worldwide dist nbu t ion . especially in warm waters. Calcareous nannoplankton is an important part of the food chain in oceans. 2. MESOZOIC NANNOFOSSILS The oldest nannofossils were revealed and reported from the Lower Lias (Jurassic) bf Germany (Stradner. This change represenf primarily a remarkable extinction of a large number of distinctive Cretaceous genera and species. although the oldest ones are found abundantly in the Lower Jurassic. Reference is made t o Text Figure No. Opacus association. defined as the body of strata comprising the total horizontal and ver tical range of occurrence of a specified taxon.g. Fossil remains are represented most often by isolated coccoliths. In order t o be most useful for the zonation. - . As has been pointed out by Shaw (1 9641. etc. Characterized by S. They consist of two species. 4. From then o n this group of organism has been flourishing through al1. It has been playing an important role in formation of calcareous oceanic oozes since the Jurassic. Subsequent studies by several authors have demonstrated that nannofossils can be used successfully for delimiting biostratigraphic zones. less frequently by entire coccospheres. Supporting evidence on this h a s been found in Europe. defined by theoverlapping ranges of specified taxa. 2 4 Note: Vertical lines -indicate the range of a species Horizontal lines .demark zone limits .46 BIOSTRATIGRAPHIC ZONES m RANGE t I i CONCURRENT RANGE I* TEXT FIGURE No. ranging from the Cenomanian t o the Maestrichtian. It is noteworthy that the number of genera and species of calcareous nannoplankton increased abruptly in the Upper Cretaceouq. Bukry(1971) reported three major evolutionary changes of the discoasters. Dominated by nan2. Turriseiffeli association. Characterized by 3.g. Cym bif or mis associa tion.41 Due to poor preservation of nannoplankton remains during the Middle and Upper Malm (Middle Jurassic). N. e. USA. Martini and Worsley (1 9 7 0 ) proposed a Standard Nrogene Calcareous Nannoplankton Zonation consisting of 21 zones. by t h e exceptionally large Arkhangelskiella cymbiformis Vekshina. Bramlette and Riedel (1954). Zugrhablithus intercisus Def landre and the related species Micula staurophora Veks hina . 2 and 3. no association have as yet been revealed. Characterized by 6. Bramlette and Wilcoxon (19671. the topmost zone of the Jurassic is characterized b y “nannoconid~”. through fewer but relatively broad-rayed in the Mid-Tertiary (Oligocene-Miocene) to finally very narrow-rayed species which occurred just before extinction in Late Pliocene time. The rekdtively easy accessibility of basic data has made many workers t o be more actively engaged in the study of calcareous nannoplankton. The ”NP” denotes ’ Paleogene N ~ ~ n ~ : i i p l a n k tZoon nation”.25. a t least in part. Among the major contributions t o the Cenoz oic Ca 1careo us N a nno p la n k t o n Zonation are those of Bramlettc and Sullivan (1961 ). In ascending order t h e seven associations of Stradner are as follows: Steinmanni association. At the end of Maestrichtian the highly developed nannoplankton group suddenly disappeared and eventually was replaced b y a quite different group in the Danian. The zones thfough NN --2 1. Hay & CFpek (1969) have recognized twelve zones. The twelve zones established by Hay and Cepek (1969) in N. correlative with Worsley’s Parhabdolithus embergeri Zone of the Caribbean Sea. Of majar significance is the evolutionary trend of the discoasters which evolved very rapidly during the Cenozoic era. The usehlness of calcareous nannofossils for solving biostratigraphic problems of the Tertiary strata have been tested succesfully during the drilling of the JOlDES Deep Sea Drilling Project and also by many oil companies operating in the Gulf Coast Area. Mohler Roth? Schmidt and Boudreaux (1967). In terms of calcareous nannoplankton t h e Mesozoic-Cenozoic boundary is very distinctive worldwide. 