PLANKTONIC FORAMINFERA IN THE SEDIMENTS OF THE ANDAMAN SEA

Transcription

1 Journal of Foraminiferal Revmrck. v. 1. no. 1, p. 1-14, pls. 1, 2, January 1971 PLANKTONIC FORAMINFERA IN THE SEDIMENTS OF THE ANDAMAN SEA WILLIAM E. FREIUCHS University of Wyoming Laramie, Wyoming ABSTRACT The distribution of planktonic foraminifers in the sediments of the Andaman Sea is controlled by surface salinity, water depth. diagenesis, and topography. Introduction of large volumes of fresh water in the northern Andaman Sea result in a lowering of surface salinity and exclusion of planktonic foraminifera. Solution of calcium carbonatc in the central deep basin results in small planktonic foraminiferal numbers in bathyal and abyssal environments. Large planktonic foraminiferal numbers occur in upper and middle bathyal environments and on scattcred sea mounts. A depth zonation of planktonic foraminifers was noted with the presence of Sphaeroidinella and numerous species of Globorotalia indicative of bathyal depths. INTRODUCTION During the 1961 and 1963 cruises of the U. S. Navy Oceanographic Ship Serrano and the 1964 cruise of the U. S. Coast and Geodetic Ship Proneer numerous sediment samples were recovered from the floor of the Andaman Sca (text fig. 1, appendix A). The purpose of this paper is to describe the quantitative distribution of planktonic foraminifers in the surface sediments of the sea. The sediment cores used in this study were split routinely in the laboratory. The upper five centimeters of the sediment cores and representative splits of the grab samples were washed upon a screen with mm openings. The washed residues were split with a modified Otto microsplitter and a representative split was counted to determine the frequency of each species. At least 200 specimens wcre counted in each sample if sufficient material was available. ACKNOWLEDGMENTS The writer is indebted to the following people and organizations for their assistance in this study. The National Science Foundation for supporting the investigation (GB 8628, GP 2530 and GA 730); the U. S. Navy Hydrographic Office for providing cores from the 1961 and 1963 cruises of the U. S. Navy oceanographic ship Serrano; the U. S. Coast and Geodetic Survey for providing cores from the 1964 cruise of the U. S. C. & G. S. ship Pioneer; the Department of Geology, University of Wyoming, for publication support; Esso Prodnction Research Company for use of their scanning electron microscope; Elaine Hertzfeldt for typing and editorial services. GENERAL DISTRIBUTION The planktonic foraminifera of the Andaman Sea constitute a typical tropical assemblage. Twenty-three species and two polyphyletic forms of planktonic foraminifera have been recognized. Three species, Globoquadrina conglomeruta, Globorotaloides hexagonus, and Globigerinella adarnsi are endemic Indo-Pacific species (Parker, 1965). 1

2 FRERICHS TEXT FIGURE 1 Location of samples. TEXT FIGURE 2 Distribution (numberigram) of planktonic foraminifers in the sediments of the Andaman Sea. The distribution of planktonic foraminifers in the sediments of the Andaman Sea (text fig. 2) is significantly modified by surface salinity, depth of water, diagenesis, and topography in addition to the local productivity of the foraminifers. Foremost among those factors modifying the distribution of planktonic foraminifers is the large volume of fresh water introduced into the northern end of the sea by the Irrawaddy and Salween Rivers. During the rainy season when the amount of fresh water flowing into the sea is greatly increased, an eastward flowing current south of the Irrawaddy Delta (text fig. 3) carries the fresh water from the Irrawaddy River to the east and a marked decrease in the salinity of the Gulf of Martaban results. As planktonic foraminifers are stenohaline, the resultant area of low salinities is reflected in low pbdnkt0nic numbers in the sediments of the continental shelf and slope south of the Gulf of Martaban, whereas numbers of more than 100 are found on the edge of the shelf directly south of the Irrawaddy Delta. This distribution illustrates the utility of plots of planktonic foraminiferal numbers as indicators of euryhalme conditions and as current tracers. Solution of calcium carbonate occurs in the deep central basin of the Andaman Sea and its effect is reflected in the distribution of planktonic foraminiferal numbers. Solution is first noted at the sill depth of 1800 meters (text fig. 2). Above 1800 meters planktonic numbers in excess of 100,000 are found at upper and middle bathyal depths. At 1800 meters, however, a decrease in planktonic numbers due to solution of calcium carbonate is noted. The completeness of solution increases with increasing depth until samples from 2

