leg 39, deep sea drilling project · 2007. 5. 11. · linella ßorealis, osangularia cordieriana,...

30. CRETACEOUS BENTHIC FORAMINIFERS FROM THE WESTERN SOUTH ATLANTICLEG 39, DEEP SEA DRILLING PROJECT

William V. Sliter, U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California

ABSTRACTCretaceous benthic foraminifers from DSDP Leg 39, Sites 355-

358, in the western South Atlantic, range in age from Albian toMaestrichtian, and indicate middle bathyal to abyssal depositionalenvironments. Foraminifers of Maestrichtian and possibly Cam-panian age from Site 355 in the Brazil Basin, and of Maestrichtianage from Site 358 in the Argentine Basin, indicate abyssal waterdepths of 3000 to 4000 meters. The Albian assemblage of Site 356 onthe Sào Paulo Plateau is from middle bathyal depths of 500 to 1500meters, whereas Santonian to Maestrichtian assemblages are lowerbathyal (1500-2500 m). Foraminiferal assemblages at Site 357 on theRio Grande Rise range from middle to lower bathyal in theSantonian to lower bathyal in the Campanian and Maestrichtian.

The distribution and preservation of the late Cretaceousforaminifers suggest the lysocline and the carbonate compensationsurface in the South Atlantic ranged between 3000 and 4000 meters.Dissolution of most agglutinated and calcareous benthic speciesoccurred at the CCD, resulting in an assemblage composed of cor-roded specimens of the Cassidulinacea, with rare resistantagglutinated species. Faunal variations in the Campanian sample ofSite 356, and similar variations—together with dissolution of plank-tonic and selected benthic species—in the Campanian of Site 357,may suggest an influx of corrosive bottom waters, or alternatively,an oxygen-minimum layer between 1000 and 1500 meters.

A mid-Cretaceous hiatus detected at Sites 356 and 357 correlateswith the hiatus at Hole 327A of Leg 36 on the Falkland Plateau.Thus the mid-Cretaceous hiatus, recognized at many DSDP sites inthe Southern Hemisphere, extends well into the South Atlantic.

INTRODUCTIONMost Cretaceous sediments recovered from the

western South Atlantic during Leg 39 proved to befossiliferous. This study describes the Cretaceousbenthic foraminifers from Sites 355 to 358 (Figure 1).These sites flank the Rio Grande Rise, and range fromabout 15° to 37°S latitude. The foraminifer faunas addconsiderably to our knowledge of Cretaceous lowerbathyal and abyssal species and paleo-oceanographicconditions in the South Atlantic. A total of 180 species,ranging in age from Albian to Maestrichtian, was iden-tified from a size fraction greater than 150 µm takenfrom samples of approximately uniform volume. Thesespecies form the basis of the biostratigraphic andenvironmental reconstructions that follow. The cosmo-politan nature of many Leg 39 species is apparent in thegeographic distribution of assemblages with faunalaffinities, such as those from the U.S. Gulf Coast(Tappan, 1940, 1943; Cushman, 1946), California(Sliter, 1968), Trinidad (Bartenstein et al., 1957),Sweden (Brotzen, 1936), Poland (Stejn, 1957; Gawor-Biedowa, 1972), Czechoslovakia (Hanzliková, 1972);Rumania (Neagu, 1965, 1968, 1970), and Australia(Belford, 1960). Within the South Atlantic and Indian

Ocean areas, foraminiferal assemblages showingsimilarities have been described by Ferreira and Rocha(1957), Scheibnerová (1974), Lambert (1971), Natlandet al. (1974), Malumian (1968), and Sliter (in press).

BIOSTRATIGRAPHY

Site 355Site 355, in the Brazil Basin, lies at a water depth of

4901 meters. Coring here recovered 44 meters of upperCretaceous clay-rich nannofossil ooze and chalk.Foraminiferal faunas consist primarily of corroded andfragmented benthic species, with planktonic speciesrare or absent. Samples from Cores 17 to 20 contain abenthic fauna suggestive of a Maestrichtian age, basedon the presence of Aragonia ouezzaensis, Gaudryinapyramidata, Gavelinella cayeuxi mangshlakensis, andSpiroplectammina dentata (Figures 2, 3; see Plates 1-13and Appendix for species identifications). TheMaestrichtian age assumed for Cores 19 and 20conflicts with a Campanian age based on calcareousnannofossils from these same cores (Bukry, thisvolume). Although a Campanian age for these species ispossible, such an extension at Site 355 would be

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45°W 30° 15° 0° 15°E

Figure 1. Location ofDSDPLeg 39 Sites 355 to 358.

surprising, in light of their Maestrichtian range at theadjacent sites of Leg 39 (see below).

Site 356Site 356 is on the southeastern edge of the Sào Paulo

Plateau, at a water depth of 3175 meters. The ninesamples examined from Hole 356 range in age fromAlbian to Maestrichtian (Figures 4, 5). Core 42 isprimarily calcareous mudstone, with a characteristicAlbian benthic foraminiferal assemblage that includessuch species as Gavelinella intermedia, Lenticulinagaultina, Pleurostomella obtusa, Saracenariabononiensis, and Tritaxia gaultina. Section 39-5, froman interval of clay-pebble conglomerate, contains nobenthic foraminifers and only rare fragments ofplanktonic foraminifers.

Cores 35 and 37, dolomitic marly calcareous chalk,contain a Santonian assemblage characterized byGloborotalites multiseptus, Gyroidinoides praeglobosus,Osangularia whitei, and Pleurostomella austinana. Noassemblage of unequivocally Coniacian age wasrecovered. The marly calcareous chalk of Core 34 isCampanian in age, based on the occurrence of speciessuch as Gavelinella nacatochensis, Globorotalitesspineus, Gyroidinoides globosus, and Osangulariacordieriana. Cores 29 to 32, consisting of nannofossilchalk ranging downward to marly calcareous chalk, areMaestrichtian in age, as evidenced by Gaudryinapyramidata, Gavelinella velascoensis, Pullenia coryelli,and P. minuta, among others.

Site 357Site 357, on the northern flank of the Rio Grande

Rise, lies at a water depth of 2086 meters. The ninesamples examined range in age from Santonian toMaestrichtian. Section 50-4, from dark greenish-graymarly limestone, contains no foraminifers. In contrast,the medium-grained gray marly chalk and marly lime-stone of Cores 47 and 48 contain a poorly preservedand fragmented benthic foraminiferal fauna of at leastSantonian age, based on Gavelinella whitei, Globo-rotalites multiseptus, Gyroidinoides praeglobosus,Osangularia whitei, Pseudospiroplectinatacompressiuscula, and Valvulineria lenticula, amongothers (Figures 6, 7). Pseudospiroplectinatacompressiuscula, described from Santonian strata ofAustralia (Chapman, 1917; Belford, 1960), and char-acteristic of a Santonian to Campanian age range inGermany (Klasz, 1953) and Czechoslovakia (Salaj andSamuel, 1966; Hanzliková, 1972), ranges into theConiacian of the Manin Group of Czechoslovakia(Salaj and Samuel, 1966) and older strata in the DonetsBasin of the USSR (Gorbenko, 1960). Alsocontributing to the Santonian affinities of these cores isthe common occurrence of Gavelinella whitei, whichranges from the Santonian to the Maestrichtian inNorth America (White, 1928; Martin, 1964; Sliter,1968), and from the Campanian to the Maestrichtian ofCzechoslovakia (Hanzliková, 1972).

The greenish-gray marly limestone of Cores 42 and44, unlike that of the lower cores, is definitely of San-tonian age, based on Bolivinoides strigillatus associatedwith Gaudryina austinana, Globorotalites spineus, andPleurostomella austinana.

