The Association for thetheGeologicalCollaboration Geological Collaboration in JapanJapan{AGCJ) (AGCJ)
Earth Sciencc(Chikyu Kagaku) vol.51,233-244. 1997
The Plio-Pleistocene stratigraphy of the Kanbara Plain, Niigata Prefecture, central Japan
and itssequence stratigraphic correlation with the Uonuma Group
HiroyukiArato'
Abstract The Plio-Pleistocene stratigraphy ef the back-arc Niigata Sedimentary Basin has
been elucidated by lithostratigraphic and tephrochronological studies of subaerial exposures
along its southern margin, in the Higashikubiki-Uonuma Hills. Correlative deposits buried
beneath the adjacent Kanbara Plain attain a maximum thickness of more than 5,OOO meters,
but their stratigraphy has not been fully understood, Recent analysis of the latter strata using geophysical and well-geological databases resulting from petroleum exploration has clarified the sequence stratigraphic framework of the Kanbara area. In this study, these subsurface
deposjts are correlated with Plio-Pleistocene strata exposed in the Higashikubjki-Uonuma area
on the basis of sequence stratigraphy. The fo11owing conclusions are based on this correlation:
i) Sequences F to N in the Kanbara area correspond to the middle and upper Pleistocene, ii) the uppermost part of the Upper Formation of the Uonuma Group possibly correlates with a part of Sequences F to H, iii) Sequences D to E2 mostly correlate with the Upper Formation of the Uonuma Group, iv) Sequence C corresponds, as a whole, to the Middle Formation of the Uonuma Group, and v) Sequence B probably correlates with the Lower and Lowermost Formations of the Uonuma Group. This correlation between subsurface Prio-Plejstocene strata of the Kanbara area and subaerial exposures in the Higashikubiki-Uonuma Hills provides in- sights into both the origin and the detailed strutigraphic framework of these deposits. Su¢ h an understanding is significant for studying changes jn paleoenvironments during the final Ml-
ing stage of the Niigata Sedimentary Basin, and for its broader applicatiQn to sequence strati- graphic correlation in other sedimentary basins.
Kay zvo7zls: Pliocene, P]eistocene, Kanbara area, depositional sequence, Uonuma Group, strati- graphic correlation, matrix trend
marg{n of the basin (Uonuma Hills Collaborative Introduction Research Group 1983, Kazaoka et al. I986, Kazao- The Niigata Sedimentary Basin is one of the ka 1988, Kobayashi et al. 1988, Kobayashi and major back-arc sedimentary basins in Japan (Fig. Tateishi 1992, Kobayashi 1996). O and is filled with Neogene and Quaternary However, the stratigraphic framework in the clastic deposits to a maximum thickness of more Kanbara area, located in the central part of the than 5,OOO meters. A PIio-P]eistocene stratigraphic Niigata Sedimentary Basin, is not yet fully under-
framework, largely based on lithostratigraphic stood. Most clastic deposits of the Kanbara
and tephrochronolegical studies, has been con- Plajn are subsurface ancl can be observed only in-
structed from surfaee exposures in the directly by geophysical and well-geological data Higashikubiki-Uonuma Hills along the southern acquired during petroleum exploration. Further-
Received January 23, 1997. Mareh 26, 1997, 'Exploration Department,AcceptedTe{koku Oil Co. Ltd,1-31-IOHatagaya,Shibuya-ku, Tokyo 151 Japan.
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234 IIirovukiArato
LEGEND Te' .NllGA7;4 PROBABLEMIDPLE- - UPPERPLEeSTOCENE DEPOSrrS Q S:iig UONUMAGReup PRE-UONUMASTAGE 3rEcr [ill] DEPOSITS MM"NllGATA.HEIYA"
KEYWELLLOCATON .;/. O o ttttteS / tttttttttt t - MAJORCrrYLOCATSON e''. :tc ,v o lekm - ses .. s ..r,r･:b,1.:1,･rg:'.neil{･, s 'iii;ii,..',!?F;;･:S.:E'i.:;3･:t ,.i:･rr･;itwi.I;･i:rr･/,:s: - tZLneaznm t- .el;c',p::･:,,'･::r..tt ,t ttt...t tt/:k. t ttt tttttt Si,.:t.J{X, ',..L.S.3,:: 1absi ,S AtDAnOUTE F./t::E.... . ssi sp, //s"NtsHiV;4-CAAREA- :/,i･s?,/.･#-l/1.1':･l-I,,s;i'ss'Sl ･' ,,t;'3',E,]/.,v･l,･z,/;･:r//}ti/,,///'i,ei･,i･E CHUO OIL fierD eELT ,?./lli/g'i.i;,.[/,'･Fg::,･e･ll,t;g'PX':::s.::i M4GA-Oie4 /1'sillS,geil,,,･s.ri'?.rtsRss..g:;."'lrtr::"e s.,...... ::..
, i"GASHIVAMA KASI-WAZAKn :?･/ MTNS. - t:t ,lg,}itg#}}i/ii･i,i/i,l,lil･i t ttt/ t't.t..et t..- :'''eil'l'i'/i:rsi.;iliffS'l'/Y;'I ..ttttt"t:tttttteStP'tttt//t:tttt･'L.･,･::.:.･･1 ... !S!4cigC/"SSS. .:SSbSt tt ttt tt ';",:',,il';';l'l･1,ig,l'ti,l,tr,z?//.//e･t ttt/..pg.. , t,.:/za?pg/e t }"CMSH-CUB-C '..is/.4: ' .. 'tzaLs ., /t/ :'::l).';Il/'ie. :t eil･1,il･:.,/f･f･}･/･i･i･ll/･1･l.[,･r･r,i,:･l･ ..,teS.'tli"ss/..s:'il･'f･1,/g･s . sstl J,:,if',IF･i,gt'//i//,i.lg.i.･x,l:;,sl//?.'//･g';･ ,/Lt:UONU .,El....ii･l[I 'E,/･/.i=.;E':,ts':9:iil;:;t,//.",tl･:･/t.･,i ,ll
.t steq'40'E HthLS ,g,E;il･t･i･i･:lll･i' ttttt -t #.s//f:/ll/I Fig. 2. Simplified geologic map showing the locations of
"Niigata-heiya" the studied areas and the MITI well, The Fig. 1, Index map showing the location of the Niigata Uonuma Greup and its correlative strata are shown Sedimentary Basin. together with probable middle to upper Pleistocene deposits (Modified after Niigata Prefectural Government more, key volcanic ash layers recognized in the 1989).
