12. paleoenvironment and biostratigraphy of …€¦ · sporadic occurrences of planktonic...
TRANSCRIPT
Pisciotto, K. A., Ingle, J. C , Jr., von Breymann, M. T., Barron, J., et al., 1992Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 127/128, Pt. 1
12. PALEOENVIRONMENT AND BIOSTRATIGRAPHY OF FORAMINIFERS AT SITES 794, 795, 796,AND 797 IN THE JAPAN SEA1
Charlotte A. Brunner2
Biostratigraphy and paleoenvironmental history of deep and surficial waters of the Japan Sea are addressed using sequences recoveredfrom the floor of the backarc basin. The study is divided into two parts: (1) foraminifer biostratigraphy and paleoenvironmental assessmentof sedimentary sequences recovered from above igneous basement at the four sites and (2) detailed planktonic foraminifer paleoenvironmentalanalysis of Quaternary and Pliocene sequences from Sites 794 and 797 in the Yamato Basin.
A total of 253 samples were examined for the foraminifer biostratigraphy and 325 samples for the detailed paleoenvironmentalstudy of Quaternary and Pliocene sequences. Low abundance and sporadic occurrence of foraminifers limited interpretation ofresults. Foraminifer-bearing intervals were correlated where possible to diatom and calcareous nannofossil zonations, and thesequences were successfully assigned to the foraminifer zonation of Matsunaga. Unfortunately, extensive barren intervals andsporadic occurrences of planktonic foraminifers prevented zonation of Quaternary and Pliocene intervals, although someinteresting conclusions about paleoenvironment were possible and are listed below.
A sequence of Neogene (sensu lato) paleoenvironmental events were identified: (1) deepening of the Yamato basins to middlebathyal depths by the early to middle Miocene, an event contemporaneous with the age of some deep basins known from upliftedsections adjacent to the Japan Basin; (2) cooling of the Japan Sea in the early middle Miocene; (3) oxygenation of deep watersin the late Miocene; (4) further cooling of surficial water masses between the Olduvai Subchron and the Brunhes/MatuyamaBoundary; and (5) extermination of lower middle bathyal faunas and replacement by upper middle bathyal faunas near the baseof the Quaternary.
INTRODUCTION
A fundamental objective long sought in the Japan Sea region is acontinuous biostratigraphic and paleoenvironmental record of themarginal sea. The scientific reward from such a sequence includesissues of multidisciplinary interest. The paleoenvironmental recordof the backarc basin could detail the events surrounding the openingand subsidence of the nascent basin, its maturation, and the effects ofcompression that may lead ultimately to its destruction. Rotation ofthe island arc during Miocene basin widening along with formationof sills across passages to the open Pacific Ocean probably arerecorded by assemblage changes in the biota of both the upper watercolumn and in bottom waters. The late Pliocene and Quaternary facies(light and dark lithologic cycles) suggest that the basin may have actedlike an amplifier in response to glacial climatic cycles. The developmentof a continuous biostratigraphy correlated to the global time scalecould place these events in historical perspective relative to those inthe Pacific Ocean and elsewhere.
The taxonomy of Japan foraminifers, the foraminifer biostratigraphy,and paleoenvironments of uplifted marine sections on western Honshuand Hokkaido have been discussed by many workers (i.e., Asano,1950-1951; Saito, 1963; Matsunaga, 1963; Asano, et al., 1969;Burckle and Todd, 1976; Kurihara, 1976; Tsuchi et al., 1984; Oda,1986). Several major events in the history of the Japan Sea wereidentified from these sequences.
1. Uplifted bathyal basins are as old as the late early Miocene, adate that marks a youngest age for bathyal depth basins during thebirth process of the backarc basin (i.e., Matoba, 1984).
2. The nascent Japan Sea supported a warm subtropical planktonicfauna in the early Miocene, but was cool by the late middle Miocene(i.e., Asano et al., 1969; Saito, 1963; Matoba, 1984; Tsuchi et al.,1984). This cooling event may be related to clockwise rotation of the
Pisciotto, K. A., Ingle, J. C , Jr., von Breymann, M. T., Barron, J., et al., 1992. Proc.ODP, Sci. Results, 127/128, Pt. 1: College Station, TX (Ocean Drilling Program).
2 Center for Marine Science, University of Southern Mississippi, Stennis SpaceCenter, MS 39529.
island arc, a process that closed southerly passages and openednortherly passages to the Pacific Ocean (Chinzei, 1986).
3. The sedimentary sequence between the early Miocene andPliocene contains sporadic occurrences of foraminifers, making itvery difficult to piece together a history during basin growth andmaturity (i.e., Matsunaga, 1963).
4. Middle Miocene to late Pliocene agglutinated foraminifer fau-nas of the Onnagawa and Funakawa Formations indicate low oxygenconditions in the deep waters of the bathyal basins (i.e., Matoba,1984). The overlying Pleistocene fauna, which is dominated bycalcareous benthic foraminifers, marks a change in deep water tomore oxygenated conditions.
5. Matoba (1984, and references therein) has noted that the late Plioceneto early Pleistocene fauna typified in the Kitaura and Wakimoto Formationsis quite different from the latest Quaternary fauna recovered in piston cores,and he suggests that a drastic change in bathyal Oceanographic conditionstriggered a major faunal turnover in the late Pleistocene.
The objective of this paper is to assess the capability of the dataset to address the goals listed above, to expand on the history knownfrom uplifted sections, and to identify additional significant eventssince the birth of the marginal sea.
METHODS
Neogene Biostratigraphy and PaleoenvironmentalAssessment
Core-catcher samples were prepared from sediment cores of thefour sites, and in a few instances samples were taken from withincores. 253 samples approximately 20 cm3 in volume were dried,soaked in a hot 1% Calgon solution, washed on a sieve of 63-µmopenings, and inspected for foraminifers. In most samples, all specimenswere picked and identified to genus or species. In samples withcommon to abundant foraminifers, representatives of each speciespresent were picked (see Tables 2 and 3 in the Biostratigraphy sectionof each site chapter in Tamaki, Pisciotto, Allan, et al., 1990). Thespecies ranges and assemblages were compared with the zonation ofMatsunaga (1963).
187
C. A. BRUNNER
Detailed Quaternary and Pliocene Biostratigraphy andPaleoenvironmental Analysis
Samples were taken from each section of the hydraulically piston-cored portions at Sites 794 and 797. As many as five samples persection were taken in the top five and six cores respectively, and onesample per section from deeper in the sequences. Samples wereweighed, dried, and soaked in a hot 1% Calgon solution for about3 hr. The disaggregated sediment was washed on a sieve of 63-µmopenings, and the sand-size residue was dried, weighed, and inspectedfor foraminifers. Samples with abundant planktonic foraminifers weresplit into about 300 specimens using an Otto microsplitter. Planktonicforaminifers were identified to species and counted, benthic foraminiferswere counted.
Several parameters were calculated from the measured data: sandpercent by weight, planktonic and benthic foraminifer numbers (num-ber of specimens per gram of sediment), benthic/planktonic ratio(number of benthic specimens/total number of foraminifer speci-mens), the coiling ratio of Neogloboquadrina pachyderma (numberof sinistral forms/total number of Neogloboquadrina pachydermatests), and relative frequency of 11 planktonic foraminifer species andcounting groups. Q-mode cluster analysis was used to objectivelyseparate planktonic foraminifer assemblages. The procedure used asimple Euclidean distance coefficient applied to the relative speciesfrequency data and amalgamated samples using the smallest averagedistance between groups. The results were compared to the biostratigra-phy of Maiya et al. (1976) and Lagoe and Thompson (1988).
RESULTS OF NEOGENE FORAMINIFERBIOSTRATIGRAPHY
Foraminifers are generally rare (Table 1) and samples with com-mon to abundant foraminifers are, with a few notable exceptions,limited to the Quaternary and upper Pliocene. Of 65 samples exam-ined at Site 794 (Tables 1 and 2), 27 are barren, 20 have fewer than10 specimens, and only 4 from the Quaternary sequence have morethan 100 specimens, which are dominated by calcareous planktonicforaminifers. Of 68 samples examined at Site 795 (Tables 1 and 3),25 are barren, 7 have fewer than 10 specimens, and 20 have more than100 specimens, which, in general, are dominated by agglutinatedforaminifers. One sample from the middle Miocene sequence bearsmore than 100 calcareous foraminifers. Of 53 samples examined fromSite 796 (Tables 1 and 4), 23 are barren, 11 have fewer than 10specimens, and 6 have greater than 100 specimens. One of the lattersamples is upper Miocene, and the others are Quaternary and upperPliocene. Of 67 samples from Site 797 (Tables 1 and 5), 23 are barren,12 have fewer than 10 specimens, and 13 have more than 100specimens. Three of these lie in the Miocene, whereas the other 10are from the Quaternary and upper Pliocene.
Quaternary Foraminifers
The Quaternary sequences (Koizumi, this volume; L. Vigliotti andJ. Wippern, pers. comm., 1990) at all sites bear several features in
làble
Site
794795796797
1. Frequency of samples bearing foraminifers.
Frequency of Samples with Specified Numbers
Barren
27252323
of Foraminifer Tests
<IO Tests
207
1112
10-99 Tests
14161319
>99 Tests
420
613
Total
of Samples
65685367
common (Tables 2 through 5). They contain almost no agglutinatedforaminifers, and have several intervals with abundant subarctic toarctic planktonic foraminifers. The sequences contain some miliolidslike Pyrgo, Nummoloculina, Quinqueloculina, and other genera, andthey have assemblages with frequent Globocassidulina subglobosa,Islandiella norcrossi, Stainforthia complanata, Brizalina pacifica,Epistominella pacifica, Fursenkoina seminuda, Bulimina striata var.mexicana, and Trifarina. There are too few foraminifers in this set ofdata to clearly distinguish benthic assemblages within the Quaternary.
Pliocene Foraminifers
The most distinctive feature of the Pliocene intervals is the con-sistent range of Miliammina echigoensis throughout the four sites(Tables 2 through 5). At all holes except Hole 796B, the top of therange of this taxon lies within the Neodenticula koizumii Diatom Zone(Koizumi, this volume). At all holes except Hole 796B, the bottom ofthe range lies in the Thalassiosira oestrupii Diatom Zone (Koizumi,this volume). The deepest occurrence at Site 794 (Table 2) is a singlespecimen, which lies in the older Neodenticula kamtschatica DiatomZone (Koizumi, this volume). This occurrence could be contamina-tion from upsection as the next occurrence of Miliammina echigoen-sis lies within the Thalassiosira oestrupii Diatom Zone (Koizumi, thisvolume).
Species that occur in the Pliocene (Koizumi, this volume) at allfour sites (Tables 2 through 5) include the agglutinated speciesMartinottiella communis, Eggerella bradyi, and Eggerella sp. A, andthe calcareous species Melonis pompilioides. Species that occur atSites 795, 796, and 797 include Chilostomella oolina and Globobu-limina auriculata. The two sites from the Japan Basin also shareQuinqueloculina akneriana and Oolina globosa. The two sites fromthe Yamato Basin, however, are difficult to compare because Site 794has the worst calcium carbonate preservation and lowest diversity ofthe four sites, whereas Site 797 has the best calcium carbonatepreservation and highest diversity of the four sites.
Upper Miocene Foraminifers
In the Japan Basin, the sequence within the Neodenticula kamt-schatica Diatom Zone (Koizumi, this volume) is nearly barren offoraminifers. In the Yamato Basin, the upper Miocene sediments ofSites 794 and 797 are also near barren except at the base of the zonewhere Sample 127-797-31X-CC, is enriched with well preservedGlobigerina bulloides, Globobulimina auriculata, Sigmavirgulinasp., Cibicides lobatulus, Elphidium subincertum, and traces of otherspecies. This sample may be displaced from shallower depth.
Correlation of foraminifers to the diatom zonation of Koizumi(this volume) is difficult below the uppermost Miocene because ofdiagenesis below the opal-A/opal-CT transition, which lies at vari-ous levels within the upper Miocene at all four sites. Diatom zonesare recognized where diatoms are preserved in carbonate concre-tions. Additionally, calcareous nannofossils provide zonal assign-ments at sporadic intervals (Rahman, this volume). With this caveatin mind, some statements can be made with caution about time andintracore correlations.
The lower part of the upper Miocene sequence in the Japan Basin,approximately equivalent to the Denticulopsis dimorpha DiatomZone (Koizumi, this volume) at Site 795 (Table 3), contains adistinctive assemblage of agglutinated and calcareous foraminifers.The agglutinated foraminifers include Cyclammina cf. C. tani, Cy-clammina pusilla, other Cyclammina species, more than six speciesof Haplophragmoides, more than three species of Ammodiscus,Trochammina spp., Martinottiella communis, Martinottiella nodu-losa, and Eggerella sp. A. The calcareous foraminifers includeMelonis pompilioides, Gyroidina soldanii, and other Gyroidinaspp., Cibicides wuellerstorfi> Globobulimina auriculata, and Glo-bigerina bulloides.
188
JAPAN SEA FORAMINIFERS
Site 796 (Table 4), also from the Japan Basin, bears a similaragglutinated assemblage near its base. The base may be early lateMiocene in age based on extrapolation of sedimentation rates fromdatums higher in the sequence (see Sediment Accumulation Ratessection, Site 796 chapter in Tamaki, Pisciotto, Allan, et al. (1990). Thecalcareous assemblage at Site 796 contains Globobulimina auricu-lata, Gyroidina lamarckiana, Nonionella miocenica, Chilostomellaoolina, Valvulineria spp., and Globigerina woodi among a few others,and looks different from the assemblage at Site 795. However, wecaution that this conclusion is reached based on very few specimens.