Core 40 is olive-gray calcareous chalk with a Cam-panian benthic fauna characterized by the firstappearances of several indicator species, such as Cory-phostoma plaitum, Gyroidinoides quadratus, Nuttal-linella ßorealis, Osangularia cordieriana, and Reussellaszajnochae, among others. The brown foraminiferalnannofossil chalk of Core 36 also belongs in theCampanian, as the continued occurrence of manyindicator species from Core 40 and the firstappearances of Gavelinella velascoensis and Pulleniacoryelli indicate. This sample contains only very rareand fragmented planktonic foraminifers and a benthicassemblage of reduced diversity and fewer individuals.

Maestrichtian sediments in Cores 32 and 33 are lightbrown nannofossil chalks. The benthic assemblageincludes the first occurrences of several Maestrichtianspecies, such as Aragonia ouezzaensis, A. velascoensis,Bolivinoides australis, B. sidestrandensis, and Pulleniaminuta; several Campanian-to-Maestrichtian speciescommon to the underlying samples persist.

Site 358Coring at Site 358 in the Argentine Basin (water

depth 4962 m) recovered 5.2 meters of Cretaceous sedi-ments. In the two samples examined, from darkreddish-brown ferruginous mudstone and from blue-gray mudstone and marly chalk, no planktonicforaminifers occur. Benthic foraminifers are onlymoderately well preserved, and specimens are corroded

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CRETACEOUS BENTHIC FORAMINIFERS

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Figure 7. Distribution of selected benthic indicator species at Site 357.

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the surface defined by compensation depths within ageographic area.

Water depth ranges used in the following inter-pretations are:

neritic (0-200 m)upper bathyal (200-500 m)

middle bathyal (500-1500 m)lower bathyal (1500-2500 m)

abyssal (>2500 m)

Site 355Benthic foraminifer assemblages from the upper

Cretaceous samples of Site 355 are abyssal in characterand suggest water depths of 3000 to 4000 meters.Benthic assemblages are dominated by genera such asAragonia, Gavelinella, Gyroidinoides, Osangularia, andseveral agglutinated genera (Figure 2). Nodosariids andpraebuliminids characteristic of bathyal and outerneritic water depths are notably lacking, whereasagglutinated genera and solution-resistant species, suchas the thicker walled members of the Cassidulinacea,increase in numbers. Several deep-water genera occur(Figure 10), such as Cribrostomoides, Glomospira,Lituotuba, Paratrochamminoides (?), Recurvoides, andRhabdammina. Planktonic species occur as scarce frag-ments, and the benthic species are corroded and frag-mented. Associated fossils in all samples are infrequentand occur only as corroded Inoceramus prisms andfragments and fish debris.

The foraminiferal assemblages from Site 355 implywater depths beneath the lysocline but above the CCD.Evidence from Leg 36 in the South Atlantic indicatesthat the carbonate compensation surface (CCS) in theSouthern Hemisphere during the late Cretaceous


ranged between 3000 and 4000 meters (Sliter, in press).The present depth estimate for Site 355 environments,interpreted to have been beneath the lysocline butabove the CCD, would fall within that range.

Site 356Benthic foraminiferal assemblages from Hole 356 are

generally more diverse and better preserved than thosefrom Hole 355. Depositional environments for samplescontaining foraminifers were above the foraminiferallysocline, and ranged from middle to lower bathyalwater depths.

The Albian benthic foraminiferal assemblage fromHole 356 (Core 42) indicates middle bathyal waterdepths (500-1500 m). Gavelinellids, gyroidinoidids, andagglutinated genera dominate; nodosariids representapproximately 48% of the assemblage (Figures 4 and11). The poor preservation of this sample can beattributed largely to post-depositional alteration.

Planktonic species are abundant but poorly pre-served; associated fossils comprise common Inoceramusprisms, scarce ostracodes, fish debris, and commonechinoid spines and fragments. Fragmented, elongatenodosariids and the composition and preservation ofassociated calcareous fossils suggest admixtures ofneritic elements. The terrigenous nature of the calcare-ous mudstone and the coarse sand-sized graded layerswithin this sequence support an interpretation thatincludes such displaced forms.

Benthic foraminifers from the Santonian interval(Cores 35 and 37) suggest lower bathyal water depths(1500-2500 m). Ellipsoidella, Globorotalites, Hyper-ammina, Osangularia, and Tritaxia dominate, andseveral species of Gavelinella and Gyroidinoides also

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Figure 10. Comparison of benthic foraminiferal groups ( cumulative percent) and preservation at Site 355.

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Figure 11. Comparison of benthic foraminiferal groups (cumulative percent) and preservation at Site 356.

occur. Nodosariids represent 26% to 37% of the faunas.Agglutinated species make up 17% or more of the

assemblages, and members of the Buliminacea maketheir first appearance (Figure 11). Associated fossils are

668


scarce and comprise Inoceramus prisms and fish debris.Fragmented nodosariids, a worn miliolid, a fistulosepolymorphinid, Inoceramus prisms, and rare glauconitegrains offer evidence of downslope transport.

The Campanian assemblage (Core 34) most closelyresembles those of the Santonian interval in numbers ofindividuals, species diversity, and generic composition.Water depths again seem to have been in the lowerbathyal range, as suggested by a fauna in whichGloborotalites, Gyroidinoides, and Osangulariadominate, with Allomorphina and Pullenia and severalgavelinellids also present. Planktonic species remainabundant and moderately well preserved. Nevertheless,a faunal change is evident in the disappearances ofHyperammina and Pleurostomella, a reduction ofagglutinated species, and an increase in praebuliminids.A marked increase in Inoceramus prisms and fragmentsaccompanies this change.

Several hypotheses would explain the faunalvariation. First, it could be explained by a reduction inwater depth. This seems unlikely, since the dominantbenthic fauna remains unchanged. Second, gravity-controlled bottom currents could have brought aboutthe changes. Following this interpretation, theindigenous lower bathyal faunas would have beenflooded by transported Inoceramus debris and upslopeforaminifers such as the typically shallower slopepraebuliminids and specimens of Conorboides,Globulina, and Stensioina. The effects of dilution on thealready rare deep-water benthic fauna would haveaccompanied this influx. This explanation is quiteplausible, judged by the terrigenous component of themarly chalks and the occasional coarse-graded layers inthis sequence.

A third hypothesis, with effects independent of orallied with gravity currents, supposes a depth just belowan oxygen-minimum layer. This hypothesis is based oncertain similarities between the Core 34 assemblage andan assemblage from a presumed late Cretaceousoxygen-minimum environment in California that lay atabout 1000 meters water depth (Sliter, 1975). Anincrease in praebuliminids and a reduction of Hyper-ammina and Pleurostomella characterize faunas in bothcases. The Core 34 assemblage, however, differsnotably in other faunal constituents and in theabundance of planktonic species. The marly bio-turbated sediments clearly were not deposited within astrongly developed oxygen-minimum layer. But theymay have been adjacent to such a layer, or a weaklydeveloped layer, in which case the association orgravity currents flowing through the oxygen-minimumlayer could have altered the fauna.

The Maestrichtian samples (Cores 29-32) indicatelower bathyal water depths of 2000 to 2500 meters. Thebenthic fauna contains dominant Gavelinella,Globorotalites, Osangularia, Reussella, and Tritaxia, aswell as Allomorphina, Ellipsoidella, Gyroidinoides,Hyperammina, Pleurostomella, Praebulimina, Pullenia,and Thalmannammina. Diversity remains about thesame, but numbers of individuals are generally smaller.Dissolution effects remain about the same as in theCampanian sample, with perhaps a slight increase infragmentation and corrosion. Displaced benthic speciesinclude large, commonly fragmented nodosariids and

worn, fistulose polymorphinids. Very rare echinoidspines and ostracodes and rare fish debris also occur.

