Late Miocene ostracodes from the Kubota Formation, Higashi-Tanagura Group, Northeast Japan, and their implications for bottom environments

17 Pages·2001·7.5 MB·English

by  Tatsuhiko Yamaguchi

Paleontological Research, vol. 5, no. 4, pp. 241-257, December 31, 2001
©
by the Palaeontological Society of Japan
Late Miocene ostracodes from the Kubota Formation,
Higashi-Tanagura Group, Northeast Japan,
and their implications for bottom environments
TATSUHIKO YAMAGUCHI1 and HIROKI HAYASHI2
'Graduate School ofNatural Science and Technology, Kanazawa University,
Kakumamachi, Kanazawa, Ishikawa Prefecture, 920-1192, Japan (e-mail: [email protected])
institute ofGeologyand Paleontology, Graduate School ofScience, Tohoku University,
Sendai. Miyagi Prefecture, 980-8578, Japan (e-mail: [email protected])
Received 23 May 2001; Revised manuscript accepted 16 August 2001
Abstract. Sixty-seven ostracode species including those in open nomenclature are identified in
thirty-six samples from the upper Miocene Kubota Formation, Higashi-Tanagura Group, distributed
in Fukushima Prefecture, northeastern Japan. The lower part of the Kubota Formation yields
Spinileberissp. dominantly. In the middle to upper part of the formation, dominant species are
Schizocythere kishinouyei(Kajiyama), Kotoracythereabnorma Ishizaki, Hanaiborchella triangularis
(Hanai), Cytheropteron miurense Hanai, Paracytheridea neolongicaudata Ishizaki and Finmarchi-
nellajaponica (Ishizaki). Most of these species live off southwestern Japan undera subtropical to
warm marine climate regime, but cryophilic and circumpolar species also occur sparsely in the
middle to upper part. The ostracode assemblages indicate that the lower and the middle to upper
parts of the Kubota Formation were deposited in an enclosed inner bay influenced by warm water
and a warm shallow sea, respectively. Principal component analysis reveals that the influence of
open sea water became strong in the upward sequence of the middle part. Analyses of ostracode
faunas indicate that the Shiobara fauna from the Kubota Formation flourished in warm-watercondi-
tions.
Key words: Kubota Formation, Late Miocene, Ostracoda, Shiobara fauna
Introduction Consequently, he recognized parallel communities between
them and defined the Shiobara-type fauna (Shiobara fauna).
The Kubota Formation is known as one of the units con- The Shiobara fauna was defined as a cold-water fauna
taining the Shiobara fauna (Iwasaki, 1970), which flourished which lived in inner bays or coastal areas (e.g. Chinzei,
in Northeast Japan during the middle to late Miocene. 1963; Chinzei and Iwasaki, 1967; Chinzei, 1986). Recently
Chinzei and Iwasaki (1967) and Iwasaki (1970) consid- some workers, however, pointed out that the fauna flour-
ered that the Akasaka and Kubota Formations of the ished in warm- to mild-temperate realms rather than cold-
Higashi-Tanagura Group were deposited contemporane- temperate ones, orcontained warm-waterspecies as well as
ously in an inner bay. Furthermore, these authors recon- cold-water ones (e.g. Ogasawara et al., 1985; Ogasawara,
structed a Higashi-Tanagura Bay on the basis of the 1994; Ozawa et al., 1996). Thus, the Shiobara fauna has
lithology and geometry of the basin, discussing the been studied by many workers paleoecologically.
paleoecology of the molluscan assemblages. In their dis- Many studies on the Miocene paleoenvironments have
cussion, Chinzei and Iwasaki (1967) compared the been made using molluscan fossils. For example, Chinzei
molluscan assemblages in the eastern Tanagura area with (1986) and Ogasawara (1994) summarized the molluscan
ones belonging to the Kadonosawa and Tatsunokuchi fau- faunas of the late Cenozoic of Japan in the light of
nas, and recognized parallel communities. Iwasaki (1970) paleoclimates. Chinzei (1986) stated that Northeast Japan
made a comparison with the molluscan assemblages in the was influenced by cold water during the middle to late
eastern Tanagura, Shiobara, and Takasaki areas, where Miocene, since he regarded the Shiobara fauna as a cold-
nearly contemporaneous deposits are distributed. waterfauna. On the other hand, Ogasawara (1994) thought
242 Tatsuhiko Yamaguchi and Hiroki Hayashi
140° E
135° E !&
40° N-4- CK -4-40° N
lAn
145° E
-35° N
+H-++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2Km
Figure 1. Geological sketch map and geological cross section ofthe eastern Tanagura area. Partly modified after Shimamoto
etal. (1998) forthe geological map.
