25. THE LATE NEOGENE OF THE GULF OF MEXICO

Lee A. Smith and John H. Beard, Esso Production Research Company, Houston, Texas

ABSTRACT The calcareous nannofossils have become important shipboard biostratigraphic tools, but the planktonic foraminifers provide the presently accepted stratigraphic framework for Cenozoic oceanic sediments. The ranges of Late Neogene calcareous nannofossils have not previously been well documented in terms of the planktonic foraminiferal zonation scheme. This multiple disci- pline effort provides that documentation, at least for the Gulf of Mexico region. The planktonic foraminiferal zonation scheme of Lamb and Beard (1972) is reviewed and its calibration with land-based stratotypes for the Late Neogene and Quaternary is discussed. Both the foraminiferal zonation and that of Martini (1971), based on calcareous nannofossils, are applied to the same samples from Late Neogene cores recovered from DSDP Holes 85, 86, 88, 89, 90, 91, 94, and 97, taken in the Gulf of Mexico on Leg 10. Documented also are the overlapping ranges of Globorotalia truncatulinoides and Discoaster brouweri in Calabrian and Emilian equivalents of the Gulf of Mexico—undoubted Early Pleistocene. INTRODUCTION modified by Blow (1969). Difficulties were encountered, especially in Late Neogene sediments. Although at that The remains of planktonic organisms play an increas- time unpublished, we actually used, quite successfully, the ingly important role in the dating and correlating of zonation proposed by Lamb and Beard (1972) for the Cretaceous and Cenozoic marine strata. The availability of post-Middle Miocene sections. Since it has now been deep-sea core data has contributed enormously to our published, it was decided to demonstrate its applicability in understanding of evolutionary trends as well as both the the laboratory study of cores recovered on Leg 10 in the temporal and geographic distributions of ancient plankton. Gulf of Mexico. Beard and Smith have been working The stimulation of interest in the study of planktonic together for several years on the integration of planktonic microfossils by the deep-sea drilling program has, in turn, foraminiferal and coccolith biostratigraphy and continued furnished both the working time stratigraphic tools for the this team effort on the Late Neogene sediments recovered shipboard geological oceanographer and the relative time from Holes 85 through 97. framework within which the geological history of ocean In the present paper, the authors attempt to shed light basins must be interpreted. In making decisions concerning on the three areas of greatest need in the study of Late the age of oceanic sediments, however, we must not neglect Neogene oceanic sediments—zonation, calibration, and the accepted points of reference that the classical land- multidiscipline integration. based sections provide for the relative time scale. Calibration with standard land-based sections is sum- In the past, emphasis has been given the planktonic marized in some depth in order to provide an understanding foraminifers with the result that they have become more or of the need for and accuracy of the Late Neogene zonation less accepted as providing the standard biostratigraphic scheme of Lamb and Beard (1972). The zonation scheme framework for the Cenozoic. The calcareous nannofossils, itself is reviewed for the reader not having access to the however, have become relatively important for rapid original publication. Its utility is demonstrated through its shipboard work, and they and the radiolarians provide application to the interpretation of the sections penetrated control where the planktonic foraminiferal assemblages on Leg 10. The relationships among the planktonic fora- may be lacking-at higher latitudes and in deeper waters. To miniferal species and between the planktonic foraminifers complete the maximum coverage for the broadest spectrum and calcareous nannofossil species are documented with of facies the dinoflagellates also should be included. The their occurrences in the cores recovered from Holes 85, 86, ultimate in biostratigraphy will be achieved through the 88, 89, 91, 94, and 97 in the Gulf of Mexico. integrated study of all the major planktonic groups in order to provide sufficient datums in all marine facies. Too little PLANKTONIC SUCCESSION WITHIN STANDARD integration has been attempted, much less achieved. REFERENCE SECTIONS-ITALY In performing the shipboard work for DSDP Leg 10 in the Gulf of Mexico, Smith and McNeely (this volume), for General purposes of communication, attempted to apply the zona- A brief account of some standard European marine tion scheme suggested by Blow and Banner (1966) stages (Figure 1) is essential to understand the measure of

643 L. A. SMITH, J. H. BEARD

AFTER SELLI (19671 Figure 1. Distribution of marine Pleistocene in Italy, outcropping (black) and covered with more recent continental terrains (dotted). White triangles show localities of important sections for the Pliocene-Pleistocene bound- ary. Black triangles show important Miocene and Pliocene localities: 1-Santa Maria di Catanzaro ("type" Calabrian); 2-Le Castella ("type" Calabrian); 3-Monte Mario; 4-Castell 'Arquato-Vernasca (type Plaisan- cian); 5-Santerno; 6-Musone; 7- Villafranca d'Asti (type Villafranchian); 8-Pasquasia-Capodarso (type Messinian); 9-Rio Massapiedi-Castellania (type Tortonian);and 10-Tabiano (type Tabianian).

accuracy that is implied with reference to stage and epoch Bologna published, under the editorial guidance of Rai- boundaries in the Caribbean and the Gulf of Mexico. mondo Selli in collaboration with many recognized author- Literature relating to the Italian late Neogene (herein ities, a multilanguage rendition in the excursion guidebooks defined as that portion of geologic time from the Middle (Number 1 and 2) of some historically important contribu- Miocene-Globorotalia menardii Zone through the Holo- tions to the understanding of type localities of the Italian cene—Globorotalia tumida Zone) sedimentary succession is Neogene succession. The full texts of the papers presented indeed voluminous and is treated in many languages. at the Bologna session are contained in Volume 35 of the Because of their somewhat provincial character, the Giornale di Geologia. Of special interest is the proposal by numerous discussions cannot be fully appreciated, however, Bertolino et al. (1968) of a subdivision of the Italian by only casual acquaintance with some of the major works. Neogene based on planktonic foraminifers (Figure 2). To remedy this, the Committee on Mediterranean Neogene A post-session discussion of the several Neogene plank- Stratigraphy (CMNS) (1967) at its fourth session in tonic zonal schemes proposed by different authors was

644 LATE NEOGENE OF THE GULF OF MEXICO organized by Hans Bolli and others at Bologna University base of the range-zone of Globorotalia acostaensis as the on May 15-17, 1968. A review of this meeting is given by base of the Tortonian Stage and the onset of the late Cati et al. (1968); the stratigraphic position and correspon- Miocene. The first appearance of G. acostaensis is proving dence of the Late Miocene and Pliocene planktonic zones to be an excellent datum for worldwide correlation. are shown in Figure 3. Messinian Stage (Late Miocene) Tortonian Stage (Late Miocene) The Messinian Stage was proposed by Mayer-Eymar The Tortonian Stage was proposed by Mayer-Eymar in (1868) to include a succession of strata near Messina in 1858. The section exposed along the Castellania and northern Sicily. Because of poor exposures and strati- Mazzapiedi rivers, chosen as the stratotype by Gianotti graphical difficulties within this sequence, Selli (1960) (1953), is about 260 meters thick and extends from the designated the Pasquasia-Capodarso section in central Sicily Serravalian ("Helvetian") at the bottom to the Messinian at as a neostratotype for this stage. These exposures occur the top. Planktonic foraminifers are abundant and display a between the towns of Caltanisetta and Enna. Although characteristic distribution. Cita et al. (1965) recognized in evaporite deposits commonly enhance recognition of the the type Tortonian the "Globorotalia mayerV/G. lenguaen- Messinian throughout Italy, the foraminiferal faunas sis Zone (corresponding to the lower part of the section for described by D'Onofrio (1964) do not lend themselves about 30 meters), the "Globorotalia mayerf/Globigerina directly to extra-Mediterranean correlation. Sulphur, nepenthes Zone (lower middle part), and the Globorotalia gypsum, and salt are common constituents of Messinian menardii/Globigerina nepenthes Zone, which they extend strata in Italy and are often the sole criteria used to up to the base of an interval they consider as Messinian. recognize the stage. The planktonic fauna of the early This planktonic zonation seemingly follows closely that Messinian becomes impoverished upward as the evaporites which Blow (1959) applied in zoning the planktonic are approached. sequence within the upper part of the Pozdn Formation of Approximately 170 meters of poorly fossiliferous strata Falcon, Venezuela, and which compared in part with and occur in the type section. An uppermost 10 meters of shale, extends upward the Trinidad zonation of Bolli (1957). however, are moderately rich in planktonic species. Samples Samples were collected from the type Tortonian section from this interval, collected by geologists of the Esso along the Castellania and Mazzapiedi rivers by Deryck D. Production Research Company, contain Sphaeroidinellopsis Bayliss and studied by Cita and Blow (1969). They sphaeroides Lamb, 1969 (=5. seminulina of authors) and maintained that the Globorotalia siakensis Zone (=Globo- Globorotalia acostaensis. In the area to the east of the type rotalia mayeri Zone of Cita et al., 1965) is not represented locality, between the town of Rossano and the Trionto in the section studied and that the lower 35 meters River, widely exposed Messinian strata are overlain uncon- (approximately) of the stratotype Tortonian are referable formably by Calabrian beds. From the upper portion of to the Globorotalia (T.) continuosa Zone (=Zone N.I5) of these Messinian strata (i.e., within the Gessi Formation) Blow (1969) and to the Globorotalia menardii Zone sensu Ogniben (1962) identified a planktonic foraminiferal facies Bolli (1957), emend. Bolli (1966). They continue by saying containing Globigerinoides conglobatus, Hastigerina aequi- that the Globorotalia acostaensis datum (earliest appear- lateralis, and Orbulina universa. These species are useful in ance of the species) is about 35 meters above the base of correlating with the Caribbean and Gulf of Mexico, where the section. Accordingly, they say that the base of the they also occur. Italian authors define the upper limit of section falls within the upper limits of the Globorotalia the Messinian as corresponding closely with the base of the menardii Zone and the upper part within the Globorotalia Globorotalia margaritae (=G. hirsuta of authors) Zone acostaensis, Globigerina dutertrei, and Globorotalia mar- (early Pliocene) in both southern and northern Italy. garitae zones of Bolli (1966), which equate with Blow's zones N. 16 and N. 17 (in part). Tabianian, Plaisancian, and Astian Stages (Early, Middle, If the base of the Pliocene is to be designated by the and Late Pliocene) Tabianian Stage, Cita and Blow (1969) saw no need for a The Pliocene terrains exposed along the southern border concept of a Messinian Stage which, according to them, is of the Apennines, that is, around the towns of Tabiano, partly coeval with the Tortonian Stage. The following Vernasca, and Castell'Arquato, constitute the type Pliocene discussion of the Messinian Stage should show convincingly according to Mayer-Eymar (1868). The Pliocene sequence that Messinian deposits are mostly younger than those of in the vicinity of Vernasca and CastelTArquato is about 950 the Tortonian and that it is highly unlikely that Tortonian meters thick (Barbieri, 1967) and is represented by three and/or Messinian strata fall within the limits of the stratigraphic units, which from bottom to top are as Tabianian Stage {Globorotalia margaritae Zone). follows: The base of the Tortonian Stage is, then, no older than 1) Vernasca Sandstone—Thickness, about 85 meters, late Globorotalia menardii Zone, while the upper limit falls Tabianian (Early Pliocene). within the range-zone of Globorotalia acostaensis. It seems 2) Lower Lugagnano Claystone—Thickness, 170 meters, acceptable to follow the decision of Cita and Blow (1969) Tabianian (Early Pliocene). to place the Tortonian in the terminal Miocene (with the Upper Lugagrians claystone-Thickness, 280 meters, Messinian) rather than in the middle Miocene as has been Plaisancian (Middle to Late Pliocene). the customary practice, but it should not be construed that 3) CastelFArquato Sandstone—Thickness, about 140 it is the time equivalent of the Messinian. meters, Astian. For purposes of regional and intercontinental faunal The the east, near the town of Tabiano, the Vernasca correlation it would be desirable to designate arbitrarily the Sandstone lies conformably on the Messinian. The maxi-