The lower part of the upper Miocene sequence in the Yamato Basinis assigned to the Rouxia californica Diatom Zone at Site 797 (Koizumi,this volume). The zone at this site is truncated by a disconformity atits base. The interval (Table 5) includes one specimen of Cyclammina,four species of Haplophragmoides, Martinottiella communis, andEggerella sp. A and is generally similar to the agglutinated assem-blage of the Japan Basin. The calcareous foraminifers include Gyroi-dina lamarckiana, Pullenia salisburyi, Globobulimina auriculata,and other Globobulimina spp., Neogloboquadrina asanoi, and Neoglo-boquadrina himiensis. This list of species is different from those ofthe Japan Basin.
The lower part of the upper Miocene sequence at Site 794 isassigned to the Rouxia californica Diatom Zone through the Denticu-lopsis katayamae Diatom Zone (Koizumi, this volume) above theopal-A/opal-CT transition, which lies in Core 127-794A-3IX. Thebase of the upper Miocene is placed near Sample 127-794A- 14R-CC,based on extrapolation of sedimentation rates and the occurrence ofthe Discoaster hamatus Calcareous Nannofossil Zone in Sample127-794B-12R-CC. Unfortunately, the foraminifers are too rare atSite 794 (Table 2) to compare with those in Site 797 (Table 5).
Middle Miocene Foraminifers
The deepest, foraminifer-bearing unit at Site 795 in the Japan Basinfalls within the Denticulopsis praedimorpha and Denticulopsis hustedtiiDiatom Zones (Koizumi, this volume). The latter zone lies near the baseof the middle Miocene. The sequence (Table 3) bears Cyclammina cf. C.tani and Cyclammina spp. with Eggerella sp. A, several species ofHaplophragmoides, Martinottiella communis, Martinottiella nodulosa,and Spirosigmoilinella compressa. With the exception of the last species,the assemblage of agglutinated foraminifers is similar to the lower upperMiocene agglutinated assemblage at Sites 795 and 796. The calcareousforaminifers at Site 795 include Globobulimina auriculata, Cibicideswuellerstorfi, Elphidium subincertum, Gyroidina lamarckiana, Gyroi-dina orbicularis, Pullenia bulloides, and pieces of nodosarids and singlespecimens of Melonis pompilioides Nonionella spp. and other species.The most common planktonic species are Globigerina bulloides andGlobigerinita glutinata, species commonly associated with cool surficialwater masses.
Middle to Lower (?) Miocene Foraminifers
In the Yamato Basin, the age of foraminifer-bearing sediment nearbasement at Sites 794 and 797 appears coincident. The intervals atSites 794 (Cores 127-794B-24R and-25R) and 797 (Cores 127-797B-47X through -52X) contain the calcareous nannofossil, Sphenolithusheteromorphus (Rahman, this volume), which ranges in age from 14.4to 17.1 Ma (Berggren et al., 1985). Its range crosses the lowerMiocene/middle Miocene boundary. The ranges of several planktonicforaminifers support this conclusion. At Site 797, Samples 127-797B-52X-CC, and -797C-3R-CC, contain Catapsydrax parvulus, whichranges in age from Zone N7 to within Zone N15 (Kennett andSrinivasan, 1983), about 17.6 to 10.2 Ma (Berggren et al., 1985), andGloborotalia praescitula, which ranges in age from Zone N10 (Ken-nett and Srinivasan, 1983), about 14-15 Ma (Berggren et al., 1985),to 17.7 Ma (Berggren et al., 1985). Additionally, Samples 127-797B-51X-CC, -797B-52X-CC, and -794B-24R-CC, are dominated by the
species Globoquadrina venezuelana of the warm subtropics, whichsuggests that the region was much warmer than assemblages higherin the sequences. The paleoenvironmental cooling occurred in theearly middle Miocene (Saito, 1963; Chinzei, 1986).
Sites 794 and 797 have similar assemblages of foraminifers. Site794 (Table 2) contains the agglutinated species Cyclammina cancel-lata, Cyclammina japonica, Cyclammina pusilla, Ammodiscus spp.,more than four species of Haplophragmoides, Martinottiella communis,Martinottiella nodulosa, Spirosigmoilinella compressa, and Trocham-mina spp. The same agglutinated assemblage occurs at Site 797 (Table5) with the additional species, Eggerella sp. A, four additional speciesof Haplophragmoides, and four additional species of Ammodiscus.Site 794 (Table 2) contains the calcareous species Chilostomellaoolina, Gyroidina orbicularis, Gyroidina sp. A, Nonionella mio-cenica, and Oridorsalis tener. Site 797 (Table 5) contains the samecalcareous species with Globobulimina auriculata and other Glo-bobulimina species, Cibicides wuellerstorfi, Eilohedra rotunda, ad-ditional Chilostomella species, Pullenia bulloides, Valvulineriasadonica, and other species.
Most of the calcareous benthic species that occur at Sites 794 and797 (Tables 2 and 5) of the Yamato Basin also occur at Site 795 (Table3) of the Japan Basin. However, the Yamato Basin assemblage is muchmore diverse, and the agglutinated assemblages differ in their cyclam-minid species. The planktonic specimens at Site 795 are few inabundance and poorly preserved in this interval so comparisons withthose at Sites 794 and 797 are unclear. Further work is suggested totest if this interval of Site 795 is correlative with the middle to lower(?)Miocene intervals of the Yamato Basin.
It is interesting to note that the deepest foraminifer-bearing inter-val at Sites 794 and 797 (Tables 2 and 5) is overlain by a distinct barreninterval as are the middle Miocene foraminifer-bearing interval at 795(Table 3) and the upper Miocene foraminifer-bearing intervals at all foursites (Tables 2 through 5).
Paleodepth Analysis
Eighteen calcareous species of benthic foraminifers were selectedas paleodepth indicators based on the work of Matoba (1977), Keller(1980), and Thompson (1980), in the Japan region and that of Ingleand Keller (1980), Culver and Buzas (1986), and Ingle et al. (1980)along the eastern rim of the Pacific Ocean. Occurrences of depthindicators were tabulated (Table 6) by basin and geologic series. Ourinspection of Table 6 reveals the assumptions made about paleodepthindicators, and inspection of Tables 1 through 5 reveals the smallsample size used to draw these conclusions. Sequences bearing ben-thic foraminifers have lain at lower middle bathyal depths since thelower to middle Miocene in the Yamato Basin in units that lie within0.55 m (Site 794) and 0.65 m (Site 797) of igneous basement. Thebasal middle Miocene sequence at Site 795 was also deposited atlower middle bathyal depths in a foraminifer-bearing unit that lies 19m above igneous basement.
Range of the Low Oxygen Facies
At all four sites the lower, middle, and lower upper Miocenesequences bear sedimentary structures suggestive of low oxygen. Thestructures consist of predominance of horizontally oriented burrows inbioturbated sections interspersed with laminated intervals where bio-turbation is absent. The features are described in the barrel sheets ofthe Initial Reports volumes. The ranges of these structures correspondvery well with the ranges of the agglutinated benthic foramini-feralassemblage bearing Cyclammina, Haplophragmoides, and Ammodis-cus, an assemblage associated with low oxygen conditions (Matoba,1984). At all four sites the association appears near the bases of thesedimentary sequences above igneous basement (Table 7). In the JapanBasin the association continues to the Neodenticula kamtschaticaDiatom Zone in the upper upper Miocene of both sites. In the Yamato
189
C. A. BRUNNER
Table 2. Range chart of foraminifers from Site 794 arranged alphabetically within the taxonomic groups, agglutinated, miliolid, rotalid, and planktonic.
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-02, 94-96A-3H-CCA-4H-05, 90-92A-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-32X-CCA-33X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-02, 8-9
1 12
12
16
2
17
190
Table 2 (continued).
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-02, 94-96A-3H-CCA-4H-05, 90-92A-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-32X-CCA-33X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-02, 8-9
u ü
191
Table 2 (continued).
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-02, 94-96A-3H-CCA-4H-05, 90-92A-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-32X-CCA-33X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CC, 8-9
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381 1 10
192
JAPAN SEA FORAMINIFERS
Table 2 (continued).
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-02, 94-96A-3H-CCA-4H-05, 90-92A-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-32X-CCA-33X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCB-IR-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CC, 8-9
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2528
6
2
chy d
erm
a
6,a
quad
ri
-Cl "β
so .2
> sEL
27311121112181
1
26
•
park
e
1
1
13
Basin, the shallowest occurrence of the association lies within therange of calcareous nannofossil, Discoaster hamatus, at Site 794 ofthe lower upper Miocene and within the Rouxia californica DiatomZone of the middle upper Miocene at Site 797.
RESULTS OF HIGH-RESOLUTION PLIOCENEAND QUATERNARY BIOSTRATIGRAPHIC
AND PALEOENVIRONMENTAL STUDY
Planktonic foraminifers are limited to a few intervals at Sites 794 and797 in the Yamato Basin. Of 325 samples examined, only 37 sampleshave more than 100 specimens, and 18 have fewer than 100 specimenspicked from the entire sediment sample (Table 8).
There are 37 samples with planktonic foraminifer numbersgreater than 40 tests/g (Fig. 1). Visual inspection of the sand-sizefraction (Table 9) reveals that planktonic foraminifers are the mostabundant constituents of the sand-size fraction in 29 of the 37samples, including two samples that have sand-size gypsum andanhydrite crystals, which may have precipitated from the porewater upon drying in the laboratory and one sample dominated byauthigenic pyrite with foraminifers as the next most commonconstituent. There is a clear relationship between above averagesand content and large foramini-feral number. All samples withgreater than 4,000 planktonic foraminifers/g have above averagesand content, average being 2% for all 325 samples of the data set.There is some relationship between above average sand content andsamples enriched with foraminifers. Sixteen samples are aboveaverage in sand content, and 11 are average or below average.
Eight of the 37 samples (Table 9) are dominated by mineralgrains, authigenic pyrite with mineral grains, ash or pumice, orsponge spicules. Four of these also have an unusually large ratio ofbenthic to planktonic foraminifers, a condition that can indicateshallow source.
The coiling ratio of Neogloboquadrina pachyderma estimatesrelative paleotemperature of surface waters. All samples with 30 ormore specimens of Neogloboquadrina pachyderma were considered(Table 10). At Site 794 (Fig. 2), all 8 samples have 90% or moresinistrally coiled forms. In contrast, Site 797 (Fig. 2) has 34 samples,26 of which have 90% or more sinistrally coiled forms, 7 havebetween 80% and 89%, and one sample, which lies within theOlduvai, has 63% sinistrally coiled forms.
Q-mode cluster analysis was used to distinguish planktonic foraminif-eral assemblages in all samples in which 100 or more specimens werecounted (Table 11). Four clusters were resolved (Fig. 3). Cluster 1 iscomposed of 11 samples, which are dominated (>81%) by sinistralNeogloboquadrina pachyderma. The species has high productionrates when the upper water column is cold, isothermal, and nutrientrich (Sautter and Thunell, 1989; Reynolds and Thunell, 1986). It isalso associated with dissolution because sinistral Neogloboquadrinapachyderma is the most solution resistant of the high-latitude species(Coulbourn et al, 1980; Sautter and Thunell, 1989).
Cluster 2 is composed of 15 samples dominated by sinistralNeogloboquadrina pachyderma with significant amounts of otherspecies, which subdivide the cluster into three groupings, a, b, and c.Cluster 2a includes accessory Globigerina quinqueloba, a speciesassociated with the spring bloom, Cluster 2b includes accessoryGlobigerina bulloides, a species associated with upwelling and a widerange of thermal conditions, and Cluster 2c includes accessory Glo-bigerina bulloides and dextral Neogloboquadrina pachyderma, thelatter of which is associated with the stratified upper water column ofthe temperate fall. The assemblage is consistent with one produced insubarctic waters during seasonal alternation of isothermal and strati-fied conditions. The fauna is, subsequently, only moderately biasedby dissolution (Sautter and Thunell, 1989; 1991).
Cluster 3 is composed of four samples and consists of nearequal proportions of sinistral Neogloboquadrina pachyderma and
193
C. A. BRUNNER
Table 3. Range chart of foraminifers from Site 795 arranged alphabetically within the taxonomic groups, agglutinated, miliolid, rotalid, and planktonic.
Core-sectioninterval (cm)
U =S
=5 =5 •S
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16H-CCA-17H-CCA-18H-CCA-19H-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCA-38X-CCA-39X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CCB-27R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CC
1 2
4
311614154
116128
1415
103
24
1
194
JAPAN SEA FORAMINIFERS
Table 3 (continued).
Core-sectioninterval (cm)
I
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16H-CCA-17H-CCA-18H-CCA-19H-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCA-38X-CCA-39X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CCB-27R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CC
2
1 I
1 1
1 3
3 1 • 13
195
C. A. BRUNNER
Table 3 (continued).
Core-sectioninterval (cm)
t 2
I:s •s
o ü 5 5A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16H-CCA-17H-CCA-18H-CCA-19H-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCA-38X-CCA-39X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-I8R-CCB-I9R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CCB-27R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CC
2 31
12 261 2
196
JAPAN SEA FORAMINIFERS
Table 3 (continued).
