␹ᄹᎹ⋵⷏ㇱጊർධ㜞ᗵᐲ࿾㔡᷹ⷰ੗߆ࠄᓧࠄࠇߚἫጊጤ㘃ߩฎ࿾⏛᳇ᭂᕈ
中満隆博 *・林広樹 *・沢田順弘 *・兵頭政幸 *2・関口渉次 *3・笠原敬司 *4

Magnetostratigraphic study of volcanic rocks from the Yamakita-Minami seismic observation well, Yamakita Town,Kanagawa Prefecture, Central Honshu, JapanbyTakahiro NAKAMITSU*, Hiroki HAYASHI*, Yorihiro SAWADA*, Masayuki HYODO*2,
Shoji SEKIGUCHI*3 and Keiji KASAHARA*4
Abstract
Five volcanic rocks obtained from the Yamakita-Minami seismic observation well in Yamakita Town, Kanagawa Prefecture,Central Honshu, Japan were examined to determine the paleomagnetic polarities. The borehole geology of the present site
mainly consists of andestic to basaltic breccia and lava associated with conglomerate and sandstone layers. After applying a
VWHSZLVHDOWHUQDWLQJ¿HOGDQGSHUIRUPLQJWKHUPDOGHPDJQHWL]DWLRQWKHVWDEOHPDJQHWLFFRPSRQHQWVRIWKHVDPSOHVZHUHFOHDUO\GHWHUPLQHG6DPSOHV1R PLQGHSWK DQG1R PLQGHSWK KDYHDVLJQL¿FDQO\ORZLQFOLQDWLRQSUREDEO\clue to the allochthonous blocks of volcanic breccia. Samples No.3 (450.0-450.2m in depth) and No.4 (621.10-620.25m in depth)
possess an inclination of 45° to 55° with normal polarity. On the other hand, the lowermost sample No.5 (898.70-898.95m in depth)shows a deep inclination of -68° to -78° . This indicates that the sample is tilted at 30°-40° with reverse polarity. With respect tothe radiometric ages, samples No.3 and No.4 should correspond to the Brunhes normal polarity Chron and sample No.5 might becorrelated with the Matuyama reverse polarity Chron.