645 L. A. SMITH, J. H. BEARD

PROPOSED STRATIGRAPHY DATUM PLANES CRESCENTI, 1966 COLALONGO & SARTONI, 1967 EPOCH Cenozones Subzones Cenozones Subzones Cenozones Subzones

Globorotalia Globorotalia inflata inflata

_ Globorotalia inflata Globorotalia Globorotalia crassaformis crassaformis Globorotalia crassaformis Globorotalia Globorotalia hirsute aemiliana hirsuta aemiliana J_ Globorotalia hirsuta aemiliana Globorotalia bononiensis J Globorotalia Globorotalia bononiensis puncticulata Globorotalia Globorotalia Globorotalia hirsuta puncticulata hirsuta \ Globorotalia puncticulata Sphaeroidin ellopsis Sphaeroidinella spp. spp.

Poor and Undefined zone oligotypical thanatocoenosis

Globorotalia pseudomiocenica Globorotalia Globorotalia Globorotalia menardii scitula ventriosa menardii

Globorotalia Globorotalia praemenardii 1 Globorotalia praemenardii menardii Globigerin oides Globigerinoides obliquus obliquus Orbulina Orbulina universe universa Globoquadrina Globoquadrina altispira spp. Orbulina Orbulina universe Orbulina suturalis Orbulina suturalis Globigerin oides Praeorbulina suturalis Globigerinoides trilobus trilobus spp. I Praeorbulina Globoquadrina spp. dehiscens

Globigerinita Globigerinita dissimilis dissimilis

Globigerinoides ΛΛ spp. Figure 2. Zonal scheme for the Miocene and Pliocene of the Mediterranean area based on planktonic foraminifers (after Bertolino and et al, 1968).

646 LATE NEOGENE OF THE GULF OF MEXICO

DALLAN & DONDI & CATI & BORSETTI, 1968 COLALONGO, 1968 SALVATORINI PAPETTI, 1968 D'ONOFRIO, 196E 1968 Cenozones Subzones Cenozones Subzones Zones Zones Cenozones

Hyalinea Hyalinea baltica baltica Globorotalia pachyderma Globigerina Globigerina pachyderma pachyderma

Globorotalia Globorotalia Globorotalia inflate inflata inflata

Globorotalia Globorotalia Globorotalia crassaformis crassaformis crassaformis

Globorotalia Globorotalia Globorotalia Globorotalia hirsute aemiliana aemiliana hirsuta aemiliana hirsuta aemiliana

Globorotalia Globorotalia bononiensis Globorotalia bononiensis puncticulata Globorotalia Globorotalia Globorotalia Globorotalia hirsuta puncticulata puncticulata hirsuta Globorotalia Globorotalia Sphaeroidinellopsis hirsuta hirsuta spp. Sphaeroidin el la Sphaeroidinellopsis seminulina spp.

Globorotalia menardii

Globigerinoides obliquus

Orbulina universe

Orbulina suturalis Praeorbulina spp. G. bisphericus

Globorotalia opima continuosa Globigerinoides trilobus Globorotalia opima nana

Figure 2. (Continued).

647 L. A. SMITH, J. H. BEARD

SPAIN CARIBBEAN AREA MEDITERRANEAN AREA (ITALY, GREECE) (WESTERN NEW ZEALAND AND JAVA ANDALUSIA)

Scheme proposed by Scheme proposed by Scheme proposed by BORSETTI.CATI.COLALONGO.CRESCENTI, BIZON, FOLLADOR, JENKINS, 1967 BOLLI, 1966 PERCONIG DONDI,d'ONOFRIO, SALVATORINI.SARTON SPROVIERI, WEZEL Zone Subzone Zone Zone Zone Zone Globoquadrina w Globorotalia inflata altispira altispira Globorotalia Globorotalia inflata Globorotalia tosaensis truncatulinoides Z Globorotalia Globorotalia UJ crassaformis inflata S.I. Globorotalia Globoquadrina crassaformiss.\. altispira altispira U Globorotalia aemiliana ( = G. crotonensisl (With nine subzones based on the change O in coiling of Globorotalia Globigerina bononiensis pachyderma.) Globorotalia Globorotalia puncticulata ouncticulata Globorotalia -i Globorotalia margaritae puncticulata Globorotalia margaritae

"•/ Globorotalia / Sphaeroidinellopsis margaritae Globorotalia / Globorotalia miozea / sphericomiozea / margaritae Sphaeroidinellopsis /Ui Globorotalia Ul Undefined zone dutertrei Globorotalia I Undefined zone Globorotalia miotumida miotumida Globorotalia menardii acostaensis

Figure 3. Zonal scheme for the Pliocene of the Mediterranean area based on planktonic foram- inifers (after Cati et at, 1968).

mum water depth of the seas is interpreted to have been which is reported to occur rarely in the late Pliocene of that of outer shelf toward the slope during Tabianian time, Italy. Although the complete bioseries leading to Sphaer- and the minimum water depth at the end of Pliocene was oidinella dehiscens has not been documented in Italy, S. within the limits of the sublittoral or littoral zone. dehiscens is reported from the late Pliocene by Follador Planktonic foraminifers of the Tabianian stratotype (1967) and Sphaeroidinellopsis sphaeroides (=S. seminulina (Early Pliocene), as described by Iaccarino (1967), include of authors) from the early and early middle Pliocene by (a) warm-water species such as Sphaeroidinellopsis sphaer- many authors. One the basis of available evidence, no oides (=S. seminulina of authors) and Globoquadrina occurrence for S. dehiscens s.s. is older than late Pliocene. altispira which make their last appearance in northern Italy In tropical regions Hays et al. (1969) showed the range during the Tabianian, (b) Globorotalia margaritae (=G. of Globorotalia margaritae to fall within the Gilbert Event hirsuta of authors) which is restricted to the Tabianian, and (greater than 4.5 m.y. to about 3.3 m.y.) and that of (c) G. crassaformis gens which appear first in the Tabianian. Sphaeroidinella dehiscens s.s. to begin at about the top of Assemblages contain common Globigerina spp. and Glo- the Mammouth Event (at 3.0 m.y.). bigerinoides spp.; Globorotalia inflata first appears in the upper Plaisancian slightly below the earliest Globigerina Calabrian Stage (Early Pleistocene) pachyderma. No specific or generally accepted type section exists for The stratigraphic distribution of important late Neogene the Calabrian, although the region of Calabria is the type planktonic species in northern Italy is given in Figure 4. On locality. At the 19th International Geological Congress in the planktonic scale the Tabianian is equivalent to the Algiers in 1952, four type sections were proposed; Monte Globorotalia margaritae Zone (Early Pliocene) and the Mario (Roma), CastelFArquato (Emilia), Santerno Plaisancian to the G. crassaformis and G. inflata Zone (Romagna), and Musone (Marche). None of these has (Middle and Late Pliocene). received popular support, except perhaps the CastelP- Although Wezel (1968) and Follador (1967) record Arquato by Ruggieri (1965). In the region of Calabria, Globorotalia truncatulinoides as appearing first in the very Emiliani et. al. (1961) selected the LeCastella section for late Pliocene, current opinion, supported by study of detailed isotopic analysis, maintaining that it was more occurrences in the type region of the Calabrian Stage, completely exposed than the Santa Maria di Catanzaro regards this species as restricted to Calabrian and younger section of Gignoux (1913). They demonstrated climatic intervals and as first occurring commonly in the Sicilian fluctuations above a proposed Pliocene-Pleistocene boun- Stage (Gradstein, 1970). There is possibly some confusion dary determined by the first appearance of Hyalinea among authors with G. tosaensis, a closely related species, baltica. Selli (1967b) stated a preference for the section at

648 LATE NEOGENE OF THE GULF OF MEXICO

EPOCH LATE MIOCENE PLIOCENE PLEISTOCENE

TABIAN- PLAISANCIAN STAGE MESSINIAN EARLY CALABRIAN* IAN* JASTIAN

Globigerina nepenthes

Globigerina eggeri (s.l.)

Sphaeroidinellopsis sp.

Globorotalia crassaformis (s.l.) — Globorotalia margaritae (= G. hirsuta of authors^ Globoquadrina altispira