Site 357Compared with Site 356 samples, Site 357 samples

contain a more diverse and somewhat better preservedbenthic foraminifer fauna, and a greater abundance ofassociated fossils. Water depths ranged from middle tolower bathyal, and were somewhat shallower thanthose for Site 356. The increase in Nodosariacea, asshown in Figure 12, reflects these depths.

Santonian assemblages (Cores 42-48) appear to fallwithin the middle to lower bathyal range of 1000 to1500 meters. Dominant in the faunas are Gaudryina,Gavelinella, Globorotalites, Gyroidinoides, Osangularia,Pullenia, Quadrimorphina, and Tritaxia. Agglutinatedspecies represent about 18% of the fauna, nodosariids26% to 40% (Figure 12). Planktonic foraminifers areabundant in these samples; foraminifer preservationranges from poor to moderate. Associated fossils arevaried and relatively abundant, and include commonInoceramus prisms and fragments, scarce to commonbivalve fragments, common echinoid spines, and scarceostracodes and fish debris. The abundance ofassociated fossils, in addition to worn miliolids, largefragmented nodosariids, and polymorphinids, providesample evidence of gravity-controlled bottom flows andproximity to shelf and upper slope environments.

The Campanian benthic assemblages are char-acteristic of lower bathyal water depths, and probablyfall within the upper reaches of the 1500 to 2500 metersrange. The Core 40 fauna is dominated byGyroidinoides, Osangularia, Praebulimina, and Tritaxia,with occurrences of Allomorphina, Dorothia,Ellipsoidella, Gaudryina, Gavelinella, Nuttallinella,Pleurostomella, Pullenia, and Quadrimorphina. Speciesdiversity increases over the Santonian assemblages, butthe number of specimens remains about the same.Planktonic species are abundant; associated fossils arescarce Inoceramus prisms, echinoid spines, fish debris,and very scarce ostracodes. A worn fistulose poly-morphinid indicates downslope transport, as do theassociated calcareous fossils and fragmented and wornnodosariids.

The Core 36 Campanian fauna records a markedenvironmental change that resulted in increaseddissolution of carbonate. The benthic fauna is muchless diverse, and planktonic specimens are absent.Preservation of foraminifers is poor and specimens arecorroded and fragmented. The fauna is characterizedby species of Ellipsoglandulina, Gavelinella,Gyroidinoides, Osangularia, Praebulimina, andReussella, with lesser occurrences of Ellipsoidella,Hyperammina, Pleurostomella, Pullenia, andSaccammina. Several agglutinated species are absent orpresent in reduced numbers. Still, agglutinated speciesrepresent about 13% of the reduced fauna (Figure 12),and the Cassidulinacea increase to 48%. Only veryscarce fish debris represents associated fossils. Theforaminiferal assemblage indicates lower bathyal waterdepths of 1500 to 2500 meters.

The abundance of praebuliminids and reduceddiversity of agglutinated forms in Core 36 recall theCampanian fauna of Site 356, Core 34. Dissolution of

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the planktonic species and of selected members of thebenthic fauna, however, clearly distinguishes Core 36.Several explanations are again possible. First, afluctuation of the CCD may have produced thedissolution effects. This is unlikely, since the waterdepths inferred from the Campanian to Maestrichtiansequence would require a 1500 to 2500 meter rise andfall of the CCD at this locality. Second, an influx ofcorrosive bottom waters from the south, through theRio Grande Gap into the Brazil Basin, as the risecontinued to subside, may have produced thedissolution effects. Third, the faunal characteristics anddissolution effects again suggest an oxygen-minimumlayer, as with Site 356, Core 34. This hypothesis isstrengthened in Core 36 by the lack of planktonicspecies, by greenish-gray sedimentary layersintercalated with the brownish chalks, and by thepreservation of some laminae despite extensive bio-turbation—all of which implies reducing conditions.The similarities in the Campanian interval at Sites 356and 357 indicate a regional event, at least within theBrazil Basin, not confined to the Rio Grande Rise. It ispossible that an inflow of bottom water migrated underan oxygen-minimum layer within the Brazil Basin andcaused it to rise during the Campanian.

Maestrichtian assemblages (Cores 32-33) resemblethe Campanian fauna of Core 40. Foraminiferal speciesresume their former diversity, planktonic species areabundant, and preservation improves. Members of theNodosariacea and Cassidulinacea remain dominant;agglutinated species increase in diversity andabundance in Core 33, only to decrease again in Core32. The benthic assemblage in the Maestrichtiansamples reflects lower bathyal water depths of 1500 to2000 meters, probably somewhat shallower than coevalsamples from Site 356. The assemblages are dominatedby species of Gavelinella, Gyroidinoides, Osangularia,and Praebulimina, with occurrences of Allomorphina,Aragonia, Ellipsoidella, Nuttallinella, Pullenia, andQuadrimorphina. Associated fossils vary from scarcebivalve fragments in Core 33 to common echinoidspines, rare ostracodes, and worn bivalve fragments inCore 32. Worn, fragmented, large nodosariids, rarepolymorphinids, and the associated fossils indicategravity flows.

Site 358Maestrichtian sediments from Site 358 (Cores 15 and

16) contain a poorly preserved, low-diversity benthicforaminiferal assemblage (Figure 8). Planktonic speciesare absent, associated organisms are limited to rare fishdebris. Foraminifers in Core 16 are more diverse, andinclude chiefly Aragonia, Ellipsoglandulina, Gavelinella,Gyroidinoides, and Osangularia, with fewer specimensof Ammodiscus, Glomospira, Nuttallinella, and Pullenia.Agglutinated foraminifers and nodosariids are equallyabundant, and the Cassidulinacea dominate theassemblage (Figure 13). Core 15 foraminifers compriseonly seven species, with species of Gyroidinoides andOsangularia the most abundant. Interestingly, all sevenspecies belong to the Cassidulinacea. TheMaestrichtian samples from both Cores 15 and 16

appear to represent abyssal water conditions of 3500 to4000 meters. The limited, corroded, and fragmentedbenthic fauna and the predominantly ferruginous mud-stones of this sequence indicate a depth near the CCD.

PALEOECOLOGIC SUMMARYSite 355 in the Brazil Basin and Site 358 in the Argen-

tine Basin were of abyssal water depths throughout thelate Cretaceous. Site 358 was deeper than Site 355, andclose to the late Cretaceous CCD (perhaps 4000 mwater depth). Foraminiferal faunas are of limiteddiversity, and specimens are more poorly preserved.The sediments are oxidized, ferruginous mudstones.

Site 355 faunas are better preserved and morediverse; the sediments are nannofossil ooze, with aminor terrigenous component. Planktonic species andless-resistant benthic species are absent, which indicatesa water depth above the CCD but below the lysocline,or between 3000 and 4000 meters.

Holes 356 and 357 both record deepening environ-ments that ranged from middle bathyal in the oldersequences to lower bathyal in the Maestrichtian.Despite this parallelism, Site 357, throughout its lateCretaceous history, remained slightly shallower thanSite 356, by perhaps 500 to 1000 meters. The differenceis indicated primarily by the foraminifer content,diversity, and abundance, the abundance and diversityof associated organisms, and the lithology at each site.

Sediments at Sites 356 and 357 are generally bio-turbated, except for some minor laminated intervals inthe Campanian sequence of Hole 357 and the laminatedmarly limestone of Section 357-50-4, which contains noforaminifers. The laminae and occasional reducedsediments in the Campanian interval correspond tofaunal characteristics, in both Cores 356-34 and 357-36,that suggest a Campanian oxygen-minimum layer, atleast within the Brazil Basin. Confirmation of thisoxygen-minimum layer at about 1000 to 1500 meters inother oceanic basins must await further studies andrecognition of more specific faunal characteristics.