Late Miocene ostracodes 243
(DTakahashi etal. (2001) (2)Takahashi etal. (in press) (3) Shimamotoetal. (1998) (4) Yanagisawa etal. (2000)
Figure 2. Diagram showing the Neogene sequence in the easternTanaguraareaand biostratigraphyand radiometricagesoftuff
layersofthe Kubota Formation. CompiledafterShimamoto etat. (1998)andYanagisawa etai (2000)forbiostratigraphyandTakahashi
etal. (2001) and Takahashi etal. (in press) for radiometric ages.
that marine climates in Northeast Japan were warm- to mild- dium- to coarse-grained sandstone; the middle part muddy
temperate during the middle to late Miocene, based on the fine-grained sandstonewith mud-pipes and tuffaceous sand-
modern distribution of molluscan genera and the marine stone; the upper part cross-bedded coarse-grained sand-
Zoogeographie divisions of Nishimura (1981). Paleocli- stone. Many felsic tuff layers are intercalated in the middle
mates suggested by molluscan fossils have been based on to upper part, in which Shimamoto et ai (1998) recognized
their biogeography and phylogeny. However, only a few seven layers as keybeds (Kt-1 to Kt-7 tuff layers).
studies have been made on other fossil groups from depos- The geological age of the Kubota Formation has been de-
its yielding the Shiobara fauna. termined by means of planktonic microfossils and radiomet-
To approach the problems mentioned above, we quantita- ric dating of tuff layers (e.g. Aita, 1988; Takahashi and
tively examined ostracodes from the upper Miocene Kubota Amano, 1989; Taketani and Aita, 1991; Shimamoto et ai,
Formation of the Higashi-Tanagura Group. 1998; Yanagisawa et ai, 2000; Takahashi et ai, 2001;
Takahashi etai, in press). Shimamoto etai (1998) verified
Geological setting that the middle and upperparts ofthe Kubota Formation can
be assigned to the calcareous nannofossil Zone CN6 to
The eastern Tanagura area lies about 70 km south of CN7/8a of Okada and Bukry (1980), planktonic foraminifer
Fukushima City, Fukushima Prefecture, northeastern Japan Zone N16 of Blow (1969) and the radiolarian Lychnocanoma
(Figure 1). magnacomuta Zone of Motoyama and Maruyama (1996).
The geology ofthe eastern Tanagura area has been stud- Yanagisawa et ai (2000) studied the diatom assemblages
ied by many workers (e.g., Chinzei and Iwasaki, 1967; from the Kubota Formation for the first time and correlated
Iwasaki, 1970; Otsuki, 1975; Shimamoto etai, 1998). The the middle part with the diatom Zone NPD5C of Yanagisawa
Miocene distributed in the eastern Tanagura area comprises and Akiba (1998) (Figure 2).
two formations: the Akasaka and Kubota Formations On the other hand, Takahashi et ai (2001) dated the ra-
(Figures 1, 2). The Kubota Formation overlies conformably diometric ages of a biotite-rich tuff layer, recognized as a
the Akasaka Formation and isoverlain unconformably by the keybed, the Kt-1 tuff layer, by Shimamoto et ai (1998).
Pliocene Nikogi Formation. On the basis of lithology, the They reported the zircon fission-track age (F.T. age) and
Kubota Formation is divided into three parts (Shimamoto et biotite potassium-argon age (K-Ar age) of the Kt 1 tuff layer
ai, 1998): the lower part is composed of muddy fine-grained to be 10.7±0.2 Ma (1 o error) and 10.6±0.2 Ma (1 aerror).
sandstone, yielding abundant molluscan fossils, and me- Moreover, Takahashi et ai (in press) dated the zircon fis-
244 Tatsuhiko Yamaguchi and Hiroki Hayashi
Figure3. Map showing the ostracode fossil localities (a part of 1:25,000 map of Tanagura" and "Hanawa" published by
Geographical Survey Institute ofJapan).
