Organic geochemistry of hydrothermal petroleum generated in the submarine Wakamiko caldera, southern Kyushu, Japan

Toshiro Yamanaka, Junichiro Ishibashi, Jun Hashimoto

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

Four sediments impregnated with hydrothermal petroleum were dredged from the shallow seafloor (≃ 200 m) of the submarine Wakamiko caldera in northern Kagoshima Bay, southern Kyushu, Japan. Their organic geochemical parameters were studied. The hydrothermal petroleums were characterized by higher Pr/n-C17 and Ph/n-C18 ratios and lower phenanthrene/methylphenanthrene ratios than hydrothermal oils known from comparable seafloor hydrothermal systems around the world. The former characteristic is interpreted to reflect the large contribution of unaltered terrigenous organic matter because of the shallow water depth and land proximity of the caldera. The latter characteristic indicates high maturity rather than simple pyrolysis of the source organic matter. Furthermore, the input of components from thermally-unaltered sediment and mild biodegradation are evident in the oil compositions. Among the collected samples, differences in hydrocarbon compositions between lithified sediments and normal shallow sea muds were notable. The lithified sediments had higher maturity levels for the sterane and triterpane distributions of the petroleums. Higher BeP/BaP [benzo(e)pyrene/benzene(a)pyrene] ratios suggest that petroleums in the lithified sediments are more altered, because the ratio reflects the extent of secondary oxidation and/or thermal loss of BaP once formed. These organic geochemical parameters suggest that the lithification sediments are derived from a significant depth below the seafloor and had erupted recently onto the seafloor. The frequent eruptions would enhance organic maturations and lithification of sediment and transport of subsurface sediment to the seafloor. (C) 2000 Elsevier Science Ltd.

Original languageEnglish
Pages (from-to)1117-1132
Number of pages16
JournalOrganic Geochemistry
Volume31
Issue number11
DOIs
Publication statusPublished - Nov 2000
Externally publishedYes

Fingerprint

organic geochemistry
Geochemistry
Petroleum
caldera
Sediments
petroleum
seafloor
sediment
lithification
pyrene
Biological materials
Oils
organic matter
oil
phenanthrene
Hydrocarbons
hydrothermal system
Biodegradation
Benzene
Chemical analysis

Keywords

  • Biomarkers
  • Eruption
  • Hydrothermal petroleum
  • Phenanthrene to methylphenanthrene ratio
  • Phytane
  • Polycyclic aromatic hydrocarbons
  • Pristane
  • Sakurajima volcano
  • Wakamiko caldera

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Organic geochemistry of hydrothermal petroleum generated in the submarine Wakamiko caldera, southern Kyushu, Japan. / Yamanaka, Toshiro; Ishibashi, Junichiro; Hashimoto, Jun.

In: Organic Geochemistry, Vol. 31, No. 11, 11.2000, p. 1117-1132.

Research output: Contribution to journalArticle

Yamanaka, Toshiro ; Ishibashi, Junichiro ; Hashimoto, Jun. / Organic geochemistry of hydrothermal petroleum generated in the submarine Wakamiko caldera, southern Kyushu, Japan. In: Organic Geochemistry. 2000 ; Vol. 31, No. 11. pp. 1117-1132.
@article{f0aa1c55e6624255970faafed3bb0c57,
title = "Organic geochemistry of hydrothermal petroleum generated in the submarine Wakamiko caldera, southern Kyushu, Japan",
abstract = "Four sediments impregnated with hydrothermal petroleum were dredged from the shallow seafloor (≃ 200 m) of the submarine Wakamiko caldera in northern Kagoshima Bay, southern Kyushu, Japan. Their organic geochemical parameters were studied. The hydrothermal petroleums were characterized by higher Pr/n-C17 and Ph/n-C18 ratios and lower phenanthrene/methylphenanthrene ratios than hydrothermal oils known from comparable seafloor hydrothermal systems around the world. The former characteristic is interpreted to reflect the large contribution of unaltered terrigenous organic matter because of the shallow water depth and land proximity of the caldera. The latter characteristic indicates high maturity rather than simple pyrolysis of the source organic matter. Furthermore, the input of components from thermally-unaltered sediment and mild biodegradation are evident in the oil compositions. Among the collected samples, differences in hydrocarbon compositions between lithified sediments and normal shallow sea muds were notable. The lithified sediments had higher maturity levels for the sterane and triterpane distributions of the petroleums. Higher BeP/BaP [benzo(e)pyrene/benzene(a)pyrene] ratios suggest that petroleums in the lithified sediments are more altered, because the ratio reflects the extent of secondary oxidation and/or thermal loss of BaP once formed. These organic geochemical parameters suggest that the lithification sediments are derived from a significant depth below the seafloor and had erupted recently onto the seafloor. The frequent eruptions would enhance organic maturations and lithification of sediment and transport of subsurface sediment to the seafloor. (C) 2000 Elsevier Science Ltd.",
keywords = "Biomarkers, Eruption, Hydrothermal petroleum, Phenanthrene to methylphenanthrene ratio, Phytane, Polycyclic aromatic hydrocarbons, Pristane, Sakurajima volcano, Wakamiko caldera",
author = "Toshiro Yamanaka and Junichiro Ishibashi and Jun Hashimoto",
year = "2000",
month = "11",
doi = "10.1016/S0146-6380(00)00119-4",
language = "English",
volume = "31",
pages = "1117--1132",
journal = "Organic Geochemistry",
issn = "0146-6380",
publisher = "Elsevier Limited",
number = "11",

