The Jabal Akhdar Dome in the Oman Mountains

evolution of a dynamic fracture system

E. Gomez Rivas, P. D. Bons, D. Koehn, J. L. Urai, M. Arndt, S. Virgo, B. Laurich, C. Zeeb, L. Stark, P. Blum

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Abstract

The Mesozoic succession of the Jabal Akhdar dome in the Oman Mountains hosts complex networks of fractures and veins in carbonates, which are a clear example of dynamic fracture opening and sealing in a highly overpressured system. The area underwent several tectonic events during the Late Cretaceous and Cenozoic, including the obduction of the Samail ophiolite and Hawasina nappes, followed by uplift and compression due to the Arabia-Eurasia convergence. This study presents the results of an extensive tectonic survey, and correlates subseismic-scale structures in Jabal Akhdar (faults, fractures, veins and stylolites) with the main tectonic events in the Northeastern Arabian plate. As some of the studied formations host large oil reserves in neighboring areas, determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs. The formation of early veins and stylolites in the Oman Mountains is followed by top-to-the-South layer-parallel shearing that may be associated with the obduction of the Samail and Hawasina nappes. This compressional tectonic event is followed by normal (dip-slip) to oblique-slip faults and veins. Top-to-the-Northeast layer-parallel shearing, which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures. Our new data indicate that this first phase of events is overprinted by complex strike-slip networks of veins and fractures, as well as by the reactivation and onset of seismic-scale faults. Strike-slip structures belong to three distinct events. The first one (NW-SE-oriented compression) is probably associated with the oblique collision of the Indian plate against the Arabian platform during the Late Campanian to the Mid Eocene. The second event (E-W-oriented compression) is likely to have been formed during the Late Oligocene-Middle Miocene during uplift. The last event (NE-SW-oriented compression) probably took place during the Miocene-Pliocene. Structures of the first two strike-slip events have the same orientation as seismic-scale faults observed in the subsurface of Oman and Abu Dhabi. In addition, increasing vein intensity towards the top of the autochthonous formations in the Oman mountains, as well as the small angle between conjugate vein sets, indicate that high fluid pressures that are thought to be present during strike-slip deformation.
Original languageEnglish
Pages (from-to)1104-1139
Number of pages36
JournalAmerican Journal of Science
Volume314
Issue number7
DOIs
Publication statusPublished - Sep 2014

Fingerprint

dome
mountain
compression
tectonics
obduction
nappe
uplift
Miocene
Arabian plate
dip-slip fault
Indian plate
fault slip
fluid pressure
Campanian
sealing
ophiolite
reactivation
exhumation
rock
Oligocene

Keywords

  • fracture
  • vein
  • crack-seal
  • fluid pressure
  • Arabian Plate
  • paleostress

Cite this

The Jabal Akhdar Dome in the Oman Mountains : evolution of a dynamic fracture system. / Gomez Rivas, E.; Bons, P. D.; Koehn, D.; Urai, J. L.; Arndt, M.; Virgo, S.; Laurich, B.; Zeeb, C.; Stark, L.; Blum, P.

In: American Journal of Science, Vol. 314, No. 7, 09.2014, p. 1104-1139.