‫ߦ߼ߓߪޓ‬ߊߣ߽ᷓᐲ⚂ 720m㧔ᮡ㜞ߢߪᶏ᳓Ḱਅ⚂ 570m㧕߹ߢ‫␹ޓ‬ᄹᎹ⋵⷏ㇱߦߪ‫ޔ‬દ⼺㧙ዊ═ේᒐߣᧄᎺ஥ፉᒐߣ㒽ᚑߩ▫ᩮฎᦼᄖベጊྃ಴‛߇ಽᏓߒߡ޿ࠆߎߣࠍ᣿ࠄߩⴣ⓭Ⴚ⇇߇૏⟎ߒߡ޿ࠆ‫ޕ‬࿾⴫ߦ߅ߌࠆਔ⠪ߩႺ⇇߆ߦߒߚ㧔═ේ߶߆‫ޔ‬2004㧕‫ߩߎޔߪࠇߎޕ‬ជ೥࿾ὐ߇ߪ‫ޔ‬࿖ᐭᵤ㧙᧻↰ᢿጀࠍߪߓ߼ߣߔࠆᄙᢙߩᵴᢿጀߣߒ▫ᩮฎᦼᄖベጊྃ಴‛ߩၸⓍᓟ‫ޔ‬ዋߥߊߣ߽ 570m એ਄ߡ⹺߼ࠄࠇߡ޿ࠆ‫ޕ‬࿖ᐭᵤ㧙᧻↰ᢿጀߪ‫᧲ޔ‬஥㧔ᄢ⏷ਐᴉ㒠ߒߚ੐ࠍ␜ߒߡ޿ࠆ‫ޕ‬ጊർධ᷹ⷰ੗ߩߔߋർ஥ߢߪ‫ޔ‬㒺஥㧕߇㓉⿠ߒ⷏஥㧔⿷ᨩᐔ㊁஥㧕߇ᴉ㒠ߔࠆㅒᢿጀߢ⿷ᨩጊ࿾ࠍ᭴ᚑߔࠆᶏᚑᦝᣂ⛔ߩ⿷ᨩጀ⟲߇ಽᏓߒߡ޿޽ࠆ‫ޕ‬ਅ⋚஥ߣߥࠆ⿷ᨩᐔ㊁ߢߪ‫▫ޔ‬ᩮฎᦼᄖベጊྃ಴ࠆߚ߼‫ߩߎޔ‬࿾ὐㄭறߦ߈ࠊ߼ߡᄌ૏ߩᄢ߈޿╙྾♿ᢿ‛ Kuno, 1950  ߩ਄㕙߇‫ޔ‬ᢿጀߦㄭ޿ዊ↰ේᏒ㡞ችߢጀߩሽ࿷߇⏕ታߣߥߞߚ㧔═ේ߶߆‫ޔ‬2004㧕‫ޕ‬ᶏ㕙ਅ 490m ᧂḩߩᮡ㜞߹ߢᴉ㒠ߒߡ޿ࠆ㧔Yamazaki㧘‫⎇ᧄޓ‬ⓥߢߪ‫ޔ‬ጊർධ᷹ⷰ੗߆ࠄᓧࠄࠇߚࠦࠕ⹜ᢱߩ߁1992㧕‫ߩࠄࠇߎޕ‬ᢿጀߩ㐳ᦼ⊛ߥ⚥Ⓧᄌ૏߿ᚑ┙ㆊ⒟ࠍߜ㧡ጀḰߩἫጊጤߦߟ޿ߡฎ࿾⏛᳇᷹ቯࠍⴕ޿‫⏛ޔ‬᳇ᭂ᣿ࠄ߆ߦߔࠆߦߪ‫ޔ‬ᢿጀߩᄌ૏߇෸ࠎߢ޿ࠆ࿾ጀࠍ⹦⚦ᕈጀᐨࠍᬌ⸛ߒߚ‫ޕ‬ߦኻᲧߔࠆᔅⷐ߇޽ࠆ‫ޕ‬‫ޓ‬‫ⴕ┙⁛ޓ‬᡽ᴺੱ㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲߪ‫⿷ޔ‬ᨩᐔ㊁ർ✼߇‫⹜ޓ‬ᢱ߅ࠃ߮ᣇᴺធߔࠆ⿷ᨩጊ࿾ධ᧲ㇱߩਐ㒺ߢᷓᐲ 2035m ߦ߅ࠃ߱ᄢ‫⎇ᧄޓ‬ⓥߢ↪޿ߚࡏ࡯࡝ࡦࠣࠦࠕ⹜ᢱߪ‫ޔ‬2003 ᐕᐲߦᷓᐲࡏ࡯࡝ࡦࠣ⺞ᩏࠍ 2003 ᐕᐲߦⴕ޿㧔ጊർධ㜞ᗵᐲ㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲߦࠃߞߡជ೥ߐࠇߚ߽ߩߢ޽ࠆ‫ޕ‬ជ࿾㔡᷹ⷰ੗㧦એਅ‫ޔ‬ጊർධ᷹ⷰ੗㧕‫ߩߎޔ‬࿾ὐߢߪዋߥ೥࿾ὐߪ␹ᄹᎹ⋵ጊർ↸ਣጊߩਛ⣻‫ޔ‬ᮡ㜞 152m ࿾ὐߢፉᩮᄢቇ✚วℂᎿቇㇱ࿾⃿⾗ḮⅣႺቇ⑼‫ޓ ޥޓ‬ፉᩮ⋵᧻ᳯᏒ⷏Ꮉᵤ↸ ␹ᚭᄢቇౝᶏၞⅣႺᢎ⢒⎇ⓥ࠮ࡦ࠲࡯‫␹ޓ ޥޓ‬ᚭᏒἥ඙౐↲บ↸ ⁛┙ⴕ᡽ᴺੱ㒐ἴ⑼ቇᛛⴚ⎇ⓥᚲ‫⨙ޓ ޥޓ‬ၔ⋵ߟߊ߫Ꮢᄤ₺บ ᧲੩ᄢቇ࿾㔡⎇ⓥᚲ‫᧲ޓ ޥޓ‬੩ㇺᢥ੩඙ᒎ↢ ⺰ᢥ㧘␹ᄹᎹ⋵᷷ᴰ࿾ቇ⎇ⓥᚲႎ๔㧘╙  Ꮞ㧘㧘㧚࿑㧝‫ޓ‬ጊർධ㜞ᗵᐲ࿾㔡᷹ⷰ੗ߩ૏⟎࿑‫ޕ‬࿖࿯࿾ℂ㒮⊒ⴕ  ࿾ᒻ࿑‫ޟ‬ጊർ‫ޕߚߒ↪૶ࠍޠ‬(KI/CRUJQYKPIVJG;COCMKVC/KPCOKUGKUOKEQDUGTXCVKQPYGNN6QRQITCRJKEOCR;COCMKVCRWDNKUJGFD[VJG)GQITQRJKECN+PUVKVWVGQH,CRCP޽ࠆ㧔࿑㧝㧕‫ޕ‬ជ೥ᷓᐲߪ 2035.4m ߢ޽ࠅ‫ߜ߁ߩߘޔ‬ᷓ᜽࿷ߒ‫ޔ‬Okada and Bukry 1980 ߩ CN13b-CN14a Ꮺߦᐲ 1076.6m ߹ߢߪࠝ࡯࡞ࠦࠕ⹜ᢱࠍណขߒߚ‫ࠦ࡞࡯ࠝޕ‬ኻᲧߐࠇࠆ⍹Ἧ⾰࠽ࡦࡁൻ⍹ࠍ฽߻ߎߣ߆ࠄ㧔ᩉᴛ߶߆‫ޔ‬ࠕ඙㑆ߩࠦࠕ࿁෼₸ߪ 95.1% ߢ޽ࠆ‫߽ࠅࠃࠇߘޕ‬ᷓ޿2005㧕‫ޔ‬ᐕઍ⊛ߦ⿷ᨩጀ⟲⋧ᒰጀߣ⠨߃ࠄࠇࠆ‫ࠃࠇߘޕ‬ጀḰߦߟ޿ߡߪ‫⹜ࠬࠣࡦࠖ࠹࠶ࠞޔ‬ᢱ߅ࠃ߮ࠬࡐ࠶࠻ࠦࠅਅ૏ߩ࿾ጀߦߟ޿ߡߪ‫ޔ‬቟ጊጤ߿Ἣጊⷺ␕ጤߦࠃࠅ᭴ࠕ⹜ᢱ߇ណขߐࠇߚ‫ޕ‬ሹ⧌௑ᢳߪᷓᐲ 50m Ფߦ᷹ቯߐᚑߐࠇࠆ߽ߩߩ‫ߪ⚦⹦ޔ‬ਇ᣿ߢ޽ࠆ‫ޕ‬ࠇ‫ޔ‬ሹᐩ߹ߢߩో඙㑆ߢ 3° એౝߢ޽ߞߚ‫ޕ‬‫ޓ‬ಽᨆኻ⽎ߣߒߚ቟ጊጤ㨪₵ᱞጤ⹜ᢱߪ‫▫ޔ‬ᩮฎᦼᄖベ‫ޓ‬ជ೥ߦࠃࠅᓧࠄࠇߚ⹜ᢱߪ‫ޔ‬቟ጊጤ㨪₵ᱞጤ⾰ߩἫጊጊྃ಴‛ߦ⋧ᒰߔࠆ 4 ⹜ᢱߣ‫ࠅࠃࠇߘޔ‬ਅ૏ߩ⿷ᨩጀⷺ␕ጤ߅ࠃ߮ṁጤࠍਥߣߒ‫⍾ޔ‬ጤ‫␕ޔ‬ጤ‫ޔ‬ಝἯጤ╬ࠍ᜽⟲⋧ᒰጀߣߺࠄࠇࠆ 1 ⹜ᢱߢ޽ࠆ㧔⴫㧝㧕‫ߩߡోޕ‬᷹ቯ࿷ߔࠆ㧔࿑㧞㧕‫ޕ‬ጤ⋧ߪ‫ޔ‬A 㨪 H ጀߩ 8 ጀߦᄢ߈ߊ඙ಽ