3 ANDAMAN SEA PLANKTONIC FORAMINIFERA 3

4 FRERICHS A. SEASONAL SURFACE SALINITY DISTRIBUTIONS 6. SEASONAL SURFACE CURRENTS TEXT FIGURE 3 Seasonal surface currents and salinity distributions in the Andaman Sea. greater than 3000 meters have planktonic numbers of 100 or less. To summarize, planktonic numbers increase from inner shelf to upper and middle bathyal depths and then decrease from middle bathyal to ahyssal depths. The patchy distribution of high planktonic foraminiferal numbers on seamounts in the western Andaman Sea and the high planktonic foraminiferal numbers on the Mergui platform are reflections of extremely slow rates of deposition. The high planktonic numbers in the western Andaman Sea are also dependent upon the elevation of the topographic highs. Owing to this elevation the calcareous tests were not subjected to solution as were the tests on the floor of the central basin. There is an apparent depth zonation of planktonic species in the sediments of the Andaman Sea. It seems likely that this is a reflection of the depths at which the individual species float in the water column, as suggested by Bandy (1956) and Polski (1959). B6 (1964 & 1965) and Bandy et al. (1967) have discussed the ecophenotypic variations resulting from changes in the depth at which species float. These observations are substantiated by the occurrence of planktonic species in the sediments of the Andaman Sea (table 1). Table 2 lists the planktonic species and polyphyletic forms, and the depths at which they first become a consistent component of the planktonic assemblages in the sediments of the Andaman Sea. Two generaliations are evident from an examination of the depth distributions: TABLE 2 Depth of first appearance of planktonic species SPECIES DEPTH (METERS) Globirerim rubescens 20 Clobigeriniru gluzinrrru 20 Turhorvtrrlita humilis 20 Glohiserinoides ruber 20 Globigerinoidcs sacculifcr 20 Nrogloboqurrdrirzu durerrrei dul<wrrei 38 Globiscrina bulloides 49 Clobigerinoides tenellus 49 Glohigerinella siphonifera 64 "Orbulina" 64 Pulleniatina obliquilocrdaro 64 Clohigerinu calida 78 Globororalia menardii 82 Ciobigerinoidrs conglobatus 105 Globorotalia crassaformis 256 Globoquadrina conglumerala 348 Globorotdoid?s hexagonus 348 "Spliueroidinella dehisced' 550 Cnndeina nirida 970 Globorotrrlia icirula 970 Globororalia hirruta 1170 First, planktonic assemblages typical of shelf deposits have globose chambers, and species of Globigerina, Globigerinoides, and Globigerinita predominate. Second, planktonic assemblages typical of bathyal deposits include species found in shelf deposits, but are characterized by the presence of a variety of species of Globorotalia and the thick cortexed "Sphaeroidinella." SPECIES DISTRIBUTION With minor exceptions, the writer has followed the classification as proposed by Parker (1962) and the appropriate synonymies can he found in her article. Distributions of individual species are based upon a representative split. Greater amounts of material were not used to determine the absolute presence or absence of the individual species. Family CANDEINIDAE Cushman, 1927 Genus Candeina d'orbigny, 1839 Caiideina uitida d'orbigny Cundeinu nitida D'ORBIGNY, 1839, p. 108, pl. 2, figs. 21, 28. Candeina nitirla is rarely found in the sediments of the Andaman Sea. It was noted in only 13 scattered samples and never forms as much as one percent of the planktonic population. 4