Higashikubiki-Uonuma area are not easily identifi-
able in wireiine logs of exploratory wells in the is an extremely flat lowland in the central part Kanbara area. This difficulty reflects differences of the Niigata Sedimentary Basin. It is bordered
in the coverage and resolution of available data to the west by the Kakuda-Yahiko rv{ountains and
(Arato and Takano 1995). to the east by the Niitsu Hills and Higashiyama Recent analysis of geophysical and well- Mountains, geological databases has significantly clarified the The Higashikubiki-Uonuma area, located to the
sequence stratigraphic frame"Tork in the Kanbara south of the Kanbara Plain, occupies the southern
area (Arato et al, l994, 1994a, 1994b, Arato and part of the Niigata Sedimentary Basin (Fig. 2). Hoyanagi 1995). This study presents a detailed The upper Pliocene-lower Pleistocene Uonuma
stratigraphic analysis and correlation between sub- Group and its correlative strata are exposed in
surface Pllo-Pleistocene strata in the Kanbara the Higashikubiki-Uonuma Hills.
area and PIio-Pleistocene surficial exposures in Method of study the Higashikubiki-Uonuma area in terms of
sequence stratigraphy. The stratigraphic subdivision of Plio-Pleistocene
deposits in the Higashikubiki-Uonuma area is Study area based mainly on lithofacies and interbedded key
The subjects of this study are the Kanbara and volcanic ash layers in the Higashikubiki-Uonuma Higashikubiki-Uonuma areas. The Kanbara area area (Niigata Volcanic Ash Research Group 1983, (62)
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The Plio-Pleistocene sequences of the Niigata Sedimentary Basin 235
Uonuma Hills Collaborative Research Group 1983, Kazaoka et al. 1986, Kobayashi et al. 1986). In the rise (A) time. Kanbara area, however, the stratigraphic frame- work and its relationship to biostratigraphic 4th-order cycles datum plains are known from seismic and well- lfael log sequence analyses (Arato et al. 1994a). Strati- + graphic correlations between the Higashikubiki- -rJse Uonuma and Kanbara areas have not been suc- < time. cessful to date because the key volcanic ash layers identiiiable in the surface outcrops of the 1tall Higashikubiki-Uonuma area are not recognizable in seismic profiles and well-log data in the Kan- bara area. fam :ng
1 1 1 In this study, stratigraphic correlation between 3rd-order cycle- , , the Higashikubiki-Uonuma area and the Kanbara
area by use of a sequence stratigraphic frame- work is based on an application of the stratigra- < phic methods of Sato et al. (1987). These workers rise established the stratigraphic relationship between time. key volcanic ash layers and biostratigraphic datums based on calcareous nannofossils and plan- 1taLl ktic foraminifers, by studying a series of outcrop samples from along the Aida route at Oginojo in the Higashikubiki-Uonuma area (Fig. 2). Calcareous nannofossil datums of Plio-
Pleistocene age in northwestern Atlantic DSDP- ODP cores (Takayama and Sato 1987) are adopt- ' ed as a reference scale for this study.
Sequence stratigraphy
"matrix Concept of trend" In general, a relative sea-level cycle at a given Fig. 3. Schematic diagram showing the relatienship Iocation is believed to be a composite of several between fourth-order cyc]es (A) and superimposed third- cycles characterized by individual frequencies, order phases {B). The curve (C) indicates effective move- amplitudes and wave forms. For instance, each ment as the sum of fourth- and third-order cycles, 1: fourth-order cyc]es on third-order falling phase, 2: fourth- fourth-order relative sea-level cycle in the Niigata order cycles on third-orcler lowstand stable phase, 3: Sedimentary Basin in late Neogene to Quaternary fourth-order cycles on thircl-order rising phase, and 4: time is divisible into following the three elements: fourth-order cyeles on third-order highstand stable phase (i) a fourth-order eustatic cycle, (ii) fifth- or (after Arato and Hoyanagi 1995), higher-order eustatic cycles, and (iii) a part of the third- and lower-order eustatic cycles and subsi- on curve (C) illustrate the wave forrns of some dence. Arato and Hoyanagi (1995) discussed the representative fourth-order cycles on the actual relationship between the elements (i) and
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236 HiroyukiiXrat･o
rise order cyc:e on T order rapid rising phase rapid rising matrixtrend
rder cycle on falling phase of rder slow rising phase ge 4th-order cycte slow rising 'S'ima,.xe...'2,/p.t:,a"gd::ot matrixtrend
e,R`: rder cycle on o rder stillstand phase O EISS'P.g,,p.h,as,e,?g stand matrix trend ･ ,･ highstandstable ,1: : rder cycle - " phaseof en 4th-erdercycle rder slow fal:ing phase slowfalljng 4th-order cycles matrixtrend / rder cycle on J rder rapid falling phase ....-- (,mpa8r.,E.t,reg,d, fall 3rderdercycle} rapid failing matrixtrend infiectionpoint
Mg. 4. Phase v･ariation diagram showing phase combination within 4th-order cycles superimposecl by clifferent third-order phases. (1): A fourth-order cycle on a third-order rapid rising phase, (2): a fourth-order cvcle on a third-orderslow rising phase, (3): a fourth-order cycle on a third-order stMstanding phase, (4): a fourth-order cycle on a third-order slo", fEdling phase, and (5)/ a fourth-orcler cycle on a third-order rapid fa]]ing phase, The fourth-order cyele (D consists mainJy of rising and stil]stand phases. In contrast to th{s, the fourth-order cycle (5) consists mainly ef falling and stillstand phases (pt'Todified after iXrate and IIoyanagi 1995).
