A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia
Although hydrocarbon-bearing fluids have been known from the alkaline igneous rocks of the Khibiny intrusion for many years, their origin remains enigmatic. A recently proposed model of post-magmatic HC generation through Fischer-Tropsch type reactions suggests a primary CO2 fluid. This hypothesis i...
Published in: | Lithos |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Elsevier
2006
|
Subjects: | |
Online Access: | https://eprints.kingston.ac.uk/id/eprint/1779/ https://doi.org/10.1016/j.lithos.2006.03.006 |
id |
ftunivkingston:oai:eprints.kingston.ac.uk:1779 |
---|---|
record_format |
openpolar |
spelling |
ftunivkingston:oai:eprints.kingston.ac.uk:1779 2023-05-15T17:05:04+02:00 A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia Beeskow, B. Treloar, P.J. Rankin, A.H. Vennemann, T.W. Spangenberg, J. 2006-10 https://eprints.kingston.ac.uk/id/eprint/1779/ https://doi.org/10.1016/j.lithos.2006.03.006 unknown Elsevier Beeskow, B., Treloar, P.J., Rankin, A.H., Vennemann, T.W. and Spangenberg, J. (2006) A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia. Lithos, 91(1-4), pp. 1-18. ISSN (print) 0024-4937 Earth systems and environmental sciences hydrocarbons Fischer-Tropsch synthesis alkaline igneous complex abiogenic Khibiny alkaline igneous rocks isotopic evidence fluid inclusions nw Russia origin Lovozero genesis methane carbon Article PeerReviewed 2006 ftunivkingston https://doi.org/10.1016/j.lithos.2006.03.006 2022-09-29T22:25:03Z Although hydrocarbon-bearing fluids have been known from the alkaline igneous rocks of the Khibiny intrusion for many years, their origin remains enigmatic. A recently proposed model of post-magmatic HC generation through Fischer-Tropsch type reactions suggests a primary CO2 fluid. This hypothesis is based upon textural data, gas bulk and isotopic composition and low entrapment temperature of fluid inclusions that indicate an abiogenic origin for the HC gases. However, new petrographic, microthermometric, laser Raman, bulk gas and isotope data are presented and discussed in the context of previously published work in order to reassess models of HC generation. The gas phase is dominated by CH4 with only minor proportions of higher hydrocarbons. No remnants of the proposed primary CO2-rich fluid are found anywhere in the complex. Primary and secondary fluid inclusions show similar compositions and entrapment conditions. The majority of the fluid inclusions are of secondary nature and trapped in healed microfractures. This indicates a high fluid flux after magma crystallisation. Entrapment condtions for primary fluid inclusions are 450-550°C at 2.8 - 4.5 kbar. These temperatures are too high for HC gas generation through the FT reaction. Chemical analyses of rims of Fe-rich phases suggest that they are not the result of alteration but instead represent changes in magma composition during crystallisation. Furthermore, there is no clear relationship between the presence of Fe-rich minerals and fluid inclusion abundance as reported elsewhere. Fluid inclusion planes generally start and terminate at mineral boundaries . δ13C values for methane range from –22.4 to -5.4‰, confirming also an abiogenic origin for the gas. These data support an abiogenic HC origin, but are not consistent with a post-magmatic FT-type reaction. The presence of primary CH4-dominated fluid and melt inclusions, which contain a methane-rich gas phase, indicate that a magmatic origin is more likely. An increase in methane content, together with a ... Article in Journal/Newspaper kola peninsula Kingston University London: Research Repository Khibiny ENVELOPE(33.210,33.210,67.679,67.679) Kola Peninsula Lovozero ENVELOPE(35.016,35.016,68.006,68.006) Lithos 91 1-4 1 18 |
institution |
Open Polar |
collection |
Kingston University London: Research Repository |
op_collection_id |
ftunivkingston |
language |
unknown |
topic |
Earth systems and environmental sciences hydrocarbons Fischer-Tropsch synthesis alkaline igneous complex abiogenic Khibiny alkaline igneous rocks isotopic evidence fluid inclusions nw Russia origin Lovozero genesis methane carbon |
spellingShingle |