1 . the so-called Nannoconus steinmanni -or simply Steinmanni association. in are numbered “-1 which the “ N N ” denotes ”Neugene Nannoplankton Zonation” Later Martini ( 1970) also proposed a Standrlrd Paleogene Calcareous Nannoplankton Zocation. noconid species having ”globate cones’: such as N. Staurophorus association.stainmanni Kamptner.Bukry (1971). consisting of 75 zones and numbered NP.and the ”Steinmanni” associations.bucheri. from the Cenomanian’s ” Turriseiffeli association” t o the Maestrichtian’s ”Cymbiformis association ”. Dauvillieri association. America were first recognized in the Gulf Coast Area. Cothicus association. Reference is made t o Chart No. ranging from massive and compact multi-rayed species in the early Tertiary (Paleocene. Ch:ir:s Nos. This zone is defined as t h e interval between the lowest occurrence of P. References are ma& t t . Roth (1970). CENOZOICN A N N O P L A N K T O N ZONATION The stratigraphic value of Cenozoic calcareous nannofossils are as good as that in Mesozoic. This zone is probably. Globulus association. 1970). . primarily in an attempt t o try t o establish zonations. In recent years samples from continuous sections including material from type lucali:ies of some Tertiary stages and deep sea mres have b e m m e avdikabie. etc. Hay. MarSini 3116 Worsley (1970).1 1hrough NP. !964. This zonation is cssentially a refinement of Stradner’s last four associations. Brainlette and Bukry(1969).Eo cene). Martini (1955. However. Characterized by 1. the first c’lccurrence of Tetralithus gothicus Defiandre. the abundance of highly developed nannoconids.embergeri Noel and the lowest occurrence of the Nsteinmanni Kamptner. Marked by the 4. the great abundance of Coccolithus pelagicus-Schiller and N. dauvillieri Deflandre. Within the Cretaceous System in Europe seven calcareous nannofossil associations were recognized by Stradner (1963). Dominated by 5. In Europe there is a missing link between the ”Bigot?’ . first occurrence of Rhabdolithus turriseiffeli Deflandre. In North America. Characterized I. U.1 DISTRIBUTION OF SOME IMPORTANT SPECIES OF CALCAREOUS NANNOPLANKTON IN THE U P P E R CRETACEOUS (GULF COAST A R E A .48 ZONATION \ CHART No.S.) (Modified after: CEPEK 8 HAY 1969) w (3 a I v) .A. J c a*_.2 ~ CALCAREOUS ~ NANNOPLANKTON E ~ ZONATION ~ I “-$Per : MAQTlNl 1970 1 ~ ~ .49 AGE - W w z I 0 0 12 W 0 z w 0 0 W w 2 w 0 Q tl1 . c STANUUHL ~ CHART No. H.CARINATUS 2 DISCOASTER DRUGGI ZONE I T j LAST H TRUNCATA FIRST D.PENTARADlATUS LAST DSURCULUS 3 w 2 w Q a 3 -N - w 0 w -J N L! NN I I DISCOASTER QUINQUERAMUS ZONE NN 1 0 D -__ l S C O A s T .HUXLEY1 6-d 5 LAST P LACUNOSA T LAST D.BROUWER1 LAST D.50 J AGE w">W Z I 5j% 3= w ' FORAM' CALCAREOUS NANNOPLANKTON ZONES ZONES N 23 NN 211EMILIANIA HUXLEYI ZONE NN 2d GEPHYROCAPSA OCEANICA ZONE N 22 PSEUDOEMILIA LACUNOSA N 2 1 NN 1 8 DISCOASTER BROUWERI ZONE NNI~-DISCOASTER -____PENTARADIAT-.HAMATUS FIRST D HAMATUS 0 c3 X [L O - ZONE NN 7 DISCOASTER KUGLERI ZONE NN 6 DISCOASTER E X l L l S ZONE N 9 NN 5 SPHENOLITHUS HETEROMORPHUS N N N ~ C A T ~ N A S COALITUS T E R -- 9 DISCOASTER HAMATUS ZONE ~ ---_j FIRST C COALITUS -FIRST D. 0 J LAST T. 8 NN 4 HELICOPONTOSPHAERA AMPLIAPERTA ZONE LAST S.BELEMNOS NN 3 SPHENOLITHUS BELEMNOS ZONE NN . .AMPLIAPERTA -- = .KUGLERI 1 LAST S. Q E D ~N AD TU ~M cATORS FIRST E. _ I _ DQUINQUERAMUS T - FIRST D QUINQUERAMUS LAST D.HETEROMORPHUS ZONE L A . DRUGGI N-j-NN N 3 ' . 1971) .51 I I AG E (EUROPEAN STAGES^ COCCOLITH ZONE I s uB zo NE I I R E C E N T I - EMILlANlA HUXLEYI _---_-_-------- ASTIAN.4 APPROXIMATE CORRELATION OF COCCOLITH ZONES RECOGNIZED IN SEDIMENTS RECOVERED ON LEG 7 I N THE TROPICAL PACIFIC (GUAM-HAWAII ) ( A f t e r : BUKRY . I /B~RTONIAN &I LUTETIAN IMI~E~ --- I-------I SPHE NO L ITHUS D IST E N T U S SPHENOLITHUS PREDISTENTUS ------- DtSCOASTER BARBADIENSIS RETICULOFENESTRA UMBlL I C A CHART No. 9IACENZIAN - --- 0 (3 * z IMlDD4 R U P E L I A N UPPER PRIABONIAN. 