Core-sectioninterval (cm) 5 S
O O
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16H-CCA-17H-CCA-18H-CCA-19H-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCA-38X-CCA-39X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-I1R-CCB-12R-CCB-I3R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-2IR-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CCB-27R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CC
23
36
4 3
53 19
197
C. A. BRUNNER
Table 4. Range chart of foraminifers from Site 796 arranged alphabetically within the taxonomic groups, agglutinated, milliolid, rotalid, and planktonic.
Core-sectioninterval (cm)
güSc
nodu
li
jg3̂
3
sp.
!§
c
chie
oe
çiδ
CS
CD CD
J! 5
I I
•i I
•5 • - - c^
I 1 1 I II I I | .aS 5 δ S c
-C -Q ~C -Q Ca o a o ^;O O ü O 5
á f
j ? j
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-8X-CCA-9X-CCA-10X-CCA-11X-CCA-12X-CCA-14X-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CC
1 I
10
1 13
8 1 7 1 3 6
3 3 1 2
99
Core-sectioninterval (cm)
•S -S
1 1 "§
i I I ė O)
B-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-24R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CCB-32R-03,B-32R-04,B-32R-05,B-33R-02,
31-33143-14524-2634-36
198
JAPAN SEA FORAMINIFERS
Table 4 (continued).
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-8X-CCA-9X-CCA-10X-CCA-11X-CCA-12X-CCA-14X-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CC
Core-sectioninterval (cm)
B 1R CCR 9R CC
B 3R CCB-4R-CCB 5R CCB 6R CCB-7R-CCB 9R CCR IΠR CC
R 1 1 R CC
R 1 ^R CC
R 1 SR CC
R iftR CC
R 1 RR CC
B-19R-CCR 90R CC
R 9QR CC
D 11D p p
B-32R-03, 31-33B-32R-04, 143-145B-32R-05, 24-26B-33R-02, 34-36
hid
es
Jo
cf.
gen
Glo
b
19
ella
ool
ina
E
Ch
ilos
to
8516
vs
ig
G/o
/>
3
akne
rian
usC
ibic
ide
1
|-33
|
i2
gen
Glo
b
1
3
cf.
E. h
ugh
eum
Elp
hidi
ufo
ram
im
3
ge
ge
nG
/o/>
i
1
1
m;'«
α a
uri
cu,
Glo
bobu
1
2
19
Gto
*i
1
min
a el
onga
Glo
bobu
1
•ne
rosa
a
s>
1
Neo
g
2
min
d sp
p.
Glo
bobu
211
-hyd
erm
a
I§
•s
S>
If
Neo
g(d
exti
2
11
35
lobo
said
ulin
a su
bgG
lobo
ca
8
"hyd
erm
a
t
S
IT?
Neo
g(s
inis
12
7
35
lam
arki
ana
Gyr
oidi
n
151
orbi
cula
ris
a
Gyr
oidi
n
1
sp.
A
3
Gyr
oidi
n
73424
nor
cros
siIs
land
iel
coba
ren
se
e
Mel
onis
1
ompi
lioi
des
ε
Mel
onis
1
D .
5.
Non
ion
s
1
j mio
cen
ica
^
Non
ione
1423
alis
bury
i
Par
afis
s
Pul
len
ia
1
1
sp.
A
3
Rob
erti
n
21
W!β
S
pp
.S
phae
ro
1
3
a co
mpl
an
a•e
Sta
info
n
1
yaba
i
3
Uvi
geri
r
4
iβ s
pp.
Val
vulin
152
t<a b
ull
oid
es
•p
Glo
bige
1
2
199
C. A. BRUNNER
Table 4 (continued).
Core-sectioninterval (cm)
A-1H-CCA-2H-CCA-3H-CCA-4H-CCA-5H-CCA-6H-CCA-8X-CCA-9X-CCA-10X-CCA-11X-CCA-12X-CCA-14X-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CC
Core-sectioninterval (cm)
B-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-I5R-CCB-16R-CCB-I7R-CCB-I8R-CCB-19R-CCB-20R-CCB-24R-CCB-28R-CCB-29R-CCB-30R-CCB-31R-CCB-32R-03, 31-33B-32R-04, 143-145B-32R-05, 24-26B-33R-02, 34-36
bull
oide
s
d
cf.
'rin
1O
1
1
uelo
ba
ssa•α
'rin
δ
l
3
'rin
β β
1δ
i
5
6
13
'rin
-1δ
4
"§
3
'rin
Se1δ
i
i
i
i
i
2
1
1
r pa
chyd
ein
c
|c α
IB
127
1
i pa
chyd
e
%a
J"^| |
1
615
Globigerina bulloides. This association is found in present-daysurficial sediments in the subarctic North Pacific Ocean at waterdepths from 3,300 to 4,300 m (Coulbourn et al., 1980). The assem-blage is produced under the same production conditions as that ofCluster 2, but it is subsequently more strongly dissolved (Sautter andThunell, 1989).
Three samples cluster above the cutoff value and are not suffi-ciently similar to be regarded a cluster. They are most similar tocluster 3. One sample bears a high relative frequency of a speciesrare in all other samples, Tenuitella parkerae. One sample containsnear equal proportions of sinistral Neogloboquadrina pachyderma,Globigerina bulloides, and Globigerina quinqueloba with acces-sory dextral Neogloboquadrina pachyderma. The last sample isdominated by sinistral Neogloboquadrina pachyderma with signifi-cant but small proportions of Globigerina bulloides, Tenuitellaparkerae, and Turborotalita humilis.
Cluster 4 is composed of three samples and is dominated byGlobigerina bulloides. These samples are the most different fromall other samples of the data subset. Globigerina bulloides produc-tion is accelerated during upwelling events (Thunell, pers. coram.,1990) but thrives in a wide range of environments and is not limitedto upwelling habitats especially in temperate and subpolar waters(Sautter and Thunell, 1991).
The Quaternary lithologic sequences at all four sites bear distinc-tive alternations in color between dark chocolate brown, mediumbrown, and light putty gray. It is interesting to note that each plank-tonic cluster has some samples from each color interval (Table 11).
DISCUSSION
Foraminifer Biostratigraphy
The benthic foraminifer sequences described above can be as-signed to the biostratigraphy of Matsunaga (1963) (Table 12), whichwas further described by Matoba (1984) and Matoba et al. (1990) forthe oil fields of Northern Japan. The low abundance of foraminifersat Sites 794 through 797 does not justify comparison to the zonulesdefined by Matsunaga (1963).
Globorotalia cf. G. fohsi Zone
The middle or lower(?) Miocene foraminifer-bearing sequencesat Sites 794 and 797 are tentatively assigned to the Globorotalia cf.G. fohsi Zone. The absence of the subtropical marker species, Glo-borotalia cf. G. fohsi, precludes certain assignment, but the occurrenceof Globorotalia praescitula supports the conclusion. The dominance of asubtropical planktonic foraminifer assemblage suggests that the JapanSea was open to southern waters during deposition of the sequences,a situation expected within the zone. The benthic species listed aresimilar to the bathyal fauna of the Nishikurosawa stage described byMatoba (1984). Some planktonic species listed (Tables 4 and 5) arereported from the Nishikurosawa by Saito and Maiya (1973), al-though some taxonomic questions need resolution.
Spirosigmoilinella compressa Zone
The barren interval above the Globorotalia cf. G. fohsi Zone at Sites794 and 797, the middle Miocene sequence at Site 795, and the upperMiocene sequences at all four sites including the barren interval withinthe Neodenticula kamtschatica Diatom Zone fit the definition of the zone.At all four sites, the lower Pliocene, foraminifer-bearing intervals belowthe first occurrence of Miliammina echigoensis are also assigned to thiszone. Evidence from the planktonic foraminifer fauna support the assign-ment. The cold-water fauna confirms that surficial waters had becomeisolated from subtropical waters that flowed on the Pacific margin of theJapanese islands during deposition of these sequences.
200
Site 794
JAPAN SEA FORAMINIFERS
Site 797
Depth o(mbsf)
20
40
60
80
I I ,n,l
10 100 1000 10000 1000 10000
Planktonic Foraminiferal Number (tests/g)
Figure 1. Planktonic foraminifer number (number of tests/g of sediment) plotted with depth in core in Hole 794A and Hole 797B. All samples plottedon the y axis are barren of planktonic foraminifers. The two lines connecting the graphs denote the Brunhes/Matuyama Boundary and the top of the
Miliammina echigoensis Zone
The Pliocene sequence that includes the range of Miliamminaechigoensis is assigned to the Miliammina echigoensis Zone. Theinterval extends from the Thalassiosira oestrupii Zone at its base tothe uppermost Neodenticula koizumii Diatom Zone.
The Quaternary interval is not similar to the zonation describedby Matsunaga. The species list, however, is similar to those reportedby Ingle (1975), Matoba (1984), Ujiié et al. (1983), and Kato (1989).
Event: Deepening of the Nascent Backarc Basin
The Yamato Basin has lain at lower middle bathyal depths sincethe middle or early(?) Miocene, and the Japan Basin has been at asimilar depth at least since the middle Miocene (Table 6). Others(Guber and Merrill, 1983; Matoba, 1984) have similarly concludedthat some sections in the Hokuroku District and other regions sur-rounding Akita were bathyal and lower bathyal in depth as early asthe early to middle Miocene. Neritic, upper bathyal, and middlebathyal elements are mixed with lower bathyal species in all of theMiocene sequences. Further, there is no clear change in paleodepthin either the Yamato or Japan basins from the middle or lower(?)Miocene sequences through the Pliocene section. Apparently, sub-sidence of the basin occurred very rapidly after emplacement of theigneous "basement" or during emplacement of the igneous "base-ment." No foraminifers at Sites 794, 795, or 797 are preserved thatrecord the subsidence in sediments above the igneous basement or insediment intercalated amid the igneous basement units.
Event: Early Middle Miocene Cooling
The accuracy of the date of change from subtropical to coldsurficial water in the Japan Sea is not increased by this data set and isessentially no different from that cited by Matoba et al. (1990). Itoccurs above the base of the Sphenolithus heteromorphus Zone andwithin or below the base of the Denticulopsis praedimorpha DiatomZone of the middle middle Miocene based on paleoenvironmentalinterpretation of the planktonic foraminifers at Sites 794, 795, and797 (Tables 2, 3, and 5). Samples in the Sphenolithus heteromorphusZone at Site 794 and 797 contain subtropical species. Two samples,127-795B-27R-CC, and 127-795B-13R-CC, contain no subtropicalspecies and are dominated by Globigerina bulloides and Globigerinacf. G. bulloides, which are characteristic of transitional faunas. Anassemblage that includes high-latitude Neogloboquadrina pachydermaappears at Site 794 within or below the Denticulopsis katayamae DiatomZone of the late Miocene. Like land-based sections, the ODP sequencesare plagued with barren intervals and unconformities.
Event: Oxygenation of Stagnant Miocene Deep Water
Matoba (1984) and others relate the range of agglutinated assem-blages in the Miocene to low-oxygen conditions. The ranges ofCyclammina-Ammodiscus-Haplophragmoides assemblages in the Mio-cene correspond with the occurrence of distinctive intervals domi-nated by horizontal burrows (Table 7) described by the shipboardsedimentologists (Tamaki, Pisciotto, Allan, et al., 1990). The upper-most occurrence of the association lies in the upper upper Miocene
201
Table 5. Range chart of foraminifers from Site 797 arranged alphabetically within the taxonomic groups, agglutinated, milliolid, rotalid, and planktonic.
1 β *' | < « u Q M * d •g « •%£ ^ < α α ^ < 5 c L c u á d , c L α « e £ 3 g δ
l l < o Q u d ^ l | ; i á ^ I I l l l l l l l i l il S ö • ö • ö • f f a i t β . f f f < i i 1 1 1 i I i 1 | I 11 I I % I | 1 I | .1 I * i | i r I I i> I I ? I I i |1 1 I I I I | 1 1 1 1 "? "S i l l l l i i l i l 11 I
fnr,r(r, i j j j j i 3 & g s g 1 g n 1 1 1 1 1 1 1 1 j 1 iA-1H-CC
B-1H-CC
B-2H-CC
B-3H-CC
B-4H-CC
B-5H-CC
B-6H-CC
B-7H-CC
B-8H-CC •
B-9H-CC
B-10H-CC 1 •
B-11H-CC 1 • 1 •
B-12H-CC 1
B-13H-CC 2
B-14H-CC 7
B-15H-CC 3 1 3 - 5
B-16H-CC 4
B-17H-CC I
B-18H-CC 7 13
B-I9H-CC 2 2 5
B-20X-CC 1 3 1 - 6
B-21X-CC 4 12 2
B-22X-CC 1 2 12
B-23X-CC
B-24X-CC 1 1 1 • •
B-25X-CC •
B-26X-CC 6 •
B-27X-CC
B-28X-CC 1 ]fl. 8
B-29X-CC
B-30X-CC
B-31X-CC •
B-32X-CC 1
B-33X-CC 2 l • 2 3 1 6 - . 7 -
B-34X-CC
B-35X-CC 1 • 1 2 • • 3 •
B-36X-CC 3 1 . . . 1 . . . 4 •
B-37X-CC 4 • • • 1 2 14
B-38X-CC •
B-39X-CC
B-40X-CC
B-41X-CC •
B-42X-CC
B-43X-CC
B-44X-CC •
B-45X-CC
B-46X-CC •
B-47X-CC 1
B-48X-CC 2 2 . • . . . 2 9 • •
B-49X-CC •
B-50X-CC
B-51X-CC 2 1 . . . . 3 1 •
B-52X-CC 2 1 2 7 • 2 • 6 3 3 1 • 4 •
C-1R-CC . . . . . . .