Research output: Contribution to journalArticle

Gomez Rivas, E, Bons, PD, Koehn, D, Urai, JL, Arndt, M, Virgo, S, Laurich, B, Zeeb, C, Stark, L & Blum, P 2014, 'The Jabal Akhdar Dome in the Oman Mountains: evolution of a dynamic fracture system', American Journal of Science, vol. 314, no. 7, pp. 1104-1139. https://doi.org/10.2475/07.2014.02
Gomez Rivas, E. ; Bons, P. D. ; Koehn, D. ; Urai, J. L. ; Arndt, M. ; Virgo, S. ; Laurich, B. ; Zeeb, C. ; Stark, L. ; Blum, P. / The Jabal Akhdar Dome in the Oman Mountains : evolution of a dynamic fracture system. In: American Journal of Science. 2014 ; Vol. 314, No. 7. pp. 1104-1139.
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abstract = "The Mesozoic succession of the Jabal Akhdar dome in the Oman Mountains hosts complex networks of fractures and veins in carbonates, which are a clear example of dynamic fracture opening and sealing in a highly overpressured system. The area underwent several tectonic events during the Late Cretaceous and Cenozoic, including the obduction of the Samail ophiolite and Hawasina nappes, followed by uplift and compression due to the Arabia-Eurasia convergence. This study presents the results of an extensive tectonic survey, and correlates subseismic-scale structures in Jabal Akhdar (faults, fractures, veins and stylolites) with the main tectonic events in the Northeastern Arabian plate. As some of the studied formations host large oil reserves in neighboring areas, determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs. The formation of early veins and stylolites in the Oman Mountains is followed by top-to-the-South layer-parallel shearing that may be associated with the obduction of the Samail and Hawasina nappes. This compressional tectonic event is followed by normal (dip-slip) to oblique-slip faults and veins. Top-to-the-Northeast layer-parallel shearing, which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures. Our new data indicate that this first phase of events is overprinted by complex strike-slip networks of veins and fractures, as well as by the reactivation and onset of seismic-scale faults. Strike-slip structures belong to three distinct events. The first one (NW-SE-oriented compression) is probably associated with the oblique collision of the Indian plate against the Arabian platform during the Late Campanian to the Mid Eocene. The second event (E-W-oriented compression) is likely to have been formed during the Late Oligocene-Middle Miocene during uplift. The last event (NE-SW-oriented compression) probably took place during the Miocene-Pliocene. Structures of the first two strike-slip events have the same orientation as seismic-scale faults observed in the subsurface of Oman and Abu Dhabi. In addition, increasing vein intensity towards the top of the autochthonous formations in the Oman mountains, as well as the small angle between conjugate vein sets, indicate that high fluid pressures that are thought to be present during strike-slip deformation.",
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author = "{Gomez Rivas}, E. and Bons, {P. D.} and D. Koehn and Urai, {J. L.} and M. Arndt and S. Virgo and B. Laurich and C. Zeeb and L. Stark and P. Blum",
note = "Acknowledgments: This study was carried out within the framework of DGMK (German Society for Petroleum and Coal Science and Technology) research project 718 “Mineral Vein Dynamics Modelling,” which is funded by the companies ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, RWE Dea AG and Wintershall Holding GmbH, within the basic research program of the WEG Wirtschaftsverband Erdo¨l- und Erdgasgewinnung e.V. We thank the companies for their financial support and their permission to publish these results. The German University of Technology in Oman (GU-Tech) is acknowledged for its logistic support. We gratefully acknowledge the reviewers Andrea Billi and Jean-Paul Breton, whose constructive reviews greatly improved the manuscript",
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AU - Stark, L.

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N1 - Acknowledgments: This study was carried out within the framework of DGMK (German Society for Petroleum and Coal Science and Technology) research project 718 “Mineral Vein Dynamics Modelling,” which is funded by the companies ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, RWE Dea AG and Wintershall Holding GmbH, within the basic research program of the WEG Wirtschaftsverband Erdo¨l- und Erdgasgewinnung e.V. We thank the companies for their financial support and their permission to publish these results. The German University of Technology in Oman (GU-Tech) is acknowledged for its logistic support. We gratefully acknowledge the reviewers Andrea Billi and Jean-Paul Breton, whose constructive reviews greatly improved the manuscript