5 - ANDAMAN SEA PLANKTONlC FORAMINIFERA Y TEXT FIGURE 5 Distribution (numberfgram) of Turhorotalita humilis in the sediments of the Andaman Sea. Genus Globigerinita Broiiiiimaiin, 1951 Globigerinita glutinata (Egger) Plate 1, figure 1 Globixcrina glutinrcra EGGCR, 1893, p. 371, pl. 13, figs, Globigerinita glurinata is very abundant in the sediments of the Andaman Sea (text fig. 4). It was noted in 50 samples and composed as much as 34 percent of the planktonic population, with absolute abundanees as large as 45,740 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, in the vicinity of the South Preparis Channel, in thc vicinity of the Great Passage, and on the scattered seamounts. Genus Turborotalita Blow aiid Baiiiier, 1962 Tiirhnrotalita hninilis (Bradyj Truncatulina hunzilis Bnauy, 1884, p. 665, pl. 94, fig. 7. Turborotah humilis is very abundant in the sediments of the Andaman Sea (tcxt fig. 5 ). It was noted in 34 samples and composed as much as 40 percent of the planktonic populations, with absolute abundances as large as 16,199 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, in the vicinity,of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Family GLOBlGERlNlDAE Carpenter, Parker and Jones, 1862 Genus Globigeiina d'orbigny, I826 Globigerina bulloides d'orbigny Plate 1, figure 2 Globigerina bulloides D'ORBICNY, 1826, p. 277; Modeles no

6 FRERICHS II GLOBIGERINA RUBESCENS NOAM TEXT FIGURE 7 Distribution (number/grarn) of Globigerina rubesccns in the sediments of the Andarnan Sea. Globigerina bulloides is very abundant in the sediments of the Andaman Sea (text fig. 6). It was noted in 54 samples and composes as much as 15 percent of the planktonic population, with absolute abundances as great as 5017 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, in the vicinity of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Globigerina calida Parka Plate 1, figures 4, 5 Globiscnm calrda PARKER, p 221, pl. I, figs 9-13, 15. Globigerina calida is a consistent component of the planktonic populations in the sediments of the Andaman Sea. It was noted in 34 samples, but never composed more than two percent of the planktonic populations. Globigerina digitata Brady Globigerinu digitora BRADY, 1879, p Globigerina digitata was not recorded in counts of a representative split of the samples, but was noted in an examination of larger quantities of the planktonic populations. Globigerina rubexens Hofker Plate 1, figures 6, 9 Globigerinn ruhescens HOFKER, 1956, p. 234, pl. 35, figs Globigerina rubescens is very abundant in the sedi- 6

7 -..~ ANDAMAN SEA PLANKTONIC FORAMINIFERA GLOBlGERlNOIDES CONGLOBATUS NO/GM II TEXT FIGURE 8 Distribution (numberlgram) of Glohigcrineila siphonifera in the sediments of the Andaman Sea. TEXT FIGURE 9 Distribution (numberlgram) of Clobigerinoides conglobatus in the sediments of the Andaman Sea. ments of the Andaman Sea (text fig. 7). It was noted in 57 samples and composed as much as 17 percent of the planktonic population with absolute abundances as large as 7282 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, in the vicinity of the Great Passage, and on the scattered seamounts. Genus Globigerinella Cushman, 1927 Globigerinella adamsi (Banncr and Blow) Plate 1, figure 8 Hostigcrinu (BollieiloJ odnmsi BaNNER and BLOW, 1959, p. 13, text fig. 4. Globigerinella adamsi was not rccorded in counts of a representative split of the samples, but was noted in an examination of larger quantities of the planktonic populations. Globigerinella siphonifcra (d'orbigny) Plate 1, figure 7 Clvbigerina siphonifera D'ORBltiNY, 1839, p. 83, pl. 4, figs Globigerinella sighonifera is abundant in the sediments of the Andaman Sea (text fig. 8). It was noted in 49 samples and composes as much as six percent of the planktonic populations with absolute ahundances as large as 1389 specimens per gram. The species was most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the South Preparis Channel, in the vicinity of the Nicobar Islands, and on the scattered seamounts. 7