Late Miocene ostracodes 245
160
.VA'JO*
155
Kamitojosection
thickness(m)
Nishikawasection
Kt-4l NK21* 150 thickness(m)
SK2Û'
140
to
Kt-3 135
-\K31'
NK14* Kt-5E
ISO
-NK30
NK13 125
45 -SK29*
Kt-2
175
-Nim*
40
-NK27* 170
115
shell
fossils
-SK26* 165
110
shell
30
Kt-1 fossils
-NK25*
105
25 LEGEND
NK4 ^^
[00 siltstone scoria
a -NK24 pumice
veryfine-tofine-grained
glassy tuff
sandstone
95 mafic mineral-
-NK23* fine-to medium-grained bearingcrystallinetuff
sandstone lamination
medium- tocoarse-grained ig==i=^ cross-bedding
fsohseslills sandstone »*•^t convolution
_NIKW23* verycoarse-grainedsandstone
m SA7* 85 or <=>°o concretion
shell -NK22 granuleconglomerate Uli bioturbalion
fossils
\K5 sample horizon IUUU) mud pipe(Rosselia)
sandpipe,root
B0
I ligrale ,\K20' ostracode-beanngsamplehorizon tf thin tufflayer
Figure 4. Columnarsectionsofthe Kubota Formation. Bold italic numbers with asterisk marks indicate the ostracode samples in
this study.
246 Tatsuhiko Yamaguchi and Hiroki Hayashi
sion-track age of a felsic tuff, Kt-7, to be 10.6±0.3 Ma (1 a can be distinctly divided into two groups (Figure 8). In the
error) (Figure 2). These reported microfossil and radiomet- lower part of the formation, Spinileberis sp. accounts for
ric ages do not contradict the biochronology of Saito (1999). more than 90% ofthe assemblage. The genus Spinileberis
has been reported to occurabundantlyon muddy bottoms in
Materials and methods Recent enclosed inner bays (e.g. Hanai, 1961; Ikeya and
Shiozaki, 1993).
We collected 60 sediment samples from two sections of In the middle to upper part, Schizocythere kishinouyei
the Kubota Formation (Figures 3, 4) and examined 40 sam- (Kajiyama), Kotoracythere abnorma Ishizaki, Hanaiborchella
ples: 33 samples from the Nishikawa section and 7 samples triangularis (Hanai), Cytheropteron miurense Hanai,
from the Kamitoyo section. The Nishikawa section along Paracytheridea neolongicaudata Ishizaki, Finmarchinellaja-
the Nishikawa River is typical of the Kubota Formation ponica (Ishizaki) and so on occurred. S. kishinouyeioccurs
(Shimàmoto etal., 1998). The upperpart is better exposed most dominantly, forming 20 to 40% of the numberofspeci-
in the Kamitoyo section along the Hokkawa River. We col- mens in the assemblage. Subordinate are K. abnormaand
lected sediment samples from the Kamitoyo section to ex- H. triangularis, accounting for 10 to 20% of the number of
amine fossil ostracodes from the upper part of the Kubota specimens in the assemblage. Other species represent
Formation. These two sections are well correlated to each less than 10%. Most species are reported to live in coastal
other by virtue of five keybeds. areas and the open sea underthe influence ofthe Kuroshio
Eighty grams of dried sediments were treated by using a Warm Current (e.g. Hanai, 1957, 1970; Ishizaki, 1981; Zhou,
saturated sodium sulfate solution and naphtha (Maiya and 1995; Tsukawaki et al., 1997, 1998). All of these species
Inoue, 1973; Oda, 1978), washed through a 200 mesh sieve are known to represent the Shiobara fauna (Ishizaki, 1966;
screen, and dried again. These procedures were repeated Irizuki and Matsubara, 1994, 1995; Ishizaki et al., 1996;
until the whole sediment sample became disintegrated. A Irizuki etal., 1998). Through the upper horizons ofthe mid-
fraction coarserthan 125pm (115 mesh) was sieved and di- dle part to the upper part, the relative abundance of
vided by a sample splitter into aliquot parts, from which 100 Kotoracythere abnorma increases (Figure 8).