third-order relative sea-level cycle, shows the gen- stable, rising, and highstand stable phases with eral rising of sea-level trend movement by its isometric time spans. In contrast to this, curves right-side-up curve-shape. Fourth-order cycles 2 {1) and (2) with rising matrix trends are char- and 4, however, locatedon the stable lowstand or acterized by longer rising phases. and the curves
highstandphases of the third-order relative sea- (4) and (5) with falling matrix trends are char-
level cycle, almost have the original curve shapes acterized by longer falling phases. Furthermore, seen relationships in Fig.3(A).These show that curves (1) and (5), respectively, do not include a the actual curve shapes of the fourth-order cycles falling phase or a rising phase as extremes. are controHed their by position on the third-order These effects suggest that the difference in a cycles. Arato and Hoyanagi {1995)tentativelv matrix trend is displayecl as a different phase named the general trend of movement in the assemblage of cycles. Arato and Hoyanagi (1995) third-order phase, (that is, the relative sea-level emphasized that the difference in the assemblage changes derived from the "matrix element (iii)) of phases for the fourth-order relative sea-level trend" for the cycles of the element (i), cycle caused by the different matrix trends results The difference in the matrix trend in fourth- in the three types of fourth-order depositional order relative sea-level cycles bringstogether the sequences having the individual combinations of individual internalcombinations of the relative systems tracts seen in the Niigata Sedimentary sea-level phases. For example, curves (1) to (5) in Basin. Fig. 4 show fourth-order relative sea-level cvcles with rapidiy-rising, gently-rising,stillstand, ge"nt]y- Kanbara area fallingand rapidly-falling matrix trends, respec- Geologic data in the area include both tively, Here, curve (3)consists of falling,]owstand seismic profiles andKanbarawell-logs acquired during
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The PIio-Pleistocene suquences of the Niigata Sedimentary Basin 23T
petroleum exploration and development, in addi- tion to observations of surface outcrops in the hilly areas surrounding the Kanbara Plain. Arato et al. (1994a, 1994b) carried out sequence stratigra- AGE phic analysis of the subsurface petroleum geologi-
cal information and delineated the following
sequence stratigraphic SequencesN framework (Fig.5(D)): v= 1) The clastic deposjts in the Kanbara area are - q- J+K e divisible into three cycles of third-order de- (4th-order}-m= .?...-L positional sequences (Sequences A, B and C- N, in ascending order). Sequencesee?gu- H-F(4th-order)Eeveg[zg 2) Twelve fourth-order depositional sequences (Sequences C, D, El, E2, F, Gl, G2, H, J+K, hlaf4a -o--･･, Gtne.5inftia)fa(4Etio8=e= L, M and N, in ascending order) are present SK020 ? SK020 ge.' innata within the youngest third-order depositional (no,1) UPPERUONUMA SequenceDgm2 sequence. (4th-erder)2e lo- 3) The fourth-order Sequences C, D, El and E2, 78 sKe3o sKe3oMIDDLEUONUMA7 characterized by a falling matrix 8G.inflstsCno,2)c9(4th) trend, con- G. infiata stitute the lowstand systems (no 2) tract of the
l SKIOO SKIOO third-order Sequence C-N. In the same man- SKIIO ner, Sequences F, Gl, G2 and H (with a rising 1011 matrix trend) and Sequences J+K, L, M and LOWERUONUMA N (with a stable matrix trend) compose the transgressive systems tract and the highstand systerns tract, respectively, of the third-order ?-SK130 SK130 Sequence C-N. SequenceB The National Oil Corporation LOWER- {3rd-order) Japan (1991)car- MOSTUONVMA ried out biostratigraphic analysis of the cuttings
and sidewall core samples from the MITI "Niigata-heiya" we]] (Fjg. 2), and the fol]owing ? G,infiAta(ne.3) biostratigraphic datums were identified: ･
1) The planktic foraminifer (;loborotalia iofata is G. infiata(no,3)HACHIOJJ 7'SequenceA abundantly recognized at 3,700-3,820 meters, 2,540-2,840 meters and 2,040-2,200 meters in (3rd-erder} drMing depth. Each of these depth intervals is thought to correspond to the No. 3, No. 2 and No. 1 Globorotalia iiofZata Beds of Kudo (1967), Fig. 5, Stratigraphic correlation chart. A: calcareous nan- in ascending order. nofossil datum planes and their geological ages in the ODP 2) The calcareous nannofossil datums of Ta- Leg 94 reference section for the northeastern Atlantic (Ta- kayama and Sato (1987) are recognized at the kayama and Sato I987); B: stratigraphic column showing following depths: i) datums No. 11 (first selected calcareous nannofossil datum planes, planktic for- appearance of Gephyroccipsa caribbeanica) aminiferal zones, and key v･olcanic ash layers (SK) on the and A{da route in' Izumozaki Town (Sate et al, 1987), C: No, 10 (last appearance of Calci;discus stratigraphic subdivisions of the Uonuma Group and their macints,rei, and the first appearance of Ce- relationship to the key volcanic ash layers (65 ) NII-Electronic Library Service TheTheAssociation Association for the Geological Collaboration in Japan (AGCJ){AGCJ) 238 Hirovuki. Arato 2,693 meters, iv) datum No. 7 (last appearance Kazaoka et