8 FRERICHS GLOBIGERINOIDES RUBER NOXM TEXT FIGURE 10 Distribution (number /gam) of Clobigerirruides rubcr in the sediments of the Andaman Sea. TEXT FIGURE 11 Distribution (numberlearn) of Clobigerinoides sacculifer in the sediments of the Andaman Sea. Gciius Globigerinoida Cushman, 1977 Glohigcrinoides conglobatus (Brddv) Plate 2, figure 4 Globigerinrr conglobaru BRADY, 1879, p Globigerinoides conglobatus is a consistent component of the planktonic populations of the Andaman Sea (text fig. 9). It was noted in 38 samples and composes as much as six percent of the planktonic populations, with absolute abundances as large as 455 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, on the Andaman- Nicobar Ridge between latitudes 6" N. and 8" N., and on the scattered seamounts. Globigerinoides ruber (d'orbignyj Plate 1, figure 3 Globigcrinu rubra D'ORBIGNY, 1839, p. 82, pl. 4, figs Globigerinoides ruber is very abundant in the sediments of the Andaman Sea (text fig. 10). It was noted in 63 samples and composed as much as 45 percent of the planktonic populations, with absolute abundances as large as 16,425 specimens per gram. The species was most abundant in the sediments of the southeastern corner of the sea, in the vicinity of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Globigerinoides sacculifer (Rrady) Plate 2, figure 1 Clubigerinu ucculiferu BRADY, 1877, p Globigerinoides sacculifer is abundant in the sediments of the Andaman Sea (text fig. 11 j. It was noted 8

9 ~ ~~ -~ ANDAMAN SEA PLANKTONIC FORAMINIFERA GLOBIGERINOIDES TENELLUS NO/GM II TEXT FIGURE 12 Distribution (numberlgram) of Clohigwinoides tcnclius in the sediments of the Andaman Sea. in 62 samples and composed as much as 39 percent of the planktonic population, with absolute ahundances as large as 2832 specimens per gram. It is most abundant in the southeastern portion of the sea, in the vicinity of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Globigerinoides tenellus Parker Plate 1, figures 11, 12 Giohigrrinoides fenellus PARKER, 1958, p. 280, pl. 6, figs Globigerinoides tenellus is abundant in the sediments of the Andaman Sea (text fig. 12). It was noted in 31 samples and composed as much as six percent of planktonic population, with absolute abundances as large as 2503 specimens per gram. The species was most abundant in the sediments of the southeastern corner of the TEXT FIGURE 13 Distribution (nunberigram) of Pulieniulina ohliquiloculafa in the sediments of the Andaman Sea. sea, in the vicinity of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Gcnus Orhnlina d Orbign~, 1839 Orbulina chambers are common in the sediments of the Andaman Sea. They were noted in 43 samples and formed as much as seven percent of the planktonic population, with absolute abundances of 463 specimens per gram. The chambers are most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the Nicobar Islands, and on the scattered seamounts. Geiius Fulleniatina C~is~imdli, 1927 Pnlleniatina obliquiluculata (l arker and Jones) 9

10 FRERICHS Pullenia spharroides (dorbigny) var. obliyuiloculata PARKER and JONES, 1865, p. 365, 368, pl. 19, fig. 4. Pulleniatina obliquiloculata is abundant in the sediments of the Andaman Sea (text fig. 13). It was noted in 55 samples and composes as much as 14 percent of the planktonic populations with absolute abundances as large as 5930 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the Nicobar Islands and the South Preparis Channel, and on the scattered seamounts. Genus Sphaeroidinella Cushnian, 1927 Sphaeroidinella dehiscens (Parker and Jones) Plate 2, figure 3 Sphaervidina bulloides d Orbigny var. delriscens PARKER and JONES, 1865, p. 369, pl. 19, fig. 5. Sphaeroidinella dehiscens is sparsely distributed in sediments of the Andaman Sea. It was noted in 22 samples, but never composed more than one percent of the planktonic population, with an absolute abundance not exceeding 25 specimens per gram. The form is most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the Nicobar Islands, and on the scattered seamounts. Family CATAPSYDRACIDAE Bolli, Loehlicb and Tappan, 1957 Genus Globoqnadrina Finlay, 1947 Globoquadrina conglomerata (Schwager) Plate 2, figure 5 Globiperina condonierata SCHw.AGER, 1866, p. 255, pl. 7, fig Globoquadrina conglomerata is rare in the sediments of the Andaman Sea (text fig. 14). It was noted in 35 samples and composes as much as seven percent of the planktonic population, with absolute abnndances of 694 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, in the vicinity of the Nicobar Islands, and on the scattered seamounts. Genus Globrotaloides Bolli, 1957 Globorotaloides hexagonus (Natland) Plate 1, figure 10 Globigerinlr hexopona NITLAND, 1938, p. 149, pl. 7, fig. 1. Globorotaloides hexagonus is rare in the sediments of the Andaman Sea (text fig. 15). It was noted in 27 samples and never composes more than one percent of the planktonic populations, with absolute abundances as PLATE 1 1, Globigerinita gliitinata (Egger), ~263. Ventral view. Specimen from 494 meters, sample Globigerina bulloides d Orbigny, x 185. Ventral view. Specimen from 30 meters, sample 191. Note obvious difference in wall structure when compared with Globigerinita glutinata Globigerinoides ruber (d orbigny), x115. Ventral view. Specimen from 30 meters, sample 191. Note the difference in wall structure compared to G. conglobatus and G. sacculifer Globigerina calida Parker. 4, Ventral view, X120; 5, Dorsal view, X102. Specimens from 494 meters, sample 67. In general morphology this species is quite similar to Globorotaloides hexagonus, but it differs in wall structure , 9. Globigerina rubescens Hofker. 6, Ventral view, X286; 9, Dorsal view, x444. Specimens from 30 meters, sample Globigerinella siphonifera (d orbigny), XIIS, Side view. Specimen from meters, sample Globigerinella adamsi (Banner and Blow), X109. Side view. Specimen from 494 meters, sample Globorotaloides hexagonus (Natland). Ventral view, x 170. Specimen from 494 meters, sample I, 12. Globigerinoides tenellus Parker. 11, Ventral view, X223, note the dorsal supplementary aperture visible through the primary aperture; 12, Dorsal view, x153. Specimens are from 494 meters, sample 67. Note the general similarity to Globigerina rubescens and the rudimentary appearance of the supplementary apertures. 9 10