The Santonian, and to a lesser degree Campanian,sequences of Holes 356 and 357 show a decreasingterrigenous influence and contain persistent Inoceramusprisms and fragments. Much of the terrigenousmaterial was derived from gravity-controlled bottomflows, as indicated by coarse graded layers, intervals ofclay-pebble conglomerate (as in Core 356-39), coarselayers of rounded glauconite grains and Inoceramusprisms, rare glauconite grains throughout much of thesequence, and transported shallower water foramin-ifers, many of which are worn, fragmented, or size-sorted. The period of terrigenous influence correspondsto similar periods recognized at other DSDP sites, suchas Sites 327A and 260, and is attributed largely tochanges in sea level that occurred primarily during theCenomanian to Santonian period (Sliter, in press).

The persistent association of Inoceramus prisms andfragments with shallow-water material indicates trans-portation and reworking by gravity currents, and possi-ble redistribution by contour currents in laminateddeposits. In addition, a dissolution sequence involvingInoceramus prisms, similar to that at Site 327A, occurs

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W.V. SLITER

Age Lith. α 0 % 25 50 75 100%

Cassidulinacea

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Figure 13. Comparison of benthic foraminiferal groups (cumulative percent) and preservation at Site 358.

at Sites 356 and 357. In samples showing increasingcarbonate dissolution, the sequence extends fromplanktonic-benthic foraminifers and prisms, to benthicforaminifers and prisms, to prisms alone, whichbecome increasingly etched until they too disappear.Apparently the prisms are more resistant to dissolutionthan most, if not all, of the foraminifers associated withthem in these samples.

BENTHIC SUCCESSION

The foraminifer assemblages from Leg 39 have addedconsiderably to our understanding of the deep-waterCretaceous benthic succession. Neritic and upperbathyal assemblages from continental exposures havebeen most accessible for study. The composition ofdeep abyssal assemblages in the North Pacific andIndian oceans has been well documented by Krashenin-nikov (1973, 1974). Interpretation of foraminiferassemblages from middle bathyal to abyssal waterdepths in different latitudes and facies has been lacking.It is within this range of water depths that the Leg 39Cretaceous samples studied here are believed to havebeen deposited.

In general, the upper Cretaceous benthic assemblagesfrom the South Atlantic show the succession describedbelow.

Genera such as Gavelinella, Globorotalites,Gyroidinoides, Osangularia, and Praebulimina char-acterize middle bathyal faunas. Nodosariids range upto 40%, agglutinated species up to 18% of the fauna.

Gavelinella, Gyroidinoides, and Osangularia continueto dominate in lower bathyal faunas, which alsocontain species of Aragonia, Ellipsoglandulina,Ellipsoidella, Hyperammina, Nuttallinella, Pleuro-stomella, and Pullenia. Nodosariids are less abundant,as are agglutinated genera and the Buliminacea, but theCassidulinacea increase to 40% or more of the fauna.

Genera such as Aragonia, Ellipsoglandulina,Gavelinella, Gyroidinoides, and Osangularia char-

acterize abyssal assemblages; species added includeCribrostomoides, Glomospira, Lituotuba, Para-trochamminoides(7), Recurvoides, and Rhabdammina.Members of the Nodosariacea represent 15% or less ofthe assemblage, the Buliminacea 10% or less. Incontrast, the Cassidulinacea progressively increasefrom 40% to 100% of the fauna. These assemblagesapparently give way—by progressive loss of calcareousspecies and by an increase in the deeper wateragglutinated genera—to deep abyssal faunas like those(described by Krasheninnikov, 1973, 1974) frommodern water depths between 5000 and 6000 meters.Such a succession would seem to follow directly fromthe assemblages at Site 355.

The faunas from Site 358 offer an interesting inter-mediate step between the abyssal assemblages of Site355 and the deep-abyssal agglutinated assemblagesfrom beneath the late Cretaceous CCD. Samples fromSite 358 contain the foraminiferal assemblage com-posed entirely of dissolution-resistant Cassidulinaceathat apparently represents the last vestige of the abyssalcalcareous fauna at the CCD. The absence ofagglutinated genera indicates that at this locality theytoo are susceptible to dissolution. This was tested bytreating agglutinated species with a 5% solution of HC1.Specimens were selected from the upper Cretaceousabyssal assemblages of Sections 355-20-2 and 355-18-3and the Santonian bathyal assemblages of Sections 356-37-5 and 357-44-4. The following species dissolved in 5minutes:

Tritaxia aspera—Samples 355-20-2, 100-102 cm; 356-37-5, 97-99 cmDorothia oxycona—Sample 355-20-2, 100-102 cmD. bulletta—Sample 357-44-4, 100-102 cmGaudryina laevigata—Sample 355-20-2, 100-102 cmG. frankei—Sample 357-44-4, 100-102 cm

Spiroplectαmminα dentαtα from Sample 355-20-2, 100-102 cm, was moderately corroded, and the followingspecies showed no reaction:

672


Ammodiscus cretaceus—Sample 355-18-3, 120-122cmGlomospira corona—Sample 355-18-3, 120-122 cmHyperammina elongata—Sample 356-37-5, 97-99 cmThe dissolved species represent the dominant

members of the bathyal-to-abyssal agglutinated assem-blage of Leg 39. Further, specimens of the same speciesdissolved whether they came from bathyal or abyssalsites. Dispersive X-ray analysis of the wall material ofthese species shows them to be calcareous, thusexplaining their scarcity or absence in samples thathave undergone dissolution. Three of the species,Dorothia bulletta, D. oxycona, and Gaudryina laevigata,occur in bathyal deposits of Southern California, wherethey and their associated agglutinated species areresistant to acid.

Several explanations of these differences come tomind. First, the susceptibility to dissolution probablyreflects the difference between the clastic, terrigenousfacies of Southern California and the largely pelagiccarbonates of the Leg 39 sites. Accordingly, the Leg 39agglutinating species had to use the calcareousmaterials available, such as the coccoliths employed byTextularia losangica (Plate 2, Figures 4, 6). Upon dis-solution, the cement, whether silica or organic, wouldbe unable to bind the material together. Agglutinatedspecies from the clastic environment would consist ofdetrital material and cement, and would thus resist dis-solution.

Second, the oxidized abyssal environments of Leg 39may have removed an organic cement or protectivecoating that would remain to protect species in thelargely reducing clastic environments of California.This seems a less likely alternative, since specimensfrom Leg 39 dissolved even in the stronger reducingenvironments of Sites 356 and 357. A third possibility isthat the Leg 39 species are homeomorphs of theshallower water California species. This does not seemlikely, on the basis of the present comparisons.

The resistant species belong to the group thatincludes Haplophragmoides, Paratrochamminoides(l),Recurvoides, and Saccammina, among others, andwhich occurs above and below the CCS. Dispersive X-ray analysis of the walls of Ammodiscus cretaceus andGlomospira corona, from Sample 355-18-3, 120-122 cm,shows the wall to be mostly silica, with smaller amountsof iron, manganese, potassium, aluminum, andtitanium. At magnifications up to 24,500 ×, the struc-ture of the wall looks extremely fine grained, perhapssecreted. Determination of whether these species areusing colloidal material or secreting silica must awaitfurther studies. Intriguingly, X-ray analysis of thematerial remaining after dissolution of the non-resistant agglutinated species shows that it is nearlyidentical in composition to the wall material of theresistant species. This siliceous material used in wallconstruction by the resistant species may also be thecement used by the nonresistant agglutinated species.

MID-CRETACEOUS HIATUSThe Cenomanian-to-Santonian hiatus or barren

interval at Site 356 is similar in duration to the hiatus at

Site 327A of Leg 36 on the Falkland Plateau. At Site356, a sequence containing Albian foraminifers of outerneritic to upper bathyal depths is succeeded by anabbreviated Cenomanian sequence of predominantlynannofossil chalk. The intervals represent an accelera-tion, during the Cenomanian, of deepening whichbegan during the Albian. Preservation of the Ceno-manian fauna indicates a water depth near or below theforaminiferal lysocline. Succeeding this fauna is a shortSantonian sequence of mottled zeolitic clay thatcontains a strongly corroded foraminiferal fauna ofresistant calcareous species and rare agglutinated speci-mens. Water depths appear to have been abyssal, 2500to 4000 meters. The succeeding Campanian toMaestrichtian faunas indicate lower bathyal waterdepths of 1500 to 2500 meters.