Globigerinoides conglobatus — —- (SHALLOW ) Globorotalia inflate D F OSTRACODE S w Globigerina pachyderma Hyalinea baltica •Locally transgressive s ** Locally regressive | Figure 4. Stratigraphic distribution of some planktonic foraminifers in the sub-Apennine region of northern Italy (after Pezzani, 1963; Barbieri, 1967;Iaccarino, 1967; and Barbieri and Petrucci, 1957). Santa Maria di Catanzaro which he provisionally dedicated appeared at different horizons. If the first occurrence of//. as the stratotype. Although he discussed the incursion of baltica is taken as the horizon to begin the Pleistocene, then boreal species as fundamental in defining the Calabrian, the the Plio-Pleistocene boundary would be below the lowest planktonic biostratigraphy was not described. bed exposed in the Santa Maria di Catanzaro section. In this Following recommendations of the 18th International case, he argued, the boundary cannot coincide with Geological Congress (1950), the base of the Quaternary or Gignoux's which was determined with A islandica. Pleistocene is widely accepted as being at the horizon of the Bayliss's study in part supports the Committee's recom- first indication of climatic deterioration in the Italian mendations for recognizing certain faunal criteria in Neogene succession. The Commission recommended further defining the upper limits of the Pliocene, which become that the lower Pleistocene should include as its basal ipso facto the limiting criteria for defining the lower limits member in the type area the Calabrian Formation (marine), of the Calabrian Stage. A number of authors have expressed together with its terrestrial equivalent, the Villafranchian. the opinion that the upper boundary of the Pliocene The work of Gignoux (1913) in the type area, where he corresponds with (a) the increase in frequency and change described the Calabrian Stage, emphasized onset of climatic in coiling (i.e., entry of sparse left-coiling forms) of deterioration as recognized by the sudden appearance in the Globigerina pachyderma, (b) the first appearance of Glo- Mediterranean region of "northern guest" species, such as borotalia truncatulinoides (only in some regions), and Arctica islandica. (c) the appearance of "northern guests" or boreal species The beginning of glaciation per se can be demonstrated such as Hyalinea baltica and Artica islandica. most effectively by physical evidence, such as glacial till, in Thus, on the basis of foraminiferal evidence, the base of continental sequences and evidence for lowering of sea level the Calabrian Stage is not completely exposed at Santa within marine sequences in reasonably tectonically stable Maria di Catazaro because it falls within the 30 meters of regions (Smith, 1965; Beard and Lamb, 1968). The covered section below the lower sandstones. This covered stratigraphic succession in northern Italy seemingly is ideal interval has Pliocene strata below and Pleistocene strata to demonstrate a relationship between the faunal (climatic) above. and eustatic events; namely, marine regressive upper Plio- Smith (1969) was the first to publish the calcareous cene (Astian) strata grade upward into continental beds nannofossil sequence within the Pleistocene sections at (Villafranchian) which precede and are laterally equivalent LeCastella and Santa Maria di Catanzaro. His was also the in part to marine Calabrian strata. Although Villafranchian earliest biostratigraphic correlation of the Santa Maria and Calabrian deposits are not contiguous, it is feasible, Catanzaro and LeCastella (Telegrafo) sections. He gave because of their stratigraphic position above the Astian cogent reasons for believing that the Telegrafo Section at sandstones, to equate the Villafranchian with possibly LeCastella is mainly Emilian equivalents (warm) and upper Pliocene and also lower Pleistocene marine strata. younger than the Calabrian at Santa Maria (Figure 5). Bayliss (1969) studied the stratigraphic distribution of At Telegrafo, the so-called "Pliocene-Pleistocene boun- the foraminifers Globorotalia truncatulinoides and Hyalinea dary" of Emiliani et al. (1961), Emiliani (1971), Bandy and baltica, together with the mollusk Arctica islandica, in the Wilcoxon (1970), and Nakagawa et al. (1971), as was area of the Calabrian at Santa Maria di Catanzaro in pointed out by Mclntyre et al. (1967), Smith (1969), and southern Italy. He maintained that the species first Bandy and Wilcoxon (1970), marks a distinct change from

649 L. A. SMITH, J. H. BEARD

SANTA MARIA AMERICAN DEEP-SEA LE CASTELLA EUROPEAN DI CATANZARO STAGES CORES ITALY STAGES ITALY

KANSAN SICILIAN

-4- • < AL TICA -IT-777 5 1 i 30M- -IT-775 - 20M- ;< UJ (=UPPER § i O 1 CALABRIAN)

GEP h 1

1 10M- TRUNCATULI -IT-762 , ) •: 83/ 0 P L EISTO C I P L E ISTO C 180M- -IT 820 f L ii

;ii 3 1 WEDI, 3 | -IT-812 Q β: NEBRASKAN Si £ § s CALABRIAN ;> 2 i I' i wre f ft s in mm -IT-796 50M- AERA M_ 1WdλOS 1

-IT-795 YPHOSPH

-IT-792 OM-

Figure 5. Correlation section for the stratotype Calabrian and Le Castella sections of Italy and a generalized section from oceanic sediments. cool to warm conditions in oceanic waters. The evident study of foraminifers from all six sections and paleo- change from cool to warm is not likely to represent the magnetic determinations on 73 samples have been reported Pliocene-Pleistocene boundary and cannot correlate with by Lamb (1971). He points out that the "Pliocene- the base of the Calabrian. Pleistocene boundary" of Emiliani et al. (1961)—the At Santa Maria di Catanzaro, Discoaster brouweri ranges so-called "marker bed" (our sample 761)—was designated as concurrently with Globorotalia truncatulinoides. In the the boundary by Carloni on "field evidence," rather than Gulf of Mexico sections this overlap occurs only in the being determined as such by study of the samples. Carloni Nebraskan (cool) and Aftonian (warm). Since the Calabrian evidently mistook the coarser bed for sand and correlated it at Santa Maria represents cooler water deposition, it must with the turbiditic units of the basal Calabrian at Santa equate with the Nebraskan. At LeCastella, in the Telegrafo Maria di Catanzaro. As determined by Lamb (1971), the section, Discoaster brouweri ranges concurrently with bed in question is almost entirely foraminiferal tests, with Gephyrocapsa oceanica in a section representing warmer no terrigineous elastics included—the least likely bed for the water deposition. In the Gulf of Mexico sections this correlation that Carloni assumed. Yet Carloni's "boundary" overlap occurs only in the Aftonian (warm). The Emilian of seemingly goes unquestioned to this day by those equipped the Telegrafo section must equate with the American to correct his miscorrelation. marine Aftonian. The data presented by Bandy and Wilcoxon (1970) also The samples used by Emiliani et al. (1961) were actually proves that the "marker bed" cannot be equated to basal collected at LeCastella by Prof. Guilio Carloni, University Calabrian, marking, as it does, a change from cool (below) of Bologna. They were from two separate sections along the to warm (above). The coiling changes in Globigerina coast, at Torre Brasolo and Telegrafo (Figure 6). Although, pachyderma, noted by Bandy and Wilcoxon (1970) from in the published work, the samples were assumed to the upper samples at Telegrafo (LeCastella), correlate with represent a continuous sequence, the SE dip of the beds is those noted from the type Sicilian at Ficarizzi (Gradstein, sufficient to render the sampling incomplete. The upper 1970; Lamb, 1971) and not with the Calabrian at Santa samples from Torre Brasolo are Middle Pliocene and the Maria di Catanzaro or elsewhere. Neither does the so-called lower samples from Telegrafo are Late Calabrian. For Beard boundary in the Telegrafo section correlate with that used (1969), Lamb (1969), and Smith (1969), Prof. Carloni by many workers in deep-sea sediments. returned to LeCastella and recollected the same sections at That the extinction of Discoaster brouweri occurs within Torre Brasolo and Telegrafo used by Emiliani et al. (1961). the warm unit above the first cool unit, rather than at the The study of these samples indicated the relationships boundary between them, has been demonstrated in many documented by Smith (1969) (Figure 5) that the Late places and is here documented from the Gulf of Mexico. Pliocene and earliest Pleistocene had not been sampled. The extinction of Discoaster brouweri, which has been As shown in Figure 6, we sampled four additional shown to occur at or within the Olduvai (Gilsa), between sections between Torre Brasolo and Telegrafo. Detailed 1.6 and 1.8 m.y. B.P., cannot even be as old as the "marker

650 LATE NEOGENE OF THE GULF OF MEXICO

TELEGRAFO

"MARKER BED"

908 A- 907A-

905A-

903A-

vwwvwi-2 TORRE BRASOLO

METERS CONTOUR INTERVAL 10 METERS

Figure 6. Correlation of stratigraphic sections measured between Torre Brasolo and Telegrafo Point, near Le Castella in southern Italy. (Longitude is in reference to the meridian of Rome, corresponding approximately to If 01 'E of Greenwich). bed" in the Telegrafo section (the Calabrian-Emilian stratotype Calabrian, it cannot be considered other than boundary=Nebraskan-Aftonian boundary in the Gulf of Pleistocene. Mexico). The 1.8 m.y. date, being used for the "Pliocene- The Pliocene-Pleistocene boundary is older than the base Pleistocene" in deep-sea sediments is more nearly an age for of Olduvai (±1.8 m.y.). (Emilian = Aftonian). It also must the Emilian-Sicilian (=Aftonian-Kansan) boundary. predate the "marker bed" in the Telegrafo section at There is no doubt that the Italian stratotype sections LeCastella (Calabrian-Emilian = Nebraskan-Aftonian bound- include much reworked older Neogene calcareous nanno- ary). The boundary is defined as the base of the Calabrian fossils. This does not, however, negate the fact that the and recognized in the type sections by the arrival of overlapping ranges of Globorotalia truncatulinoides and "northern guests" (onset of cooling) following the warm Discoaster brouweri include only Early Pleistocene sedi- Pliocene. All of the absolute ages on evidence for this ments there and elsewhere. Their concurrence was not cooling, tills, ice-rafted glacial debris, etc., fall between 2.5 established in the Italian sections but was observed there and 3.0 m.y. We have, therefore, taken as the approximate (Smith, 1969). It is here documented from the Gulf of age of the Pliocene—Pleistocene boundary 2.8 m.y. It is Mexico and, considering that the evolutionary appearance entirely possible that the boundary is 3.0 m.y. B.P., as of Globorotalia truncatulinoides is recorded within the suggested by Berggren's work on DSDP Leg 12 in the North