11 WILLIAM E. FRERICHS Journal of Foraminifeid Resea&, PLATE Volume 1, Number 1 1

12 WILLIAM E. FRERICHS Journd of Forumiaiferal Research, Volume 1, Number 1 PLATE 2

13 -~ ANDAMAN SEA PLANKTONIC FORAMINIFERA TEXT FIGURE 14 Distribution (numberlgram) of Cloboquadrina conglvmrrda in the sediments of the Andaman Sea. PLATE 2 I. Globigerinoides sacculifer (Brady), X84. Ventral view. Specimen from 30 meters, sample Globigerinoides succulifer (Brady), x 112. Ventral view. Specimen from 494 meters, sample 67. Specimen is intermediate to G. sacculifer and Sphaeroidinella dehiscens. 3. Sphaeroidinellu dehiscens (Parker and Jones), x135. Ventral view. Specimen from 1024 meters, sample Globigerinoides conglobafus (Brady), Ventral view, x125. Specimen from 494 meters, sample Globoquadrina conglomerata (Schwagerj, Ventral view, ~94. Specimen from 494 meters, sample Neogloboquadrina dutertrei dutertrei (Orbignyj. 6, Ventral view: x105, umbilical flaps are faintly visible in photograph; 9, Dorsal view, x115. Specimens from 494 meters, sample Globorotaliu menardii (Orbigny), x60. Dorsal view. Specimen from 494 meters, sample Globorotaliu tumida (Brady), ~70. Dorsal view. Specimen from 494 meters, sample

14 FRERICHS GLOBOROTALIA MENARDII NOAM TEXT FIGURE 17 Distribution (numberlgram) of Globorotalia menardii in the sediments of the Andaman Sea. large as 436 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, and in the vicinity of the South Preparis Channel, in the vicinity of the Great Passage, and on the scattered seamounts. Genas Neoglobcquadrina Bandy, Frerichs and \'incent, 1967 h-eogloboquadrina dutertrei dutcrtrei (d'orbignp) Plate 2, figures 6, 9 Globigerirru dutertrei ~'ORBIGNY, 1839, p. 84, pl. 4, figs Neogloboquadrina dutertrei dutertrei is abundant in the sediments of the Andaman Sea (text fig. 16). It was noted in 60 samples and composes as much as 20 percent of the planktonic population, with absolute abundances as large as 8437 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicohar Ridge in the vicinity of the Nicobar Islands and the South Preparis Channel, and on the scattered seamounts. Family GLOBOROTALLIDAE Cushman, 1927 Genus Globorotalia Cushman, 1927 Globorotalia crassaformis (Galloway and Wissler) Clobigerinu crassaformis GALLOWAY and WISSLER, 1927, p. 41, PI. 7, fig. 12. Globorotalia crassuformis is sparsely distributed in the sediments of the Andaman Sea. It was noted in 11 samples and nowhere forms as much as one percent of the planktonic populations, with absolute ahundances as great as 228 specimens per gram. The species is most abundant in the southeastern comer of the sea and on the scattered seamounts. 12