}

TY - JOUR

T1 - Organic geochemistry of hydrothermal petroleum generated in the submarine Wakamiko caldera, southern Kyushu, Japan

AU - Yamanaka, Toshiro

AU - Ishibashi, Junichiro

AU - Hashimoto, Jun

PY - 2000/11

Y1 - 2000/11

N2 - Four sediments impregnated with hydrothermal petroleum were dredged from the shallow seafloor (≃ 200 m) of the submarine Wakamiko caldera in northern Kagoshima Bay, southern Kyushu, Japan. Their organic geochemical parameters were studied. The hydrothermal petroleums were characterized by higher Pr/n-C17 and Ph/n-C18 ratios and lower phenanthrene/methylphenanthrene ratios than hydrothermal oils known from comparable seafloor hydrothermal systems around the world. The former characteristic is interpreted to reflect the large contribution of unaltered terrigenous organic matter because of the shallow water depth and land proximity of the caldera. The latter characteristic indicates high maturity rather than simple pyrolysis of the source organic matter. Furthermore, the input of components from thermally-unaltered sediment and mild biodegradation are evident in the oil compositions. Among the collected samples, differences in hydrocarbon compositions between lithified sediments and normal shallow sea muds were notable. The lithified sediments had higher maturity levels for the sterane and triterpane distributions of the petroleums. Higher BeP/BaP [benzo(e)pyrene/benzene(a)pyrene] ratios suggest that petroleums in the lithified sediments are more altered, because the ratio reflects the extent of secondary oxidation and/or thermal loss of BaP once formed. These organic geochemical parameters suggest that the lithification sediments are derived from a significant depth below the seafloor and had erupted recently onto the seafloor. The frequent eruptions would enhance organic maturations and lithification of sediment and transport of subsurface sediment to the seafloor. (C) 2000 Elsevier Science Ltd.

AB - Four sediments impregnated with hydrothermal petroleum were dredged from the shallow seafloor (≃ 200 m) of the submarine Wakamiko caldera in northern Kagoshima Bay, southern Kyushu, Japan. Their organic geochemical parameters were studied. The hydrothermal petroleums were characterized by higher Pr/n-C17 and Ph/n-C18 ratios and lower phenanthrene/methylphenanthrene ratios than hydrothermal oils known from comparable seafloor hydrothermal systems around the world. The former characteristic is interpreted to reflect the large contribution of unaltered terrigenous organic matter because of the shallow water depth and land proximity of the caldera. The latter characteristic indicates high maturity rather than simple pyrolysis of the source organic matter. Furthermore, the input of components from thermally-unaltered sediment and mild biodegradation are evident in the oil compositions. Among the collected samples, differences in hydrocarbon compositions between lithified sediments and normal shallow sea muds were notable. The lithified sediments had higher maturity levels for the sterane and triterpane distributions of the petroleums. Higher BeP/BaP [benzo(e)pyrene/benzene(a)pyrene] ratios suggest that petroleums in the lithified sediments are more altered, because the ratio reflects the extent of secondary oxidation and/or thermal loss of BaP once formed. These organic geochemical parameters suggest that the lithification sediments are derived from a significant depth below the seafloor and had erupted recently onto the seafloor. The frequent eruptions would enhance organic maturations and lithification of sediment and transport of subsurface sediment to the seafloor. (C) 2000 Elsevier Science Ltd.

KW - Biomarkers

KW - Eruption

KW - Hydrothermal petroleum

KW - Phenanthrene to methylphenanthrene ratio

KW - Phytane

KW - Polycyclic aromatic hydrocarbons

KW - Pristane

KW - Sakurajima volcano

KW - Wakamiko caldera

UR - http://www.scopus.com/inward/record.url?scp=0034325597&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034325597&partnerID=8YFLogxK

U2 - 10.1016/S0146-6380(00)00119-4

DO - 10.1016/S0146-6380(00)00119-4

M3 - Article

AN - SCOPUS:0034325597

VL - 31

SP - 1117

EP - 1132

JO - Organic Geochemistry

JF - Organic Geochemistry

SN - 0146-6380

IS - 11

ER -