651 L. A. SMITH, J. H. BEARD

Atlantic (1972), but it is absolutely impossible for it to be Sphaeroidinellopsis seminulina Subzone as young as 1.8 m.y. (probably no younger than 2.5, or, for Author: Lamb and Beard, 1972. those preferring the advent of man as the beginning of the Definition: Interval with zonal marker, from the first Pleistocene, no younger than 2.6 m.y. B.P.). occurrence of Globorotalia acostaensis to last occurrence The preceding discussion gives evidence for a broad of zonal marker. subdivision of the Italian Late Neogene planktonic succes- Remarks: Globorotalia lenguaensis and Globoquad- sion along the following lines: rina dehiscens have their last occurrence in the subzone, 1) The Tortonian (late Miocene) includes a short interval and Globigerinoides obliquus extremus has its first of the Globorotalia menardü Zone followed upward occurrence in the upper part of the subzone. by an interval characterized by the first occurrence of Sphaeroidinellopsis sphaeroides Subzone Globorotalia acostaensis. For the practical purpose of Author: Lamb and Beard, 1972. faunal correlation it is desirable to begin the Tor- Definition: Interval with zonal marker, from its first tonian Stage with the first appearance of G. occurrence to first occurrence of Globorotalia acostaensis. margaritae. 2) For reasons given, the Messinian (Late Miocene) does Remarks: Globoquadrina humerosa and Globigerin- not lend itself to extra-Mediterranean comparison on oides conglobatus have their first occurrence in the the basis of planktonic foraminifers. The lower upper part of this subzone. boundary is arbitrary, as is the upper limit of the Tortonian. Globigerinoides conglobatus, Sphaeroid- PLIOCENE inellopsis sphaeroides, and Globorotalia acostaensis Globorotalia margaritae Zone are among those species that occur in the Late Author: Bolli and Bermudez, 1965, p. 132. Messinian. Much of the Messinian is characterized by Definition: Range of zonal marker. evaporites. Globorotalia multicamerata Subzone 3) The lower limit of the Tabianian (Early Pliocene) Author: Lamb and Beard, 1972. corresponds closely with the earliest occurrence of Definition: Interval from first occurrence of Glo- Globorotalia margaritae followed upward by the borotalia margaritae to first occurrence of Pulleniatina appearance of G. puncticulata and G. bononiensis. primalis. 4) The Plaisancian (Middle-late Pliocene) begins with the Remarks: G. aemiliana, and G. crassacrotonensis earliest occurrence of Globorotalia aemiliana and G. have their first occurrence in this subzone. crassacrotonensis followed upward by G. crassaformis Pulleniatina primalis Subzone sensu stricto, G. inflata, Globigerina pachyderma, Author: Lamb and Beard, 1972. Sphaeroidinella dehiscens. Definition: Interval with zonal marker, from its first 5) The upper limit of the Pliocene or beginning of the occurrence to the last occurrence of Globorotalia mar- Calabrian Stage corresponds with the earliest occur- garitae. rence of northern guest species such as Arctica Remarks: Globigerina nepenthes and Globorotalia islandica, Hyalinea baltica, left-coiling forms of crassacrotonensis have their last occurrence in this Globigerina pachyderma, and decrease in the percent- subzone. age of warm-water planktonic species. The first Pulleniatina obliquiloculata Zone occurrence of Globorotalia truncatulinoides sensu Author: Lamb and Beard, 1972. stricto is above the base of the Calabrian. Definition: Interval from last occurrence of Glo- borotalia margaritae to the extinction horizon of Globo- SUMMARY OF PLANKTONIC ZONATIONS quadrina altispira. Remarks: Glorobotalia praehirsuta, G. inflata, G. Planktonic Foraminifers tosaensis, G. pertenuis, G. miocenica, s.s., Pulleniatina Descriptions of the Late Middle Miocene to Holocene obliquiloculata (in tropical regions), and Sphaeroidinella planktonic zones applied in this study are given (Figure 7). dehiscens have their first occurrence in this zone. A full description and documentation of the zones, as well PLEISTOCENE as stereoscan illustrations of the planktonic foraminiferal species was published by Lamb and Beard (1972). Globorotalia truncatulinoides Zone Author: Lamb and Beard, 1972. LATE MIDDLE MIOCENE Definition: Interval from the extinction horizon of Globorotalia menardü Zone Globoquadrina altispira to the first occurrence of large Author: Stainforth, 1948, p. 1303. forms of the species Globorotalia tumida in the Gulf of Definition: Interval with zonal marker, from last occur- Mexico region. rence of Globorotalia siakensis to first occurrence of Globorotalia tosaensis Subzone Globorotalia acostaensis. Author: Lamb and Beard, 1972. Definition: Interval with zonal marker, from the LATE MIOCENE horizon of extinction of Globoquadrina altispira to last Globorotalia acostaensis Zone occurrence of zonal marker. Author: Lamb and Beard, 1972. Remarks: In upward fashion, Globigerinoides obli- Definition: Interval with zonal marker, from its first quus extremus, Globorotalia multicamerata, G. mio- occurrence to first occurrence of Globorotalia margaritae. cenica, and G. pertenuis have their last occurrence in this

652 LATE NEOGENE OF THE GULF OF MEXICO

FIRST !_L> AND LAST (J) APPEARANCES EPOCH PLANKTONIC ZONES PLANKTONIC SUBZONES OF SIGNIFICANT SPECIES

HOLOCENE GLOBOROTALIA TUMID A i LARGE G. TUMIDA PULLENIATINA FINALIS 1 P. FINALIS GLOBOQUADRINA PLEISTOCENE GLOBOROTALIA TRUNCA TU LI NO IDES OUTER TR El ~T G. TOSAENSIS GLOBOROTALIA TOSAENSIS -1- G. TRUNCATULINOIDES I G.MIOCENICA ~TG. ALTISPIRA PULLENIATINA OBLIQUILOCULATA 1 S. DEHISCENS S.S.

PLIOCENE ~T~ -r G• MARGARITAE PULLENIATINA 1 G. NEPENTHES \ PRIMALIS GLOBOROTALIA _L P. PRIMALIS | MARGARITAE GLOBOROTALIA I CRASSAFORMIS S.L. MULTICAMERATA } G. MARGARITAE

SPHAEROIDINELL OPSIS SPHAEROIDES }, S. SPHAEROIDES LATE MIOCENE GLOBOROTALIA ACOSTAENSIS \~ S. SEMINULINA SPHAEROIDINELLOPSIS SEMI NULIN A

J G. ACOSTAENSIS

LATE GLOBOROTALIA MIDDLE MIOCENE MENARDII X~T~ A. SIAKENSIS "]

Figure 7. Miocene to Holocene planktonic foraminiferal zonation.

subzone. Globorotalia menardü reappears in the upper Definition: Interval from the first occurrence of part of the subzone in the Gulf of Mexico region during Pulleniatina finalis to first occurrence of large forms of the Aftonian warm interglacial period. The horizon of Globorotalia tumida sensu stricto. extinction of G. miocenica within this subzone is Remarks: The development of Pulleniatina finalis considered by some oil company paleontologists to mark from P. obliquiloculata characterizes the base of the the upper limit of the Nebraskan glacial stage. This zone. Globorotalia flexuosa, G. inflata, and Globigerina species is reliable for subdividing the G. tosaensis hexagona have their last occurrence in this subzone in Subzone in the Gulf of Mexico and the Caribbean. the Gulf of Mexico. Globoquadrina dutertrei Subzone Author: Lamb and Beard, 1972. HOLOCENE Definition: Interval with zonal marker above last Globorotalia tumida Zone occurrence of Globorotalia tosaensis to first occurrence Author: Lamb and Beard, 1972. [=Holocene (post- of Pulleniatina finalis. glacial)] . Remarks: The first abundant Globorotalia truncatu- Definition: Interval with very large forms of the species linoides occur at the base of this subzone with large, Globorotalia tumida. turbinate forms of Globoquadrina dutertrei. Remarks: Base of zone in Gulf of Mexico is character- Pulleniatina finalis Subzone ized by a faunal boundary between cold-water species such Author: Lamb and Beard, 1972. as Globorotalia inflata below and warm-water species such

653 L. A. SMITH, J. H. BEARD as G. tumida (large forms) and common G. menardii above. LATE MIDDLE MIOCENE TO LATE MIOCENE The boundary seems to correspond to the end of the last NN-9 — Discoaster hamatus Zone glacial period and the beginning of the Holocene Epoch. Author: Bramlette and Wilcoxon, 1967. (Beard, in press). Definition: Interval from the first occurrence to the last occurrence of Discoaster hamatus. Calcareous Nannofossils Associated Species: Discoaster variabilis, D. challengeri, D. calcaris, D. exilis, and D. bollii. Calcareous nannofossil-based zones were not used in the Remarks: As indicated by Martini (1971), the zone shipboard reporting. Dating with calcareous nannofossils seems to span the Middle to Late Miocene boundary. The for Leg 10 has been in terms of planktonic foraminiferal end of Middle Miocene may be approximated by the last zonal equivalency, primarily because of the confusion of occurrence of Triquetrorhabdulus rugosus Bramlette and ill-defined calcareous nannofossil zonal nomenclature Wilcoxon. already in existence at the time of the cruise. The situation has improved somewhat, but different authors are still LATE MIOCENE treating formally named zones differently, with or without NN-10 — Discoaster calcaris Zone obvious emendation. The planktonic foraminiferal-based Author: Martini, 1969. zonation scheme is still better defined and better known Definition: Interval from the last occurrence of Dis- because the precise ranges are well documented for most coaster hamatus to the first occurrence of D. parts of the Cenozoic. Defined biostratigraphic units, quinqueramus. whether range, concurrent-range, or partial-range zones, are, Associated Species: Martini (1971) states that Catin- in any case, more for purposes of communication than for aster calyculus and Discoaster bollii have their last occur- application by the expert worker. There are too many rence and Sphenolithus abies its first occurrence in the possibilities for the absence of a species within its life zone lower part of the zone. for precision based on one or two forms. Remarks: Since NN-9 is defined as a range-zone for Despite these well-understood shortcomings, many Discoaster hamatus Martini and Bramlette and our data readers will be interested in the application of the better indicate an overlap of that species with D. quinqueramus known calcareous nannofossil zones to material from which Gartner, we were unable to recognize zone NN-10. This the species occurrences are documented in terms of datums does not, however, preclude its existence as a valid zone based on appearances and extinctions of planktonic fora- because we were not separating D. neohamatus Bukry and minifers. For this purpose, the calcareous nannofossil Bramlette at the time of this work. Martini's remarks zonation scheme of Martini (1971) was chosen. It is, of indicate that the zone would be restricted to the Late course, a compilation of the works of several authors, but is Miocene, but we record Discoaster quinqueramus Gartner the best known scheme for the complete Cenozoic. overlapping with D. bolli Martini and Bramlette, so that Martini (1971) draws mainly from Hay et al. (1967), application of the zone is probably not without difficulties. Bramlette and Wilcoxon (1967), Gartner (1969), Martini and Worsley (1970), and Martini (1970). In the summary of LATE MIOCENE TO EARLY PLIOCENE data from Leg 10 coreholes on the distribution of plank- NN-11 — Discoaster quinqueramus Zone tonic foraminifers and calcareous nannofossils (Figure 8), Author: Gartner, 1969. the calcareous nannofossil zones are applied as defined by Definition: Interval from the first to the last occurrence Martini (1971). Several problems arose in the rigorous of Discoaster quinqueramus. application to well-documented calcareous nannofossil dis- Associated Species: Discoaster variabilis, D. challengeri, tribution. In one case, for example, Zone NN-17, the D. brouweri, D. pentaradiatus, and Sphenolithus abies. interval of deposition represented seemingly is almost of Remarks: Since we record a much longer range for the too short a duration to be useful, at least for work with nominate species than does Martini (1971), it is difficult discontinuous coring. The maximum separation between to say more than that the zone probably does straddle the the last occurrence of Discoaster surculus and the last Miocene-Pliocene boundary. occurrence of D. pentaradiatus found was 42 cm (Core 1, Hole 97). Additionally, the last occurrences of both species PLIOCENE consistently fall within the Pleistocene, rather than Pliocene NN-12 - Ceratolithus tricornulatus Zone as indicated by Martini (1971). In another case, the Author: Gartner, 1969. occurrences in the sections from the Gulf of Mexico would Definition: Interval from the last occurrence of Dis- not allow separation of Zones NN-10, NN-11, and NN-12, coaster quinqueramus to the first occurrence of Cerato- because indicated ranges for the definitive species do lithus rugosus. disagree markedly with those previously published. Associated Species: Discoaster surculus, D. pentaradia- Following is a brief summary of the late Middle Miocene tus, D. variabilis, D. brouweri, and Reticulofenestra to Holocene calcareous nannofossil zones as defined by pseudoumbilica. Martini (1971). In each case, the original authorship is Remarks: The nominate species is not common in our indicated, the definition is given, and brief notes on material, yet we record an overlap of Discoaster quin- associated species are included. Difficulties encountered queramus Gartner and Ceratolithus rugosus Bukry and with the zonal application, as defined, are mentioned in the Bramlette. We cannot, therefore, precisely place the zone, if remarks. indeed it exists.