at. (1986), Kobayashi et al. (1986), of GePhyrocaPsa spp. (large form)) at 2,442 Yanagisawa et al, (1986), Kazaoka (1988), Kobaya- meters, v) datum No. 6 (first appearance of shi et al. (1988), Kobayashi and Tateishi (1992), GePdyrocopsa Parallela) at 2,326 meters, and vi) and Research Group for Depositional Environ- datum No. 5 (top of acme Reticuloflanstra sp. ments of the Uonuma Formation (1996) among A) at 2,227 meters, others. Major resuits of these studies are sum- ' The above-mentioned biostratigraphic datums marized as follows: (Japan National Oil Corporation 1991) show the 1) The upper Pliocene to lewer Pleistocene non- following relationships with the sequence strati- marine to brackish-water deposits which crop graphic framework (Arato et al. 1994a; Fig, 5): out widely in the Higashikubiki-Uonuma area 1) The No. 3 Globorotalia injlata Bed corresponds are placed in the Uonuma Group. closely to the bounding discontinuity between 2) The Uonuma Group overlies and partly inter- Sequences A and B. fingers with the marine Hachioji Formation. 2) The No. 2 Globorotalia injlata Bed correlates The Uonurna Group also interfingers with the with all but the uppermost and lowermost marine Nishiyama and Haizttme Fermations. parts of Sequence C. 3) The Uonuma Group is subdivided into the 3) The No. 1 Globorotalia injZata Bed is recog- Lowermost, Lower, Middle and Upper Forma- nized in the lowermost part of Sequence El. tions, based on lithostratigraphic characteris- 4) Calcareous nannofossil datums No. 10 and 11 tics. are included within the upper part of 4) The Lowermost Formation is bounded above Sequence B. by key volcanic ash layer SK130 (Sennosawa 5) Calcareous nannofossil datum No. 9, which is Ash Bed). included within the No, 2 Globorotalia injZata 5) The Lower Formation is bounded above by Bed, is recognized in the lower part of key volcanic ash layer SKIIO and at its base Sequence C. by the SK130 (Sennosawa Ash Bed). 6) Calcareous nannofossil datum No. 8, which is 6) The Middle Formation is bounded above by also included within the No. 2 Globorotalia in- SK030 and its base by SKIIO, The key vol- fZdta Bed, is recognized in the upper part of canic ash Iayer SKIOO is included in this for- Sequence C. matlon. 7) Calcareous nannofossil datum No. 7 is 7) The base of the Upper Formation coincides contained within the lower part of Sequence with SK030. The key volcanic ash layer ･ D. SK020 is included near the top of the Upper 8) Calcareeus nannofossil datum No. 6 is recog- Formation. nized in the upper part of Sequence D. 8) A number of widely occurring pyroclastic and 9) The calcareous nannofossil daturn 5, which is marine deposits are traceable in surface expo- recognized below the No. 1 Globorotalia in- sures oi the Uonuma Group as significant key fZdeta Bed, corresponds to the bounding discon- beds, in addition to the ash tayers noted tinuity between Sequences D and El. above. Stratigraphic correlation between the Kanbara Higashikubiki-Uonuma area - and Higashikubiki-Uonuma areas Since the 1970s the late Pliocene early Pleis- tocene stratigraphy and sedimentary history of Sequences F to N the Higashikubiki-Uonuma area have been de- In the Kanbara area the fourth-order Sequences scribed by the Uonuma Hills Collaborative C, D, El and E2, with a falling matrix trend, con- Research Group (1983), the Niigata Quaternary stitute the lowstand systems tract of the third- Research Group (1983), the Niigata Volcanic Ash order Sequence C-N (Fig. 5). In contrast to this, Research Group (1983), the Niigata Foraminifera the fourth-order Sequences F, Gl, G2 and H, char- Research Group (1983), and by Yasui et al, (1986),acterized by a rising matrix trend, compose the ( 66 ) NII-Electronic LibraryMbrary Service TheTheAssociation Association for the Geological Collaboration in Japan (AGCJ){AGCJ) The Plio-Pleistocene sequences of the Niigata Sedimentary Basin 239 transgressive systems tract of the third-order Middle Formations of the Uonuma Group Sequence C-N (Arato and Hoyanagi 1995). The (Kobayashi et a). 1988, 1994). The Barnea Trans- beunding discontinuity between Sequences E2 and gression, therefore, demonstrates that the previous F, therefore, corresponds to a third-order trans- falling matrix trend changed to a rising trend in gressive surface. the last higher-order relative sea-level cycle of the The Uonuma Group contains fifteen interbedded Upper Formation of the Uonuma Group, This sug- marine in deposits the Higashikubiki-Uonuma gests that the uppermost part of the Upper For- area Kazaoka (MaOIO-Ma140: et al. 1986,Kazao- rnation of the Uonuma Group is probably a part ka 1988). The marine deposits within the Lower- of the third-order transgressive systems tract. most and Lower Formations of the Uonuma Based on these observations, a third-order trans- occur Group extensively in the southern part of gressive surface, corresponding to the bounding the Higashikubiki-Uonuma area. Marine deposits discontinuity between Sequences E2 and F in the within the Middle and Upper Formations of the Kanbara area, can be expected beneath the Ma140 Group (except for uppermost marine deposit marine deposits in the Higashikubiki-Uonuma Ma140) are