to 200 individuals were picked with a fine brush under the
binocular microscope. We took micrographs with a JEOL Faunal structures
Field Emission Scanning Electron Microscope, JSM-6330F
to identify the taxonomic relationships of the fossil The faunal structures of ostracode assemblages were ex-
ostracodes (Figures 5, 6). The results of our identifications pressed by the following four indices: species diversity [H
are listed in Figure7. In thisfigure, the estimated preserva- (S)], equitability (Eq.), the numberofspecies, and numberof
tion ofostracodes in each sample is as follows: good means individuals per 10 g sediment sample. These indices have
the sample contained abundant specimens easily identified been used extensively in paleoecology. Figure 9 shows
to species level; poor, the sample contained mostly speci- vertical changes of these indices. Changes in faunal struc-
mens identified with difficultyto species level; moderate indi- tures may be related to environmental changes (e.g., Buzas
cates somewhere between good and poor. and Hayek, 1998). Species diversity [H(S)] and equitability
We examined ostracode assemblages in detail from those (Eq.) areexpressed bytheShannon-Wienerformulaandthe
samples, each represented by more than fifty individuals by equation of Buzas and Gibson (1969), respectively:
means ofthe proportions (relative abundance) of majorspe-
cies, species diversity and equitability and performed princi- H(S) = -Epjnp and Eq. = exp[H(S)]/S
pal componentanalysison dataforabundance ofmajorforty
species. where p, means the proportion (relative abundance) of the
/-th species in a sample and S the number of species.
Ostracode assemblages from the Kubota Formation In the middle part of the Kubota Formation, the values of
H{S) and Eq. range from 2.08 to 3.00 and from 0.44to 0.64,
Ostracodes occurred in 36 samples and did not occur in 4 respectively. The numberofspecies in each samplevaries
samples (samples NK1, 17, 18 and 45). We identified 67 from 20 to 40. Vertical changes of Eq. values are little.
ostracode taxa including those left in open nomenclature H(S) values and the number of species change synchro-
(Figure 7). nously. Through the upper horizon of the middle to upper
The ostracode assemblages from the Kubota Formation part (samples NK41 and KM3) H{S)values andthe number
,
-
Figure 5. Scanning electron micrographs of selected ostracode species from the Kubota Formation. All specimens, expectfor
onejuvenile one (7), representadultvalves. All scale bars indicate 100 urn. RV= rightvalve; LV= leftvalve. 1: Aurilasp., RV, loc.
NK27. 2: CallistocytherehatatatensisIshizaki, RV, loc. NK34.5. 3: CallistocytherekotoraiIshizaki, RV, loc. NK35. 4: Callistocythere
sp.2, LV, loc. NK36. 5: Coquimbacf. ishizaki!Yajima, RV, loc. NK25. 6: Coquimbasp.1, RV, loc. NK10. 7: Coquimbasp.2, RV, loc.
NK27. 8: Cornuçoquimba saitoi (Ishizaki), LV, loc. NK35. 9: Cornucoquimba moniwensis (Ishizaki), LV, loc. NK21. 10: Cythere
omotenipponicaHanai, RV, loc. NK27. 11: CytheropteronmiurenseHanai, LV, loc. KM3. 12: Cytheropteroncf. sawanenseHanai, LV,
loc. NK10. 13: CytheropteronsubuchioiZhao, LV, loc. NK27. 14: Eucytheruraneoalae Ishizaki, RV, loc. NK21. 15: Finmarchinella
japonica(Ishizaki), RV, loc. NK27. 16: Hanaiborchellatriangularis(Hanai), RV, loc. NK27. 17: Yezocytheregorokuensis(Ishizaki), LV,
loc. NK27. 18: Trachyleberissp., RC, loc. NK35.