654 LATE NEOGENE OF THE GULF OF MEXICO

NN-13 - Ceratolithus rugosus Zone NN-17 — Discoaster pentaradiatus Zone Author: Gartner, 1969. Authors: Martini and Worsley, 1970. Definition: Interval from the first occurrence of Cerato- Definition: Interval from the last occurrence of Dis- lithus rugosus to the first occurrence of Discoaster coaster surculus to the last occurrence of D. pentaradiatus. asymmetricus. Associated Species: Discoaster brouweri, Cyclococ- Associated Species: Discoaster variabilis, D. surculus, D. colithus macintyrei, Helicopontosphaera sellii, and Pseudo- pentaradiatus, D. brouweri, and Reticulofenestra emiliania lacunosa. pseudoumbilica. Remarks: In the Gulf of Mexico cores (Leg 10) this Remarks: Neither of the definitive species is common in zone could not demonstrably be more than 42 cm in the Gulf of Mexico (Leg 10) sections. This is, however, the vertical thickness and probably does not represent much oldest of the Late Neogene zones that can be placed, as time. Gartner (1969) also reported a thickness for the defined, where it was originally conceived by the author interval of only 40 cm from the Atlantic and did not (late Early Pliocene). choose to propose it as a zone. NN-14 — Discoaster asymmetricus Zone NN-18 - Discoaster brouweri Zone Author: Gartner, 1969. Authors: Hay and Schmidt, in Hay et al., 1967; emend. Definition: Interval from the first occurrence of Dis- Martini and Worsley, 1970. coaster asymmetricus to the last occurrence of Ceratolithus Definition: Interval from the last occurrence of Dis tricomulatus. coaster pentaradiatus to the last occurrence of D. brouweri. Associated Species: Reticulofenestra pseudoumbilica, Associated Species: Cyclococcolithus macintyrei, Sphenolithus abies, Discoaster variabilis, D. surculus, D. Coccolithus pelagicus, s.l. (large, with bar), Helicoponto- pentaradiatus, and D. brouweri. sphaera selli, Pseudoemiliania lacunosa, Lithostromation cf. Remarks: Neither of the definitive species is common in perdurum, and Gephyrocapsa oceanica. the Leg 10 cores, but, applied to the occurrences, the zone Remarks: The cooccurrence of Globorotalia truncatu- seemingly falls entirely within the Middle Pliocene and linoides (d'Orbigny), Discoaster brouweri Tan Sin Hok, and approximates the Pulleniatina primalis Subzone. Gephyrocapsa oceanica Kamptner has been noted only in NN-15 — Reticulofenestra pseudoumbilica Zone the warmer interval overlying the first cooler interval Author: Gartner, 1969. post-dating the warm Pliocene. This overlap (D. brouweri Definition: Interval from the last occurrence of Cerato- and G. oceanica) is found within the range of G. truncatu- lithus tricomulatus to the last occurrence of Reticulo- linoides both in the stratotype sections of Italy (Emilian) fenestra pseudoumbilica. and the Gulf of Mexico (Aftonian). There is little doubt of Associated Species: Discoaster variabilis, D. surculus, D. the correlation of the units and no doubt concerning their pentaradiatus, D. brouweri, and Cyclococcolithus macin- Pleistocene age. tyrei. NN-19 — Pseudoemiliania lacunosa Zone Remarks: As conceived by its author, the top of this Author: Gartner, 1969. zone would mark the base of the Nebraskan. This is the last Definition: Interval from the last occurrence of Dis- common occurrence of the species rather than its extinc- coaster brouweri to the last occurrence of Pseudoemiliania tion, however, and, if it is to be used in the sense originally lacunosa. intended, must be emended. The most abundant occur- Associated Species: Gephyrocapsa oceanica, Cerato- rences of the nominate form in the Gulf of Mexico sections lithus cristatus, Coccolithus pataecus, Oolithotus antil- are below the zone, as defined. The end of the Pliocene is larum, and Discoaster? perplexus. more nearly marked by the extinction of Discoaster Remarks: In the Gulf of Mexico the nominate form is variabilis Martini and Bramlette; Sphenolithus abies Deflan- usually the dominant species of the assemblage, except in dre becomes extinct at about the middle of the zone. the uppermost part of the zone, where Gephyrocapsa becomes relatively more abundant. The lower third of the zone may be recognized in the Gulf of Mexico by the PLEISTOCENE presence of Cyclococcolithus macintyrei Bukry and Bram- lette. The middle third of the zone may be recognized as NN-16 — Discoaster surculus Zone the interval from the last occurrence of C. macintyrei Authors: Hay and Schmidt, in Hay et al., 1967; Bukry and Bramlette to the last occurrence of Scypho- emended Gartner, 1969. sphaera pulcherrima Deflandre. Definition: Interval from the last occurrence of Reti- NN-20 — Gephyrocapsa oceanica Zone culofenestra pseudoumbilica to the last occurrence of Authors: Boudreaux and Hay, in Hay et al., 1967; Discoaster surculus. emend. Gartner, 1969. Associated Species: Discoaster pentaradiatus, D. brou- Definition: Interval from the last occurrence of Pseu- weri, D. asymmetricus, Ceratolithus rugosus, Cyclococ- doemiliania lacunosa to the first occurrence of Emiliania colithus macintyrei, and Pseudoemiliania lacunosa. huxleyi. Remarks: Since the nominate species occurs with Glo- Associated Species: Coccolithus pelagicus, s. s., Ceratoli- borotalia truncatulinoides (d'Orbigny) in sediments depo- thus cristatus, Helicopontosphaera kamptneri, H. wallachi, sited after the onset of cooling both in the Gulf of Mexico and Cyclococcolithus leptoporus. and in the Italian stratotypical Calabrian, it is probably Remarks: Although neither the base nor top of the zone entirely Pleistocene in age. is defined as the nominate species appearance or extinction,

655 L. A. SMITH, J.H. BEARD it is usually the dominant form in assemblages from the extinction. It should be noted that Gephyrocapsa oceanica Gulf of Mexico above the extinction of Pseudoemiliania and other delicate forms other than P. lacunosa also are lacunosa (Kamptner). The lower part of the zone may be absent from Core 3 and rare in Core 4. recognized by the presence of Scyphosphaera recurvata Considerable reworking of Cretaceous and Pliocene Deflandre. fossils was noted. The core catcher sample from Core 4 contained definite Pliocene assemblages of both the fora- LATE PLEISTOCENE-HOLOCENE minifers and calcareous nannofossils. Since, however, NN-21 - Emiliania huxleyi Zone definite Pleistocene sediments were recovered lower in the Authors: Boudreaux and Hay, in Hay et. al., 1967. section (Core 5), the Pliocene material must have been Definition: Interval above the first occurrence of Emi- displaced, probably by slumping from the nearby liania huxleyi. Campeche Bank. Associated Species: Gephyrocapsa oceanica, G. aperta, G. kamptneri, Coccolithus pelagicus, Cyclococcolithus lep- Hole 86 toporus, Ceratolithus cristatus, Helicopontosphaera kampt- Four Late Neogene cores were recovered—the oldest neri, and//, wallachi. being interpreted as Early Pliocene {Globorotalia margaritae Remarks: Considerable difficulty is encountered trying Zone, ^Globorotalia multicamerata Subzone). In the cal- to recognize the nominate species with the light micro- careous nannofossil-based zonal scheme of Martini (1971), scope, although it is very distinctive with EM. The species the recovered samples are considered to be representative of appears in the Late Wisconsinan, but seemingly does not his NN-13 to NN-21 {Ceratolithus rugosus to Emiliania dominate the assemblage until Holocene. There are any huxleyi Zones). number of better ways of recognizing the Pleistocene- The distribution of both planktonic foraminifers and Holocene boundary. calcareous nannofossils is shown in Figure 10. The concur- rence of Discoaster brouweri, Gephyrocapsa oceanica, and APPLICATION TO DSDP LEG 10 CORES Globorotalia truncatulinoides is recorded in Core 2. The Figure 8 summarizes interpreted ranges, both planktonic presence of G. truncatulinoides demonstrates that it is foraminifers and calcareous nannofossils, from all of the Pleistocene and, from the concurrence of G. oceanica and Late Neogene and Quaternary sections penetrated on DSDP D. brouweri, it is interpreted to be representative of marine Leg 10. It is considered interpretative because of the deposition during the Aftonian Interstadial. Globorotalia discontinuous coring at each site, but, as a composite margaritae occurs in Cores 3 and 4, and Pulleniatina section of all cores, it leaves very little of the stratigraphic primalis only in Core 3, indicating that Core 4 is in the interval unsampled. Both the planktonic foraminiferal- Globorotalia multicamerata Zone. This conclusion as to based zonation (Lamb and Beard, 1972) and the calcareous stratigraphic position is supported by the occurrence in nannofossil zonation (Martini, 1971) are applied, as Core 4 of Discoaster subsurculus with Ceratolithus rugosus defined, to the ranges determined for the Gulf of Mexico and below the appearance in Core 3 of Discoaster asym- (Figure 8). metricus. Distribution of the planktonic foraminifers and cal- Nannofossil occurrences shown indicate some reworking careous nannofossils in cores recovered from each of the of Pliocene sediments into the Pleistocene section. This is DSDP Leg 10 holes (85, 86, 88, 89, 90, 91, 94, and 97) are probably especially true during the cooler low-stands documented on Figures 9 through 16. The remarks con- (stadials) and less so during interstadials. It should be kept cerning each hole are brief, as the figures are considered in mind, however, that the site of drilling is presently on primary. the continental slope and particularly subject to basinward movement of recycled materials. The site may have been in Hole 85 a slope position through much or most of the Quaternary, Five Quaternary cores were recovered—the oldest being if not longer. interpreted as Pleistocene (Illinoian) {Globorotalia trunca- tulinoides Zone, Globoquadrina dutertrei Subzone). In the Hole 88 calcareous nannofossil-based zonal scheme of Martini Five Late Neogene cores were recovered—the oldest (1970), the recovered samples are considered to be repre- being interpreted as Early to Middle Pliocene {Globorotalia sentative of his NN-19 to NN-20 {Pseudoemiliania lacunosa margaritae Zone). In the calcareous nannofossil-based zonal to Gephyrocapsa oceanica zones). scheme of Martini (1971), the recovered samples are The distribution of both planktonic foraminifers and considered to represent his NN-13 to NN-20 {Ceratolithus calcareous nannofossils is shown in Figure 9. The Globo- rugosus to Gephyrocapsa oceanica zones). quadrina dutertrei-Pulleniatina finalis subzonal boundary is The distributions of both planktonic foraminifers and interpreted as occurring within Core 4, because the earliest calcareous nannofossils is shown in Figure 11. The concur- occurrence of Pulleniatina finalis is between 42 and 110 cm rence of Discoaster brouweri and Gephyrocapsa oceanica in the core. Although Pseudoemiliania lacunosa was not and Globorotalia truncatulinoides is recorded in Core 2. noted, zonal equivalency is inferred because the apparent This core is interpreted as primarily Aftonian. The presence extinctions of Scyphosphaera recurvata and "Discoaster" of G. truncatulinoides with them again illustrates that Dis- perplexus are within Cores 3 and 4 respectively. Pseudo- coasters range into the Pleistocene and that their extinction emiliania lacunosa ranges concurrently with Pulleniatina (and the associated so-called Olduvai paleomagnetic event) finalis elsewhere and must be absent for reasons other than cannot define the Pliocene-Pleistocene boundary.