exposed more restrictedly in the area, Also, the uppermost part of the Upper For- northern part of this area {Yasui et al. 1983, mation of the Uonuma Group may correlate with Yanagisawa et al. 1986, Kazaoka 1988). This indi- a part of Sequences F to H. Such a sequence cates that the depositional environment of the stratigraphic correlation shows that most parts of Middle and Upper Formations, except for the Sequences F to N in the Kanbara area, which uppermost part',gradually changed from marine might be younger in age than the Uonuma Group to non-marine through repeated transgressive- in the Higashikubiki-Uonuma area, could be inter- regressive cycles (Kazaokaet al. 1986).In other preted to be middle-upper Pleistocene and words, except for the last cycle, the higher-order Holocene deposits (Fig. 6), and supports the latest relative sea-level cycles in the Middle and Upper results of biostratigraphic correlation by Kobaya- Formations of the Uonuma Group are interpreted shi (1996). to have a falling matrix trend, This suggests that The Barnea Transgression, according to Urabe these strata constitute a third-order lowstand sys- et al. (1995), may correlate wjth a warm peak at tems tract. approximately O,9 Ma on the oxygen isotope On the other hand, the uppermost marine curve of Williams (1990), although no direct evi- deposit Ma140, overlies SK020 within the other- dence for its geological age is available yet, The wise non-marine Upper Formation of the Uonuma key volcanic ash layer SK020 that lies stratigra- northern Group in the part of the Higashikubiki phicatly below Ma140 (Yasui et ai. 1983, Kobaya- area. The stratigraphic separation between Ma140 shi et al. 1993), however, is recognized just above and SK020 in this area ranges from 50 to 100 the No. 1 Globorotalia intata Bed on the Aida meters (Kobayashiet al. 1988).This marine event route (Fig, 5(B); Sato et al, 1987), Beneath the No. "Barnea is called the Transgression," because the 1 Globorotalia injZata Bed, calcareous nannofossil "Niigata- Mal40 deposits contain abundant Barnea delatata, datum No. 5 is present in the MITI which is a bivalvemollusc indicativeof innersub- heiya" well in the Kanbara area (Japan Nation littoral embayment environments (Kobayashi et al. Oil Corporation, 1991; Fig. 2), Therefore, the Bar- 1994, Research Group for Depositional Environ- nea Transgression, which is represented by the ments of the Uonuma Formation 1996). The Bar- marine deposits of Ma140 (Kobayashi 1996), must nea Transgression possibly corresponds to a ris- be yeunger in age than O.83 Ma, as is indicated ing phase in a fourth- or higher-order relative by calcareous nannofossil datum No. 5 (Fig. 5(A)). sea-level cycle rather than to a rising phase in a The rising phase of the third-order glacio-eustatic third-order cycle, with reference to the scale of cycle is supposed to have started after about O.85 deposition. There is, however, no doubt that the Ma on the oxygen isotope curve of Williams Barnea Transgression was one of the largest (I990) (Urabe et al. 1995; Fig. 11), and this is con- transgressions during deposition of the Upper and sistent with the stratigraphic interpretation discus- ( 67 ) NII-Electronic Library Service The Association for thetheGeologicalCollaboration Geological Collaboration inJapan{AGCJ)in Japan (AGCJ) 240 HirovukiArato AGE and STRATtGRAPHYOF STRATIGRAPHY SEQUENCES OF STRATLGRAPHIC UONUMA and OF KANBARA HIGASHIKUBIKI HILLS NIITSUHILLS 1 UNIT 3 AREA modified after Kebayashi et al. (1988), Arate et a]. Kano et al. Tateishi(1989)4 (1991}2 Kazaoka {1988), etc. (1994) ' HOLOCENE Q3 votcanicash layers Sequences late J+K, L, M and N ' rv ? ? - umiddle o non-marlne Sequences shallow marine Z-oo5 F, Gl, G2 and H deposits ? UPPER FORMATtON 1.0 Sequences ' a SK030 C, D, El and E2 re Do MIDDLE :early FORMATION ece SKtlO (E= LOWER FORMATION zo 3rd-order 2.0 SK130 Sequence B =LOWERMOST -Zslate coZ FORMATION o-"a HACHIOJI 3rd-order FORMATION Sequence A (Ma) Fig. 6. Stratigraphic relationships amoung the Higashikubiki-Uonuma area, the Niitsu Hills, and the Kanbara areas. 1: glebal stratigraphic framework aiid units (Kano et al. 1991), 2i general stratigraphic column for the IIigashikubiki-Uonuma area (Kazaoka 1988, Kobayashi et al, l988, Urabe et al. 1995), 3: stratigraphic eolumn for the Niitsu Hills area (modified frem Tateishi ]989), and 4: sequence stratigraphic framework of the Kanbara area (Arato et al, l994a), sed above. Niigata Sedimentary Basin. Based on their alti- Sparse outcrops of non-marine to shallow tudes of occurrence and their stratal stacking marine clastlcs of probable PIeistocene age occur relationships, these strata are thought to have on the western flanks of the Niitsu Hills and been deposited during the maximurn transgression Higashiyama Mountains and on the northeastern of the late Pliocene to PIeistocene. Therefore, flank of the Higashikubiki Hills (Fig. 6(3); Omura they are possibly correlative with a part of the l930, Fukuzawa and Okada 1980, Tateishi 1989, last third-order transgressive systems tract, which Kobayashi et al. 1991, Niigata P]ain Eastern Mar- is composed of Sequences F to H, in the subsur- gin Collaborative