⹜ᢱߪဋ⾰ߥἫጊጤߢ޽ࠅ‫ޔ‬㘑ൻ߿ᄌ⾰ߩ⹺߼ࠄࠇࠆߐࠇࠆ㧔ᵤਭ੗߶߆‫ޔ‬2006㧕‫ ߜ߁ߩߎޕ‬B 㨪 D ጀߦ߆ߌ▎ᚲࠍㆱߌߡㆬቯߐࠇߚ‫ᦨޕ‬਄ㇱߩ⹜ᢱ 1㧔ᷓᐲ 16.6-ߡߩጀḰߪ‫₵ޔ‬ᱞጤ㨪቟ጊጤ⾰Ἣጊⷺ␕ጤ߅ࠃ߮ṁጤ߆

16.7m㧕ࠍ㒰޿ߚ⹜ᢱߦߟ޿ߡߪ‫ޔ‬ߘߩ⹜ᢱࠍ฽߻ጤ૕ߦࠄਥߦ᭴ᚑߐࠇ‫▫ޔ‬ᩮฎᦼᄖベጊྃ಴‛ Kuno, 1950)ߟ޿ߡᵤਭ੗߶߆ 2006 ߦࠃࠅࡕ࡯࠼⚵ᚑ߅ࠃ߮ోጤ

ߦ⋧ᒰߔࠆ㧔ᵤਭ੗߶߆‫ޔ‬2006㧕‫ޕ‬E ጀߪ⽴ൻ⍹⍾ጤࠍൻቇ⚵ᚑಽᨆ߇ⴕࠊࠇ‫ߚ߹ޔ‬ᩉᴛ߶߆ 2005 ߦࠃࠅోጤ K-Ar ᐕઍ߇᷹ቯߐࠇߡ޿ࠆ‫ޕ‬⴫㧝‫ޓ‬ฎ࿾⏛᳇ಽᨆࠍⴕߞߚ⹜ᢱߩ৻ⷩ‫ޓ‬ಽขߒߚἫጊጤ⹜ᢱߪ‫߮ࠃ߅࡞࡝࠼ࠕࠦޔ‬ጤ⍹ࠞ࠶

6CDNG.KUVQHUCORNGUHQTRCNGQOCIPGVKECPCN[UKU‫ޓ‬࠲࡯ߦࠃߞߡ‫⋥ޔ‬ᓘ 2.5cm‫ޔ‬㜞ߐ 2.5cm ߩ౞ᩇ⁁ߦᚑ("ᒻߒߚ‫ޕ‬ᚑᒻߒߚ⹜ᢱߩ⥄ὼᱷ⇐⏛ൻߩ᷹ቯߦߪ‫ޔ‬ፉ&$!         &'%#'%#
'%#'%#)'ᩮᄢቇ✚วℂᎿቇㇱᚲ᦭ߩࠬࡇ࠽࡯⏛ജ⸘㧔ᄐේᛛ⎇⵾‫ޔ‬SMM-85㧕ࠍ↪޿ߚ‫ޕ‬Ბ㓏ᾲᶖ⏛ታ㛎ߦߪ‫ޔ‬ᾲᶖ⏛ⵝ⟎㧔ᄐේᛛ⎇⵾‫ޔ‬TDF-97㧕ࠍ↪޿‫ ߪ߼ߓߪޔ‬100͠‫ޔ‬ߘߩᓟ 500͠߹ߢߪ 50͠ߏߣ‫ޔ‬500͠એ਄ߪ 30͠ߏߣ

Lithology Radiometric age
0Unit

A

Magnetic Polarity
No.1?

No.2?

0.57±0.29 Ma (K-Ar)

Brunhes

B
200

C
400
0.31±0.08 Ma (K-Ar)

600

No.3 ●

D
0.34±0.39 Ma (K-Ar)

No.4 ●

E800

Matuyama

depth(m)(unconformity?)

No.5 ○

1.45±0.19 Ma (K-Ar)

F1000

࿑㧞‫ޓ‬ጊർධ㜞ᗵᐲ࿾㔡᷹ⷰ੗ߩሹ੗ᩇ⁁࿑‫ޓ‬᡼኿ᐕ

1.1±0.3 Ma (FT)G1200ઍߪᩉᴛ߶߆  ‫ޔ‬ጤ⋧ጀᐨ࡙࠾࠶࠻ #*Legend
Lithologyߪᵤਭ੗߶߆  ߦၮߠߊ‫ޕ‬EQPINQ ␕ጤ‫ޔ‬loam

UCPFUV ⍾ጤ‫ޔ‬(6ࡈࠖ࠶࡚ࠪࡦ࠻࡜࠶ࠢᐕઍ‫ޔ‬

volcanic
breccia

1400

basalt/andesite

1600-#Tࠞ࡝࠙ࡓ㧙ࠕ࡞ࠧࡦᐕઍ
(KI  %QNWOCT UGEVKQP QH VJG ;COCMKVC/KPCOK

conglo.

H

seismic observation well. Lithobgic

sandst.

1800

2.14±0.53 Ma (K-Ar)

2000

7 P K V  6 U W M W K  G V C N      T G F  Q O E V T K EPolarity● normal○reverse?

unknown

CIG;CPCIKUCYC GVCN  EQPINQEQPINQOG
TCVGUCPFUVUCPFUVQPG(6HKUUKQPVTCEM-
#TRQVCUUKWOCTIQPߦ 680͠߹ߢടᾲߒߚ‫ޕ‬੤ᵹᶖ⏛ታ㛎ߦߪ‫ޔ‬੤ᵹᶖ⏛ⵝᚑಽࠍ␜ߒ‫ޔ‬ફⷺߪ 3° ೨ᓟߣߥߞߚ‫ޕ‬⟎㧔ᄐේᛛ⎇⵾‫ޔ‬DEM-93㧕ࠍ↪޿‫ ߪ߼ߓߪޔ‬5mT‫ޔ‬ᰴ‫⹜ޓ‬ᢱ 3㧔ᷓᐲ 450.0-450.2m㧕ߪᾲᶖ⏛ߢ 450͠߹ߢ 1