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N2 - The Mesozoic succession of the Jabal Akhdar dome in the Oman Mountains hosts complex networks of fractures and veins in carbonates, which are a clear example of dynamic fracture opening and sealing in a highly overpressured system. The area underwent several tectonic events during the Late Cretaceous and Cenozoic, including the obduction of the Samail ophiolite and Hawasina nappes, followed by uplift and compression due to the Arabia-Eurasia convergence. This study presents the results of an extensive tectonic survey, and correlates subseismic-scale structures in Jabal Akhdar (faults, fractures, veins and stylolites) with the main tectonic events in the Northeastern Arabian plate. As some of the studied formations host large oil reserves in neighboring areas, determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs. The formation of early veins and stylolites in the Oman Mountains is followed by top-to-the-South layer-parallel shearing that may be associated with the obduction of the Samail and Hawasina nappes. This compressional tectonic event is followed by normal (dip-slip) to oblique-slip faults and veins. Top-to-the-Northeast layer-parallel shearing, which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures. Our new data indicate that this first phase of events is overprinted by complex strike-slip networks of veins and fractures, as well as by the reactivation and onset of seismic-scale faults. Strike-slip structures belong to three distinct events. The first one (NW-SE-oriented compression) is probably associated with the oblique collision of the Indian plate against the Arabian platform during the Late Campanian to the Mid Eocene. The second event (E-W-oriented compression) is likely to have been formed during the Late Oligocene-Middle Miocene during uplift. The last event (NE-SW-oriented compression) probably took place during the Miocene-Pliocene. Structures of the first two strike-slip events have the same orientation as seismic-scale faults observed in the subsurface of Oman and Abu Dhabi. In addition, increasing vein intensity towards the top of the autochthonous formations in the Oman mountains, as well as the small angle between conjugate vein sets, indicate that high fluid pressures that are thought to be present during strike-slip deformation.

AB - The Mesozoic succession of the Jabal Akhdar dome in the Oman Mountains hosts complex networks of fractures and veins in carbonates, which are a clear example of dynamic fracture opening and sealing in a highly overpressured system. The area underwent several tectonic events during the Late Cretaceous and Cenozoic, including the obduction of the Samail ophiolite and Hawasina nappes, followed by uplift and compression due to the Arabia-Eurasia convergence. This study presents the results of an extensive tectonic survey, and correlates subseismic-scale structures in Jabal Akhdar (faults, fractures, veins and stylolites) with the main tectonic events in the Northeastern Arabian plate. As some of the studied formations host large oil reserves in neighboring areas, determining the relative timing of these events in the exhumed rocks is important to understand hydrocarbon distribution and fracture patterns in these reservoirs. The formation of early veins and stylolites in the Oman Mountains is followed by top-to-the-South layer-parallel shearing that may be associated with the obduction of the Samail and Hawasina nappes. This compressional tectonic event is followed by normal (dip-slip) to oblique-slip faults and veins. Top-to-the-Northeast layer-parallel shearing, which corresponds to the first stage of exhumation of the autochthonous rocks offsets these structures. Our new data indicate that this first phase of events is overprinted by complex strike-slip networks of veins and fractures, as well as by the reactivation and onset of seismic-scale faults. Strike-slip structures belong to three distinct events. The first one (NW-SE-oriented compression) is probably associated with the oblique collision of the Indian plate against the Arabian platform during the Late Campanian to the Mid Eocene. The second event (E-W-oriented compression) is likely to have been formed during the Late Oligocene-Middle Miocene during uplift. The last event (NE-SW-oriented compression) probably took place during the Miocene-Pliocene. Structures of the first two strike-slip events have the same orientation as seismic-scale faults observed in the subsurface of Oman and Abu Dhabi. In addition, increasing vein intensity towards the top of the autochthonous formations in the Oman mountains, as well as the small angle between conjugate vein sets, indicate that high fluid pressures that are thought to be present during strike-slip deformation.

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KW - vein

KW - crack-seal

KW - fluid pressure

KW - Arabian Plate

KW - paleostress

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DO - 10.2475/07.2014.02

M3 - Article

VL - 314

SP - 1104

EP - 1139

JO - American Journal of Science

JF - American Journal of Science

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