Research Group 1992, Shimazu face Kanbara area. et al. 1992), Little stratigraphic information is yet available for these deposits, even though Inaba et Sequences D, El and E2 al. (1976) and the Niigata Quaternary Research In the Kanbara area, the bounding discontinuity Group (l983) emphasized the necessity of research between Sequences C and D occupies a stratigra- on these deposits for basin analysis of the phic position between calcareous nannofossil (68 ) NII-Electronic Library Service TheTheAssociation Association for the Geological Collaboration in Japan (AGCJ){AGCJ) The Plio-Pleistocene scquences of the Niigata Sedimentar.y Basin 241 datum No. 7 and the upper Iimit of the under- intercaiations of non-marine deposits. Though the lying No. 2 Globorotalia inflata Bed (Fig. 5(D); geological age of the base of the Uonuma Group Arato et al, 1994a). In the Higashikubiki-Uonuma has not been agreed upon, it is estimated to be area, on the other hand, key volcanic ash layer approximately 3.0 Ma on the basis of overall SK03e at the base of the Upper Formation in the stratigraphic relationships (Uonurna Hills Col- Uonuma Group is present at about the same hori- laborative Research Group 1983, Kobayashi et al. zon as calcareous nannofossil datum No. 7 on the 1986). Urabe et al. (1995) proposed an age ,of 2.4- Aida route (Fig, 5(B); Sato et al. 1987). This dem- 2.5 Ma for the start of Uonuma deposition, based onstrates that the bounding discentinuity corre- on the assumption that the beginning of Uonuma sponds approximately to the base of the Upper deposition in the Niigata Sedimentary Basin cor- Formation jn the Uonuma Group. Because the responds to a third-order glacio-eustatic fall in- bounding discontinutty between Sequences E2 and dicated by the oxygen isotope curve of Williams F is estimated to correspond approximately to (1990). Ma140, as djscussed above, Sequences D, EI and The stratigraphic information presented here E2 in the Kanbara area correlate with all but the does not convincingly support cerrelation of the uppermost part of the Upper Formation of the basal bounding discontinuity of Sequence B wfth Uonuma Group in the Higashikubiki-Uonuma the base of the Uonuma Group. However, the area. third-order sequence boundary at the beginning of Uonuma deposition probably correlates w･ith the Sequence C basal sequence boundary of Sequence B in the The basal discontinuity of Sequence C is strati Kanbara area, accordjng to Urabe et a].[s (1995) graphically berow the base of the No. 2 Ggobo- notion that the start of Uonuma deposition corre- rotalia iptata Bed and above calcareous nannofos- sponds to a third-order relative sea-level fall. The sil datum No. 10 in the Kanbara area (Fig. 5(D); sequence stratigraphic concept suggests that the Arato et al. 1994a). On the Aida route, on the third-order sequence boundary which was formed other hand, key volcanic ash layer SKIOO occurs during the glacio-eustatic fall at 2.4-2.5 Ma may stratigraphically below･ the No. 2 Globorotalia in- not always be at the base of the Uonuma Group flata Bed (Fig. 5(B); Sato et al. 1987). In the that is everywhere characterized by intercalations Higashikubiki-Uonuma area, key volcanic ash of non-marine deposits. This is the case because layer SKIOO is stratigraphica]ly right above sedimentary facies of the Uonuma Group in the SKIIO ash that bounds the Middle and Lower Higashikubiki-Uonuma area are characterized by Formations (Fig. 5(C); Kazaoka 1988). The bound- deltas and fan-deltas that filled the basin pro- ing discontinuity between Sequences C and D cor- gradationally from the south or east, so that dep- responds closely to the base of the Upper Forma- osition of non-marine strata did not start tion of the Uonuma Group, as discussed above, so synchronously in alr areas where the Uonurna Sequence C may approximately correlate with the Group occurs. The sequence stratigraphic interpre- Middle Formation of the Uonuma Group in the tation given here for the age of the base of the Higashikubiki-Uonuma area (Fig, 6). Uonuma Group appears to be consistent with the interfingering relationship between the non-marine Sequence B Uonurna Group and the underlying marine Ha- The ba$al bounding discontinuity of Sequence B chioji Formation (Yasui et al. 1983, Kazaoka et is stratigraphically･ within the No. 3 Globorotalia aL 1986). injZata Bed a]most exactly corresponds to the Gauss Normal Sequences B and C almost always corresponds to Epoch, and ranges in age from 3.4 to 2.5 Ma the base of the Middle Formation of the Uonuma (Sato et al. 1988). Group, as discussed above, most parts of The base of the Uonuma Group in the Sequence B in the Kanbara area correlate with Higashikubiki-Uonuma area is characterized by the Lower and Lowermost Formations of the ( 69 ) NII-Electronic Library Service The Association for thetheGeological Geological Collaboration in JapanJapan{AGCJ) (AGCJ) 242 Hiroyuki Arato Uonuma Group in the Higashikubiki-Uonuma area lation between subsurface PIio-Pleistocene deposits (Fig. 6). in the Kanbara area and subaerially exposed strata in the Higashikubiki-Uonuma Hills Conclusions provides a detailed stratigraphic framework for