ߦ 7.5mT‫ޔ‬10mT‫ ߩ ߘ ߦ ࠄ ߐ ޔ‬ᓟ 30mT ߹ ߢ ߪ 5mT ߏᚑಽࠍ␜ߒ‫ޔ‬੤ᵹᶖ⏛ߩ⚿ᨐ߽቟ቯߒߡ޿ߚ‫ࠄࠇߎޕ‬ߣ‫ޔ‬30mT એ ਄ ߪ 10mT ߏ ߣ‫ޔ‬60mT એ ਄ ߪ 20mT ߏ ߣ޿ߕࠇߩᶖ⏛⚿ᨐߦ߅޿ߡ߽ફⷺߪ 49 ޯ 55°㧔ᱜᏪ⏛㧕ߦ 100mT ߹ߢታᣉߒߚ‫ޕ‬ᶖ⏛ߐࠇߚ⹜ᢱߩᱷ⇐⏛ൻࠍ‫ޔ‬ࠍ␜ߒߚ‫ޕ‬ߘࠇߙࠇߦߟ޿ߡ᷹ቯߒߚ‫ޕ‬એ਄ߩ᷹ቯ࠺࡯࠲߆ࠄ‫ޔ‬‫⹜ޓ‬ᢱ 4㧔ᷓᐲ 621.1-621.5m㧕ߪᾲᶖ⏛ߢ 560͠߹ߢ 1

Kirschvink 1980 ߩਥᚑಽಽᨆߦࠃࠅ⏛ൻᣇ૏ߩ⸃ᨆࠍ

ᚑಽࠍ␜ߒ‫ޔ‬੤ᵹᶖ⏛ߩ⚿ᨐ߽቟ቯߒߡ޿ߚ‫ࠄࠇߎޕ‬ⴕߞߚ‫⹜ᧄޕ‬ᢱߪࡠ࡯࠲࡝࡯ជ೥ߦࠃࠅᓧࠄࠇߚ⹜ᢱߩ

޿ߕࠇߩᶖ⏛⚿ᨐߦ߅޿ߡ߽ફⷺߪ 45 ޯ 53°㧔ᱜᏪ⏛㧕ߚ߼࿁ォߒߡ߅ࠅ‫ߡߞ߇ߚߒޔ‬ᓧࠄࠇߚ⏛ൻᣇ૏ߩ߁ߜࠍ␜ߒߚ‫ޕ‬ફⷺᚑಽߩߺߦߟ޿ߡ⠨ኤߒߚ‫ޕ‬‫⹜ޓ‬ᢱ 5㧔ᷓᐲ 898.70-898.95m㧕ߪᾲᶖ⏛ߢ 560͠߹ߢ㧝ᚑಽࠍ␜ߒ‫ޔ‬੤ᵹᶖ⏛ߩ⚿ᨐ߽቟ቯߒߡ޿ߚ‫ࠄࠇߎޕ‬‫ޓ‬᷹ቯ⚿ᨐ޿ߕࠇߩᶖ⏛⚿ᨐߦ߅޿ߡ߽ફⷺߪ -68 ޯ -78°㧔ㅒᏪ⏛㧕‫ޓ‬ᓧࠄࠇߚ⹜ᢱߩߘࠇߙࠇߦߟ޿ߡ‫ޔ‬ᾲᶖ⏛ߣ੤ᵹᶖ⏛ࠍ␜ߒߚ‫ޕ‬ߩ⚿ᨐࠍࠨࠗ࠳࡯ࡌ࡞࠻࿑ߣࠪࡘࡒ࠶࠻ࡀ࠶࠻ᛩᓇ࿑ߦ
ࠃࠅ␜ߒߚ㧔࿑㧟㧕‫ޕ‬ಽᨆߒߚ޿ߕࠇߩ⹜ᢱߦߟ޿ߡ߽

‫ޓ‬⠨ኤਇ቟ቯߥ⏛ൻᚑಽ߇⹺߼ࠄࠇ‫ޔ‬ੑᰴ⊛ߥ⏛ൻ߇ઃ⌕ߒߡ‫ޓ‬ಽᨆߒߚ޿ߕࠇߩ⹜ᢱߦߟ޿ߡ߽‫ޔ‬Ბ㓏ᾲᶖ⏛ߦࠃࠅ޿ࠆ߽ߩߣ⠨߃ࠄࠇࠆ߇‫ޔ‬ㆡಾߥᾲᶖ⏛߅ࠃ߮੤ᵹᶖ⏛560 㨪 590͠೨ᓟ߹ߢߦ߶߷ේὐㄭߊ߹ߢᶖ⏛ߐࠇߚ‫ޕ‬ߦࠃࠅ߶߷቟ቯߥᣇ૏ᚑಽࠍᓧࠆߎߣ߇ߢ߈ߚ‫ޕ‬ߒߚ߇ߞߡ‫⹜ࠄࠇߎޔ‬ᢱߩ⏛ൻߪ‫ߪߚ߹࠻ࠗ࠲ࡀࠣࡑޔ‬‫⹜ޓ‬ᢱ 1㧔ᷓᐲ 16.6-16.7m㧕ߪᾲᶖ⏛ߢ 500͠߹ߢ 1 ᚑTi ࠍዋ㊂฽߻࠴࠲ࡁࡑࠣࡀ࠲ࠗ࠻ߦࠃࠅߘߩ߶ߣࠎߤ