656 LATE NEOGENE OF THE GULF OF MEXICO

Globorotalia margaritae occurs only in Core 5 and sentative of his NN-9 to NN-20 {Discoaster hamatus to Pulleniatina primalis was not noted from the cored inter- Gephyrocapsa oceanicà zones). vals. Since, however, Ceratolithus rugosus occurs in Core 5 The distributions of both planktonic foraminifers and and Discoaster asymmetricus appears in Core 4 (NN-13 of calcareous nannofossils is shown in Figure 14. The section Martini, 1971), we may be able to correlate that interval is incompletely cored, Sangamonian, Yarmouthian, and approximately with Core 4 of Hole 86 {Globorotalia Aftonian age sediments not being recovered. There is multicamerata Sub zone). considerable reworking of calcareous nannofossils into Most of the detected reworking of older sediments is in Kansan and younger sediments. Core 8 is earliest Pleisto- section dated as Pleistocene (Wisconsinan). Seemingly, cene (Early Nebraskan-Early Calabrian), being pre- Yarmouthian and Nebraskan age sediments were not cored. Globorotalia truncatulinoides and post-Globoquadrina altispira. Since the rest of Nebraskan and the entire Hole 89 Aftonian were not cored, the Pleistocene overlap of G. Six Late Neogene cores were recovered—the oldest being truncatulinoides and Discoaster brouweri (in situ) is not interpreted as early Late Miocene {Globorotalia acostaensis observed in this hole, according to the ages assigned on the Zone, Sphaeroidinellopsis seminulina Subzone). In the basis of planktonic foraminifers. calcareous nannofossil-based zonal scheme of Martini (1971), the recovered samples are considered to be repre- Hole 94 sentative of his NN-9 to NN-21 {Discoaster hamatus to Eight Late Neogene cores were recovered—the oldest Emiliania huxleyi zones). being interpreted as late Late Miocene {Globorotalia The distributions of both planktonic foraminifers and acostaensis Zone, Sphaeroidinellopsis sphaeroides Sub- calcareous nannofossils is shown in Figure 12. The zone). In the calcareous nannofossil-based zonal scheme of boundary between the NN-19 and NN-20 {Pseudoemiliania Martini (1971), the recovered samples are considered to be lacunosa and Gephyrocapsa oceanicà) zones, would fall representative of his NN-11 to NN-21 {Discoaster quin- somewhere between Cores 1 and 2. The Aftonian queramus to Emiliania huxleyi zones). (=Emilian) section, with the overlap of Discoaster brouweri The distributions of both planktonic foraminifers and and G. oceanicà, was not cored. However, the concurrence calcareous nannofossils is shown in Figure 15. Coverage of Globorotalia truncatulinoides and Discoaster brouweri (stratigraphic) is incomplete, being best for illustrating the (Nebraskan-Calabrian) in the Early Pleistocene is recorded subdivisions of the Pliocene (Cores 2 through 6). Core 1 is in Core 3. In Core 6, the concurrence of Globorotalia Late Wisconsinan to Holocene and Cores 7 and 8 are Late acostaensis and Discoaster bollii indicates an early Late Miocene. Cores 2 through 6 provide good stratigraphic Miocene age. Some reworking of calcareous nannofossils is control for marine, essentially pelagic, sedimentation during evident, but this is primarily in the younger Pleistocene the Pliocene. (Core 1). Hole 97 Hole 90 Three cores were recovered from the Late Neogene—the Six Late Neogene cores were recovered—the oldest being oldest being early Late Miocene {Globorotalia acostaensis interpreted as early Late Miocene {Globorotalia acostaensis Zone, Sphaeroidinellopsis seminulina Subzone). In the Zone, Sphaeroidinellopsis seminulina Subzone). In the calcareous nannofossil-based zonal scheme of Martini calcareous nannofossil-based zonal scheme of Martini (1971), the recovered samples are considered to be repre- (1971), the recovered samples are considered to be repre- sentative of his NN-9 to NN-21 {Discoaster hamatus to sentative of his NN-9 to NN-20 {Discoaster hamatus to Emiliania huxleyi zones). Gephyrocapsa oceanicà zones). The distributions of both planktonic foraminifers and The distributions of both planktonic foraminifers and calcareous nannofossils is shown in Figure 16. Stratigraphic calcareous nannofossils is shown in Figure 13. The section coverage of the cored intervals is very incomplete. An is incompletely cored, the Aftonian, Kansan, Yarmouthian, unconformity of considerable extent (Late Kansan to and Sangamon not being recovered. The concurrence of Middle Wisconsinan) is evidenced within Core 1, and Cores Discoaster brouweri and Gephyrocapsa oceanicà (Aftonian- 2 and 3 are representative only of Late Miocene deposition. Emilian) is not represented, but the overlap of A brouweri The overlap of Globorotalia truncatulinoides and Discoaster with Globorotalia truncatulinoides (Early Pleistocene; brouweri (Early Pleistocene) can be seen in the lower part Nebraskan-Calabrian) is recorded from Core 3. Core 4 of Core 1. contains Globorotalia margaritae and lacks Pulleniatina Core 1, of Hole 97, seemingly provides evidence that primalis, again suggesting Early Pliocene. Some reworking is Martinfs NN-16 and NN-17 are probably not very signi- evident in the Late Pleistocene (Wisconsinan). ficant in terms of elapsed time. Martinfs NN-16 (the Discoaster surculus Zone of Hay and Schmidt, 1967, Hole 91 emended by Gartner, 1969) is defined as the "interval from Ten Late Neogene cores were recovered—the oldest the last occurrence of Reticulofenestra pseudoumbilica being interpreted as early Late Miocene {Globorotalia (Gartner) to the last occurrence of Discoaster surculus acostaensis Zone, Sphaeroidinellopsis seminulina Subzone). Martini and Bramlette." Both these "last occurrences" are In the calcareous nannofossil-based zonal scheme of Martini in the core catcher sample of Core 1 in Hole 97 (a scant 40 (1971), the recovered samples are considered to be repre- cm below the next higher sample).

657 L. A. SMITH, J. H. BEARD

COILING

S = SINISTRAL D = DEXTRAL R = RANDOM

STRATIGRAPHY SPECIES

PLANKTONIC I ' rrTTT^TTirX Ar, FORAMINIFERAL PLANKTONICl At7t ZONE AGE DATUMS %

(RELATIVE) LAMB AND /MY) —JAPPEARENCE 1 BEARD, 1972 "^EXTINCTION '

I Wiscoπsinqn~ ^T""™" ~ 3=! ™ HUXLEYI .Sαngαmoniαn. Pulieniatina ^ s RECURVATA "*~l P. LACUNOSA finalis lllinoiαn ^ _j; -—i p. FINALIS 72 -—i S. PULCHERRIMA O

Z Yαrmouthiαn | Globoquadrina _] , a MACINTYREt ^ i dutertrei _ Kαnsαn "^ "•—i L PER DURUM

JJ •S -—| 6. TOSAENSIS r-1 . " -—I D. BROUWERI °- Aftoniαn ° —> G. OCEANICA o —0^ 7T G/oborofαl/α -f"1 G. MIOCENICA

^ >jiuuuroioiiα -—, fl PENTARADIATU -"—I C. RUGOSUS , • ^--1 S. INTERMEDIA

Kie>urn,Lnn rosαensis ^--i G. EXTREMUS iNeorαsKαn -^_ ATUUNO ; ) G TRUNC IDES --—I 0. VARIABILIS 1 1 -—I G. ALTISPIRA

Putlen>atina -3_ =J J SSS ob/iqui/ocu/αta "" I S /AS/FS 1 — 1 G. MARGARITAE

I C. TRICORNULATUt

5 Pulieniatina -—i G. NEPENTHES

PLIOCENE I primalis "4" E o •~ -r-1 O. QUINQUIRAMUS 5 — 1 PULLENIATINA 0 I G. AEMILIANA O _. , -. I P. LACUNOSA

j G/oboroto/iα »_, D CHALLεNGERI O ~5~ - I C. RUGOSUS mu/ficαmerσta I G. MARGARITAE

Sphaeroid- , —' σ NGLOBATUS

inellopsis

•5 "" 1 D. HAMATUS C 1 A TC £Φ spnαeroide. . s 8 -7-

MIOCENE I —^ C ™ mULATUS ~g „ I S. SPHAEROIDES o -O o (j) Sphaeroid- • n • -8-

iπβfk>pS" —, D. BOLLII

. 1. 1 G. LENGUAENSIS seminulma

I Q_ I G. ACOSTAENSIS MIDDLE Globorotalia MIOCENE menardii

Figure 8. Microfossil distribution chart, DSDP Leg 10, Summary of ranges.

658 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART "LOCAL.TY: DSDP LEG I CALCAREOUS NANNOFOSSILS SUMMARY OF RANGES I

CALCAREOUS

NANNOFOSSIL

ZONES

MARTINI, 1971

NN-21 _NN-20_

- NN-19

I NN-18 IIIINN-171V. - NN-16 ,'' - × - S

: NN-15

I NN-14

: NN-13

f

-– NN-12

:: TO

NN-9

Figure 8. (Continued). L.A. SMITH, J. H. BEARD

CO.LING I MICROFOSSIL S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

B STRATIGRAPHY \ SPECIES g |§ g| _f§l s_ 1 \ S w 5 § 5; _ ^ ** 2 "* S * t _ _ g _ S~^-Ò JIH- § _ »SE \ § |l§S«^ü t - s 2 •* ii° , §ö§-w^°w§li^rls=>5§l2ësgs ill W ö a \ ^°*§| ^Ö2 gδ 5 SaSg = gg ^2 g c § g K g 11 3 §§§ 9§ §| I g lull Ö ^s S I* ε \ §S»aw£l3§|°lsg3^1^|2gös,gδSsE^*aεs^S;!2^§Ssièa^sθl£55^|5^^ PLANKTONIC \ sss99|ssü§glssç5^*^||||°ssss|93sss§||^sssg9||ss|§ss |ss AGE FORAMINIFERAL £ ...... A 1g is 1111 is | II1g g s 11111 1111 s 111 g g11111 g 11111 £ g 11111 o | s o || 1 g I g SAMPLE NO.\ §§§ëOS§|§S5§§§gSëOSëSSaS!s§§§§§S§gg§s§8s§§§2s§§§§SS§ëa§§§ Z°NE _^_ A•MP PERTH \^ §.|§§§l§§tll§§§§§§§§ll§§§l§§§§§l§ §|§|§ § §§§§§§§i§§§§§ië §,§ § § § §

i(io 85-i i,4o-4icm) ~ ~ ~~~~~ ~~~~~~~¥~~ ~~~~~~~¥~~ Z~I~ZZZZ~ 1Z Z~~~~~~~ZZ ZZZZZZ~L Woodfordian 2(10 85-1-3,39•40cm) •_••__ •__ "_•__ c 3(10-85-1-3,109-110cm) •••# •• JZ _ ^ __•.__ g A 4(10•85•1-5,39-40cml .- l-armdalian | 5(10-85-1-5,109-110cm) i~M | » » _•._•_ g 6(10 85•1-6,39-40cm) u 7(10•85-1-6,109•110cm) .•ù LateAltonian 8110-85-1-core catcher) _••• §_ < ZjZ