Site 356 faunas, as seen above, indicate Albianmiddle bathyal water depths in Core 42, succeeded bySantonian lower bathyal depths in Core 37. Interveningsamples, other than the barren sample from Core 39,were not examined in the present investigation, butstudies of planktonic foraminifers and nannofossilsfrom samples within this interval indicate that the earlyTuronian and the Cenomanian are missing (Premoli-Silva and Boersma, this volume; Bukry, this volume).Santonian assemblages from Sites 356 and 357 do showfaunal changes that, although not as extreme as thosefrom the Falkland Plateau, seem to record a deepening.This is best seen by the abundance of Ellipsoidella,Hyperammina, Osangularia, and Tritaxia, in Section356-37-5, and to a lesser extent by the abundance ofGavelinella, Gyroidinoides, Osangularia, Pullenia, andTritaxia in Sections 357-48-4 to 357-44-4. These faunalvariations suggest that conditions contributing to theevents on the Falkland Plateau must have involvedeustatic changes and fluctuations in termperature;similar evidence of tectonic events appears in thesediments of the South Atlantic north of the RioGrande Rise.

ACKNOWLEDGMENTSI wish to thank P.R. Supko and K. Perch-Nielsen (Co-chief

Scientists, Leg 39) for making available the material for thisstudy. Thanks are also extended to A. Boersma (Leg 36Paleontologist) for alerting me to the project and sending methe necessary material.

K. McDougall and R.Z. Poore (U.S. Geological Survey,Menlo Park, California) kindly read and commented uponthe manuscript. I am particularly indebted to R.L. Oscarsonfor operating the Cambridge S-180 scanning electron micro-scope and the attached EDAX energy dispersive X-rayanalyzer, and for taking scanning electron micrographs; andto S.E. Murphy for her help in several phases of manuscriptpreparation. The help of A.G. Coffman and M.A. Breeden insample and illustration preparation was also appreciated.

REFERENCES

Bartenstein, H., Bettenstaedt, F., and Bolli, H.M., 1957. DieForaminiferen der Unterkreide von Trinidad, B.W.I.:Ecolog. Geol. Helv., v. 50, p. 5-68.

Belford, D.J., 1960. Upper Cretaceous foraminifera from theToolonga Calcilutite and Gingin Chalk, WesternAustralia: Australia Bur. Min. Res., Geol. Geophys. Bull.57, 198 p.

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Brotzen, F., 1936. Foraminiferen aus dem schwedischenuntersten Senon von Eriksdal in Schonen: Sveriges Geol.Undersokning Arsb., ser. C, v. 396, p. 1-206.

Chapman, F., 1917. Monograph of the foraminifera andostracoda of the Gingin Chalk: Western Australia Geol.Surv. Bull. 72, p. 9-59.

Cushman, J.A., 1946. Upper Cretaceous foraminifera of theGulf Coast Region of the United States and adjacentareas: U.S. Geol. Surv. Prof. Paper 206, 241 p.

Ferreira, J.M. and Rocha, A.T., 1957. Foraminiferos doSenoniano de Catumbela (Angola): Garcia de Orta, v. 5,p. 517-545.

Gawor-Biedowa, E., 1972. The Albian, Cenomanian andTuronian foraminifera of Poland and their stratigraphicimportance: Acta Paleontol. Polonica, v. 17, p. 1-155.

Gorbenko, V.I., 1960. Novye vidy foraminifer iz otlozheniiverkhnego mela severo-zapadnoi okrainy Donetskogobasseina: Vyssh. Ucheb. Zavedneiy Izy., v. 1, p. 67-76,Moskva.

Hanzlikova, E., 1972. Carpathian Upper CretaceousForaminiferida of Moravia (Turonian-Maestrichtian):Ustred Ustav. Geol. Rozpravy, v. 39, p. 5-159.

Klasz, I. de, 1953. Einige neue oder wenig bekannteForaminiferen aus der helvetischen Oberkreide derBayerischen Alpen, sudlich Traustein (Obergayern): Geol.Bavarica, v. 17, p. 223-239.

Krasheninnikov, V.A., 1973. Cretaceous benthonicforaminifera, Leg 20 of the Deep Sea Drilling Project. InHeezan, B.C., MacGregor, I., et al., Initial Reports of theDeep Sea Drilling Project, Volume 20: Washington (U.S.Government Printing Office), p. 205-219.

, 1974. Upper Cretaceous benthonic agglutinatedforaminifera, Leg 27 of the Deep Sea Drilling Project. InHeirtzler, J., Veevers, J., et al., Initial Reports of the DeepSea Drilling Project, Volume 27: Washington (U.S.Government Printing Office), p. 631-662.

Lambert, G., 1971. A study of the Cretaceous foraminifera ofnorthern Zululand, South Africa: N. Se. Natal Univ.,Durban, South Africa, 375 p.

Malumian, N., 1968. Foraminiferos del Cretacico Superior yTerrciario del Subsuelo de la Provincia de Santa Cruz,Argentina: Ameghiniana, v. 5, p. 191-227.

Martin, L., 1964. Upper Cretaceous and Lower Tertiaryforaminifera from Fresno County, California: (Austria)Geol. Bundesanst. Jahrb., Sonderb. 9, 128 p.

Natland, M.L., Gonzalez, P.E., Canon, A., and Ernst, M.,1974. A system of stages for correlation of MagallanesBasin sediments: Geol. Soc. Am. Mem. 139, 126 p.

Neagu, T., 1965. Albian foraminifera of the RumanianPlains: Microplaeontology, v. 11, p. 1-38.

, 1968. Biostratigraphy of Upper Cretaceousdeposits in the southern Eastern Carpathians near Brasov:Micropaleontology, v. 14, p. 225-241.

., 1970. Micropaleontological and stratigraphical

, 1975. Foraminiferal life and residue assemblagesfrom Cretaceous slope deposits: Geol. Soc. Am. Bull.,v. 86, p. 897-906.

, in press. Cretaceous foraminifers from the South-

study of the Upper Cretaceous deposits between the uppervalleys of the Buzau and Riul rivers (Eastern Carpathians):Inst. Geol. Mem., v. 12.

Salaj, J. and Samuel, O., 1966. Foraminifera der West-karpaten-kreide: Geologicky ustav dionyza stura,Bratslava, 291 p.

Scheibnerova, V., 1974. Aptian-Albian benthonic foram-inifera from DSDP Leg 27, Sites 259, 260, and 263,Eastern Indian Ocean. In Heritzler, J., et al., InitialReports of the Deep Sea Drilling Project, Volume 27:Washington (U.S. Government Printing Office), p. 697-741.

Sliter, W.V., 1968. Upper Cretaceous foraminifera fromSouthern California and northwestern Baja California,Mexico: Kansas Univ. Paleontol. Contrib., Art. 7, 141 p.

western Atlantic Ocean, Leg 36, Deep Sea Drilling Project.In Barker, P., Dalziel, I.W.D., et al., Initial Reports of theDeep Sea Drilling Project, Volume 36: Washington (U.S.Government Printing Office).

Sliter, W.V. and Baker, R.A., 1972. Cretaceous bathymetricdistribution of benthic foraminifers: J. Foram. Res., v. 2,p. 167-183.

Stejn, J., 1957. Micropaleontological stratigraphy of theLower Cretaceous in Central Poland: (Poland) Inst. Geol.Prace, v. 22, p. 191-263.

Tappan, H., 1940. Foraminifera from the Grayson Forma-tion of northern Texas: J. Paleontol., v. 14, p. 93-126.