ಽࠍ␜ߒ‫ޔ‬ફⷺߪ 0° ߦㄭ߆ߞߚ‫ޕ‬߇ᜂࠊࠇߡ޿ࠆ߽ߩߣ⠨߃ࠄࠇࠆ‫ޕ‬Ბ㓏੤ᵹᶖ⏛ߢߪ‫ޔ‬‫⹜ޓ‬ᢱ 2㧔ᷓᐲ 210.1-210.3m㧕ߪᾲᶖ⏛ߢ 450͠߹ߢ 1⹜ᢱ 3 ߩࠃ߁ߦ 100mT ታᣉᓟߢ߽⏛ൻ߇ේὐߦ㆐ߒߡ࿑㧟‫ޓ‬ฦ⹜ᢱߦ߅ߌࠆಽᨆ⚿ᨐߩࠪࡘࡒ࠶࠻ࡀ࠶࠻ᛩᓇ࿑߅ࠃ߮ࠨࠗ࠳࡯ࡌ࡞࠻࿑‫ޓ‬#(&Ბ㓏੤ᵹᶖ⏛‫ޔ‬6*&Ბ㓏ᾲᶖ⏛‫ࡘࠪޕ‬ࡒ࠶࠻ࡀ࠶࠻ᛩᓇ࿑ߩ㤥ਣߪ਄ඨ⃿ᛩᓇ‫⊕ޔ‬ਣߪਅඨ⃿ᛩᓇ‫࠻࡞ࡌ࡯࠳ࠗࠨޕ‬࿑ߩ㤥ਣߪ㋦⋥㕙߳ߩᛩᓇ‫⊕ޔ‬ਣߪ᳓ᐔ㕙߳ߩᛩᓇ㧔ࡠ࡯࠲࡝࡯ជ೥ߦࠃࠅ⹜ᢱ߇࿁ォߒߡ޿ࠆߚ߼‫⎇ᧄޔ‬ⓥߢߪ᳓ᐔᚑಽࠍ⠨ᘦߒߥ޿㧕‫ޕ‬(KI2CNGQOCIJGVKETGUWNVFKURNC[GFD[5EJOKFVPGVRTQLGEVKQPCPF<KLFGTXGNFFKCITCO#(&UTGRYKUGCNVGTPCVKPIH KGNF6*&VJGTOCNFGOCITGVK\CVKQP޿ߥ޿߽ߩ߇޽ߞߚ‫⹜ޕ‬ᢱ 3 ࠍណขߒߚṁጤߪࠞࡦ࡜ࡦ‫ޓ‬ᵤਭ੗߶߆ 2006 ߪ Kato 1985MS ߦࠃࠆ▫ᩮฎᦼ⍹₵ᱞጤߦ⋧ᒰߒ‫⚵࠼࡯ࡕޔ‬ᚑಽᨆߦࠃࠆߣ‫⹜ߩઁޔ‬ᢱᄖベጊྃ಴‛ߩਥᚑಽൻቇ⚵ᚑࠍ⚫੺ߒ‫⎇ᧄޔ‬ⓥߩ⹜ߩጀḰࠃࠅ߽⋧ኻ⊛ߦਇㅘ᣿㋶‛ࠍᄙߊ฽ࠎߢ޿ࠆ㧔ᵤᢱ 1 㨪 4 ࠍ฽߻࿾⾰࡙࠾࠶࠻ B 㨪 D ߣߩᲧセࠍⴕߞߚ‫ޕ‬ਭ੗߶߆‫ޔ‬2006㧕‫⎇ᧄޕ‬ⓥߦࠃࠆ⹜ᢱߏߣߩ଻⏛ജߩ㆑ᓐࠄߦࠃࠆߣ‫ޔ‬࿾⾰࡙࠾࠶࠻ B 㨪 D ߩ▫ᩮฎᦼᄖベጊ޿ߪ‫⏛ޔ‬ᕈ㋶‛ߩ☸ᓘ߿ᒻ⁁╬ߩ㆑޿ߦࠃࠆ߽ߩߣ⠨߃ྃ಴‛ߪ‫ޔ‬Kato 1985MS ߅ࠃ߮㐳੗࡮㜞ᯅ 2000 ߩࠄࠇࠆ‫ޕ‬㤥⊕ጀ߹ߚߪἫᛂ⍹ጪጀߦ⋧ᒰߔࠆน⢻ᕈ߇㜞޿‫ࠇߎޕ‬‫ޓ‬ᓧࠄࠇߚ⚿ᨐ߅ࠃ߮ጤ⋧⸥タ‫ޔ‬᡼኿ᐕઍߦၮߠ߈ฎ࿾ࠄߪ‫ޔ‬ᣣᧄ࿾⾰ቇળ࿖┙౏࿦࿾⾰࡝࡯ࡈ࡟࠶࠻✬㓸ᆔຬ⏛᳇ᭂᕈߦߟ޿ߡ⸃㉼ࠍⴕ߁‫⹜ޕ‬ᢱ 1 ߅ࠃ߮ 2 ߩጀḰߪ‫ޔ‬

ળ 2007 ߦࠃࠆ▫ᩮᄖベጊྃ಴‛㧔ᚑጀἫጊ⟲ᒻᚑᦼ㧦ជ೥ᤨߩ⸥タߢߪࠞࡦ࡜ࡦ⍹₵ᱞጤṁጤߣߐࠇߡ޿ࠆ0.60 㨪 0.24Ma㧕ߩ⁚Ꮉṁጤࠣ࡞࡯ࡊ߅ࠃ߮㊄ᤨጊṁጤ߇‫ߩ╬࡯ࠞࡦ࡝ࠢޔ‬ṁጤࠍ․ᓽߠߌࠆࠃ߁ߥ᭴ㅧߪ⹺߼ࠣ࡞࡯ࡊߦ߶߷⋧ᒰߔࠆߣ⠨߃ࠄࠇࠆ‫ߩߎޕ‬ኻᲧ⚿ᨐࠄࠇߡ޿ߥ޿㧔ᨋ߶߆‫ޔ‬2006㧕‫⎇ᧄޕ‬ⓥߦࠃࠅᓧࠄࠇߚ

ߪ‫⎇ᧄޔ‬ⓥߦࠃࠆ Brunhes ᱜ⏛ᭂᦼ߳ߩኻᲧߣ⍦⋫ߒߥߎࠇࠄ⹜ᢱߩફⷺߪ㕖Ᏹߦᵻߊ‫⃻ޔ‬࿷ߩફⷺߣߪ⪺ߒߊ޿‫⹜ޔߚ߹ޕ‬ᢱ 5 ࠍណขߒߚ቟ጊጤṁጤߪᷓᐲ 856.5 㨪⇣ߥࠆ‫ߩࠄࠇߎޕ‬ጀḰ߇฽߹ࠇࠆ▫ᩮฎᦼᄖベጊྃ಴‛