52 Another extensive use of the nannofossils has been contemplated by the JOIDES Deep Sea Drilling Project. most of them have wide geographic the nannoplankton zonation of the Tertiary is distributions. the planktonic foraminifera. A question may arise. The study of calcareous nannoplankton.g. it can be said that the proposed zonation will certainly cover most. Many of them have even purchased more sophisticated instruments.g. As has been mentioned earlier.g. an example of Calcareous Nannoplankton Zonation used by the JOIDES Leg 7. The zonal boundaries in these standard zonations are defined by nannoplankton datum planes. are controlled by water temperature (e. This corresponds to the Globigeri. most of the Mid-and Late Tertiary zones are based on the discoasters. biostratigraphically? The answer is short and simple: because they deserve it. e. as well as intercontinental correlations.1965) they have been using ted. reputation due to its high reliability. Zygrhablithus bijugatus). At any rate. noplankton is not as expensive complicaArea. such as Scanning and Transmission Electron Microscopes. D u e t o its simple forms.1 of Martini (1 970). about 1000 X. the discpaster group is the one that has been used extensively for the zonation. ease of generic and specific identifiof calcareous nannofossils as new biostratigracation. if not all. that is. Why? Firstly. S i n c e then(ca. 1971). aroused the interest of the oil industry. usually they are extremely abundant rai Zonation. Isthmolithus recurvus which is rare or completely absent in the tropical region). usually large and easily recognizable. the shidy of calcareous nanthe oil companies operating in the Gulf Coast 2. In the attached Chart No. why in such a rhtively short time have the nannofossils gained such an international reputation. phic tool by the oil industry has come from Secondly. live or fossil. calcareous nannoplankton. have all the ”ingredients” of being excellent NANNOPLANKTONOLOGY A N D T H E OIL biostratigraphic indicators. At preseht b. this In less than two decades the calcareous group of fossils offers the following adSnannoplankton has been widely used as stravantages: tigraphical indicators and gained worldwide a. noides datum in terms of the Standard Planktonic Foraminifera1 Zonation. as good as the Standard Planktonic Foraminifec. or simply called nannoplanktod. It would be extremely expensive for the oil industry if the Transmission and/or Scanning Electron Microscope (s) had to be used for this purpose. in many samples. this group of nannofossils has evolved rapidly during the Cenozoic (Bukry. ease of preparation for microscopic examination. 4. first and/or last occurrence of a certain species. or show influence of both (temperature and facies). . The success of calcareous nannofossils as ”new” biostratigraphical tool in the JOIDES Project and the Gulf Coast Area. In addition INDUSTRY to their biostratigraphic importance. and academic institutions have provided themselves with up-to-date laboratory equipment and personnel to conduct the nannoplankton study. . most of the major oil companies . and sophisticated as that of spore these fossils extensively in addition and comand pollen. a very useful biostratigraphical tool for accurate age determination is available. research consultants. The Paleogene Neogene boundary is by definition between the Chattian ( U p per Oligocene) and the Aquitanian (Lowermost Miocene). In this regard nannofossils have been used for age determinations. biostratigraphic zonation. It is advantageous that these standard nannoplankton zonations are based only on species that can be identified by transmitted light (polarized) with a normal petrographic microscope. like 1. many species have very short ranges. Recent studies have indicated that some species show preference for nearshore environments (e. the marine environments in the Tertiary strata. At present. As a mattel of fact. ?he first recognition of the usefulness e. Since all the nannoplankton species chosen as zonal marker can be ”easily” recognized by a normal petrographic microscope with adequate magnification.. nology has entered the oil industry in the last fewyears. In this regard the N-4 of Banner and Blow (1965) is correlative with NN. Althongh it is not as simple plementary to the foraminifera.from Hawaii t o Guam (which is closest to Indonesia) is fhown. Scyphos phaera and some of the Sphenolithus and Helicopontosphaera species. 