15 ANDAMAN SEA PLANKTONIC FORAMINIFERA Globorotalia hirsuta (dlorbigny) Rotalinu hirsuta D'ORBIGNY, 1839, p. 131, pl. 1, figs Globorotalia hirsrtta is sparsely distributed in the sediments of the Andaman Sea. It was noted in eight samples and never composes as much as one percent of the planktonic population, with absolute abundances as large as four specimens per gram. It is most abundant in the vicinity of the Nicobar Islands. Globorotalia menardii (d'orbigny) Plate 2, figure 7 Rotuliu (Rotuliu) nlenurdii D'ORBIGNY, 1826, p. 273, no. 26; Modeles no. 10. Globorotalia menardii is a consistent component of the planktonic populations in the sediments of the Andaman Sea (text fig. 17). It was noted in 48 samples, but never composes more than five percent of the planktonic populations, with abundances as great as 456 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the South Preparis Channel and on the scattered seamounts. Globorotalia scitula (Brady) Pulvinulinu scitulu BRADY, 1882, p Globorotalia scitrtla is sparsely distributed in the sediments of the Andaman Sea. It was noted in 15 samples and never forms as much as one percent of the planktonic population. The maximum absolute abundance is 76 specimens per gram. The species is most abundant in the sediments of the southeastern corner of the sea, on the Andaman-Nicobar Ridge in the vicinity of the Great Passage, and on the scattered seamounts. Globorotalia truncatulinoides (d'orbigny) Rotaline trur~cat~clinoides D'ORBIGNY, 1839, p. 132, pl. 2, figs Globorotalia truncatulinoides is very rare in the sediments of the Andaman Sea. It was noted in only two samples and the presence of this species probably indicates a relict Pleistocene assemblage. The maximum absolute abundance is two specimens per gram. Specimens are dextrally coiled. Globosrotalia tumida (Brady) Plate 2, figure 8 Pulvinulinu nzenurdii (d'orbigny) var. tunzida BRADY, 1877, p Globorotalia trtmida is sparsely distributed in the sediments of the Andaman Sea. It was noted in 15 samples and never composes as much as one percent of the planktonic populations. The maximum absolute abundance is five specimens per gram. REFERENCES BANDY, 0. L., 1956, Ecology of foraminifera in northeastern Gulf of Mexico: U. S. Geol. Survey Prof. Paper 274-G, p , FRERICHS, W. E., and VINCENT, EDITH, 1967, Origin, development, and geologic significance of Neogloboquadritrrr: Cushman Found. Foram. Research Contr., v. 18, pt. 4, p , INGLE, J. C. JR., and FRERICHS, W. E., 1967, Isomorphism in Sphaeroidinella and Sphueroidinellopsis: Micropaleontology, v. 13, no. 4, p BANNER, F. T., and BLOW, W. H., 1959, The classification and stratigraphical distribution of the Globigerinaceae: Palaeontology, v. 2, pt. 1, p Bi, A. W. H., 1964, Influence of depth on shell growth in planktonic foraminifera, in Abstracts for 1963: Geol. Soc. America Spec. Paper 76, p , 1965, The influence of depth on shell growth in Globigerinoides succulif~,r (Brady) : Micropaleontology, v. 11, no. 1, p BLOW, W. H., and BANNER, F. T., 1962, The mid-tertiary (upper Eocene to Aquitanian) Globigerinaceae, in Eames, F. E., Banner, F. T., Blow, W. H. and Clarke, W. J., Fundamentals of mid-tertiary stratigraphical correlation: Cambridge Univ. Press, p BOLLI, H. M., 1957, Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B. W. I.: U. S. Natl. Mus. Bull. 215, p , LOEBLICH, A. R., JR., and TAPPAN, H., 1957, Planktonic foraminifera1 families Hantkeninidae, Orbulinidae, Globorotaliidae and Globotruncanidae: U. S. Natl. Mus. Bull. 215, p BRADY, H. B., 1877, Supplementary notes on the foraminifera of the Chalk (?) of the new Britain group: Geol. Mag., new ser., decade 2, v. 4, p , 1879, Notes on some of the reticularian Rhizopoda of the Challenger Expedition: Part 2, Additions to the knowledge of porcellanous and hyaline types: Quart. Jour. Micr. Sci., new ser., v. 19, p , 1882, Report on the foraminifera, in Tizard and Murray, Exploration of the Faroe Channel during the summer of 1880, HMS Knight Errunt, with subsidiary reports: Royal Soc. Edinburgh Proc., v. 11, ( ), no. 11 1, p