C-2R-CC 2 l • 5 2 1 1C-3R-CC 4 2 • •
C - 6 R - C C 3 1 4 1 - 1 - 3 3 1 6 3 - 5 8 1 -
C-7R-CC 6 1 3 1 - 1 6 3 • 1 1 6 - 4 1
C-8R-02,36-38 2 3 2 - 1 - 5 1 - 2 • 5 8 2 • - 8 6 1 -
C-18R-01,88-90
C-20R-02,42-44
C-22R-CC
C-23R-CC
C-25R-06,33-35
C-27R-CC
C-33R-03,42-44
C-34R-CC
JAPAN SEA FORAMINIFERS
Table 5 (continued).
Core-sectioninterval (cm)
•S -3 .s
O) O) Ol
S.
.5 s á
A-1H-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-11H-CCB-12H-CCB-I3H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-18H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCB-25X-CCB-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-3IX-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-02, 36-38C-18R-01,88-90C-20R-02,42-^4C-22R-CCC-23R-CCC-25R-06, 33-35C-27R-CCC-33R-03,42-44C-34R-CC
203
C. A. BRUNNER
Table 5 (continued).
Core-sectioninterval (cm)
-S -5S.
A-1H-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-1IH-CCB-12H-CCB-13H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-18H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCB-25X-CCB-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-31X-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-02, 36-38C-18R-01,88-90C-20R-02, 42^4C-22R-CCC-23R-CCC-25R-06, 33-35C-27R-CCC-33R-O3, 42^4C-34R-CC
20
I
10
204
JAPAN SEA FORAMINIFERS
Table 5 (continued).
Core-sectioninterval (cm)
9 •S
I 31 s
8- I
3 .3
o. <s
& -S •S as 1 IS
A-1H-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-11H-CCB-12H-CCB-13H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-I8H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCB-25X-CCB-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-3IX-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-02, 36-38C-18R-01,88-90C-20R-02, 42^4C-22R-CCC-23R-CCC-25R-06, 33-35C-27R-CCC-33R-03,42-UC-34R-CC
18
I 1
205
C. A. BRUNNER
Table 5 (continued).
Core-sectioninterval (cm)
A-1H-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-11H-CCB-12H-CCB-13H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-18H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCB-25X-CCB-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-31X-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-02, 36-38C-18R-01,88-90C-20R-02, 42^4C-22R-CCC-23R-CCC-25R-06, 33-35C-27R-CCC-33R-03, 42^4C-34R-CC
è "s 7? ,3•S ' •
á iO O O ü
29
206
JAPAN SEA FORAMINIFERS
Table 5 (continued).
Core-sectioninterval (cm)
A-IH-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-11H-CCB-12H-CCB-13H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-18H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCR 9SY CCD-iJA-Lv
B-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-31X-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-02, 36-38C-18R-01,88-90C-20R-02, 42-44C-22R-CCC-23R-CCC-25R-06, 33-35C-27R-CCC-33R-O3, 42-44C-34R-CC
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207
C. A. BRUNNER
Table 6. Summary of benthic foraminifer upper depth limits and species distribution in the Yamato and Japan Basins.
UpperDepthLimit
NNN
UB<UMB<UMB>UMBUMB
>UMB>UMB<MBMB
LMBLMB
>LMB>LMB>LMB>LMB
Species
Cibicides lobatulusElphidium subincertumNonionella miocenicaEpistominella pacificaChilostomella oolina
Stainforthia complanataGyroidina orbicularis
Bulimina striataCibicides wuellerstorfi
Oridorsalis tenerPullenia salisburyi
Islandiella norcrossiEggerella bradyiGlobobulimina
auriculataMartinottiella communis
Pullenia bulloidesMelonis pompilioides
Gyroidina soldanii
Quaternary
X
X
X
X
Pliocene
XX
X
X
Yamato Basin
upperupper
Miocene
XX
X
lowerupper
Miocene
X
X
mid-lower
Miocene
X
X
X
XX
X
X
Quaternary
X
X
X
X
Japan Basin
Pliocene
XX
X
X
lowerupper
Miocene
X
X
X
X
XX
midMiocene
XX
X
X
X
XX
N neritic depth (<200 m)UB upper bathyal depth (150-500 m)
<UMB upper middle bathyal to shallower depths (<l ,500 m)UMB upper middle bathyal depth (500-1,500 m)
>UMB upper middle bathyal to greater depths (>500 m)< MB middle bathyal to shallower depths (<2,500 m)MB middle bathyal depth (500-2,500 m)
LMB lower middle bathyal depth (1,500-2,500 m)>LMB lower middle bathyal to greater depths (>l ,500 m)
in the Japan Basin and the lower, upper, and middle upper Miocenein the Yamato Basin. Based on this evidence, low-oxygen bottomwaters persisted through much of the Miocene but oxygenated bottomwaters were well established by the uppermost Miocene, and similarconditions persisted throughout the Pliocene sequence. It is interest-ing to consider whether or not high-latitude Late Miocene coolingmight have driven renewal of Japan Sea deep water.
Event: Appearance of Anomalously Shallow QuaternaryFauna
The Quaternary fauna appears shallower than that of the oldersequences (Table 6) because it bears middle to upper bathyal species,but the present lower bathyal depth of the basin argues against sucha shallowing. The anomalous fauna is either entirely displaced fromshallow depth, or unusual conditions in the silled Japan Sea haveexcluded a lower bathyal fauna. The change to this unusual Quater-nary fauna that was originally pointed out by Matoba (1984, andreferences therein) occurs near the Pliocene/Pleistocene Boundaryrather than in the upper Pleistocene. The event may be related toshallowing of sills, which exclude from the marginal sea the deepfauna on the Pacific side of the Japan islands, and to altered bathyalconditions that exterminated the Pliocene fauna.
Detailed Pliocene and Quaternary PlanktonicForaminifer Biostratigraphy
Correlation of the Japan Sea sequences to the assemblage zonesof Maiya et al. (1976) is not possible because abundant occurrencesof planktonic foraminifers are limited mostly to the upper Quaternary.Furthermore, preservation is sporadic with many gaps within theupper Quaternary sequence. The deepest sample that bears planktonicforaminifers at Site 797 contains only Neogloboquadrina pachy-derma with no Neogloboquadrina asanoi and lies within the upper-most Olduvai Subchron. This is consistent with the date of the last
appearance of Neogloboquadrina asanoi at the base of the OlduvaiSubchron as reported by Maiya et al. (1976) and confirmed by Lagoeand Thompson (1988).
Correlation to the coiling direction zones of Lagoe and Thompson(1988) is not possible because all Quaternary samples are dominated(>80%) by sinistral Neogloboquadrina pachyderma (Table 10), andno dextral coiling intervals were found even though both sequencescontain the Brunhes/Matuyama Boundary (at 38.4 mbsf in Hole 797Band at 24.6 or 34.1 mbsf in Hole 794A; L. Vigliotti and J. Wippern,pers. comm., 1990) at which the CD8/CD9 coiling change boundaryis expected from near 90% sinistral forms above to near 50% sinistralforms below. The ratio of 63% sinistral forms in the Olduvai sampleof Site 797 is higher than predicted if it lies with Zone CD11, whichspans the middle and upper Olduvai sequence. The Holocene intervalof dextral coiling is absent either due to disturbance during thedrill-string entry into the bottom or due to dissolution beneath theCCD, which lies between 1,500 and 2,000 m water depth (Ichikuraand Ujiié, 1976) in the Holocene Japan Sea.
Character of the Upper Water Column during theQuaternary
Cluster analysis separates four distinct groupings of planktonicforaminifers in this data set (Fig. 3, Table 11). Cluster 1 is a coldsubarctic fauna produced during isothermal subarctic conditions,Cluster 2 is a well-preserved subarctic fauna produced by seasonalalternation of isothermal and stratified conditions, Cluster 3 is asubarctic fauna that appears similar to the more-dissolved end mem-ber of Cluster 2, and Cluster 4 is an upwelling(?) fauna.
The succession of clusters up-hole can be interpreted environmen-tally (Fig. 4). The deepest sample at Hole 797B is an unclusteredsample with an assemblage most like that of the present-day transi-tional biogeographic province (Coulbourn et al., 1980). Between 50and 40 mbsf, samples alternate between the cold, subpolar Cluster 1and the seasonal, well-preserved subpolar Cluster 2. Near the
208
JAPAN SEA FORAMINIFERS
Table 7. Cores bearing a low oxygen facies determined by style of bioturbation and by foraminiferassemblage.
Yamato Basin
Occurrences of horizontallyflattened burrows and
laminations
Hole 794B
12R13R14R15R16R17R
20R21R22R24R25R26R
Hole 797C
34X
41X43X44X46X47X48X49 X51X52X2R
5R6R
8R
Occurrences of Cyclammina-Haplophragmoides-
Ammodiscus assemblage
Hole 794B
13R14R
18R
24R25R26R
Hole 797C
33X
35X36X37X
47X48X
5IX52X2R3R
6R7R8R
Japan Basin
Occurrences of horizontally Occurrences of Cyclammina-flattened burrows and Haplophragmoides-
laminations
Hole 796B
11R12R14R15R18R
28R29R30R
32R
Hole 795B
1R2R3R7RLOR11RI2RI3RI4R15R16R17R18R19R
21R22R23R24R25R26R27R28R29R30R3IR32R
Ammodiscus assemblage
Hole 796B
19R28R29R
31R32R
Hole 795B
7R10R11R12R13RI4R15R16R17R18R
20R2IR
23R24R
28R29R30R
Brunhes/Matuyama boundary at 38.40 mbsf, samples alternate be-tween the cold subpolar Cluster 1 and the seasonal, somewhatdissolved Cluster 3. Between 35 and 28 mbsf, approximately 0.57Ma, the surface-water column alternates between the seasonalsubarctic conditions represented by Cluster 2 and upwelling(?)conditions represented by Cluster 4. Above 25 mbsf, conditionsreturn to those seen deeper in the core (between 50 and 40 mbsf) andalternate between the cold, subpolar Cluster 1 and the seasonal,well-preserved subpolar Cluster 2. A similar alternation of these twoclusters is observed in the upper Pleistocene sequence of Hole 794A.
The four assemblages defined by the cluster analysis resemblethe assemblages in latest Pleistocene piston cores from the JapanSea, including the Globigerina bulloides enriched assemblage ofCluster 4 (Ujiié and Ichikura, 1973; Ichikura and Ujiié, 1976; Kato,1984). In contrast, the Olduvai sample of Hole 797B has no latestPleistocene or Holocene analog in the Japan Sea, but resembles thefauna of the modern transitional North Pacific Ocean (Coulbourn etal., 1980).
CONCLUSIONS
1. The abundance of foraminifers, in general, is low at all sites inthe deep Japan and Yamato basins. Preservation, diversity, and abun-dance of the calcareous fauna are best at Site 797 and worst at Site794. The assemblages of agglutinated foraminifers are best developedat Sites 795 and 796 in the Japan Basin.
2. The succession of benthic foraminifers in the Neogene se-quences can be assigned to the zonation of Matsunaga (1963), whereasthe planktonic foraminifers of the Quaternary cannot be assigned tothe zonations of Maiyaet al. (1976) or Lagoe and Thompson (1988).
3. Both the Japan and Yamato basins had subsided to lower middlebathyal depths by the time the first foraminifer-bearing sedimentswere deposited above igneous basement at the three sites wherebasement was drilled.
4. The Miocene cooling of the Japan Basin occurred in the earlymiddle Miocene. The data set does not yield improved resolution ofthe event compared to land-based sequences.
2(W
C. A. BRUNNER
Table 8. Listing of data including total sediment weight, weight of sand-size fraction, percent sand-size material by weight, fraction (split) of sampleexamined for foraminifers, planktonic and benthic foraminifer numbers, benthic/planktonic ratio, coiling ratio of Neogloboquadrina pachyderma, thenumber of planktonic and benthic tests counted, and relative frequency taxa of planktonic foraminifers.