Late Miocene ostracodes 247
248 Tatsuhiko Yamaguchi and Hiroki Hayashi
Late Miocene ostracodes 249
speciessample 2Z 2 a i2ïc. ^2 s2Te X'•/•o- Ov $s ? 2R1 £a S th |e* f 'i f .jji îg S c'4 % »1 ?g g:. Ï g •ïc CgA o1 T„j 12
. spp G a n II II u 1 II II II
•/4l-w'i_:....s-p..-.. Hr*:. s 1 2 2 n 5 7 12 5 6 4 4 10 6 II 1 1
•Aurtla spp 1 1 2 2 3 3 3 2 1 il
CalHstocythtretatonu IshizaJj 1 : 1 1' o 1 1 il II
* Callisucylmeremaalaleniis lihizali 1 1 a 1 1 : : 3 14 4 11 S o 1 o II o 11 II
*Callislocylhertngosoforma Ishizjii i 1 3 1 II
*CaUisttxytheresubsetaneruis Ishizaki 1 i 1 3 1
Caflmpcyrtertwirf»lrwy>>,-jato Hanai 1 1 o
Callulec\lliere spI e 2 u II 11 il II il o o 11 II (1 11
Callishxythere sp2 i ! : •• 1 1 il 11 o o II o 11 II II
*CCaaalhmumotattanedrtu/sltpzpalùi Yajirrj 1 1 i 4 2 1 3 5 1 7 il 1
*Coquimttv sp1 1 2 1 4 5 12 3 14 14 12 10 1 1 1 II
CiViwm/Kj sp2 a 1 1 1 1 1 1 II 11 il 11 11 11 II
Coejràtbo spp 2 1 il il il II II II 11
CoawatAu 'spp 1 4 1
*CtWMCttJMiwNl«KMhtfrJUlS (IshlEakl) s 7 g 5 5 4 12 4 4 2 8 7 2 10 1 3 S 1 1 1
*Conwcactaatpasoiioi (Ishixakiisl 8 9 2 1 6 7 14 16 4 13 14 6 5 4 7 19 9 7 1 4 14 9 1 5 2
**OCutiViricnyoHm»o*firaippsoppA.ica Hanu -1 1 11 2 : 2 u3 3 1 2 : 1 1 5 4o 12! I1I1 II 1 I1I1 o1 3 2 iill iIlI IIII iIlI o1
' C-tthert spp. 1 6 1 6 4 14 l 9 10 4 3 6 4 6 2 8 9 2 1 3 1 1
OtAerr ?spp 1 1 1
•CytSeroçteronmutrerue Hanai 11 12 10 6 10 8 18 17 6 28 24 II 15 10 18 9 1 6 14 7 5 2 2
• ; -•- - - ^--i-.: Hj". 2 (I J il u 1 n o II 1 II o 11 II
C^theroptcrvn cf.sm«2AeAS* Hanai a D o 1 II o il o 11
CuVrofV^rcnsm&ulAkn Zhao 1
•Crtheraptenxittcfttoi Hum 1 3 3 3 2 6 1 1 1 3 4 1 2 4 2
C-ytk.er.o.pt.e.ro.n sp1 a 21 II II 2 il o 11 II 1 II il n II 1
••-Ej-t.cM.h-en-r•ame.oa.l-ae-Is-hizaki-.-j 4- 1J0 33 11 D 1 J3 162 s1 m: 11 :: 134 332 ::1 20 9il 17 24 7 1I1I on I1I il i1l 1
Finmarxkmetla sp a ) a 1 11 II il 1 11 11
FuvrurduneUa spp. 1 1 i l 1
*•HFainnawirtcohricnneettlljat?risapnpg.ularis (Hanai) 1 13 16 39 M 1 2 8 232 II IS 8 22 17 7 7 4 5 81 51 1 7 2 2 1 2 20 1 3 1
•HamctlhtnInampponica Tabuki û 2 3 a 1 i' 3 10 4 : u 11 il II II II II 1
HemucyOiere spp 1 a 2 û 1 1 i 1 2 1 2 2 il II II 1
Hemicyllteniraclalhrala (San) 1 2 1 1 i 1 1 u
*Ikmicyfmntracmnifn Hanai 1 1 3 2 1 i 1 1
*ftemjcytheryratapyamai Hanai 1 1 1 1 4 1 1
HemucytkermrayOMmaguchii (Tabuki) a û 1 1 1 1 II 11 II II II 1
*Hcrmafulespoucrocoualut Ishizaki : ? 1 1 I 3 2 2 3 2 5 11 1 4 2 II u 1 o u II 1
"Kmoracythereabnorma Ishizaki 5 9 s 6 4 5 4 12 8 4 3 10 16 12 10 27 37 42 27 4 1 1 2 14 4 23 13 1 1 2 1 4
*Koioracythere spp 6 3
*LaiocotKha nozoliensn Ishizaki 1 1 3 1 4 8 4 5 17 10 7 7 u 3 1
" LottxcK-tv spp V 7 U 1 7 1 o 1 II 1 II 3 II 11 II
*Loioconüathu* sp. ] 3 6 il 1 6 3 4 II 1 4 4 11 1 1 i il II II 1