, 1943. Foraminifera from the Duck Creek Forma-tion of Oklahoma and Texas: J. Paleontol., v. 17, p. 476-517.

Webb, P.N., 1973. Upper Cretaceous-Paleocene foraminiferafrom Site 28 (Lord Howe Rise, Tasman Sea), DSDP Leg21 of the Deep Sea Drilling Project. In Burns, R.E.,Andrews, J.E., et al., Initial Reports of the Deep SeaDrilling Project, Volume 21: Washington (U.S. Govern-ment Printing Office), p. 541-560.

White, M.P., 1928. Some index foraminifera of the Tampicoembayment area of Mexico, pt. 2: J. Paleontol., v. 2,p. 280-317.

APPENDIXFaunal Reference List

Alabamina dorsoplana (Brotzen) = Eponides dorsoplana BrotzenÅllomorphina cretacea ReussA. trochoides (Reuss) = Globigerina trochoides ReussAmmodiscus cretaceus ReussA. glabratus Cushman and JarvisAragonia ouezzaensis (Rey) = Bolivinoides ouezzaensis ReyA. velascoensis (Cushman) = Textularia velascoensis CushmanArenobulimina preslii (Reuss) = Bulimina preslii ReussAstacolus bradyiana (Chapman) = Cristellaria bradyiana ChapmanA. liebusi (Brotzen) = Planularia liebusi BrotzenA. richteri (Brotzen) = Planularia richteri BrotzenA. jarvisi (Cushman) = Marginulina jarvisi CushmanBandyella greatvalleyensis (Trujillo) = Pleurostomella greatvalleyensis

TrujilloBifarina hispidula (Cushman) = Rectogümbelina hispidula CushmanBolivina decurrens (Ehrenberg) = Grammostomumi decurrens

EhrenbergB, incrassata ReussBolivinoides australis EdgellB. sidestrandensis BarrB. strigillatus (Chapman) = Bolivina strigillata ChapmanConorboides cf. C. scanica (Brotzen) = Discorbis scanica BrotzenCoryphostoma plaitwn (Carsey) = Bolivina plaita CarseyCribrostomoides cretaceus Cushman and GoudkoffDentalina basiplanata Cushman .D. communis (d'Orbigny) = Nodosaria (Dentalina) communis

d'OrbignyD. cylindroides ReussD. gracilis (d'Orbigny) = Nodosaria (Dentalina) gracilis d'OrbignyD. legumen (Reuss) Nodosaria (Dentalina) legumen ReussD. pertinens CushmanD. solvata CushmanD. velascoensis (Cushman) = Nodosaria velascoensis CushmanDorothia bulletta (Carsey) = Gaudryina bulletta CarseyD. ellipsorae (Cushman) = Marssonella ellisorae CushmanD. oxycona (Reuss) = Gaudryina oxycona ReussEllipsoglandulina concinna OlbertzE. cf. E. exponens (Brady) = Ellipsoidina exponens BradyE. obesa HanzlikovaEllipsoidella binaria BelfordE. elongata (Storm) = Ellipsodimorphina elongata StormE. divergens (Storm) = Ellipsodimorphina divergens Storm

674


E. gracillima (Cushman) = Nodosarella gracillima CushmanE. kugleri (Cushman and Renz) = Nodosarella kugleri Cushman and

RenzE. subnodosa (Guppy) = Ellipsonodosaria subnodosa GuppyEllipsodimorphina subtuberosa LiebusEllipsopolymorphina velascoensis (Cushman) = Ellipsoglandulina

velascoensis CushmanFissurina alata ReussF. bicornis NeaguF. oblonga ReussF. orbignyiana SequenzaFrondicularia cf. F. aclis MorrowF. frankei CushmanF. linearis FrankeF. lomaensis SliterFrondicularia mucronata ReussF. tetragonia (Reuss) = Nodosaria tetragona ReussF. cf. F. ungeri ReussGaudryina austinana (Cushman) = Gaudryina (Siphogaudryina)

austinana CushmanG. cushmani TappanG. frankei BrotzenG. laevigata FrankeG. pyramidata CushmanGavelinella cayeuxi mangshlakensis (Vassilenko) = Anomalina

(Pseudovalvulineria) cayeuxi mangshlakensis VassilenkoG. eriksdalensis (Brotzen) = Cibicides (Cibicidoides) eriksdalensis

BrotzenG. intermedia (Berthelin) = Anomalina intermedia BerthelinG. nacatochensis (Cushman) = Planulina nacatochensis CushmanG. sandidgei (Brotzen) = Cibicides sandidgei BrotzenG. stephensoni (Cushman) = Cibicides stephensoni CushmanG. cf. G. tormarpensis BrotzenG. velascoensis (Cushman) = Anomalina velascoensis CushmanG. whitei (Martin) = Anomalina whitei MartinGloborotalites conicus (Carsey) = Truncatulina refulgens (Montfort)

var. conica CarseyG. michelinianus (d'Orbigny) = Rotalina michelinianus d'OrbignyG. multiseptus (Brotzen) = Globorotalia multiseptus BrotzenG. spineus (Cushman) = Truncatulina spineus CushmanG. tappanae SliterGlobulina lacrima (Reuss) = Polymorphina {Globulina) lacrima ReussG. prisca ReussG. subsphaerica (Berthelin) = Polymorphina subsphaerica BerthelinGlomospira corona (Cushman and Jarvis) = Glomospira charoides

(Jones and Parker) var. corona Cushman and JarvisG. gordialis (Jones and Parker) = Trochammina squamata var.

gordialis Jones and ParkerGyroidina cf. G. nonionoides (Bandy) = Valvulinaria nonionoides

BandyGyroidinoides beisseli (Schijfsma) = Eponides beisseli SchijfsmaG. depressus (Alth) = Rotalina depressa AlthG. globosus (Hagenow) = Nonionina globosa HagenowG. infracretacea (Morozova) = Gyroidina nitida Reuss var.

infracretacea MorozovaG. nitidus (Reuss) = Rotalina nitida ReussG. praeglobosus (Brotzen) = Gyroidina praeglobosus BrotzenG. quadratus (Cushman and Church) = Gyroidina quadratus

Cushman and ChurchG. lunata (Brotzen) = Eponides lunata BrotzenHeterolepa cf. H. sparksi (White) = Gyroidina sparksi WhiteHyperammina elongata BradyLagena acuticosta ReussL. apiculata ReussL. ellipsoidalis SchwagerL. hispida ReussL. paucicosta FrankeL. stavensis BandyLenticulina acuta (Reuss) = Cristellaria acuta ReussL. discrepans (Reuss) = Robulina discrepans ReussL. gaultina (Berthelin) = Cristellaria gaultina BerthelinL. muensteri (Roemer) = Robulina münsteri RoemerL. ovalis (Reuss) = Cristellaria ovalis ReussL. revoluta (Israelsky) = Robulus revoluta IsraelskyL. velascoensis WhiteLingulina pygmaea Reuss

L. aff. L. taylorana CushmanLituotuba lituoformis (Brady) = Trochammina lituoformis BradyLoxostomum eleyi (Cushman) = Bolivinita eleyi CushmanMarginulina armata ReussM. bullata ReussM. curvatura CushmanM. hamuloides BrotzenM. inaequalis ReussM. juncea CushmanMarginulinopsis texasensis (Cushman) = Marginulina texasensis