Sample 127-
794A-1H-1,2-4 cm794A-1H-1,62-64794A-1H-1,93-98794A-1H-1, 135-137794A-1H-2, 21-24794A-1H-2.65-67794A-1H-2, 93-98794A-1H-2, 133-136794A-1H-3, 26-28794A-1H-3, 65-67794A-1H-3, 69-70794A-1H-3, 93-98794A-1H-4, 26-31794A-1H-4, 56-58794A-1H-4, 92-94794A-1H-4, 136-138794A-1H-5, 3-5794A-1H-5, 25-27794A-2H-1,22-24794A-2H-1,50-53794A-2H-I.96-98794A-2H-1, 118-120794A-2H-1, 142-144794A-2H-2, 10-12794A-2H-2, 50-52794A-2H-2, 113-116794A-2H-2, 136-138794A-2H-3, 8-11794A-2H-3, 56-58794A-2H-3, 96-98794A-2H-3, 127-129794A-2H-3, 135-138794A-2H-4, 17-20794A-2H-4, 46-49794A-2H-4, 87-89794A-2H-4, 96-98794A-2H-4, 132-135794A-2H-5, 10-12794A-2H-5, 39-42794A-2H-5, 77-79794A-2H-5, 96-98794A-2H-5, 126-128794A-2H-6, 8-10794A-2H-6, 17-20794A-2H-6, 84-87794A-2H-6, 91-93794A-2H-6, 96-98794A-2H-6, 99-102794A-2H-7, 8-10794A-2H-7, 48-50794A-3H-1, 23-25794A-3H-1,65-67794A-3H-1,94-99
Depth(mbsf)
0.020.620.931.351.712.152.432.833.263.653.693.934.765.06•5.425.866.036.257.027.307.767.988.228.408.809.439.669.88
10.3610.7611.0711.1511.4711.7612.1712.2612.6212.9013.1913.5713.7614.0614.3814.4715.1415.2115.2615.2915.8816.2816.5316.9517.24
SandWeight
0.11830.01070.04310.19570.21010.08520.33090.13330.32700.01050.02530.11560.02750.01040.00930.01920.00000.65840.02200.01310.12090.06480.19350.25700.20410.09730.09360.05050.01660.00190.10090.10100.16380.08830.00620.00000.00390.00520.01910.03980.13800.12620.12670.37390.06080.21460.83400.02130.01640.00770.02520.12%1.2430
SedWeight
6.89404.5130
13.241020.473010.27605.6200
13.26308.8800
10.87105.26802.3920
11.446023.0630
7.35906.98607.2040
11.510011.199010.97108.19509.8870
10.845011.496012.840012.32109.6230
11.746010.88408.95809.8430
12.49309.3420
12.151011.81707.92287.35709.33408.29007.11409.21408.3130
10.48548.1140
12.069010.67407.1680
10.98306.82608.41506.63747.66809.7010
21.1400
Sand%
1.720.240.330 . %2.041.522.491.503.010.201.061.010.120.140.130.270.005.880.200.161.220.601.682.001.661.010.800.460.190.020.811.081.350.750.080.000.040.060.270.431.661.201.563.100.572.997.590.310.190.120.331.345.88
Split
1.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00000.00391.00001.00000.00101.00001.00001.00001.00001.00000.0012
PlaNum
00
30000000140000000000000000000000000000000
641642
027770
10000
13836
BenNum
0000000000000000000000000000000000000000000
19100
145700000
394
B/PRat
0000000000080
10000000000
000000000000000000000
3005000003
CoilRat
00
10000
1000000
100100
00
00000000000000000000000000000
9894
092
1000000
99
#Pla
00
4603100
012
480000000000000000000000000000000
302444
0305
50000
351
#Ben
00000
00000040100000000000000000000000000000900
1600000
10
Part.%
00
2400
1000000
5085
0000000000000000000000000000000
9238
05140
0000
67
PacR%
00000000000000000000000000000000000000000002204000001
Bui%
00
740
100000000
1200000000000000000000000000000006
580
1360
0000
14
Umb%
00000000000000000000000000000000000000000000100000000
Qui%
0020000000
5020000000000000000000000000000000010600000
17
Glu%
000000000
1000000000000000000000000000000000000000000000
Min%
00000000000000000000000000000000000000000000000000000
Uvu%
00000000000000000000000000000000000000000000001000000
Par%
0000000000000000000000000000000000000000000000
10000001
Hum%
0000000000000000000000000000000000000000000000
13000000
Ind%
00000000000000000000000000000000000000000000001000000
210
JAPAN SEA FORAMINIFERS
Table 8 (continued).
Sample 127-
794A-3H-1, 117-120794A-3H-2, 19-22794A-3H-2, 65-67794A-3H-2, 119-121794A-3H-3, 5-7794A-3H-3, 46-49794A-3H-3, 119-121794A-3H-4, 24-26794A-3H-4, 51-53794A-3H-4, 94-99794A-3H-4, 119-122794A-3H-5, 31-33794A-3H-5, 65-67794A-3H-5, 93-98794A-3H-5, 116-118794A-3H-6, 25-27794A-3H-6, 56-58794A-3H-6, 94-98794A-3H-6, 117-119794A-3H-7, 24-26794A-3H-7, 33-35794A-3H-7, 54-58794A-4H-1,29-32794 A-4H-1,65-67794A-4H-1,93-99794A-4H-1, 117-119794A-4H-2, 47^9794A-4H-2, 74-77794A-4H-2, 99-105794A-4H-2, 144-146794A-4H-3, 29-31794A-4H-3, 64-67794A-4H-3, 94-100794A-4H-3, 142-144794A-4H-4, 38-41794A-4H-4,47-50794A-4H-4, 90-95794A-4H-4, 132-134794A-4H-5, 12-15794A-4H-5, 46-49794A-4H-5, 118-121794A-4H-6, 17-20794A-4H-6, 92-94794A-4H-6, 95-100794A-4H-6, 99-102794A-4H-7, 32-34794A-4H-7, 40-42794A-5H-1, 15-17794A-5H-1, 80-83794A-5H-1,92-97794A-5H-1, 134-136794A-5H-2, 13-16794A-5H-2, 71-73794A-5H-2, 93-97794A-5H-2, 142-145
Depth(mbsf)
17.4717.9918.4518.9919.3519.7620.4921.0421.3121.7421.9922.6122.9523.2323.4624.0524.3624.7424.9725.5425.6325.8426.0926.4526.7326.9727.7728.0428.2928.7429.0829.4429.7430.2230.6830.7731.2031.6231.9232.2632.9833.4734.2234.2534.2935.1235.2035.4536.1036.2236.6436.9337.5137.7338.22
SandWeight
1.02760.10020.19380.02100.00830.03860.20120.32630.71200.07670.09010.08040.07550.08410.12820.00800.01790.57280.18180.01520.06970.03420.00940.20630.52800.20161.04100.16220.41630.03180.01780.05410.01800.02790.13170.18433.47460.04400.11020.03070.00900.00360.16480.00000.15060.12811.52190.23250.09220.47810.02280.03320.19280.42930.0579
SedWeight
10.887010.146011.41906.84919.1821
12.97805.0730
14.764012.522021.860010.276010.486012.838020.546013.02809.69839.0520
23.402012.91808.03809.8020
18.22407.6150
14.306028.384012.75409.56608.6340
22.446010.28308.22109.1447
17.61909.5600
10.634011.459018.98809.5920
10.95809.19409.04809.42369.3352
22.10007.5660
14.918114.58809.5742
11.141020.8400
8.54308.0790
14.747025.2900
9.1830
Sand%
9.440.991.700.310.090.303.972.215.690.350.880.770.590.410.980.080.202.451.410.190.710.190.121.441.861.58
10.881.881.850.310.220.590.100.291.241.61
18.300.461.010.330.100.041.770.001.990.86
10.432.430.832.290.270.411.311.700.63
Split
0.00201.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00000.15631.00001.00000.00201.00001.00001.00001.00001.00001.00001.00001.0000
PlaNum
22366000000000000000020000000000000000000000000
8900
1127600000000
BenNum
1056000000000000000000000000000000000000000000000
17100000000
B/PRat
500000000000
0000000000000000000000000000000000100000000
CoilRat
9800000000
1000000000
900000000000000000000000000
9000
960000000
#Pla
4870000000060000000
410000000000000000000000000
30600
32900000000
#Ben
23000000000000000000000000000000000000000000000500000000
PacL%
7700000000
1000000000
0000000000000000000000000
6500
9100000000
PacR%
1000000000000000020000000000000000000000000700400000000
Bui9c
180000000000000000
760000000000000000000000000
2600000000000
Umb%
00000000000000000000000000000000000000000001
00000000000
Qui%
1000000000000000000000000000000000000000000000400000000
Glu%
0000000000000000000000000000000000000000000000000000000
Min%
0000000000000000000000000000000000000000000000
000000000
Uvu7c
0000000000000000000000000000000000000000000000000000000
Par%
2000000000000000000000000000000000000000000000000000000
Hum%
0000000000000000000000000000000000000000000000000000000
Ind%
0000000000000000000000000000000000000000000000000000000
211
C. A. BRUNNER
Table 8 (continued).
Sample 127-
794A-5H-3, 27-30794A-5H-3, 66-68794A-5H-3, 93-97794A-5H-3, 135-137794A-5H-4, 8-10794A-5H-4, 22-25794A-5H-4, 54-57794A-5H-4, 92-97794A-5H-5, 93-98794A-5H-6, 93-98794A-6H-1,92-97794A-6H-2, 92-97794A-6H-3, 90-96794A-6H-4, 92-97794A-6H-5, 93-98794A-6H-6, 84-89794A-7H-1,92-96794A-7H-2, 94-96794A-7H-3, 92-96794A-7H-4, 92-96794A-7H-5, 92-96794A-7H-6, 92-96794A-8H-1,93-97794A-8H-2, 93-97794A-8H-3, 93-97794A-8H-4, 93-97794A-8H-5, 93-97794A-8H-6, 94-98794A-9H-1,93-97794A-9H-2, 93-97794A-9H-3, 93-97794A-9H-4, 93-97794A-9H-5, 93-97794A-9H-6, 93-97794A-1 OH-1,93-97794A-10H-2,93-97794A-10H-3,93-97794A-10H^, 93-97794A-10H-5,93-97794A-10H-6,93-97794A-UH-1,92-96794A-1IH-2,92-96794A-11H-3.91-95794A-1IHA 93-97794A-11H-5,93-97794A-11H-6,93-97794A-12H-1,93-97794A-12H-2,93-97794A-12H-3,93-97794A-12H-4,93-97794A-12H-5,93-97794A-12H-6,93-97794A-13H-1,92-97794A-13H-2,92-97794A-13H-3,93-97
Depth(mbsf)
38.5738.9639.2339.6539.8840.0240.3440.7242.2343.7345.7247.2248.7050.2251.7353.1455.2256.7258.2259.7261.2262.7264.7366.2367.7369.2370.7372.2474.2375.7377.2378.7380.2381.7383.7385.2386.7388.2389.7391.2393.2294.7296.2197.7399.23
100.73102.73104.23105.73107.23108.73110.23112.22113.72115.22
SandWeight
0.32200.26130.31700.17020.00420.19340.13600.00790.03810.02050.03640.13920.61920.03750.07590.00000.01020.00690.03780.05050.01970.00930.01970.21960.12840.03540.01740.16010.13920.10290.10900.19550.69520.86200.24330.19190.65800.98420.02891.19830.17950.45210.09140.24310.13750.45700.06450.11820.81370.84300.29030.16720.60590.20700.1849
SedWeight
8.636010.102025.1400
8.01007.20407.3970
13.730017.596018.465017.936015.932024.281017.985017.626016.934025.420124.757027.308020.87400.0000
20.168322.566016.293019.071019.638015.886014.913018.600014.471016.489016.374013.644013.709010.383011.602614.661017.493011.920017.779019.335017.819017.242015.783016.509017.739013.648015.198015.092016.065021.781014.524016.697016.237017.870015.6080
Sand°h
3.732.591.262.120.062.610.990.040.210.110.230.573.440.210.450.000.040.030.18
0.100.040.121.150.650.220.120.860 .%0.620.671.435.078.302.101.313.768.260.166.201.012.620.581.470.783.350.420.785.073.872.001.003.731.161.18
Split
1.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
PlaNuni
00000000(I00000
00000
00000000000000000000000000000000000
BenNum
0000000000000000000
00000000000000000000000000000000000
B/PRat
00000000000000000000000000000000000000000000
00000000000
CoilRat
000000000000
00000
00000000000000000000000000000000000
000
#Pla
000
000000000000000000000000(I000000000000000000000000000
#Ben
000000000
000
00
00000000000000000000000000000000
000000000
PacLIk
00000000000000000
000000000000000000000000(I0000000000
000
PacR%
00000000000000
00000000000000000000000000000000000000000
Bui%
0000000000000000000000000000000000000000000000000000
000
Umb%
0000000000000000000000000000000000000000000000000000000
Qui%
0000000000000
0000000000000000000000000000000000000
00000
Glu%
000000000000000000000000000000000000000000000000
0000000
Min%
00000000
00000000000000000000000000000000000000000000000
Uvu%
000000000000000
000000000000000000000000000000000000
0000
Par9c
0000000000000000000000000000000000000000000000000000000
Hum%
00
0000000000000000000000000000000000
0000000000000000
000
Ind%
0000000000000
000000000000000000000000000000000000000000
212
JAPAN SEA FORAMINIFERS
Table 8 (continued).