23.l 5 0 / 5 0 0 microns) and “micro” (@ . until 1954 when Bramlette and Riedel published their classical paper entitled “Stritigraphic value of Discoasters and some other microfossils related t o Recent Cocc. Calcareous nannoplanktcn studies have indicated that some nannofossils were found in those virtually barren samples rhis gave 3. Several oil companies have been actively engaged in this study and are using local zonation for their respective operations. provided that the strata are of marine origin. Several years ago in Central Sumatra the calcareous nannoplankton study was “resumed”.1 thru N . and the Neogene numbered N . In recent years the emphasis of foraminiferal study in t h e field of economic paleontology has changed from “Larger” t o “small” (4 . The distribution of Paleozoic and Mesozoic strata is limited t o a number of locations scattered throughout t h e country. Nobody ever paid enough attention to what he did. but results are unpublished. For Indonesia this study is also considered as “ n e w ” if the pioneering studies by Tan Sin Hok in the late twenties were overlooked. and probably the most important reason is that occasionally the economically important strata contain few. the chance of finding nannofossils is good. In fact he is considered as the first worker who ever really made a taxonomic study of the discoasters.olithophorids”. All these types of lithology are favorable for the occurrence of calcareous nannoplankton. Prior t o World War 11. shale. The problem was that the economically important Lower Miocene strata were proven t o be poor in foraminiferal content and occasionally devoid of any other fossils. using numerical classification. However. in Indonesia. Tan in 1927 -. The Paleogene zones were numbered P . The practical application of the planktonic foraminiferal zonation for the Cenozoic is academically not very well known. West Indies. Only very few papers dealing with this subject have been published. in which “ N ” indicates the Neogene Planktonic Foraminifera1 Zone. Most of the Cenozoic sediments are of marine origin and are predominantly. considering that it had been started by Tan Sin Hok in 1927. Based on the above discussion i t is believed that the usefulness of calcareous nannofossils as biostraphic indicators has been well proven.53 and inexpensive as the formanifera either. the most commonly used stratigraphic method of correlation and age determination was Van der Vlerk‘s “Letter Classification” based on larger foraminifera.50/150 microns) foraminifera. it is necessary at least t o have high quality optical equipment (polarized petrographic microscope preferably with camera attachment) to study these fossils.193 1 published several papers on the “discoasters”. In 1957 Bolli published his famous and classical planktonic foraminiferal zonation of the Mid-Tertiary strata of Trinidad. Therefore. he was t o o early for his time.1 thru P . The capital investment is reasonably inexpensive for the oil industry. the Indonesian Archipelago is for the greater part built u p of sedimentary rocks of t h e Cenozoic age. Unfortunately. These two factors are most interesting economic paleontology. planktonic foraminifera have very wide lateral distribution. In recent years nannoplanktonology ha5 emerged conspicuously all over the world as new and very reliable biostratigraphic indicators.22 in which the “P” denotes the Paleogene Planktonic Foraminiferal Zone. Eventually. on account of their ultra-micro sizes. Only then the world woke up and the study of what is now called calcareous nannoplankton has been rejuvenated. This is very useful for zonations and intercontinental correlations. Thirdly. NANNOPLANKTON I N INDONESIA Stratigraphically. clayshale and fine grained sandstone. Many workers have made elaborate studics from many parts of t h e world that are In essence supporting the zonation prgposed