960.0m ߹ߢㅪ⛯⊛ߦಽᏓߒ‫ޔ‬ફⷺ߆ࠄ␜ໂߐࠇࠆ௑ᢳߪ‫₵ޔ‬ᱞጤ㨪቟ጊጤࡉࡠ࠶ࠢࠍᄙߊ฽߻Ἣጊⷺ␕ጤ߆ࠄ

ⷺ 30° ࠍ઒ቯߔࠆߣ‫ޔ‬ጀෘ߇ 89.6m ߦ߽㆐ߔࠆ‫ߩߎޕ‬ṁਥߦ᭴ᚑߐࠇߡ߅ࠅ‫ޔ‬᜽࿷ߔࠆ☻☸ಝἯጤߢ⹺߼ࠄࠇߚጤߩోጤൻቇ⚵ᚑߪ‫⿷ޔ‬ᨩጀ⟲ߦ฽߹ࠇࠆṁጤ߅ࠃ߮⽾2006㧕
ጀℂ㕙ߪ߶߷᳓ᐔߣߥߞߡ޿ࠆ㧔ᨋ߶߆‫ޔ‬‫ޕ‬ߒߚ߇ߞ౉ጤߩ⚵ᚑ▸࿐ߦ฽߹ࠇࠆ㧔ᵤਭ੗߶߆‫ޔ‬2006㧕‫⿷ޕ‬ᨩߡ‫⹜ޔ‬ᢱ 1 ߅ࠃ߮ 2 ࠍណขߒߚ₵ᱞጤߪ‫ޔ‬Ἣጊⷺ␕ጤਛጀ⟲ߪἑᚭጀ߆ࠄႮᴛጀਅㇱ߹ߢߩ඙㑆߇ Matuyama ㅒߩᏂᄢࡉࡠ࠶ࠢߣߒߡ฽߹ࠇߡ޿ࠆ߽ߩߢ޽ࠆน⢻ᕈ߇⏛ᭂᦼߦ‫ޔ‬Ⴎᴛጀ਄ㇱ߇ Brunhes ᱜ⏛ᭂᦼߦኻᲧߐࠇߡ

㜞޿‫⹜ߜ߁ߩߎޕ‬ᢱ 2 ߩ₵ᱞጤߦߟ޿ߡߪ‫ޔ‬0.57±0.29Ma޿ࠆ㧔ዊጊ‫ޔ‬1986㧕‫⹜ޔߡߞ߇ߚߒޕ‬ᢱ 5 ࠍណขߒߚ቟

ߩోጤ K-Ar ᐕઍ߇ᓧࠄࠇߡ޿ࠆ߇㧔ᩉᴛ߶߆‫ޔ‬2005㧕‫ޔ‬ጊጤṁጤߪ⿷ᨩጀ⟲ߩἑᚭጀ߆ࠄႮᴛጀਅㇱ߹ߢߩ඙㑆ߎࠇߪᓟㅀߩ⹜ᢱ 3 ߅ࠃ߮ 4 ߩᐕઍࠃࠅ߽ฎ޿୯ߢ޽ࠆ‫ޕ‬ߦ⋧ᒰߔࠆน⢻ᕈ߇޽ࠆ߇‫ޔ‬቟ጊጤṁጤࠍ᜽߻਄ਅߩጀ

ߎߩߎߣ߆ࠄ߽‫⹜ޔ‬ᢱ 2 ߪࠃࠅฎ޿₵ᱞጤ႙߇ࡉࡠ࠶ࠢ

Ḱߪ⍹Ἧ⾰⍾ጤ߿Ἣጊⷺ␕ጤ╬ߦࠃࠅਥߦ᭴ᚑߐࠇߡ߅ߣߒߡౣၸⓍߒߚ߽ߩߢ޽ࠆߎߣ߇ᒝߊ␜ໂߐࠇࠆ‫ޕ‬ࠅ㧔ᨋ߶߆‫ޔ‬2006㧕‫⿷ޔ‬ᨩጀ⟲ߦ․ᓽ⊛ߥ⧎ፘጤ␕ࠍ฽‫⹜ޓ‬ᢱ 3 ߅ࠃ߮ 4 ߦߟ޿ߡߪ‫ޔ‬ᾲᶖ⏛ߣ੤ᵹᶖ⏛ߩ޿ߕ߻␕ጤ߇⹺߼ࠄࠇߥ޿‫ߩߎޔߡߞ߇ߚߒޕ‬቟ጊጤṁጤߩࠇߩ⚿ᨐߦࠃߞߡ߽቟ቯߒߚᚑಽ߇ᓧࠄࠇ‫ޔ‬ફⷺߪ 45⹦⚦ߥኻᲧߦߟ޿ߡߪ੹ᓟߩ⺖㗴ߣ⸒߃ࠆ‫ޕ‬

㨪 55° ߢ⃻࿷ߣ߶߷หߓߢ޽ࠅ‫ޔ‬ᱜᏪ⏛ߣ⠨߃ߡࠃ޿‫ޕ‬ߎࠇࠄߩ⹜ᢱࠍណขߒߚ₵ᱞጤߪ‫ᦨޔ‬ਅㇱߦ᣿⍎ߥࠢ࡝‫⺰⚿ޓ‬ࡦࠞ࡯ࠍ઻߁ṁጤߢ޽ࠆ㧔ᨋ߶߆‫ޔ‬2006㧕‫ోޕ‬ጤ᡼኿ᐕ‫␹ޓ‬ᄹᎹ⋵ጊർ↸ධㇱ‫ޔ‬ਣጊߩጊർධ᷹ⷰ੗ߢជ೥ߐࠇ

ઍ୯ߪߘࠇߙࠇ 0.31±0.08Ma‫ޔ‬ 0.34±0.39Ma ࠍ␜ߒ㧔ᩉ

ߚᷓᐲ 2035.4m ߦ㆐ߔࠆࡏ࡯࡝ࡦࠣߢᓧࠄࠇߚࠦࠕ⹜ᢱᴛ߶߆‫ޔ‬2005㧕
‫ޔ‬Brunhes ᱜ⏛ᭂᦼߦ⋧ᒰߔࠆน⢻ᕈ߇ߩ߁ߜ‫ޔ‬5 ጀḰߩἫጊጤߦߟ޿ߡฎ࿾⏛᳇᷹ቯࠍⴕߞߚ‫ޕ‬㜞޿‫ޕ‬