Sample 127-
794A-13HA 92-97794A-13H-5, 92-97794A-13H-6, 92-97794A-14H-1, 92-97794A-14H-2, 92-97794A-14H-3,92-97794A-14H4,92-97794A-14H-5,92-97794A-14H-6,92-97797A-1H-1.76-78797A-1H-2, 76-78797A-1H-3, 76-78797A-1H-4, 76-78797A-1H-5, 76-78797B-1H-1,76-78797B-1H-1, 134-136797B-1H-2, 13-15797B-1H-2,44-^6797B-1H-3, 134-136797B-lH^t, 74-76797B-1H-4, 104-106797B-2H-1, 102-104797B-2H-2,76-78797B-2H-3,74-76797B-2H-3, 76-78797B-2H4, 14-16797B-2H-4, 76-78797B-2H-5, 76-78797B-2H-6, 76-78797B-2H-6, 134-136797B-3H-1, 77-79797B-3H-2, 77-79797B-3H-3,77-79797B-3FM, 77-79797B-3H-5,77-79797B-3H-6,77-79797B-3H-6, 103-105797B-3H-6, 135-137797B-3H-7, 14-16797B4H-1,77-79797B4H-2,20-22797B-4H-2,77-79797B^H-3,44-46797B-4H-3,77-79797B-*H-3, 102-104797B-4H-3, 135-137797B4H^, 13-15797B4HA 77-79797B4HA 102-104797B-4H-4, 135-137797B4H-5,43-45797B4H-5,74-76797B-4H-6,77-79797B-4H-6, 135-137797B-5H-1,78-80
Depth(mbsf)
116.72118.22119.72121.72123.22124.72126.22127.72129.22
4.165.667.168.66
10.160.761.341.631.944.345.245.546.928.169.649.66
10.5411.1612.6614.1614.7416.1717.6719.1720.6722.1723.6723.9324.2524.5425.6726.6027.1728.3428.6728.9229.2529.5330.1730.4230.7531.3331.6433.1733.7535.18
SandWeight
0.05860.44590.02240.08560.06740.08060.29950.06110.19910.00000.23840.05310.0109O.i 1920.08350.04120.02090.01010.00960.02400.02800.11460.00000.25440.38850.03580.09170.01060.40810.11010.08910.03870.13500.03500.17020.09990.00930.13710.07990.03270.00270.04390.03530.05710.08380.80970.00930.06610.07210.25880.11240.01930.03000.03190.0927
SedWeight
16.600019.142026.290023.748036.802021.660923.890917.169120.96939.48995.48907.45734.99824.51668.61603.36951.27481.66003.06124.82293.12922.77195.47834.56867.26542.35509.39265.92518.57112.0578
10.36197.22587.18006.10817.12587.54713.82483.55523.74235.46822.88184.98040.76674.95493.25823.23703.16898.19562.30061.77631.64165.75123.39543.39559.5903
Sand%
0.352.330.090.360.180.371.250.360.950.004.340.710.222.640.971.221.640.610.310.500.894.130.005.575.351.520.980.184.765.350.860.541.880.572.391.320.243.862.140.600.090.884.601.152.57
25.010.290.813.13
14.576.850.340.880.940.97
Split
1.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00000.25001.00001.00001.00001.00000.12501.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00000.01560.01561.00001.00001.00001.00001.00000.03130.04691.00001.00000.07810.00780.02341.00001.00000.06251.0000
PlaNum
000000000440000
731174
0II0
35877
0000000
1550200000
125858428
000
5054
33441943
110
1864324078304
0
02837
9
BenNum
0000000000000000
69000
1135
000000000000000
1081593
000
380
125519823
0189144234
00
190
B/PRat
00000000004000
006000
2440000000000000001
16000
430
279
6809030010
CoilRat
000000000
10086
0000
9196
091
09898
0000000
980
2000000
9795
000
80755698
1000
809898
0
09693
#Pla
000000000
38220000
245374
033
0108304
0000000
3190
13
00000
698492
00
038
268341295
350
335449319
20
60283
#Ben
0000000000100001
22000
34120000000000000006
93000
290
1283073
034
290040
PacL%
000000000
7186
0000
6991
064
09771
0000000
8308
00000
7732000
1111
74100
06
7275
00
82
PacR%
0000000000
1400007306021000000020
3100000220003011001120044
Bui%
000000000
2900000
2410
3001
28000000000
5400000
120000
219980
800
872120
10003
45
Umb%
0000000000000000000000000000000000000000000000002100000
Qui''-/<
000000000000000010000000000001080000057000
500
16160033100
110
Glu%
0000000000000000100000000000000000000040000000000000000
Min%
00000000000000000000000000000000000000100000
00o•00000
000
Uvu%
000000000000000020000000000004000000000000
1601100010000
0
Par%
00000000000000001000000000000
1000000003
520000011000100
000
Hum%
0000000000000000000000000000000000000000000000000000000
Ind%
0000000000000000000000000000000000000120000000000020000
213
C. A. BRUNNER
Table 8 (continued).
Sample 127-
797B-5H-1, 132-134797B-5H-2,44-46797B-5H-2, 78-80797B-5H-2, 103-105797B-5H-3, 78-80797B-5H^, 43-45797B-5H^, 74-76797B-5H-4, 78-80797B-5H-5, 11-13797B-5H-5,43-45797B-5H-5, 74-76797B-5H-5, 78-80797B-5H-5, 131-133797B-5H-6, 14-16797B-5H-6,78-80797B-5H-6, 102-104797B-5H-7, 14-16797B-5H-7, 43-45797B-6H-1,78-80797B-6H-1, 132-134797B-6H-2, 74-76797B-6H-2, 78-80797B-6H-2, 102-104797B-6H-3, 13-15797B-6H-3, 74-76797B-6H-3, 78-80797B-6H-3, 102-104797B-6H^t, 78-80797B-6H-5, 78-80797B-6H-6, 78-80797B-7H-1, 78-80797B-7H-2, 78-80797B-7H-3, 78-80797B-7H-4, 78-80797B-7H-5, 78-80797B-7H-6, 78-80797B-8H-1, 78-80797B-8H-2, 78-80797B-8H-3, 78-80797B-8HA 77-79797B-8H-5,77-79797B-8H-6, 78-80797B-9H-1, 78-80797B-9H-2, 78-80797B-9H-3, 78-80797B-9H-4,78-80797B-9H-5, 78-80797B-9H-6, 78-80797B-10H-1, 78-80797B-10H-2, 78-80797B-10H-3, 78-80797B-10H-4, 78-80797B-10H-5, 78-80797B-10H-6, 78-80797B-11H-1, 78-80
Depth(mbsf)
35.7236.3436.6836.9338.1839.3339.6439.6840.5140.8341.1441.1841.7142.0442.6842.9243.5443.8344.6845.2246.1446.1846.4247.0347.6447.6847.9249.1850.6852.1854.1855.6857.1858.6860.1861.6863.6865.1866.6868.1769.6771.1873.1874.6876.1877.6879.1880.6882.6884.1885.6887.1888.6890.1892.18
SandWeight
0.06660.09660.29930.O4030.02980.03660.03091.58500.02140.03300.02847.10450.03%0.15870.21030.21360.05530.07250.06140.15040.04270.15050.09180.00870.25870.07460.10020.07250.34090.26060.19970.05240.09140.05030.03280.04820.05660.04050.00370.01500.01720.00990.19710.11700.19120.05440.00910.01990.02760.05190.01310.02840.11550.06970.0981
Sed
Weight
3.90712.42838.84243.02096.25124.24213.8578
10.86502.73292.84483.50869.75982.70383.2753
13.78002.66032.66703.59386.69453.26904.26807.44284.71402.99102.89607.80282.91100.98046.18347.5699
12.95157.07579.88328.8535
11.572710.45098.97619.89365.96827.44285.64976.67638.0221
15.872410.33067.27959.70218.9368
10.040613.41389.11358.5812
15.43008.89988.0499
Sand
1.703.983.381.330.480.860.80
14.590.781.160.81
72.791.464.851.538.032.072.020.924.601.002.021.950.298.930.963.447.395.513.441.540.740.920.570.280.460.630.410.060.200.300.152.460.741.850.750.090.220.270.390.140.330.750.781.22
Split
0.09381.00001.00001.00001.00001.00001.00000.00200.50001.00001.00001.00000.04691.00001.00000.01561.00000.06251.00000.12500.12500.02340.12501.00000.03130.06250.02341.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00000.12501.00001.00001.00001.00001.0000
Pla
Num
881
0
0
113
0
0
61
17073544
51
0
0
26890
0
100480
14290
110
609
2107608
0
3961687
51970
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
361
0
0
0
0
0
Ben
Num
134
0
0
19
0
0
1
46
50
73
0
0
197
0
0
13490
31
0
5
6
17
15
0
177
14
132
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
B/P
Rat
13
0
0
14
0
0
1
0
8
59
0
0
7
0
0
12
0
2
0
4
1
1
2
0
4
2
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
CoilRat
98
0
0
87
0
0
98
97
98
100
0
0
81
0
0
96
0
87
0
100
90
94
92
0
80
85
91
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
63
0
0
0
0
0
#
Pla
323
0
0
340
0
0
237
371
744
144
0
0
341
0
0
417
0
321
0
45
325
367
358
0
359
335
354
00
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0606
0
0
0
0
0
#
Ben
49
0
0
56
0
0
2
1
68
209
0
0
25
0
0
56
0
7
0
2
3
3
9
0
16
79
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
2
0
0
0
0
n
PacL%
46
0
0
43
0
0
95
56
87
98
0
0
70
0
0
71
0
56
0
73
70
90
82
0
62
84
87
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
23
0
0
0
0
0
PacR%
1
0
0
6
0
0
2
2
2
0
0
0
16
0
0
3
0
8
0
0
8
6
8
0
16
14
9
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
13
0
0
0
0
0
Bui
%
49
0
0
48
0
0
3
41
4
1
0
0
9
0
0
4
0
20
0
0
0
1
1
0
15
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
27
0
0
0
0
0
Umb
%
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
8
0
13
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Qui
%
0
0
0
3
0
0
0
1
6
1
0
0
3
0
0
15
0
7
0
0
10
1
3
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
24
0
0
0
0
0
Glu
%
0
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Min
%
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
10
0
0
0
0
Uvu
%
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
0
0
0
0
0
Par
%
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
7
0
0
0
0
0
Hum
%
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
00
0
0
0
000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
000
0
0
0
00
0
Iπd
%
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
13
12
2
7
0
7
1
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
1
0
0
0
0
0
214
Table 8 (continued).
JAPAN SEA FORAMINIFERS
Sample 127-
797B-1IH-2, 78-80797B-IIH-3, 78-80797B-1IH-4, 78-80797B-1IH-5. 78-80797B-I1H-6. 78-80797B-12H-1,78-80797B-12H-2, 78-80797B-12H-3, 78-80797B-12H-4, 78-80797B-I2H-5, 78-80797B-12H-6, 78-80797B-13H-1,78-80797B-13H-2, 78-80797B-13H-3, 78-80797B-I3H-4, 78-80797B-13H-5, 78-80797B-13H-6, 78-80797B-I4H-1,78-80797B-14H-2, 78-80797B-14H-3, 78-80797B-14H-4, 78-80797B-14H-5, 78-80797B-15H-1,79-81797B-15H-2, 79-81797B-15H-3, 79-81797B-15H-4, 80-82797B-15H-5, 79-81797B-15H-6, 79-81797B-16H-1,80-82797B-I6H-2, 80-82797B-16H-3, 80-82797B-16H-4, 80-82797B-16H-5, 77-79797B-16H-6, 79-81797B-17H-1,79-81797B-17H-3, 40-42797B-17H-4, 79-81797B-17H-5, 79-81797B-17H-6, 79-81797B-17H-7, 79-81797B-18H-1,80-82797B-I8H-2, 80-82797B-18H-3, 70-72797B-18H-4, 80-82797B-18H-5, 80-82797B-18H-6, 60-62797B-19H-1,79-81797B-19H-2, 79-81797B-19H-3, 79-81797B-19H-4, 79-81797B-19H-5, 79-81797B-19H-6, 79-81
Depth(mbsf)
93.6895.1896.6898.1899.68
101.68103.18104.68106.18107.68109.18111.18112.68114.18115.68117.18118.68120.68122.18123.68125.18126.68130.19131.69133.19134.70136.19137.69139.70141.20142.70144.20145.67147.19149.19150.60151.56153.06154.56156.06158.70160.20161.60163.20164.70166.00167.19168.69170.19171.69173.19174.69
SandWeight
0.09350.06200.05400.09840.17420.25590.00620.03260.06350.09980.08240.00000.09530.25980.28880.15330.18930.14390.16230.09010.07420.22460.10080.03590.02300.03400.05%0.06660.49780.05770.14560.12950.09220.10050.09350.06540.03360.14%0.03450.15300.08630.16110.23100.25060.11720.13600.33180.08020.12040.17430.14520.1300
SedWeight
9.66817.52638.30248.56258.52087.74306.41326.64607.66486.37146.00836.66508.96049.91608.59177.83828.32267.62486.99186.85966.15737.40315.20814.62885.38325.27894.40175.11326.72178.00138.80908.3125
11.78568.10147.43315.81694.35327.35176.19627.64297.36546.69407.46628.66537.37985.57496.53837.61726.94547.13948.04608.3638
Sand%
0.970.820.651.152.043.300.100.490.831.571.370.001.062.623.361.962.271.892.321.311.213.031.940.780.430.641.351.307.410.721.651.560.781.241.261.120.772.030.562.001.172.413.092.891.592.445.071.051.732.441.801.55
Split
1.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.00001.0000
PlaNum
0000000000000000000000000000000000000000000000000000
BenNum
000(I000000000000000000000000000000000000000000000000
B/PRat
0000000000000000000000000000000000000000000000000000
CoilRat
0000000000000000000000000000000000000000000000000000
#Pla
0000000000000000000000000000000000000000000000000000
#Ben
0000000000000000000000000000000000000000000000000000
PacL*
0000000000000000000000000000000000000000000000000000
PacR%
000000000000000000000(I000000000000000000000000000000
Bui%
0000000000000000000000000000000000000000000000000000
Umb%
0000000000000000000000000000000000000000000000000000
Quic/c
0000000000000000000000000000000000000000000000000000
Glu%
0000000000000000000000000000000000000000000000000000
Min%
0000000000000000000000000000000000000000000000000000
Uvu%
0000000000000000000000000000000000000000000000000000
Par%
0000000000000000000000000000000000000000000000000000
Hum%
0000000000000000000000000000000000000000000000000000
Ind%
0000000000000000000000000000000000000000000000000000
Sand weightSed weightSand "ftSplitPla numBen numB/P RatCoil Rat#Pla#BenPACL%PACR %BUL%UMB%QUI%GLU%MIN%UVU%PAR%HUM%IND%
weight of >63-µm fractionweight of the total, dry sediment sample
percent by weight of the >63-µm fractionfraction of the sample counted for foraminifersnumber of planktonic foraminifer tests per gram of sedimentnumber of benthonic foraminiferal tests per gram of sedimentratio: 100 × (planktonic)/(planktonic + benthic foraminifers)ratio: lOO× (sinistral Nq. pachydermala W Nq. pαchxdermα)number of planktonic foraminifers countednumber of benthic foraminifers countedrelative frequency of sinistral Neogloboquadrina pachyderma in planktonic foraminiferal assemblage
ve frequency of dextral Neogloboquadrina pachyderma in planktonic foraminifer assemblageve frequency of Globigerina bulloides in planktonic foraminifer assemblageve frequency of Globigerina umbilicata in planktonic foraminifer assemblageve frequency of Globigerina quinqueloba in planktonic foraminifer assemblageve frequency of Globigerinita glutinata in planktonic foraminifer assemblageve frequency of Globigerinita minuta in planktonic foraminifer assemblageve frequency of Globigerinita uvula in planktonic foraminifer assemblageve frequency of Tenuitella parkerae in planktonic foraminifer assemblage
relative frequency of Turborotalita humilis in planktonic foraminifer assemblagerelative frequency of indeterminate tests in planktonic foraminifer assemblage
215
C. A. BRUNNER
Table 9. Constituents of sand-size fraction.
