Modelling hydrothermal venting in volcanic sedimentary basins

Impact on hydrocarbon maturation and paleoclimate

Karthik Iyer*, Daniel W. Schmid, Sverre Planke, John Millett

*Corresponding author for this work

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Wring and More Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Voring and More Basins alone and that a contribution from other regions in the NAIP is also required to drive catastrophic climate change. 

Original languageEnglish
Pages (from-to)30-42
Number of pages13
JournalEarth and Planetary Science Letters
Volume467
Early online date30 Mar 2017
DOIs
Publication statusPublished - 1 Jun 2017

Keywords

  • sill intrusions in sedimentary basins
  • numerical model
  • hydrothermal vent complex
  • PETM
  • methane generation
  • hydrocarbons

Cite this

Modelling hydrothermal venting in volcanic sedimentary basins : Impact on hydrocarbon maturation and paleoclimate. / Iyer, Karthik; Schmid, Daniel W.; Planke, Sverre; Millett, John.

In: Earth and Planetary Science Letters, Vol. 467, 01.06.2017, p. 30-42.

Research output: Contribution to journalArticle

@article{361733bdc913473da555f8ef6d7ec3d0,
title = "Modelling hydrothermal venting in volcanic sedimentary basins: Impact on hydrocarbon maturation and paleoclimate",
abstract = "Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16{\%}) of the methane generated at depth. Upscaling to the Wring and More Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Voring and More Basins alone and that a contribution from other regions in the NAIP is also required to drive catastrophic climate change. ",
keywords = "sill intrusions in sedimentary basins, numerical model, hydrothermal vent complex, PETM, methane generation, hydrocarbons",
author = "Karthik Iyer and Schmid, {Daniel W.} and Sverre Planke and John Millett",
note = "Acknowledgments The authors would like thank Shell Norge for the use of seismic data and permission to publish part of the work based on a case study in the Harstad Basin. The authors would also like to thank the editor and reviewer for their constructive comments.",
year = "2017",
month = "6",
day = "1",
doi = "10.1016/j.epsl.2017.03.023",
language = "English",
volume = "467",
pages = "30--42",
journal = "Earth and Planetary Science Letters",
issn = "0012-821X",
publisher = "ELSEVIER SCIENCE BV",

}

TY - JOUR

T1 - Modelling hydrothermal venting in volcanic sedimentary basins

T2 - Impact on hydrocarbon maturation and paleoclimate

AU - Iyer, Karthik

AU - Schmid, Daniel W.

AU - Planke, Sverre

AU - Millett, John

N1 - Acknowledgments The authors would like thank Shell Norge for the use of seismic data and permission to publish part of the work based on a case study in the Harstad Basin. The authors would also like to thank the editor and reviewer for their constructive comments.

PY - 2017/6/1

Y1 - 2017/6/1

N2 - Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Wring and More Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Voring and More Basins alone and that a contribution from other regions in the NAIP is also required to drive catastrophic climate change. 

AB - Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Wring and More Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Voring and More Basins alone and that a contribution from other regions in the NAIP is also required to drive catastrophic climate change. 

KW - sill intrusions in sedimentary basins

KW - numerical model

KW - hydrothermal vent complex

KW - PETM

KW - methane generation

KW - hydrocarbons

U2 - 10.1016/j.epsl.2017.03.023

DO - 10.1016/j.epsl.2017.03.023

M3 - Article

VL - 467

SP - 30

EP - 42

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

ER -