understand- The Plio-Pleistocenestrata which underlie the ing the genesis of these strata, Kanbara Plain, are correlative with the upper Such an understanding is significant for study- PIiocene-lower Pleistocene Uonuma Group that is ing changes in paleoenvironments during the fill- widely exposed in the Higashikubiki-Uonuma ing stage of the back-arc Niigata Sedimentary Hills to the south, As a result, the following Basin. In this study, furthermore, correlation was relationships were elucidated: done on the basis of sequence stratigraphic units 1. Allbut lower the part of Sequences F to N in such as third- or fourth-order depositional the area, interpreted Kanbara to be middle to sequences and their systems tracts. Correlation upper Pleistocene deposits, are younger age was also done with bounding discontinuities such than the Uonuma Group. as sequence boundaries, transgressive surfaces, 2. Non-marine and shallow marine deposits crop and maximum flooding surfaces, and the concept out sporadically on the western flanks of the of matrix trends of the depositional sequences, in Niitsu Hills and Higashiyama Mountains, and addition to the usual lithostratigraphy, biostrati- on the northeastern flank of the Higashikubi- graphic datums, and tephrochronological informa- ki Hills.They are interpreted to be deposits tion, The comprehensive method of stratigraphic maximum formed duringthe transgression of correlation used here is widely applicable to late Pliocene to Pleistocene age. These strata sequence stratigraphic studies in other sedimen- possibly correlate with a part of the last tary bastns. third-order transgressive systems tract consist- Acknowledgments ing of Sequences F to H. 3. The marine Ma140 deposits in the The author is greatly indebted to Prof. H, Higashikubiki-Uonuma area must be younger Okada (Department of Earth and Planetary Sci- than O.83 Ma. The uppermost part of the ences, Kyushu University) for his critical reading overlying Uonuma Group, Ma140, may corre- of the manuscript and for gracious guidance. He spond a of to part the lastthird-ordertrans- also wish to thank Prof. I. Kobayashi (DeparV gressive systems tract consisting of the ment of Geology, Niigata University), Prof. T. fourth-order SequencesF to H. Sato (Mining College, Akita University), Prof. 4. Sequences D, El and E2 in the Kanbara area Koichi Hoyanagi (Department of Geology, Shinshu Iargely correspond to most parts of the Upper University), and Mr. Tetsuro Kudo (Technical Formation of the Uonuma Group in the Research Center, Teikoku Oil Co., Ltd,) for their Higashikubiki-Uonuma area, encouraging discussions and edifying comments, 5. Sequence C in the Kanbara area is correlative He is grateful to Mr. Toru Watanabe (Technical with the MicldleFormation of the Uonuma Research Center, Teikoku Oil Co., Ltd.) for many the Higashikubiki-Uonuma Group in area. helpful suggestions during the course of this 6. The basal discontinuity of Sequence B may work. correspond to the third-order sequence bound- References ary formed when Uonuma deposition started. Sequence B in the Kanbara area, therefore, Arato H, Hoyanagi K (1995) Three types of 4th-order de- mostly correlates with the Lowermost and the positienal sequence model in the Niigata sedimentary basin, Mem Geo] Soc Japan, 45 I 118-139. Lower Formations of the Uonuma Group and Arato H, Hoyanagi K, Kameo K, Swift DJP, Niedroda with part of the underlying and interfingering AW (1994) A sequence model for fourth-order de- marine Hachioji Formation in the positional sequences in the Niigata back-arc sedimen- Higashikubiki-Uonuma area. tary basin, central Japan, Abstracts of AAPG Hedberg "Application The results of this sequence stratigraphic corre- Research Conference of Sequence Strati- ( 7e ) NII-Electronic Library Service TheTheAssociation Association for the Geological Collaboration in Japan (AGCJ){AGCJ) The Plio-Pleistocene sequences of Lhe Niigata Sedimentary Basin 243 graphy to Oil Field Development," September 5-8, Basin. Jour Geol Soc Japan. 92: 375-390. 1994, I'aris, France, 12-l6. Kebayashi I, Tateishi M, Yoshioka T, Shimazu M (1991) Arato H, Kameo K, Hoyanagi K (1994a) Sequence strati- Geology of the Nagaoka district, ";'ith geelogical sheet graphic analysis of a back-arc sedimentary basin in map at 1I50,OOO, Geol Surv Japan, 132p. Kanbara area, Niigata, central Japan. J Japanese Kudo T (1967) Application of foraminiferal ratio in the Assoc Petro] Technol, 59i ]8-'29, Ni{gata basin {AbstracO, Jour Japan Assoc Petre] Te- Arato H, Kameo K, IIoyanagi K <1994b) A sequence model chnoL, 321 317-318. for the Niigata back-arc sedimentary basin, central Niigata Feraminiferal Research Group (1983) Pliocene and Japan, Abstracts ef AAPG 1994 Annual Convention, Early Pleistocene foraminiferal fauna from the 94.Arato Uonuma region, Niigata Prefecture, central Japan. H, Takano O (l995) Significance of sequence strati- Monograph of the Association for the Geological Col- graphy in petroleum exploration. rvTem Geel Soc Japan, laboration in Japan, 26I 91- 102. 