ᷓᐲ 16.6-16.7m ߅ࠃ߮ᷓᐲ 210.1-210.3m ߢᓧࠄࠇߚ₵‫⹜ޓ‬ᢱ 5 ߩફⷺߪ -68 㨪 -78° ߣ߿߿ᷓ޿୯ࠍ␜ߔ‫ߎޕ‬ᱞጤߩફⷺߪᢙᐲએਅߢ߈ࠊ߼ߡૐߊ‫ޔ‬Ꮒ␕ߢ޽ࠆน⢻ߩ⹜ᢱࠍណขߒߚ቟ጊጤߪ৻ㇱ⊒ᵃߒߡ߅ࠅ‫ࠄ߆⁁↥ޔ‬ᕈ߇㜞޿‫ޕ‬ᷓᐲ 450.0-450.2m ߅ࠃ߮ 621.10-620.25m ߢṁጤߣ⠨߃ࠄࠇࠆ㧔ᨋ߶߆‫ޔ‬2006㧕‫⊒ޕ‬ᵃߒߡ޿ࠆ▎ᚲᓧࠄࠇߚ₵ᱞጤṁጤߩફⷺߪ⃻࿷ߣ߶߷หߓ୯ࠍ␜ߒ‫ޔ‬ߢߪ᳇ሹ߇ቯะ㈩೉ߒ‫ޔ‬30° ೨ᓟߩ௑ᢳ߇␜ໂߐࠇࠆ‫ޕ‬ᱜᏪ⏛ࠍ␜ߔ‫₵ࠄࠇߎޕ‬ᱞጤߩోጤ K-Ar ᐕઍ߇ߘࠇߙ߹ߚ‫ߩߎޔ‬ṁጤࠍ฽߻࿾⾰࡙࠾࠶࠻ F ߩਅㇱߦߪಝἯࠇ 0.31±0.08Ma‫ ޔ‬0.34±0.39Ma ࠍ␜ߔߎߣ߆ࠄ‫ޔ‬Brunhes⾰⍾ጤ߇⹺߼ࠄࠇ‫ߩߘޔ‬ጀℂ㕙ߪ 40° ೨ᓟߩ௑ᢳࠍ␜ᱜ ⏛ ᭂ ᦼ ߦ ኻ Ყ ߐ ࠇ ࠆ‫ ޕ‬ᷓ ᐲ 898.70-898.95m ߢ ᓧ ࠄߔ㧔ᨋ߶߆‫ޔ‬2006㧕
‫ߩߎߒ߽ޕ‬ṁጤ߇ྃ಴ᓟߦ 30° ೨ᓟࠇߚ቟ጊጤṁጤߩફⷺߪ -68 㨪 -78° ߣ߿߿ᷓ޿୯ࠍ␜௑ᢳߒߚߣ઒ቯߔࠆߣ‫⃻߷߶ޔ‬࿷ߣห᭽ߩ✲ᐲߢㅒᏪ⏛ߒ‫ޔ‬ㅒᏪ⏛ߢ޽ࠆ‫ߩߎޕ‬቟ጊጤṁጤߩోጤ K-Ar ᐕઍߪߣ⷗ߥߔߎߣ߇ߢ߈ࠆ‫⹜ߩߎޕ‬ᢱࠍណขߒߚ቟ጊጤߩో

1.45±0.19Ma ߢ޽ࠆߎߣ߆ࠄ‫ޔ‬Matuyama ㅒ⏛ᭂᦼߦኻጤ K-Ar ᐕઍ߇ 1.45±0.19Ma ߢ޽ࠆߎߣ߆ࠄ㧔ᩉᴛ߶߆‫ޔ‬Ყߐࠇࠆ‫ޕ‬2005㧕
‫ߩߎޔ‬ጀḰߪ Matuyama ㅒ⏛ᭂᦼߦ⋧ᒰߔࠆ߽ߩߣ⠨߃ࠄࠇࠆ‫⹜ޕ‬ᢱ 4 ߣ 5 ߩ㑆ߦߪᐕઍ߅ࠃ߮᭴ㅧߦ

⻢ㄉࠡࡖ࠶ࡊ߇⹺߼ࠄࠇࠆߎߣ߆ࠄ‫ޔ‬ਇᢛว߹ߚߪᢿጀ߇ሽ‫ޓ‬એਅߩᣇ‫ޔߪߦޘ‬ጊർධ᷹ⷰ੗ߢᓧࠄࠇߚࠦࠕ⹜ᢱߦ࿷ߔࠆน⢻ᕈ߇㜞޿‫ޕ‬ߟ޿ߡ‫ޔ‬⃻࿾ⷰኤળ߿ࠦࠕⷰኤળ╬ߩ႐ߢߏ⸛⺰㗂޿ߚ‫ޕ‬ජ⪲ᄢቇદ⮮⼱↢ᢎ᝼‫ޔ‬ችౝፏ⵨ᢎ᝼‫ޔ‬ᵤਭ੗㓷ᔒಎᢎዊጊ⌀ੱ 1986 દ⼺ඨፉߩ࿾ผߣ⿷ᨩ࡮ᄢ⏷࿾ၞߩᦝ᝼‫ޔ‬ㇺ⇐ᢥ⑼ᄢቇ਄᧖‫ޓ‬㓁ฬ⹷ᢎ᝼‫ޔ‬㒐ἴ⑼ቇᛛⴚ⎇ⓥ

ᣂ਎‫᦬ޔ‬ೀ࿾⃿‫ ޔ‬743-752.

ᚲጊ᳓ผ↢ඳ჻‫ޔ‬ጊ↰㓉ੑඳ჻‫↥ޔ‬ᬺᛛⴚ✚ว⎇ⓥᚲᩉ

Kuno, H. 1950) Geology of Hakone volcano andᴛᐘᄦඳ჻‫ޔ‬㜞ᯅ㓷♿ඳ჻‫ޔ‬ᷰㄝ⌀ੱඳ჻‫⹜ޕ‬ᢱណข߿adjacent areas, part I, Jour. Fac. Sci. Univ. Tokyo,᷹ቯߦߪ‫ޔ‬ජ⪲ᄢቇ߅ࠃ߮ፉᩮᄢቇߩቇ↢࡮㒮↢ߩ⊝᭽

ser. II,  257-279.