16 FRERICHS -, 1884, Report on the foraminifera dredged by HMS Challenger, during the years : Rept. Scientific Results Explor. Voyage HMS Challenger, Zoology, v. 9, p BRONNIMANN, P., 1951, Globigerinifrr naprrrimaensis n. gen., n. sp., from the Miocene of Trinidad, B. W. I.: Cushman Found. Foram. Research Contr., v. 2, pi. 1, p CARPENTER, W. B., PARKER, W. K., and JONES, T. R., 1862, Introduction to the study of the foraminifera: Ray SOC. Publs., p, CUSHMAN, J. A,, 1927, An outline of a re-classification of the foraminifera: Cushman Lab. Foram. Research, Contr., v. 3, pt. 1, p, EGGER, 1. G., 1893, Foraminiferen aus Meeresgrundproben, gelothet von 1874 bis 1876 von S. M. Sch. Gazelle: K. Bayer, Akad. Wiss., Munchen, Math.-Phys. CI., Abhandl., v. 18, pt. 2, p , pl FINLAY, H. I., 1947, New Zealand foraminifera; key species in stratigraphy-no. 5: New Zealand Jour. Sci. Technol., v. 28, no, 5 (sec. B), p GALLOWAY, J. J., and WISSLER, S. G., 1927, Pleistocene foraminifera from the Lomita Quarry, Palos Verdes Hills, California: Jour. Paleontology, v. 1, p HOFKER, JAN, 1956, Foraminifera Dentata-Foraminifera of Santa Cruz and Thatch Island Virginia-Archipelago West Indies: Spolia Zool. Musei Hauniensis XV, p NATLANO, M. L., 1938, New species of foraminifera from off the west coast of North America and from the later Terti- ary of the Los Angdes Basin: California UniV., Scripps Inst. Oceanography Tech. Ser. Bull., v. 4, no. 5, p ORBIGNY, A. D. o', 1826, Tableau Methodique de la classe des Cephalopodes: Ann. Sci. Nat., Paris, ser. 1, v. 7, p, , 1839, Foraminifhres, in Barker-Webb, P., and Berthelot, S., Histoire naturelle des Iles Canaries: Paris, v. 2, pt. 2, p , 1839, Foraminifires: in de la Sagra, Histoire physique, politique, et naturelle de I'ile de Cuba: p PARER, F. L., 1958, Eastern Mediterranean foraminifera: Repts. Swedish DeepSea Exped., , v. 8, no. 4, p , 1962, Planktonic foraminiferal species in Pacific sediments: Micropaleontology, v. 8, no. 2, p , 1966, Irregular distributions of planktonic foraminifera and stratigraphic correlation: Progress in Oceanography, v. 3, p PARKER, W. K., and JONES, T. R., 1865, On some foraminifera from the North Atlantic and Arctic Oceans, including Davis Straits and Baffin's Bay: Royal SOC. London Philos. Trans., v. 155, p POLSKI, W., 1959, Foraminiferal biofacies off the north Asiatic coast: Jour. Paleontology, v. 33, no. 4, p SCHWAGER, CONRAD, 1866, Fossile Foraminiferen von Kar- Nicobar: Novara-Exped., Geol. Theil, v. 2, p Ms submiflcd November 1969 APPENDlX A Samples, locations, and depths JSS Serrano samples collected in 1961 BS-176 7"48.0' 98"08.5' 180 s I station Latitude L"ngiluae Depth 1 station Latitude Lonpifude Denth Uurnhzr North East Kumller North East in m USS Serrano samples collected in 1963 BS- 3 6'00.0' 97"SS.O' IS D o1.n USS Pioneer samples collected in 1965 P ' '