45I 43-60, Niigata Plain Eastern Margin Collaborative Research Fukuzawa E, Okada Y (1980) Quaternary of Yashireda and Group (199Z) Quaternary ef Niitsu Hills, Field Trip Muraniatsu areas, Niigata Prefecture. Letters of Guidebook for Fiscal 1992 Semiannual Meeting of Niigata Quaternary Research Group, 26 : 8-9. Sedimentologieal Seciety of Japan, I-5. Inaba A, Ito K, Kameyama Y, Kurokawa K, Muramatsu Niigata PrefecturaL Government (1989) Geological rnap of T, Naka"ma T, Yamazaki K, Yeshikeshi M (1976) Niigata Prefecture, 2 sheets, 1:200,OOO. The problems of the Yashiroda Forrnation, Centribu- Niigata Quatemary Research Greup (1983) Some problems tions from the Department of Geology and Mineralogy, on the 1'lio-Pleistocene Uonuma Group in Niigata I're- Niigata Univ･ersity, 4 [ 51-56. fecture, central Japan, Monograph of the Assoeiation Japan National Oil Corporation (199]> Completion report for the Geological Collaboration in Japan, 251 125- "Niigata-heiya" for MITI w･ell, 132p. ]3S.Niigata Kano K, Kato H, Yanagisawa Y, Yoshida F <]991, eds} Volcanic Ash Research Group (1983> Pyroc]astic Stratigraphy and geologic history of the Cenozoic of deposits of the Uonuma Group, Njigata Prefecture, the Japan, Geelogieal Surve}, uf Japan, Report 274, 114p. central Japan.Monograph of the Association for l Kazuoka O (1988) Stratigraphy and sedimentary facies of GeelogicalCo]laborationin Japan,26 23-31. the tJonuma Group in the Higashikubiki IIills, Niigata Omura I (1930) On the (}eology of Echigo oiL-fields. 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Abstracts, The 101st Annual Meeting of the nol, 52: 231-242. T, Kameo K Geelogical Society of Japan, 108. Sato T, Takayama T, Kato M, Kudo (1988) of the Kobayashi I, Tateishi M (1992) Neogene stratigraphy and Calcareous micrefossil biostratigraphy Upper- paleegeugraphy in the Niigata region, central Japan. most Cenozoic formations distributed in the coast of Mem Geo] Soc Japan, 371 53-70, the Japan Sea-Part 4: Conclusion-. Jour Japan Assoc Kebayashi Y, Tateishi )"I, Kazaoka O (1988) Quaternary Petrol Technol, 53: 475-491. Kikuchi Y deposits in N{igata district, Japan- with special refer- Shimazu M, Tateishi M, Kutahira T, (1992) ence to the Plio-Pleistocene Uonuma Group and its Cenozoic systems and petroleum accumulations in the correlatives-. rvTem Geol Soe Japan, 45 : 77'90. Niigata basin. 29th IGC Field Trip A15 Guidebook, Kobayashi L Tateishi M, Uemura T (1993) Geology of the 25p.Takayama Izumozaki district. With geological sheet map at 1 i T, Sato T (19S7) Coccolith biostratigraphy of 50,UOO. Geol Surv Japan, 91p. the North Atlantic Ocean, Deep Sea Drilling Project Kobayashi I, Tateishi )C, Yasui S, Kazaoka O, Kurukawa Leg 94. In: Ruddiman WF et al (eds) In{t repts DSDP, Printing Office,651- K, Aburai H, Watanabe K (1986) Stratigraphy und 94, Washington, D,C., U.S. Gov･t, pa]eoenvironment of Njshiyama and I{aizume Forrna- 702.Tateishi tions and Uonuma Group in Niigata Sedimentary M (1989> The Lower Pleistucene. In Niigta Prefec- ( 71 ) NII-Electronic Library Service The AssooiationAssociation for the GeologioalGeological Collaboration in Japan (AGCJ)（AGCJ ｝ 244 IIlrovuki Arato tural Government ed notes of ， ．，Explanatory geological dyllamic stratigraphy ．王n ： Cross TA （ed ）Quantitative map of Niigata Prefecture． − NiigataPrefecture，55 Dynarnic Stratigraphy， Prentice Hall， New Jersey， − 61． 543 565． U 〔muma Hills Collab〔）rative Research GrQup 1983 Yanagisawa Y KQbayashi I Takeuchi − 〔 ）Geology ， ， K ，TateishiM ，Chi of the Uonuma Group il／ the Uonuma region ． Mo 駒 ・ K Kato H 1986 hara ， （ ）Geology of the Ojiyadistrict． − graph of the Association for the Geological Collabora With ge 〔〕10gical sheet rnap at l ： 50，000， Geol Surv − tion in Japan，26 ： 5 21， Japan， 177P． Tateishi Urabe A ， M ， Kazaoka O （IY95）Depositional cycle Yasui S， Kobayashi I， Tateishi M （1983）Stratigraphy of ・ of marine beds and relative sea level changes of the the Uonuma Formation in the Hachikoku oil field and Plio．Pleistocene Uonuma Group Niigata ， 、central Japan． the southern part of Chuo oil field， Niigata Prefecture， − − Mem Geol Soc Japan，45 ： 140 153， central Japan． Earth Sci 〔Chikyu Kagaku ），37 ： 22 WMiams DF （1990）Se 】ected approaches of chemical strati． 37， ・ graphy to time scale resolution and quantitative ・ Arato ， H ．， 1997， The PHo Pleistocene stratigraphy of the Kanbara Plain Niigata Prefecture ・ ， ， cen tral Japan and its sequence stratigraphic correlation with the Uonuma Group． Earth Science（Chi− − kyu Kagaku ）， 51， 233 244． 荒戸 裕之 潟 原 地 の に 〜 ー ， 1997， 新 県蒲 域 平 野地 下 分 布 す る 鮮新 更新統 の 層序 と そ の 魚沼 層群 との シ ケ ン ス 層序対 − 比 ． 地 球科学 ， 51， 233 244 要 旨 〜 新潟背弧堆積盆地 の 鮮 新 更新統 の 層序 は ，お もに 南部 の 魚沼 丘 陵地域 の 地 表 に お 露頭 け る岩柑層序学 的， 火 山灰 編年学的研究 に よ り解 明 され て きた． こ れ に 対 して 盆地 の 〜 一 ， 新潟堆積 中部 蒲原地域 を埋積 する鮮新 更 新統は，大 部分が 平野地 ドに伏在す る こ とか ら， こ れ まで 序学 研 の 対 と さ か っ た 層 的 究 象 れ な 。近年 ， 石油探鉱 で 得 られ た地 ー ー ー ー 震探鉱デ タや 坑井地 質 デ タの シ ケ ン ス 解析 が す す み ，蒲原地 域 の シ ケ ン ス 層序学 的枠組 み が 明 らか に さ れ ー て きた ．そ こ で 本研究 で は その シ ケ ン ス 層序 を枠組 み として ，既 存の 層序学的デ ータ も加味 し て ，蒲原地域地 ド 〜 ー の 鮮 新 更 新統 と魚沼丘 陵地域地 表の地 層の シ ケ ン ス 層序対比 を行 っ た． こ の 層序対 比 の 結 果 は ，新潟堆積 盆地 の 埋積最末期 に お ける古環境変遷過 程 を研 る 上 で っ 究す 重要 な ， 詳細 で か 成 因 論的な 層序学 的枠組み を提供す るば ・ ー りで な く，堆積盆地内 にお け るシ ケ ン ス 層序学的 な地 層対比 の 実例 の ひ とつ とな る で あろ う， 一 （72 ） 一 NII-ElectronicN 工 工 Eleotronio Library Service