ߦߏදജ㗂޿ߚ‫ޕ‬ᗵ⻢↳ߒ਄ߍ߹ߔ‫ޕ‬㐳੗㓷ผ࡮㜞ᯅᱜ᮸ 2000  ▫ᩮฎᦼᄖベጊߩᒻᚑผ‫ޔ‬‫⎇ᧄޓ‬ⓥߪ 2002 㨪 2006 ᐕᐲߦ߆ߌߡታᣉߐࠇߚᢥㇱ⑼ᐔᚑ 11 ᐕᐲ᧲੩ᄢቇ࿾㔡⎇ⓥᚲ⎇ⓥ㓸ળႎ๔ᦠ‫ޟ‬ንቇ⋭ߩ⎇ⓥᆔ⸤੐ᬺ RR2002࡮ᄢㇺᏒᄢ㔡ἴシᷫൻ․೎჻࡮▫ᩮ߅ࠃ߮๟ㄝἫጊߦ߅ߌࠆྃἫ㐳ᦼ੍᷹ߩߚࡊࡠࠫࠚࠢ࠻ I ߩ‫ޔ‬ᄢㇺᏒ࿤࿾Ზ᭴ㅧ⺞ᩏ⎇ⓥ㧔⎇ⓥઍ

߼ߩ⎇ⓥ㓸ળ‫ޠ‬‫ޔ‬37-46.

⴫⠪㧦᧲੩ᄢቇ࿾㔡⎇ⓥᚲ‫ޓ‬ᐔ↰‫⋥ޓ‬ᢎ᝼㧕ߩ৻Ⅳߣߒᣣᧄ࿾⾰ቇળ࿖┙౏࿦࿾⾰࡝࡯ࡈ࡟࠶࠻✬㓸ᆔຬળߡⴕࠊࠇߚ‫ޕ‬2007) 1.▫ᩮἫጊ㧚ᣣᧄ࿾⾰ቇળ㧚
Okada, H. and Bukry, D. 1980) Supplementaryෳ⠨ᢥ₂PRGL¿FDWLRQ and introduction of code numbers to theᨋ‫ޓ‬ᐢ᮸࡮દ⮮⼱↢࡮਄᧖‫ޓ‬㓁࡮ዊጊ↰ᶈሶ࡮═ේᢘม࡮

low-latitude coccolith biostratigraphic zonation Bukry,1973; 1975), Mar. Micropaleont., 321-325.

㑐ญᷤᰴ࡮㜞ᯅ㓷♿࡮↰ਛ⵨৻㇢࡮ᵤਭ੗㓷ᔒ࡮᧻੗ᥓਯ࡮᧻ᧄᜏᏆ࡮ጊፒ‫ޓ‬ఝ࡮ጊ↰㓉ੑ࡮ጊ᳓ผ↢࡮ᵤਭ੗㓷ᔒ࡮ጊፒ‫ޓ‬ఝ࡮᧻੗ᥓਯ࡮ዊጊ↰ᶈሶ࡮਄᧖‫ޓ‬㓁࡮ᩉᴛᐘᄦ࡮ᷰㄝ⌀ੱ 2006 ␹ᄹᎹ⋵⷏ㇱጊർධ㜞ᨋ‫ޓ‬ᐢ᮸࡮ᩉᴛᐘᄦ࡮═ේᢘม 2006 દ⼺ᒐർ┵ᗵᐲ࿾㔡᷹ⷰ੗ߩជ೥߅ࠃ߮ሹౝᬌጀ‫ޔ‬㒐ἴ⑼⎇⎇ߩἫጊጤ㘃ߣ࿾Ზ᭴ㅧ㧙ጊർධᄢᷓᐲ᷹ⷰ੗ߩ▫ᩮⓥ⾗ᢱ‫ޔ‬298, 1-32.

Ἣጊ‫ޔ‬వ▫ᩮἫጊጤ㘃߆ࠄ㧙‫ޔ‬࿾⺞⎇ႎ‫ ޔ‬197-═ේᢘม࡮ᨋ‫ޓ‬ᐢ᮸࡮㑐ญᷤᰴ 2004 દ⼺㧙ਤᴛⴣ⓭215.

ၞߦᧂ⊒⷗ A ⚖ᵴᢿጀߩሽ࿷⏕ታ㧙␹ᄹᎹ⋵ጊർYamazaki, H. 1992) Techtonics of a plate collision↸ߦ߅ߌࠆ 2000m ជ೥ㅦႎ㧙‫ޔ‬ᣣᧄ࿾⾰ቇળ╙ 111

along the northern margin of Izu Peninsula, centralᐕቇⴚᄢળ⻠Ṷⷐᣦ‫ޔ‬S-4㧚

Japan, Bull. Geol. Surv. Japan, 603-657.

Kato, T. 1985MS) Geology and petrology of the northᩉᴛᐘᄦ࡮㜞ᯅ㓷♿࡮ᷰㄝ⌀ੱ࡮↰ਛ⵨৻㇢࡮ᨋ‫ޓ‬ᐢ᮸

and west old somma of Hakone volcano, Japan.

2005 ᄢᷓᐲࡏ࡯࡝ࡦࠣ⹜ᢱߦࠃࠆ࿾⾰ᐕઍ⺞ᩏ‫ޔ‬Masterʼs thesis, University of Tokyo, 106p.

ᄢㇺᏒᄢ㔡ἴシᷫൻ․೎ࡊࡠࠫࠚࠢ࠻ 1㧦࿾㔡േ㧔ᒝ޿ំࠇ㧕ߩ੍᷹‫ޟ‬ᄢㇺᏒ࿤࿾Ზ᭴ㅧ⺞ᩏ⎇ⓥ‫ޠ‬㧔ᐔ

Kirschvink, J.L. 1980) The latest squares line and planeᚑ 16 ᐕᐲ㧕ᚑᨐႎ๔ᦠ‫ޔ‬337-358㧚

and the analysis of paleomagnetic data, Geophys.
Jour. Roy. Aust. Soc.,  699-718.

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