Mid Aitonian Pulleniatina ~ IZIIZI IIIZZZZZZZZZ IZZü~~~ „, 9(10-85-2-1,40-42cm) ~ ~ •"••""• " •.„•• -g tl 10(10-85-2-1,110•112cm) LU Earlv Aitonian δ V l• *" 11 (10-85-2-2,110112cm) ' JT __ ^ Early Aitonian g fmallS __ 12(10•85-2•core catcher) >~>~H » p LU I i -f , o sαngαmoniαn J ~~ SilSSSSS l !!!!:!::!:!!:!!:! iiEüi: tO n m 15(10-85-3-3,40-42cm) — , ~ 0 16(10•85-3 3,110-112cm) |j £ 17(10-8B-3-4,40-42cm) Q_ g 18(10•85•3•4,110-112cm) Late O 19(10-85-3-6,40-42cm) Z I Z Z Z Z I Z Z Z Z Z Z Z± *. ZtZ _O - o —j I j —-– -4-—+-— zHzz~zlz Interstadial 20(10-85-4-1,12-14cm) Z Z^ZZ ZZZ Z" !_•__•_! g J 21(10-85-4-1,40-42cm) •••• ••••' •5 T 22(10-85-4-1,110112cm) " ~~ •{• Z[Z I ç Middle 23(10•85-4-core catcher) ItZfi ft I

24(10-85-5-1,110-112cm) S~ ~ cf ~ •" ~'_ •" j Interstadial r ll J• 5 25(10-85-5-2,36-38cm) _ | j ZU ZJZ ZLZZTI (j/oboquαdπno 0 26(10-85-5-2,loβ-ioscm) 1 27(10-85-5-core catcher) ••••••• durerfrei ~~r~ ~i~ | j ~

1 —j-

iizzzzzzzzzzzz: : zµ^iµ‰: ======5======|=^=i======S======SzzEzEEEz:Ez

.— __ 1

Figure 9. Microfossil distribution chart, DSDP Hole 85.

660 LATE NEOGENE OF THE GULF OF MEXICO

D1STRIBUTI0N CHART l^ow HOLE 85 I CALCAREOUS NANNOFOSSILS 1 UOUr "UH. OU |

Figure 9. (Continued).

661 L. A. SMITH, J.H. BEARD

COILING I MICROFOSSIL

S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \

AGE FORAMINIFERAL £ SAMPLE Nc\

ZONE u AND DEPTH \

HOLOCENE Globorofalio tumidα 2110-86-1-1 40-420^1 ill I I Woodfordian I 3(10•86-1-i;i10-112cm) UJ v>ooaiorαian „ _ „ 1 4(10-86-1-2,42-44cm) Z- o-3{ Pulleniatina * s(io-86•i-2,iio-n2cm) LLJ . ~ •= 6(10-86 1 3,40-42cm) U » Farmdalian -2 g finα/ic 7(10-86 1-3,110•112cml O^ IIIIUMS 8(10-86-1•core catcher) 1 J••g ÇΛ ^ £ "H ftnninn ° i Gl°bθrθtalia —*- 9(10-86-2-1,100-102cm) α. fosoensis -*- lon° 862corecatcherl

Pulleniαfinσ TTfi 0-86-3-1,4i-43cmi

,,..., Λ 12(10-86-3-1,107-109cm| θb/iqu/lθCUlσrα 3 13(10•86-3-2 38•40cml „.,-._._ 14(10•86-3-2,108-110cm) PLIOCENE 15110-86-3-core catcher)

Globorotaliα

.. T~ Tβli 0-86-4-1,38-40cm)

mαrgαπtae _4_ 17(io•86-4-core catcher)

Figure 10. Microfossil distribution chart, DSDP Hole 86.

662 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART LOCALITY: CALCAREOUS NANNOFOSSILS UOUr HULL Oü |

Figure 10. (Continued).

663 L. A. SMITH, J.H. BEARD

CO.LING I MICROFOSSIL

S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \ AGE FORAMINIFERAL g SAMPLE Nc\

ZONE u AND DEpTH \

•£ _ z Woodfordian £ 1(10-8B-1 1,38-40cm) zlZE^ü^ I Pulleniatina ^ofstl^T LU 8 4(10-88-1-2.112-114cm) CJ Late C 5(10-88-1 3.38-40cm) O Altoπian 2 πnαlis 6(10-88-1-3,108-110cmI Mid *~ 7( 10-88-1-4,38-40cm) [T _| | Early ^5 8(10-88•1•4,108-110cm|

— r . D 9(10-88-1 -core catcher) II i Sαπgαmoniαn "δ at J KαnSαn -2 G. duferfrei 10(10-88-2-1,38-40cm) O A 11(10•88•2-4,110 112cm) , . G/oborofα/io *. 12(10-88-2-6,108-110cm) AHoniαn 13(10•88-2-core catcherl tosaensis

14(10 88•3 3,133-135cm) 15(10-88-3•4,23•25cm| 16(10-88-3-S.117-119cm) 3 17(10-88-3-6.87-89cm) 18(10-88 3-6,141-143cm| Pulleniatina 19(10 88•3 core catcher) e'"U '"" 20(10-88 4-1,37-39cm) 21(10-88•4•2,129•131cm) PLIOCENE obfiqu/fecüfata 4 g{S£t*;SSE| 24(10-88•4•5,39-41cm) 25(10-88-4-5.128 130cm) 26110-88-4-core catcher)

S; Globorotalia ~Z 27(io•88-5-i,9-Hcm) p R 28(10-88•5•5,36-38cm) multkamerata 29(10•88-5-core catcher) _ _oj_

Figure 11. Microfossil distribution chart, DSDP Hole 88.

664 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART l^‰p Mfil F Rft I CALCAREOUS NANNOFOSSILS | UOUr πULL OO

Figure 11. (Continued).

665 L. A. SMITH, J.H. BEARD

COIL.NG " MICROFOSSIL S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \ AGE FORAMINIFERAL £ SAMPLE Nc\ ZONE u AND DEPTH \

HQLOCENE GloborotaJiα fumida mo-89•i-i,i46-i42cm) 2(10-89-1-2,38 40cm) Woodfordian _ .. . 4 3(10-89-1-2,108-110cm) ^ ruiieniatma I 4( 10-89-1-3,38-40cm) S , 5(10-89-1-3,108•110cm| Farmdalian S rmol/S 6(10-89 1-core catcher) UJ -J | ^^ZZZ^^^Z 2 Yαrmouthiαn 1 ^uadnna ~J~ ^^^^^ v> c duterfrei O E I—• *• 5^2 i§ 9(10-89-3-1,38-40cm) UJ £ 10(10-89-3-1,108-110cm) —" P G/θbθrθfα//α 11(10-89•3•2,38-40cm) O. g 12(10-89-3-2,119-121cm) Nebrαskαπ -2 Q i3(io-89-3-3,38-4θcm| 7? fosσensis 14(10-89-33,114-116cm)

O fOSOenSIS 15(10-89-3-4,38-40cm) 16(10 89•3-4,108-110cm) 17(10-89-3-core catcher)

? „, , , 18(10 89•4-1,30-32cm) nnorrkir 2 ^'ODOrofα/iα 19(10-89-4-2,34-36cm) rLIULcNt = I 20(10-89-4•5,108-110cm) -t muif/cαmerαta 2Kio-89-4-6,iθ5-iθ7cm) (^ 22|10-89-4-core catcher)

LATE I Ssp/iαero;des 1" SS"^ o ~

MIOCENE ° sem(W( nα T 25(10-89-6.1,138.140cm) ». O. SemmUlina Q 26(10•89-6-CQre catcher) ü ~

Figure 12. Microfossil distribution chart, DSDPHole 89.

666 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART L0CAL1TY: ~~ "~~ CALCAREOUS NANNOFOSSILS UθU" HULfc OJ

Figure 12. (Continued).

667 L. A. SMITH, J.H. BEARD

COILING MICROFOSSIL S = SIMSTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \ AGE FORAM.NIFERAL g SAMPLE Nc\ ZONE u AND DEPTH \ ^"^T^^ákjéràr^™ """1 " TπαSö^àJSöcm'^^ Twocreekán— 2(10-90-1-1,70•72cm) 3(10-90-1-1,108•110cm| 4<10-90•1-2,48•50cm) Woodfordian 5(10-90-1-2,108-110cm) O 6(10-90 1•3,38-40cm) .E .. 1 7(10-90•1-3,108•110cm) c Farmdalian Pullewatina • 8(10-90 1 4,38-40cm) O 9(10-90-1•4,108-110cm) y ~T " Jjj 10(10-90-1-5,30-32cm) >: i=« -D I• J 11(10•90-1-5,108-110cm) ~Z. • ò tmallS 12(10•90-1-6,38-40cm) ll i 5 c 13(10•90-1-6,108-110cm| . , ~ 14(10-90-1•core catcher) O^ -Li Middle =σ • u CO = 15(10-90-2-1,108-110cm) — i 16(10 90•2-2,38-40cm|

*H o 17(10•90-2-2,108 110cm) O- lllinoiαn ^ Globoquadrina % ^^^‰ "θ 20(10 90-2-4,38•40cm) O duterhei 21(10•90•2-4,108 110cm) _Q uuiβ>Kβi 22(10-90-2-core catcher) o ~ 23(10-90-3-1,80-82cm) G/oborotaliα 24(10-90-3•1,107•109cm)

β 25(10-90 3-2,38•40cm) Nebrαskαn 0 26(io-9θ-3-2,iθ6-iθ8cm) fo•JOPnsis 27(1090-3•3,38•40cm) rosσeπsis 28(10-90-3-3.108-110cm) 29(10-90•3-core catcher)

PLIOCENE i á 332!«:9^32:3808^m> t mu/f/ccerofo _]_ gSSáüg

<Λ 35(10-90-5-1,38-4 0cm) S S. sphaeroides R 36 . . __ ai W 37(10-90-5-2,109-111cm) LA I C £ 38(10-90-5-core catcher)

MIOCENE I " " ^,0,30^33^7" (3 o. seminulina h 4θ(io-9θ-6•2,iθ8-iiθcm) 41 (10-90-6•core catcher)

f 42(10-90•7-1,38•40cm) MIDDLE G/oborofα/iα ft 43(10-90-8 core catcher) MIOCENE menardü ~IZ

ST~ 44(10-90-9-1,33-35cm| g 45|10-90•9-core catcher)

Figure 13. Micro fossil distribution chart, DSDP Hole 90.