CushmanNonionella austinana CushmanN. robusta PlummerNodosaria aspera ReussNuttallinella florealis (White) = Gyroidina florealis WhiteOolina apiculata ReussO. delicata SliterOsangularia cordieriana (d'Orbigny) = Rotalina cordieriana

d'OrbignyO. velascoensis (Cushman) = Truncatulina velascoensis CushmanO. whitei (Brotzen) = Eponides whitei BrotzenParatrochamminoidesl intricatus KrasheninnikovPleurostomella austinana CushmanP. obtusa BerthelinP. reussi BerthelinP. subnodosa ReussPraebulimina carseyi (Plummer) = Buliminella carseyae PlummerP. cushmani (Sandidge) = Buliminella cushmani SandidgeP. reussi (Morrow) = Bulimina reussi MorrowP. spinata (Cushman and Campbell) = Bulimina spinata Cushman

and CampbellP. taylorensis (Cushman and Parker) = Bulimina taylorensis

Cushman and ParkerPseudonodosaria humilis (Roemer) = Nodosaria humilis RoemerP. manifesto (Reuss) = Glandulina manifesto ReussP. mutabilis (Reuss) = Glandulina mutabilis ReussP. obesa (Loeblich and Tappan) = Rectoglandulina obesa Loeblich

and Tappan.Pseudospiroplectinata compressiuscula (Chapman) = Bigenerina com-

pressiuscula ChapmanPullenia cretacea CushmanP. coryelli WhiteP. minuta CushmanPyrulina apiculata (Marie) = Pyrulina cylindroides (Roemer) var.

apiculata MarieP. cylindroides (Roemer) = Polymorphina cylindroides RoemerQuadrimorphina allomorphinoides (Reuss) = Valvulineria allo-

morphinoides ReussQ. camerata (Brotzen) = Valvulineria camerata BrotzenRamulina aculeata (d'Orbigny) = Dentalina aculeata d'OrbignyR. arkadelphiana CushmanR. pseudoaculeata (Olsson) = Dentalina pseudoaculeata OlssonRecurvoides globulosus (Grzybowski) = Cyclammina globulosus

GrzybowskiReussella pseudospinulosa TroelsenR. szajnochae (Grzybowski) = Verneuilina szajnochae GrzybowskiRhabdammina discreta BradySaccammina complanata (Franke) = Pelosina complanata FrankeSaracenaria bononiensis (Berthelin) = Cristellaria bononiensis

BerthelinS. navicula (d'Orbigny) = Cristellaria navicula d'OrbignyS. triangularis (d'Orbigny) = Cristellaria triangularis d'OrbignySerovaina orbicella (Bandy) = Gyroidina globosa (Hagenow) var.

orbicella BandySpiroplectammina dentata (Alth) = Textularia dentata AlthS. nuda LalickerS. praelonga (Reuss) = Textularia praelonga ReussS. semicomplanata (Carsey) = Textularia semicomplanata CarseyS. sigmoidina LalickerStensioina pommerana BrotzenStilostomella pseudoscripta (Cushman) = Ellipsonodosaria pseudo-

scripta CushmanTappanina selmensis (Cushman) = Bolivinita selmensis CushmanTextularia losangica Loeblich and TappanThalmannammina subturbinata (Grzybowski) = Haplophragmium

subturbinatum Grzybowski

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W.V. SLITER

CushmanT. gaultina (Morozova) = Clavulina gaultina MorozovaValvulineria lenticula (Reuss) = Rotalina lenticula Reuss

Tribrachia excavata (Reuss) = Rhabdogonium excavatum ReussTritaxia aspera (Cushman) = Clavulina trilatera Cushman var. aspera

676


Figures 1,4

Figure 2

Figure 3

Figures 5,6

Figure 7

Figure 8

Figure 9

PLATE 1

Hyperammina elongata Brady.1. Sample 357-42-4, 100-102 cm. Dot width 300

µm.4. Sample 356-29-5, 102-104 cm. Dot width 100

µm.

Saccammina complanata (Franke).Sample 357-26-4, 100-102 cm. Dot width 100 µm.

Ammodiscus cretaceus Reuss.Sample 358-16-2, 92-94 cm. Dot width 100 µm.

Glomospira corona (Cushman and Jarvis).5. Sample 355-18-3, 120-122 cm. Dot width 30


µm.

Glomospira gordialis (Jones and Parker).Sample 355-19-3, 120-122 cm. Dot width 100 µm.

Paratrochamminoidesi intricatus Krasheninnikov.Sample 355-18-3, 120-122 cm. Dot width 100 µm.

Spiroplectammina dentata (Alth).

(see page 678)

PLATE 2

Figure 1 Spiroplectammina nuda Lalicker.Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figures 2, 3 Spiroplectammina sigmoidina Lalicker.2. Sample 355-17-5, 58-60 cm. Dot width 30 µm.3. Sample 357-33-4, 100-102 cm. Dot width 100

µm.

Figures 4, 6 Textularia losangica Loeblich and Tappan.4. Sample 356-42-5, 100-102 cm. Dot width 100

µm.6. Enlargement of Figure 4 showing wall com-

posed in part of corroded coccoliths. Dotwidth 3 µm.

Figure 5 Gaudryina austinana (Cushman).Sample 357-34-4, 100-102 cm. Dot width 100 µm.

Figure 7 Gaudryina cushmani Tappan.Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 8 Gaudryina laevigata Franke.Sample 357-40-4, 100-102 cm. Dot width 100 µm.

Figure 9 Gaudryina pyramidata Cushman.Sample 356-29-5, 102-104 cm. Dot width 100 µm.

(see page 679)

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W.V. SLITER

PLATE 1

678

PLATE 2


W.V. SLITER

PLATE 3

Figure 1 Pseudospiroplectinata compressiuscula (Chapman).Sample 357-44-4, 100-102 cm. Dot width 100 µm.

Figures 2-4 Tritaxia aspera (Cushman).2. Sample 357-44-4, 100-102 cm. Dot width 300


µm.4. Juvenile specimen, Sample 356-32-5, 101-103

cm. Dot width 100 µm.

Figures 5, 6 Tritaxia gaultina (Morozova).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 7 Dorothia bulletta (Carsey).Sample 357-40-4, 100-102 cm. Dot width 100 µm.

Figure 8 Dorothia oxycona (Reuss).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 9 Astacolus bradyiana (Chapman).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 10 Frondicularia cf. F. ungeri Reuss.Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 11 Lenticulina gaultina (Berthelin).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 12 Marginulina juncea Cushman.Sample 357-40-4, 100-102 cm. Dot width 100 µm.

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PLATE 3

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W.V. SLITER

PLATE4

Figure 1 Saracenaria bononiensis (Berthelin).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 2 Tribrachia excavata (Reuss).Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figure 3 Lingulina pygmaea Reuss.Sample 356-32-5, 101-103 cm. Dot width 100 µm.

Figure 4 Globulina lacrima (Reuss).Sample 356-29-5, 102-104 cm. Dot width 100 µm.

Figure 5 Globulina subsphaerica (Berthelin).Sample 356-30-5, 100-102 cm. Dot width 100 µm.

Figure 6 Fissurina sp.Sample 356-32-5, 101-103 cm. Dot width 100 µm.

Figures 7, 8 Praebulimina cushmani (Sandidge).Sample 357-32-4, 99-101 cm.7. Dot width 100 µm.8. Dot width 30 µm.

Figures 9, 10 Praebulimina reussi (Morrow).Dot width 100 µm.9. Sample 356-29-5, 102-104 cm.

10. Sample 356-32-5, 101-103 cm.

PLATE 5

Figure 1 Bolivina incrassata Reuss.Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figures 2, 3 Bolivinoides australis Edgell.Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figure 4 Bolivinoides sidestrandensis Barr.Sample 357-32-4, 99-101 cm. Dot width 100 µm.

Figures 5, 6 Bolivinoides strigillatus (Chapman).Sample 357-44-4, 100-102 cm. Dot width 100 µm.

Figure 7 Stilostomella pseudoscripta (Cushman).Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figures 8,11 Reussella pseudospinulosa Troelsen.8. Sample 356-30-5, 100-102 cm. Dot width 100


µm.