Earth systems and environmental sciences hydrocarbons Fischer-Tropsch synthesis alkaline igneous complex abiogenic Khibiny alkaline igneous rocks isotopic evidence fluid inclusions nw Russia origin Lovozero genesis methane carbon Beeskow, B. Treloar, P.J. Rankin, A.H. Vennemann, T.W. Spangenberg, J. A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
topic_facet |
Earth systems and environmental sciences hydrocarbons Fischer-Tropsch synthesis alkaline igneous complex abiogenic Khibiny alkaline igneous rocks isotopic evidence fluid inclusions nw Russia origin Lovozero genesis methane carbon |
description |
Although hydrocarbon-bearing fluids have been known from the alkaline igneous rocks of the Khibiny intrusion for many years, their origin remains enigmatic. A recently proposed model of post-magmatic HC generation through Fischer-Tropsch type reactions suggests a primary CO2 fluid. This hypothesis is based upon textural data, gas bulk and isotopic composition and low entrapment temperature of fluid inclusions that indicate an abiogenic origin for the HC gases. However, new petrographic, microthermometric, laser Raman, bulk gas and isotope data are presented and discussed in the context of previously published work in order to reassess models of HC generation. The gas phase is dominated by CH4 with only minor proportions of higher hydrocarbons. No remnants of the proposed primary CO2-rich fluid are found anywhere in the complex. Primary and secondary fluid inclusions show similar compositions and entrapment conditions. The majority of the fluid inclusions are of secondary nature and trapped in healed microfractures. This indicates a high fluid flux after magma crystallisation. Entrapment condtions for primary fluid inclusions are 450-550°C at 2.8 - 4.5 kbar. These temperatures are too high for HC gas generation through the FT reaction. Chemical analyses of rims of Fe-rich phases suggest that they are not the result of alteration but instead represent changes in magma composition during crystallisation. Furthermore, there is no clear relationship between the presence of Fe-rich minerals and fluid inclusion abundance as reported elsewhere. Fluid inclusion planes generally start and terminate at mineral boundaries . δ13C values for methane range from –22.4 to -5.4‰, confirming also an abiogenic origin for the gas. These data support an abiogenic HC origin, but are not consistent with a post-magmatic FT-type reaction. The presence of primary CH4-dominated fluid and melt inclusions, which contain a methane-rich gas phase, indicate that a magmatic origin is more likely. An increase in methane content, together with a ... |
format |
Article in Journal/Newspaper |
author |
Beeskow, B. Treloar, P.J. Rankin, A.H. Vennemann, T.W. Spangenberg, J. |
author_facet |
Beeskow, B. Treloar, P.J. Rankin, A.H. Vennemann, T.W. Spangenberg, J. |
author_sort |
Beeskow, B. |
title |
A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
title_short |
A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
title_full |
A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
title_fullStr |
A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
title_full_unstemmed |
A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia |
title_sort |
reassessment of models for hydrocarbon generation in the khibiny nepheline syenite complex, kola peninsula, russia |
publisher |
Elsevier |
publishDate |
2006 |
url |
https://eprints.kingston.ac.uk/id/eprint/1779/ https://doi.org/10.1016/j.lithos.2006.03.006 |
long_lat |
ENVELOPE(33.210,33.210,67.679,67.679) ENVELOPE(35.016,35.016,68.006,68.006) |
geographic |
Khibiny Kola Peninsula Lovozero |
geographic_facet |
Khibiny Kola Peninsula Lovozero |
genre |
kola peninsula |
genre_facet |
kola peninsula |
op_relation |
Beeskow, B., Treloar, P.J., Rankin, A.H., Vennemann, T.W. and Spangenberg, J. (2006) A reassessment of models for hydrocarbon generation in the Khibiny nepheline syenite complex, Kola Peninsula, Russia. Lithos, 91(1-4), pp. 1-18. ISSN (print) 0024-4937 |
op_doi |
https://doi.org/10.1016/j.lithos.2006.03.006 |
container_title |
Lithos |
container_volume |
91 |
container_issue |
1-4 |
container_start_page |
1 |
op_container_end_page |
18 |
_version_ |
1766059443262324736 |