668 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART LOCALITY: ~~~ CALCAREOUS NANNOFOSSILS UoUr HULL jU

Figure 13. (Continued).

669 L. A. SMITH, J. H. BEARD

COIL.NG I MICROFOSSIL

S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \

AGE FORAMINIFERAL g SAMpLE N(λ

ZONE u AND DEpTH \

1(10-91-1-1,108-110cm) 2(10-91-1-2,108-110cm) ui• „ • 1 3( 10-91 •1•6,38-40cm) Wisconsinαn I 4(io-9i-i-6.384θcm) S(10-91-1-core catcher)

6(10-91-2-1,135-137cm) 7(10-91-2-1, cm) 8(10-91 2•2,38-40cm) 9(10-91•2-2,108-110cm) 10(10-91-2-3,3840cm) 2 11(10-91-2 3,108-110cm) 12(10-91-2-4,3840cm) 13(10•91-2-4,108•110cm) 14(10•91-2-5,108-110cm) 15(10•91-2-core catcher) Pulleniatina —

~ 16(10-91 3•1,3840cm) 17(10-91-3-1,108-110cm) 3 18110-91-3-2,32 •34cm)

lllinoiαn ftπα'is £ ~ 19(10-91-41,38-40cm) U-1 ~O 20(10-91-4-1,106•108cm) -7 5 21(10-91-4•2,38-40cm) •*- .£ J 22(10-91-4-2,108•110cm) LU ~5 T 23(10-91-4-5,108-110cm) , . *; 24(10-91•4•6,37-39cm) ×J u 25(10-91-4-6,107•109cm) O C 26 (10-91-4 core catcher) = 27(10-91-5-1,37 39cm) (― *• 28(10-91-5-1,108•110cm) O 29(10•91-5-4,38-40cm) <" -~ 30(10•91-5-4,108-110cm) — -2 H 31(10-91-5-5,38-40cm) MI 2 32(10-91-5-5.108•110cm) O 33(10-91-5•6,38-40cm) —' -O 34110-91-5-6,108-110cm) Q_ -2 35|10-91-5•core catcher)

36(10•91-6-1,2•4cm) 37(10-91-6-1,108-110cm) 6 38(10•91-6-5,108-110cm) 39 (10-91-6-core catcher) Globoquadrina

Kαnsαn 40(10-91-7-1, i07-i09cm) 41(10•91-7•2,40-42cm) 1 , , 42(10-91-7-2,108•110cm) duterkei 43(1091-7•3,4042cm) / 44(10-91-7-3,111-113cm) 45(10-91•7•4,37-39cm) 46(10-91-7-4,108-110cm) 47(10-91-7-core catcher)

Globorotaliσ 48(10-91-8•1,38-40cm) N i I 49(10-91-8-1,108-110cm) ebrαskαn β 5ono-9i-8-2,35-37cm) fosαensis 51(10•91-8-2,104-106cm) 52110-91-8-core catcher)

~ 53(10-91-9-2,38-4 0cm) 11 . . 54(10•91-9-2,108-110cm) rullematinD a 55(10•91-9-3,38•40cm) 56(10-91-9-3,108-110cm) „..__,-..,_ _ 57(10-91•9•4,37-39cm) PLIOCENE 9 58(10-91 9-4,107•109cm) . 59(10•91-9-5,34-36cm) ob/iqui/oCUIOta 60(10-91 9•5,108-110cm) 61(10-91-9•6,36-38cm) 62(10-91-9-6,110•112cm) 63110-91-9-core catcher)

2 S. spfiαeroides . . £ K 64(10-91-10-2,38-40cm) LA TI Ct D _ 65(10-91-10•2,108•110cm) "ft ill 66(10-91•10-4,36-38cm) ° S

Figure 14. Microfossil distribution chart, DSDP Hole 91.

670 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART I LOCALITY: "1 CALCAREOUS NANNOFOSSILS UoUr HULt "l

Figure 14. (Continued).

671 L. A. SMITH, J. H. BEARD

COILING I MICROFOSSIL

S = SINISTRAL D = DEXTRAL R = RANDOMJ PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \ AGE FORAMINIFERAL £ SAMPLE Nc\

ZONE u AND DEPTH \

i—* IZZZZZZZZIZIZ! ¥2 HOLOCENE Globorofalia tumida 1110-94-1-1,107-IMcm) ^J " ~£~l rT~ü 1 2{10-94•1-2!38 40cm> O. ë Woodfordian | ^J^0 _L ZSZSEZS!

Pulleniatina ~~Z 5(io-94-2-i,38-4θcm) 7 6(10-94-2-6,108-110cm) obliquilocuhta 7(10-94-2-core catcher)

P r>r.'~.~l;, ~~5 8(10-94-3-1,36•38cm)

β r Primal* J 9(10-94 3-core catcher) J3 •c PLIOCENE ? ~i~ 10(10-94-4 1,38-40cm) O % 11(10-94-4-core catcher) ^ Globorotaliσ -2 -g— 12(10-94-5-1,38•40cm) £ |. 3 13(10-94-5-core catcher) _o multicamerata —— _g " O I 14(10-94•6•1,38-40cm) 8 15(10-94-6-corβ catcher)

S 16(10-94-7-1,130-132cm)

, A Tr• S . 17(10-94•7 2,38 40cm) LA ItS 7 18(10-94-7•2,108-110cm) "ft S. Sp/iαero/deS 19(10•94-7-3,38-40cm| Ul^rCkir 8 20(10-94•7-core catcherl mlULtlNt O 21(10-94-8 1,130-132cm) »; R 22(10-94-8-3,108-110cm) Λ 23(10-94-8-core catcher)

Figure 15. Microfossil distribution chart, DSDPHole 94.

672 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART L0CALITY: ~~ CALCAREOUS NANNOFOSSILS UθUr HULL J*r |

Figure 15. (Continued).

673 L. A. SMITH, J. H. BEARD

CO.LING MICROFOSSIL S = SINISTRAL D = DEXTRAL R = RANDOM | PLANKTONIC FORAMINIFERS

STRATIGRAPHY \ SPECIES

PLANKTONIC \ AGE FORAMINIFERAL jjj SAMPLE Nc\ ZONE <-> AND DEPTH \

HOLOCENE Globorotaliatumióa 2! l‰™ kg | Woo.or.an I finolis IJSS‰ ,Λ Kαnsαn u G. dutertrβi 5(io•97•i-3,38•4θcm)

— Ahn.^, § 6(10-97 -1-3,108-110cm| LU Mπoniαn £ 7(10-97-14,38-40cml —I ^ O/oborofα/lO 8(10-97•1•4.108-110cm) °- Nebrαskαn ò tosαensis 9(io-97-i-core catcher)

.2 10(10•97-2-1,38•40cm) c S SDhaprniJp<; 9 11(10-97-2-1,108-110cm) IATF Φ spooeroides ^ i2(io•97•2-3.iθ8•nocmi " ' •- £ 13(10-97-2•core catcher) MICENE o _ _ = t: C cominn/Jnr, 0 14(10-97-3-2,38-40cm) O ò• seminu»na _J_ 1S(10-97-3core catcher)

Figure 16. Microfossil distribution chart, DSDP Hole 97.

674 LATE NEOGENE OF THE GULF OF MEXICO

DISTRIBUTION CHART l^ncnp MHIF Q7 I CALCAREOUS NANNOFOSSILS | UOUr πULL Jl

Figure 16. (Continued).

675 L. A. SMITH, J. H. BEARD

Martinfs NN-17 (the Discoaster pentaradiatus Zone of Blow, W. H. and Banner, F. T., 1966. Zonation of Martini and Worsley, 1970) is defined as the "interval from Cretaceous to Pliocene marine sediments based on the last occurrence of Discoaster surculus Martini and planktonic foraminifera—a comment. Bol. Inf. 9, 55. Bramlette to the last occurrence of D. pentaradiatus Tan Bolli, H. M., 1957. Planktonic Foraminifera from the Sin Hok." These two "last occurrences" are separated by Oligocene-Miocene Cipero and Lengua Formations of Trinidad, B. W. I.. Bull. U. S. Natl. Museum. 215, 97. 40 to 42 cm in Core 1 of Hole 97. Additionally, since all of , 1966. Zonation of Cretaceous to Pliocene marine these planktonic events take place within the range of sediments based on planktonic Foraminifera. Bol. Globorotalia truncatulinoides, which first appears above the Inform. Asoc. Venez. Geol. Min. Petr. 9, 3. base of the stratotypical Calabrian of Italy, they occur Bolli, H. M. and Bermúdex, P. J., 1965. Zonation based on during the Pleistocene rather than Pliocene, as suggested by planktonic Foraminifera of middle Miocene to Pliocene many authors. warm-water sediments. Bol. Inform. Asoc. Venez. Geol. Min. Petr. 8, 119. ACKNOWLEDGMENTS Bramlette, M. N. and Wilcoxon, J. A., 1967. Middle Much of the review of planktonic successions in standard Tertiary calcareous nannoplankton of the Cipero reference sections summarized in this paper was taken from section, Trinidad, W. I.. Tulane Studies Geol. 5, 93. Lamb and Beard (1972). We gratefully acknowledge the Cati, F. and Borsetti, A. M., 1968. Stratigrafia del Miocene invaluable assistance of Jim Lamb in the preparation of this marchigiano in facies di "Schlier". In G. C. Carloni, F. paper and for allowing us to draw freely from his earlier Cati, and A. M. Borsetti. Gior. Geol. Ser. 2. 35(2), 351. work with John Beard. We wish also to thank J. Lamar Cati, F. et al., 1968. Biostratigraphia del Neogene Worzel for allowing Mr. Beard's participation in the mediterraneo basata sui foraminiferi planctonici. Boll. laboratory studies and Blake McNeely for relinquishing the Soc. Geol. Italiana. 87, 491. foraminiferal work on the Late Neogene samples so as to Cita, M. B. and Blow, W. H., 1969. The biostratigraphy of make this team effort possible. the Langhian, Serravallian and Tortonian stages in the type sections in Italy. Riv. Italiana Paleontol. Stratig. 75, 549. REFERENCES Cita, M. B., Premoli-Silva, I. and Rossi, R. C, 1965. Foraminiferi planctonici del Tortoniano-tipo. Riv. Bandy, O. L. and Wilcoxon, J. A., 1970. The Italiana Paleontol. Stratig. 71, 217. Pliocene-Pleistocene boundary, Italy and California. Colalongo, M. L., 1968. Cenozone a foraminiferi ed Bull. Geol. Soc. Am. 81, 2939. ostracodi nel Pliocene e basso Pleistocene della serie del Barbieri, F., 1967. The Foraminifera in the Pliocene section Santerno e dell'Appennino Romagnolo. Gior. Geol. 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