Figures 9, 10 Reussella szajnochae (Grzybowski).Dot width 100 µm.9. Sample 355-19-3, 120-122 cm.

10. Sample 355-18-3, 120-122 cm.

(see page 684)

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PLATE 5

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PLATE 6

Figures 1,4 Valvulineria lenticula (Reuss).Sample 357-47-4, 100-102 cm. Dot width 100 µm.1. Umbilical view.4. Spiral view.

Figures 2, 3 Nuttallinella florealis (White).Sample 357-33-4, 100-102 cm. Dot width 100 µm.2. Umbilical view.3. Peripheral view of same specimen.

Figure 5 Pleurostomella austinana Cushman.Broken specimen from Sample 357-44-4, 100-102cm. Dot width 300 µm.

Figure 6 Pleurostomella obtusa Berthelin.Sample 356-42-5, 100-102 cm. Dot width 100 µm.Oblique view.

Figure 7 Pleurostomella reussi Berthelin.Sample 356-42-5, 100-102 cm. Dot width 100 µm.

Figures 8, 9 Pleurostomella subnodosa Reuss.Dot width 300 µm.8. Sample 356-30-5, 100-102 cm.9. Sample 356-32-5, 101-103 cm.

Figure 10 Ellipsodimorphina subtuberosa Liebus.Sample 357-40-4, 100-102 cm. Dot width 100 µm.

Figure 11 Ellipsoglandulina concinna Olbertz.Sample 358-16-2, 92-94 cm. Dot width 100 µm.

(see page 686)

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Figures 1, 2 Ellipsoidella divergens (Storm).Dot width 100 µm.

1. Side view. Sample 356-32-5, 101-103 cm.2. Apertural view. Sample 356-29-5, 102-104

cm.

Figure 3 Ellipsoidella gracillima (Cushman).Sample 357-40-4, 100-102 cm. Dot width 100 µm.

Figure 4 Ellipsoidella sp.Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figure 5 Ellipsoidella'] sp.Sample 356-29-5, 102-104 cm. Dot width 100 µm.Side view.

Figure 6 Ellipsopolymorphina velascoensis (Cushman).Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figure 7 Coryphostoma plaitwn (Carsey).Sample 357-32-4, 99-101 cm. Dot width 100 µm.Side view.

Figure 8 Loxostomum eleyi (Cushman).Sample 357-40-4, 100-102 cm. Dot width 30 µm.

Figures 9, 10 Aragonia ouezzaensis (Rey).Sample 355-19-3, 120-122 cm. Dot width 30 µm.9. Side view.

10. Oblique apertural view of same specimen,showing etched surface.

Figure 11 Aragonia velascoensis (Cushman).Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figure 12 Quadrimorphina allomorphinoides (Reuss).Sample 357-32-4, 99-101 cm. Dot width 100 µm.

(see page 688)

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Figure 1 Allomorphina cretacea Reuss.Sample 356-34-5, 102-104 cm. Dot width 30 µm.

Figure 2 Allomorphina trochoides (Reuss).Sample 356-29-5, 102-104 cm. Dot width 100 µm.

Figure 3 Nonionella austinana Cushman.Sample 357-47-4, 100-102 cm. Dot width 30 µm.

Figure 4 Nonionella robusta Plummer.Sample 356-32-5, 101-103 cm. Dot width 30 µm.

Figure 5 Pullenia coryelli White.Sample 355-17-5, 58-60 cm. Dot width 100 µm.

Figures 6, 7 Pullenia cretacea Cushman.Dot width 100 µm.6. Sample 356-32-5, 101-103 cm.7. Sample 357-33-4, 100-102 cm.

Figures 8,9 Pullenia minuta Cushman.Sample 356-29-5, 102-104 cm. Dot width 30 µm.8. Side view.9. Apertural view of same specimen.

(see page 690)

PLATE 9

Figures 1-3, 6 Osangularia cordieriana (d'Orbigny).Sample 356-29-5, 102-104 cm. Dot width 30 µm.1. Umbilical view.2. Peripheral view of same specimen.3. Umbilical view.6. Peripheral view of same specimen.

Figures 4, 5 Osangularia whitei (Brotzen).Sample 357-44-4, 100-102 cm. Dot width 100 µm.4. Umbilical view.5. Peripheral view of same specimen.

Figures 7, 8 Globorotalites conicus (Carsey).Sample 355-18-3, 120-122 cm. Dot width 100 µm.7. Umbilical view.8. Peripheral view of same specimen.

(see page 691)

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Figures 1, 2 Globorotalites multiseptus (Brotzen).Sample 357-47-4, 100-102 cm. Dot width 100 µm.1. Umbilical view.2. Peripheral view of same specimen.

Figures 3-6 Gyroidinoides beisseli (Schijfsma).3. 6. Sample 357-33-4, 100-102 cm. Dot width 100µm.3. Umbilical view.6. Peripheral view of same specimen.4, 5. Sample 357-36-4, 100-102 cm. Dot width 100

µm.4. Umbilical view.5. Peripheral view of same specimen.

Figures 7, 8 Gyroidinoides globosus (Hagenow).Dot width 100 µm.7. Sample 358-16-2, 92-94 cm.8. Sample 356-32-5, 101-103 cm.

PLATE 11

Figures 1,2 Gyroidinoides infracretacea (Morozova).Sample 356-42-5, 100-102 cm.1. Umbilical view. Dot width 100 µm.2. Peripheral view of same specimen. Dot width

30 µm.

Figures 3, 6 Gyroidinoides praeglobosus (Brotzen).Sample 357-44-4, 100-102 cm. Dot width 100 µm.3. Umbilical view.6. Peripheral view of same specimen.

Figures 4, 5, 7 Gyroidinoides quadratus (Cushman and Church).Dot width 100 µm.4. 5. Sample 358-16-2, 92-94 cm.4. Spiral view.5. Peripheral view of same specimen.7. Sample 356-32-5, 101-103 cm. Peripheral view.

Figure 8 Globorotalites spineus (Cushman).Sample 355-18-3, 120-122 cm. Dot width 100 µm.Umbilical view.

(see page 694)

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Figures 1-3 Gavelinella cayeuxi mangshlakensis (Vassilenko).Dot width 100 µm.1, 2. Sample 355-18-3, 120-122 cm.1. Peripheral view.2. Umbilical view of same specimen.3. Sample 355-19-3, 120-122 cm. Oblique

umbilical view.

Figure 4 Gavelinella eriksdalensis (Brotzen).Sample 357-36-4, 100-102 cm. Dot width 100 µm.

Figure 5 Gavelinella intermedia (Berthelin).Sample 356-42-5, 100-102 cm. Dot width lOOµrn.Umbilical view.

Figure 6 Gavelinella nacatochensis (Cushman).Sample 356-30-5, 100-102 cm. Dot width 100 µm.

Figures 7, 8 Gyroidinoides nitidus (Reuss).Sample 356-32-5, 101-103 cm. Dot width 100 µm.7. Umbilical view.8. Peripheral view of same specimen.

Figure 9 Gavelinella stephensoni (Cushman).Sample 356-34-5, 102-104 cm. Dot width 100 µm.

(see page 696)

PLATE 13

Figure 1 Gavelinella velascoensis (Cushman).Sample 357-33-4, 100-102 cm. Dot width 100 µm.

Figures 2-5 Gavelinella whitei (Martin).2-4. Sample 357-33-4, 100-102 cm. Dot width 100

µm.2. Umbilical view.3. Peripheral view of same specimen.4. Umbilical view.5. Sample 355-19-3, 120-122 cm. Dot width 30

µm. Umbilical view.

Figures 6, 7 Stensioina pommerana Brotzen.Sample 356-34-5, 102-104 cm. Dot width 100 µm.6. Spiral view.7. Peripheral view.

(see page 697)

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leg 39, deep sea drilling project · 2007. 5. 11. · linella ßorealis, osangularia cordieriana,...

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