Uaacytheropleron sp 1 1 1 1 1 1
*mmmteyellahatalalensis Ishizaki 1 2 1 1 2 3 1
MmhcjWIii spp 1 1 1 2 1 1 1 1
fteamaidea sp 1 Ü 1 1 1 1 1 i o 1
PalmenellattMucola (Norman) 1 3 9 : 2 6 4 14 5 3 6 3 3 4 4 4 12 10 2 il II 4 II Ü
*Paracytherideaneokmgtcaudaia Ishizaki 12 5 7 4 1 5 6 14 9 1 14 8 11 22 10 11 26 17 25 22 2 3 3 1 1 1 1
Poniocythert sp 1 2 1 2 1 1
*Rcbemoruia sp 3 2 1 1 1 2 1 1
•' 5•.-.-:•—-'-*;-f"r"-atoÊ:em i hüakj -J1 i:I a5 I1I 91 4 6 6 11 3 II1 71 7: I1 32 41 21 3 (s 2 3 4 3 11 1 <5l iIlI 1' 2 11 o 1
ScAcorTCterr cf.hatatalensa Ishizaki 1
*ScfcosoïV**luhmomei (Kajiyama) 1 50 55 23 33 2 32 34 54 42 37 64 42 38 78 48 51 45 39 40 48 7 10 4 17 10 1 1 4
•S.c'n-axyt"h.e'r-i*-'s.p-p.-'- TmmmWAVUXl - f, » 5 l'I 1 2 51 5 71 31 2 2 1 2 11 21 1 1 o 1 1 2 II 2
Sçèùleberu sp 21 a (J || o i ii o 1 o II 1 11 I
•Tracnylebeni sp 1 1 1 3 1 1 1 2 2
Trachytebem spp 1 1
* »3x-iîVrejarctueiisif (Ishizaki) 1 2 1 5 1 2 6 6 6 7 2 4 4 3 6
^YeTz'o^--rr->.:inhe~rf--'.s-pp G22 >.:9 iGya* 1G81o 1G01f. M95 ••1D- MI'I( 1'0•'5 iGr 2M:-y !>r>.•) 1G641 2G34 \M-'( 2G00 2G59 IMK2 2Gy :G." 2M09 2M01ij VGIS M0o1 Y'1 M2 G10 M76 G2^il G«7I G46 Iï i1l G12 M11 G\v
Figure 7. Listofostracode species from the Kubota Formation. Asterisk marks indicate samples and species used for with prin-
cipal component analysis. Abbreviation for preservation: G = good, M = moderate and P = poor.
<- Figure 6. Scanning electron micrographs of selected ostracode species from the Kubota Formation. All are adult specimens.
All scale bars indicate 100 urn. RC = right lateral view of carapace. 1: Hermanites posterocostatus Ishizaki, RV, loc. NK27. 2:
Hemicythere kitanipponica (Tabuki), RV, loc. NK34.5. 3: Hemicytherura cuneata Hanai, LV, loc. NK27. 4: Kotoracythere abnorma
Ishizaki. LV, loc.NK35. 5: Loxoconcha nozokiensis Ishizaki, RV, loc. NK36. 6: Loxocorniculum sp., LV, loc. NK27. 7: Munseyella
hatatatensisIshizaki. LV, loc. NK40. 8: Palmenellalimicola(Norman), LV, loc. NK21. 9: ParacytherideaneolongicaudataIshizaki, RV,
loc. NK34. 10: Robertsonites sp.. LV, loc. NK35. 11: Rotundracythere ? sp., RV, loc. NK27. 12: Schizocythere kishinouyei
(Kajiyama), RV. loc. KM3. 13: SchizocytherehatatatensisIshizaki. LV, loc. KM3. 14: SemicytherurahenryhoweiHanai and Ikeya, RV,
loc. NK21. 15: Spinilebehssp.. LV, loc. NK3.
250 Tatsuhiko Yamaguchi and Hiroki Hayashi
thickness
" (m)
1—210 SampleNo.
KM14
—200
NK45
—190
—180
—170
KM6
KM5
—
160
NK40
—150 .,^L;Lh^NK839:^./-NN„,KK.,33.,76„
- -NK34.5S-NK35
—
140
—
130
—
120
—
110
—
100
—90
—80
—70
—60
—50 NK14-
Kt-2 NK12-
—40 -NKll
NK10
Lj
—30 1 i i i 40i% I i i 30i% I i i 30i% I i 20i% I i 20i% I i 20i% 10%
Kt-1
NK6
:'<':
—20
—10
^0