Sample 127-
794A-2H-6, 17-20 cm794A-2H-6, 84-87794A-2H-6, 96-98794 A-3H-1,94-99794A-3H-1, 117-120794A-4H-6, 95-100794A-4H-7, 40-42797B-1H-1, 134-136797B-1H-2, 13-15797B-2H-1, 102-104797B-2H-6, 134-136797B-3H-6, 135-137797B-3H-7, 14-16797B-4H-3,44-^6797B-4H-3, 77-79797B-4H-3, 102-104797B-4H-3, 135-137797B-4H-4, 102-104*797B-4H-4, 135-137797B-4H-5, 4 3 ^ 5797B-4H-6, 135-137797B-5H-1, 132-134797B-5H-2, 103-105*797B-5H-4, 74-76797B-5H-4, 78-80797B-5H-5, 11-13*797B-5H-5, 4 3 ^ 5797B-5H-5, 131-133797B-5H-6, 102-104*797B-5H-7, 43-45797B-6H-1, 132-134797B-6H-2, 74-76797B-6H-2, 78-80797B-6H-2, 102-104797B-6H-3, 74-76797B-6H-3, 78-80797B-6H-3, 102-104797B-10H-2, 78-80
Depth(mbsf)
14.4715.1415.2617.2417.4734.2535.20
1.341.636.92
14.7424.2524.5428.3428.6728.9229.2530.4230.7531.3333.7535.7236.9339.6439.6840.5140.8341.7142.9243.8345.2246.1446.1846.4247.6447.6847.9284.18
Sand(%)
3.100.577.595.889.44
10.431.221.644.135.353.862.144.601.152.57
25.013.13
14.576.850.941.701.330.80
14.590.781.161.468.032.024.601.002.021.958.930.963.440.39
Plank.foram.number
(#/g)
641642
277701383622366
8911276
731174877155
125858428
5054
334419431864
3240783042837
88111361
17073544
512689
100481429
110609
2107608
3961687
5197361
Major constituent
ForaminifersMinerals
ForaminifersForaminifersForaminifers
GypsumForaminifers
PyriteForaminifersForaminifers
PumiceForaminifersForaminifers
PumiceAnhydrite
ForaminifersPyrite
ForaminifersForaminifersForaminifersForaminifersForaminifers
MineralsMinerals
ForaminifersMinerals
AshForaminifersForaminifersForaminifers
SpiculesForaminifersForaminifersForaminifersForaminifersForaminifersForaminifersForaminifers
Minor constituent-1
MineralsLithic fragments
AnhydriteGypsum
AnhydritePyrite
MineralsMinerals
PyritePyrite
Spicules
Foraminifers
ForaminifersPyrite
Pyrite
PyritePyrite
AnhydriteForaminifers
Radiolarians and Diatoms
SpiculesPyritePyritePyritePyrite
PyriteRadiolarians and Diatoms
PyritePyrite
Minor constituent-2
ForaminifersAnhydrite
RadiolariansRadiolarians
Radiolarians and Diatoms
MineralsForaminifers
SpiculesForaminifers
OrganicsMinerals
MineralsMinerals
MineralsMineralsMinerals
<=thin, foraminifer-rich layer
5. Deep waters of the nascent and mature backarc basin werepoorly oxygenated throughout most of the Miocene sequences. Oxy-genation improved in the uppermost Miocene and continued throughthe Pliocene.
6. The Quaternary assemblage of benthic foraminifers appearsshallower than the basins they were cored from, based on depth rangesof selected foraminifers. The anomalous assemblage was introducedinto the basin near the base of the Pleistocene and persists to thepresent day.
7. Quaternary planktonic assemblages are similar to assemblagesknown from the latest Pleistocene of the Japan Sea, whereas theOlduvai assemblage is similar to present-day faunas of the transitionalNorth Pacific Ocean.
ACKNOWLEDGMENTS
Yasumochi Matoba and Michio Kato deserve special thanks fortheir help and advice concerning identification of benthic foramini-fers and assistance in collection of comparative material from the OgaPeninsula. Ryuji Tada generously provided key samples at Sites 794and 797. Jim Ingle and Tara Kheradyar helped in many useful discus-sions of the data as did Itaru Koizumi, Atiur Rahman, Lisa White,Joanne Alexandrovich, and all my colleagues on board Leg 127. Thereviews by Peter Thompson and Kristin McDougall are greatly ap-preciated as are the editorial comments of John Barron. This researchwas supported by JOI.
REFERENCES
Asano, K., 1950-1951. Illustrated Catalogue of Japanese Tertiary SmallerForaminifera (Parts 1-15): Tokyo (Hosokawa Printing Co.).
Asano, K., Ingle, J. C , Jr., and Takayanagi, Y., 1969. Neogene planktonicforaminiferal sequence in northern Honshu. In Brönniman, R. P., and Renz, H.(Eds.), Proc, lstlnt. Conf. PlanktonicMicrofossils: Leiden (E. J. Brill), 1:14-25.
Berggren, W. A., Kent, D. V., and Van Couvering, J. A., 1985. The Neogene: Part 2.Neogene geochronology and chronostratigraphy. In Snelling, N. J. (Ed.), TheChronology of the Geological Record. Geol. Soc. London Mem., 10:211-260.
Burckle, L. H., and Todd, A., 1976. Correlation of Late Neogene sections ofthe Noto and Oga peninsulas, Japan. In Takayanagi, U., and Saito, T. (Eds.),Progress in Micropaleontology: New York (Micropaleontology Press), 20-26.
Chinzei, K., 1986. Opening of the Japan Sea and marine biogeography duringthe Miocene. J. Geomagn. Geoelectr., 38:487^194.
Coulbourn, W. T., Parker, F. L., and Berger, W. H., 1980. Faunal and solutionpatterns of planktonic foraminifera in surface sediments of the NorthPacific. Mar. Micropaleontol., 5:329-399.
Culver, S. J., and Buzas, M. A., 1986. Distribution of Recent benthic forami-nifera off the North American Pacific coast from California to Baja.Smithsonian Contrib. Mar. Sci., 28:1-634.
Guber, A. L., and Merrill, S., Ill, 1983. Paleobathymetric significance of theforaminifera from the Hokuroku District. Econ. Geol. Monogr., 5:55-70.
Ichikura, M., and Ujiié, H., 1976. Lithology and planktonic foraminifera of theSea of Japan piston cores. Bull. Nat. Sci. Mus., Sen C (Geol.), 2:151-178.
Ingle, J. C , Jr., 1975. Pleistocene and Pliocene foraminifera from the Sea ofJapan, Leg 31, Deep Sea Drilling Project. In Karig, D. E., Ingle, J. C , Jr.,et al., Init. Repts. DSDP, 31: Washington (U.S. Govt. Printing Office),693-701.
216
JAPAN SEA FORAMINIFERS
Ingle, J. C, Jr., and Keller, G., 1980. Benthic foraminiferal biofacies of theeastern Pacific margin between 40°S and 32°N. In Quaternary Deposi-tional Environments of the Pacific Coast. Paleogeogr. Symp. 4, PacificSect., Soc. Econ. Paleontol. Mineral., 341-355.
Ingle, J. C, Jr., Keller, G., and Kolpack, R. L., 1980. Benthic foraminiferalbiofacies, sediments and water masses of the southern Peru-Chile Trencharea, southeastern Pacific Ocean. Micropaleontology, 26:113-150.
Kato, M., 1984. Foraminifera: analysis of the piston core, KH-79-3, C-3.Gekkan Chikyu, 6:529-537.
, 1989. Benthic foraminifers from the Japan Sea piston cores. InTakayanagi, Y., and Ishizaki, K. (Eds.), Collected Papers on Foraminiferafrom the Japanese Islands: Sendai, Japan, 111-116.
Keller, G., 1980. Benthic foraminifers and paleobathymetry ofthe Japan Trench area,Leg 57, Deep Sea Drilling Project. In von Huene, R., Nasu, N., et al., Init. Repts.DSDP, 56,57 (Pt. 2): Washington (U.S. Govt. Printing Office), 835-865.
Kennett, J. P., and Srinivasan, M. S., 1983. Neogene Planktonic Foraminifera:Stroudsburg, PA (Hutchinson Ross).
Kurihara, K., 1976. Correlation of Neogene formations between the Japan Seaand the Pacific coast regions of Japan, by benthonic foraminifera. Rev. Esp.Micropaleontol., 9:307-315.
Lagoe, M. B., and Thompson, P. R., 1988. Chronostratigraphic significance ofLate Cenozoic planktonic foraminifera from the Ventura Basin, California:potential for improving tectonic and depositional interpretation. J. Forami-niferal. Res., 18:250-266.
Maiya, S., Saito, T, and Sato, T, 1976. Late Cenozoic planktonic foraminiferalbiostratigraphy of northwest Pacific sedimentary sequences. In Takay-anagi, Y., and Saito, T. (Eds.), Progress in Micropaleontology: New York(Micropaleontology Press), 395-422.
Matoba, Y, 1977. Recent foraminiferal assemblages off Sendai, northeastern Japan.In Schafer, C. T, and Pelletier, B. R. (Eds.), First Int. Symp, on BenthonicForaminifera of Continental Margins, Maritime Sediments, 205-220.
, 1984. Paleoenvironment ofthe Sea of Japan. In Oertli, J. J. (Ed.), Benthos'83: Proc. 2nd Int. Symp. Benthic Foraminifera (Pau, April 1983), 409-414.
Matoba, Y, Tomizawa, A., Maruyama, T, Shiraishi,T., Aita, Y, and Okamoto,K., 1990. Neogene and Quaternary sedimentary sequences in the Oga Pen-insula. Benthos '90, Proc. 4th Int. Symp. Benthic Foraminifera, Sendai,Japan, Guidebook for Field Trip No. 2: B1-B62 with 12 plates appended.
Matsunaga, T, 1963. Benthonic smaller foraminifera from the oil fields of NorthernJapan. Sci. Rep. Tohoku Univ., Ser. 2, 35:67-122 and 52 plates.
Oda, M., 1986. Some aspects and problems concerned with microfossilbiochronology for the Neogene in Central and Northeast Honshu, Japan.In Nakagawa, H., Kotaka, T, and Takayanagi, Y (Eds.), The Essays onGeology of Professor N. Kitamura: Sendai (Sasaki Print Co.), 195-211.
Reynolds, L., and Thunell, R. C , 1986. Seasonal production and morphologicvariation of Neogloboquadrina pachyderma (Ehrenberg) in the northeastPacific. Micropaleontology, 32:1-18.
Saito, T., 1963. Miocene planktonic foraminifera from Honshu, Japan. 5c/.Rep. Tohoko Univ., Ser. 2, 35:123-209.
Saito, T, and Maiya, S., 1973. Planktonic foraminifera ofthe Nishikurosawa Forma-tion, northeast Honshu, Japan. Trans. Proc. Paleontol. Soc. Jpn., 91:113-125.
Sautter, L. R., and Thunell, R. C, 1989. Seasonal succession of planktonic forami-nifera: results from a four-year time-series sediment trap experiment in thenortheast Pacific. J. Foraminiferal Res., 19:253-267.
, 1991. Planktonic foraminiferal response to upwelling and seasonalhydrographic conditions: sediment trap results from San Pedro Basin,Southern California Bight. J. Foraminiferal Res., 21:347-363.
Tamaki, K., Pisciotto, K., Allan, J., et al., 1990. Proc. ODP, Init. Repts., 127:College Station, TX (Ocean Drilling Program).
Thompson, P. R., 1980. Foraminifers from Deep Sea Drilling Project Sites434, 435, and 436, Japan Trench. In von Huene, R., Nasu, N., et al., Init.Repts. DSDP, 56, 57 (Pt. 2): Washington (U.S. Govt. Printing Office),775-808.
Tsuchi, R., and IGCP-114 National Working Group of Japan, 1984. Neogenechronostratigraphy and bio-events in the Japanese Islands. Paleogeogr.,Paleoclimatol, Paleoecol, 46:38-51.
Ujiié, H., and Ichikura, M., 1973. Holocene to uppermost Pleistocene plank-tonic foraminifers in a piston core from off San'in District, Sea of Japan.Trans. Proc. Palaeontol. Soc. Jpn., 91:137-150.
Date of initial receipt: 18 March 1991Date of acceptance: 5 December 1991Ms 127/128B-124
217
C. A. BRUNNER
Depth 0(mbsf)
80
Site 794
90 100 60 70 80
Site 797
I ' ' I ' ' ' ' ' " ' ' I é ' ' ' ' ',' ' '.