by Bolli. Because they are found in open sea environments. in 1968 Banner and Blow established a Standard Planktonic Foraminifera1 Zonation. Experience has indicated that even in samples virtually barren of fora minifera. their practical application in the oil industry will be undoubtedly very promising and encouraging. By t h e late fifties the first priority on foraminiferal study was put on planktonic . foraminifera. maintenance and operating costs are similar t o those required for the study of forami nifera. poor o r are completely barren of foraminifera o r other fossils. In such cases the best alternative appears t o be using nannoplankton. 2.. so that eventually a “standard” calcareous nannoplankton zonation for the Tertiary of Indonesia can be established. No. 1 pp.N.W.. vol.. Initial Report. 19.. Reference is made to the attached Idealized Stratigraphic Column. H. 3. pp.p. & Riedel. 4.W. - BRAMLETTE. BRAMLETTE. D. D. SCHMEDT. Coccolith Stratigraphy Leg 7 Deep Sea Drilling Project. & BOUDREAUX. Trinidad.W. vol 10. 43 - 52. vol. 323 . 7. pp. 5 . 101 . P. 379 . pp. The calcareous nannoplankton zonation may be in the future become one of the most important stratigraphic classification methods for Indonesia. 3.188. BRAMLETTE. both in the industrial as well as in academic circles.H.. 2. 5 . No.R.. (in press. Calcareous Nannofossils from Nal’chik (NW Caucasus). M.8 No. R. No. vol. HAY. W. Geol. 197I). Establishing a standard calcareous nannoplankton zonation for the Cenezoic in Indonesia is quite possible. 4. CONCLUSIONS 1. in terms that it is used in addition and complementary to the foraminifera. 3. No.... 385 . vot.. 648 . 1 . which will be of substantial importance for the oil industry in addition and complementary to the planktonic foraminifera. M. Trans.R. Text Figure No. No. N. Calcareous Nannoplankton Zonation of the Cenozoic of the Gulf Coast and . 17. If this can be realized it will certainly be a substantial contribution to the stratigraphic studies in Indonesia. 1964. M.399 BRAMLETTE.E. & Pal. A nonexclusive report by Dennis I. West Indies. J.N. M. 196 1. vol.- HAY. P. Eclogae Geologicae Helvetiae.. E. The Petroleum Geology and evaluations of the Sedimentary Basins of Indonesia.142. Hopefully. Stratigraphic value of Discoasters and some other Microfossils related to Recent Coccolithophores. Pal.P.I. BUKRY. ~ . 1969.N.336. CEPEK. 1967. Holliss & Associates. & WILCOXON. D. On establishing a REFERENCES AMERICAN COMMISSION ON STRATIGRAPHIC NOMENCLATURE.N. F.W. vol.A. 7. Middle Tertiary Calcareous Nannoplankton of the Cipero Section. & MARTINI.49.. Singapore 10. 1971. 28. BUKRY. pp. Micropal. & SULLIVAN. W. MOHLER.W.111.P. Tulane Studies in Geol. 197 1. D. & HAY. Calcareous nannoplankton is a very useful new stratigraphical tool... “he great change in Calcareous Nannoplankt on fossils between the Maestrichtian and Danian. Tulane Studies in Geol. 129 . Micropal. vol. Washington D. ROTIi. Gulf Coast Ass. pp. 59. 3. GARTNER. W. 1966. S . 291-322. W.121.C. If studied thoroughly the prospective results are very bright and most encouraging for both the industrial and academic world. 1971). Central Sumatra (Modified after Hamilton and Holliss. H.W. Coccolithophorids and related Nan noplanktonof the Early Tertiary of California. .. & BRAMLETTE. & HOLLISS. Journ. pp. HAY. the study of calcareous nannoplankton will be canied out by many others.54 spark of optimism to further use the calcareous nannoplankton as a new biostratigraphical tool.R. HAMILTON. 3.403.N. & Pal. p. pp 91 . Tulane Studies in Geol. vol. (from Hawai to Guam).. V O 45. MOHLER.1. AAPG Bull.. M. Discoaster evolutionarytrends. SOC. 1969. BUKRY. 1961 Code on Stratigraphic Nomenclature. Calcareous Nannofossils from the JOIDES Blake Plateau cores.. The results obtained thus far in Central Sumatra should be an incentive t o conduct nannoplankton studies elsewhere in Indonesia. System of high resolution probabilistic biostratigraphy with Calcareous NannofossiIs. 1954. Micropal. 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