90 100
Coiling Ratio of Sinistral Neogloboquadrina pachyderma (%)
Figure 2. The coiling ratio of Neogloboquadrina pachyderma (sinistral forms/total number of Neogloboquadrina pachyderma in sample) plotted withdepth at Holes 794A and 797B. All samples that plot on the y axis are barren or have fewer than 20 specimens of the species. The two lines connectingthe graphs denote the Brunhes/Matuyama boundary and the top of the Olduvai.
218
JAPAN SEA FORAMINIFERS
Table 10. Coiling ratio of Neogloboquadrina pachy-derma with number of tests of sinistral and dextralforms counted to calculate the ratio.
Sample 127-Depth(mbsf) PacL PacR
794A-1H-3, 93-98 cm794A-2H-6, 17-20794A-2H-6, 84-87794A-2H-6, 96-98794A-3H-1,94-99794A-3H-1,117-120794A-4H-6, 95-100794A-4H-7, 40-42797 A-1H-1,76-78797A-1H-2.76-78797B-1H-1, 134-136797B-1H-2, 13-15797B-1H-3, 134-136797B-1H-4, 104-106797B-2H-1, 102-104797B-2H-6, 134-136797B-3H-6, 135-137797B-3H-7, 14-16797B-4H-3, 135-137797B-4H-4, 13-15797B-4H-4, 102-104797B-4H-4, 135-137797B-4H-5, 43-45797B-4H-6, 135-137797B-5H-1,78-80797B-5H-1, 132-134797B-5H-2, 103-105797B-5H-4, 74-76797B-5H-4,78-80797B-5H-5, 11-13797B-5H-5, 4 3 ^ 5797B-5H-5, 131-133797B-5H-6, 102-104797B-5H-7,43^15797B-6H-1, 132-134797B-6H-2, 74-76797B-6H-2, 78-80797B-6H-2, 102-104797B-6H-3, 74-76797B-6H-3, 78-80797B-6H-3, 102-104797B-10H-2, 78-80
Coil
3.9314.4715.1415.2617.2417.4734.2535.204.165.661.341.634.345.546.9214.7424.2524.5429.2529.5330.4230.7531.3333.7535.1835.7236.9339.6439.6840.5140.8341.7142.9243.8345.2246.1446.1846.4247.6447.6847.9284.18
4127161562323712003012719169339211052162645261402163519
320240487431481462252086481412382681813322633029222128130889
05113262114031713224615740366223321461403392602522275648310
10098949299989096100869196919898989795981008098989693988798979810081968710090949280859163
PacL-number of tests of sinistral Neogloboquadrina pachy-derma counted
PacR-number of tests of dextral Neogloboquadrina pachy der-ma counted
Coil-ratio of sinistral to total number of specimens of Neoglo-boquadrina pachyderma
219
C. A. BRUNNER
EUCLIDEAN DISTANCE COEFFICIENT
EUCLIDEAN DISTANCE COEFFICIENT
Figure 3. Dendrogram of Q-mode analysis of all samples with 100 or morespecimens of planktonic foraminifers.
220
JAPAN SEA FORAMINIFERS
Table 11. Relative frequencies of planktonic foraminifers in samples arranged by cluster.
Sample 127-
Cluster 1794A-2H-6, 17-20 cm794A-4H-7, 40-42797B-1H-2, 13-15797B-1H-4, 104-106797B-2H-6, 134-136797B-5H-4, 74-76797B-5H-5, 11-13797B-5H-5, 4 3 ^ 5797B-6H-2, 78-80797B-6H-2, 102-104797B-6H-3, 78-80797B-6H-3, 102-104
Cluster 2
Subgroup a794A-3H-1,94-99797B-4H-3, 135-137797B-4H-6, 135-137797B-5H-6, 102-104797B-6H-2, 74-76
Subgroup b794A-3H-1,117-120794A-4H-6, 95-100797B-1H-1, 134-136797B-2H-1, 102-104797B-3H-6, 135-137797B-4H-4, 135-137797B-4H-5, 4 3 ^ 5
Subgroup c797B-5H-5, 131-133797B-5H-7, 4 3 ^ 5797B-6H-3, 74-76
Cluster 3794A-2H-6, 84-87797B-5H-1, 132-134797B-5H-2, 103-105797B-5H-4, 78-80
Cluster 4797B-4H-3, 77-79797B-4H-3, 102-104797B-4H-4, 102-104
Unclusterd samples794A-2H-6, 96-98797B-3H-7, 14-16797B-10H-2, 78-80
Depth(mbsf)
14.4735.20
1.635.54
14.7439.6440.5140.8346.1846.4247.6847.92
17.2429.2533.7542.9246.14
17.4734.25
1.346.92
24.2530.7531.33
41.7143.8347.64
15.1435.7236.9339.68
28.6728.9230.42
15.2624.5484.18
Col
11
m1
m1
1/d1m
m/dm
1/m
1dmmm
1dmdmm1
11/dd
11/m1/md
d1
1/d
dmm
PacL
929191978395879890828487
6774827170
77656971777275
705662
38464356
116
513223
PacR
2432222068
149
11438
1771212
168
16
2162
011
42
13
Bui
601103411100
148340
18262428122120
92015
58494841
998087
130
27
Umb
000000000000
00000
0100010
080
1400
002
000
Qui
041010611310
1716111510
1000531
370
1031
0163
67
24
Glu
001000000000
00000
0000000
000
0000
000
040
Min
000000000000
00000
0000000
000
0000
000
011
Uvu
002040010(J00
01020
0000010
100
0000
010
104
Par
0010
100000000
11030
2000310
100
0000
010
1052
7
Hum
000000000000
00000
0000000
000
0000
000
1300
Oth
000000002714
0001
12
0000102
107
0000
000
121
Col sediment colorPacL sinistral Neogloboquadrina pachydermaPacR dextral Neogloboquadrina pachydermaBui Globigerina bulloidesUmb Globigerina umbilicataQui Globigerina quinquelobaGlu Globigerinita glutinataMin Globigerinita minutaUvu Globigerinita uvulaPar Tenuitella parkeraeHum Turborotalita humilisOth other planktonic foraminiferal speciesd dark chocolate brown sedimentm medium brown sediment1 light putty gray sediment
221
C. A. BRUNNER
Table 12. Correlation of diatom and foraminifer zones.
A. Site 794
Table 12 (continued).
B. Site 795
Site 794Sample
A-1H-CCA-2H-CCA-3H-2, 94-99A-3H-CCA-4H-5, 90-95A-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-32X-CCA-33X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCB-7R-CCB-8R-CCB-9R-CCB-10R-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-2, 8-9
Diatom andNannofossil
Zones
Neodenticulaseminae
Rhizosoleniacurvirostris
?
Neodenticulakoizumii
,M koizumii,-N. kamtschatica
Thalassiosira
oestrupii
Neodenticulakamtschatica
Rouxiacalifornica
Thalassionemaschraderi
Denticulopsis —katayamae
— Discoasterhamatus
™ SphenolithusA heteromorphis<
ForaminiferZone
7
Miliamminaechigoensis
• Opal-A/Opal-CT ••
Spirosigmoilinellacompressa
Globorotalia cf.G. fohsi
Epoch
Quaternary
Pliocene
lateMiocene
••••••••••••••
middleMiocene
Site 795Sample
A-1H-CCA-2H-CC
A-3H-CCA-4H-CCA-5H-CCA-6H-CCA-7H-CCA-8H-CCA-9H-CCA-10H-CCA-11H-CCA-12H-CCA-13H-CCA-14H-CCA-15H-CCA-16H-CCA-17H-CCA-18H-CCA-19H-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CCA-28X-CCA-29X-CCA-30X-CCA-31X-CCA-34X-CCA-35X-CCA-36X-CCA-37X-CCA-38X-CCA-39X-CCB-1R-CCB-2R-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-8R-CCB-9R-CCB-1OR-CCB-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-21R-CCB-22R-CCB-23R-CCB-24R-CCB-25R-CCB-26R-CCB-27R-CCB-28R-CCB-29R-CCB-3OR-CCB-31R-CC
Diatom Zone
Neodenticulaseminae
Rhizosolenia
curvirostris
Actinocyclusoculatus
Neodenticulakoizumii
Neodenticulakoizumii-
Neodenticulakamtschatica
Thalassiosiraoestrupii
• Opal-A/Opal-CT ••
Neodenticula^ kamtschatica
^ Denticulopsisdimorpha
Denticulopsispraedimorpha
^ Denticulopsispraedimorpha
Denticulopsispraedimorpha
A Denticulopsispraedimorpha
M l
•^ Denticulopsishustedtii
ForaminiferalZone
7
Miliamminaechigoensis
Spirosigmoilinellacompressa
Epoch
Quaternary
Pliocene
lateMiocene
middleMiocene
222
JAPAN SEA FORAMINIFERS
Table 12 (continued). Table 12 (continued).
C. Site 796 D. Site 797
Site 796ASample
A-1H-CCA-2H-CCA-3H-CC
A-4H-CCA-5H-CCA-6H-CCA-8H-CCA-9X-CCA-10X-CCA-11X-CCA-12X-CCA-14X-CCA-15X-CCA-16X-CCA-17X-CCA-18X-CCA-19X-CCA-20X-CCA-21X-CCA-22X-CCA-23X-CCA-24X-CCA-25X-CCA-26X-CCA-27X-CC
Diatom Zone
Neodenticula
seminae
Rhizosolenia
curvirostris—Actinocyclus—
oculπtuiNeodenticula
koizumii
N. koizumii-N. kamtschatica
Thalassiosira
oestrupü
Neodenticulakamtschatica
Site 796BSample
B-1R-CC
B-2W-CCB-3R-CCB-4R-CCB-5R-CCB-6R-CCB-7R-CCB-9R-CCB-1OR-CC
B-11R-CCB-12R-CCB-13R-CCB-14R-CCB-15R-CCB-16R-CCB-17R-CCB-18R-CCB-19R-CCB-20R-CCB-24R-CCB-28R-CCB-29R-CCB-3OR-CCB-31R-CCB-32R-3, 31-33B-32R-4, 143-145B-32R-5, 24-26B-33R-2, 34-36
ForaminiferZone
Miliamminaechigoensis
Spirosigmoilinellacompressa
. . Opal-A/Opal-CT «
Diatom Zone
Neodenticulaseminae
R. curvirostris
Actinocyclusoculatus
Neodenticulakoizumii
N. koizumii-N. kamtschatica
. JV. kamtschatica _
Epoch
Quaternary
Pliocene
lateMiocene
ForaminiferZone
7
Miliamminaechigoensis
* Opal-A/Opal-CT
Spirosigmoilinellacompressa
Epoch
Quaternary
Pliocene
lateMiocene
Site 797Sample
A-1H-CCB-1H-CCB-2H-CCB-3H-CCB-4H-CCB-5H-CCB-6H-CCB-7H-CCB-8H-CCB-9H-CCB-10H-CCB-l 1H-CCB-12H-CCB-13H-CCB-14H-CCB-15H-CCB-16H-CCB-17H-CCB-18H-CCB-19H-CCB-20X-CCB-21X-CCB-22X-CCB-23X-CCB-24X-CCB-25X-CCB-26X-CCB-27X-CCB-28X-CCB-29X-CCB-30X-CCB-31X-CCB-32X-CCB-33X-CCB-34X-CCB-35X-CCB-36X-CCB-37X-CCB-38X-CCB-39X-CCB-40X-CCB-41X-CCB-42X-CCB-43X-CCB-44X-CCB-45X-CCB-46X-CCB-47X-CCB-48X-CCB-49X-CCB-50X-CCB-51X-CCB-52X-CCC-1R-CCC-2R-CCC-3R-CCC-6R-CCC-7R-CCC-8R-2, 36-38C-18R-1,88-90C-20R-2, 4 2 ^ 4C-22R-CCC-23R-CCC-25R-6, 33-35C-27R-CCC-33R-3,42-44C-34R-CC
Diatom andNannofossil
Zones
Neodenticulaseminae
Rhizosoleniacurvirostris
Actinocyclusoculatus
Neodenticulakoizumii
N. koizumii-N. kamtschatica
Thalassiosiraoestrupü
Neodenticulakamtschatica
Rouxiacalifornica
Discoasterextensus
Discoasterexilis Zone
Sphenolithusheteromorphis
ForaminiferZone
Miliamminaechigoensis
• •• Opal-A/Opal-CT <
Spirosigmoilinellacompressa
Globorotalia cf.G. fohsi
Epoch
Quaternary
Pliocene
lateMiocene
middleMiocene
early(?)Miocene
223
C. A. BRUNNER
Site 7971
-r
i , . . - , . . . .
i i
_
Upwelling
Unclustered
Subpolar, dissolved
Subpolar, seasonal
Subpolar, cool
Site 794
1 ,
1 ,
1 ,
i, 1
-
20 40
Depth (mbsf)
60 80
Upwelling
Unclustered
Subpolar, dissolved
Subpolar, seasonal
Subpolar, cool
Figure 4. Succession of clusters in Holes 794A and 797B plotted against depth in hole. The subpolar cool assemblage is equivalentto Cluster 1; the subpolar seasonal assemblage is equivalent to Cluster 2; the subpolar, dissolved assemblage is equivalent to Cluster3; the unclustered samples are those distinctly different from all other samples; and the upwelling(?) assemblage is equivalent toCluster 4. The two lines connecting the graphs denote the Brunhes/Matuyama Boundary and the top of the Olduvai.
224