Advanced

Origin of oil and bitumen in the Late Devonian Siljan impact structure, central Sweden

Ahmed, Manzur; Lehnert, Oliver LU ; Fuentes, David and Meinhold, Guido (2014) In Organic Geochemistry 68. p.13-26
Abstract
Organic geochemical assessment of seep oil from the Upper Ordovician (Hirnantian) Boda Limestone and solid bitumens from the Middle Ordovician (Darriwilian) limestone formations in the Siljan Crater, Sweden indicates their generation primarily from peak oil window maturity, clay-rich marine source rocks that contained aquatic algal organic matter and were deposited in an anoxic environment. Biomarkers indicate some significant differences between the seep oil and solid bitumens and their alteration by moderate to severe biodegradation. The Solberga quarry seep oil from the Boda Limestone and Solberga-1 solid bitumen from the Skarlov-Seby-Folkslunda Limestone equivalents do not show signs of mixing and the similarity in their biomarker... (More)
Organic geochemical assessment of seep oil from the Upper Ordovician (Hirnantian) Boda Limestone and solid bitumens from the Middle Ordovician (Darriwilian) limestone formations in the Siljan Crater, Sweden indicates their generation primarily from peak oil window maturity, clay-rich marine source rocks that contained aquatic algal organic matter and were deposited in an anoxic environment. Biomarkers indicate some significant differences between the seep oil and solid bitumens and their alteration by moderate to severe biodegradation. The Solberga quarry seep oil from the Boda Limestone and Solberga-1 solid bitumen from the Skarlov-Seby-Folkslunda Limestone equivalents do not show signs of mixing and the similarity in their biomarker distributions indicates a genetic relationship. However, solid bitumens recovered from cavities in the underlying Segerstad and Holen limestones were derived predominantly from clay-rich source rocks that contained mixed marine and lacustrine algal organic matter and minor inputs of prokaryotic organic matter, possibly from thin beds of calcareous rocks interbedded within the main clay-rich source rocks. It is inferred that the Siljan Crater seep oil and solid bitumens were generated from the organic rich Upper Ordovician Fjacka Shale, a source rock for economic accumulation of oil in the eastern Baltic region, and/or from Silurian shale units. The presence of various compounds of known biological origin and existence of organic rich Fjacka Shale/Silurian Shale units are consistent with the biogenic origin of Siljan Crater petroleum. Although these seep oil and solid bitumens were generated at peak oil window maturities, the intense heat generated by meteorite impact caused secondary reactions resulting in unusual distributions of maturity sensitive aromatic hydrocarbon isomers and conflicting molecular maturities. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Organic Geochemistry
volume
68
pages
13 - 26
publisher
Elsevier
external identifiers
  • wos:000332403900003
  • scopus:84893389016
ISSN
1873-5290
DOI
10.1016/j.orggeochem.2013.12.010
language
English
LU publication?
yes
id
eb66e7ed-5cff-4a2a-b4af-6e8246166be2 (old id 4417742)
date added to LUP
2014-04-30 12:20:33
date last changed
2017-06-11 03:08:06
@article{eb66e7ed-5cff-4a2a-b4af-6e8246166be2,
  abstract     = {Organic geochemical assessment of seep oil from the Upper Ordovician (Hirnantian) Boda Limestone and solid bitumens from the Middle Ordovician (Darriwilian) limestone formations in the Siljan Crater, Sweden indicates their generation primarily from peak oil window maturity, clay-rich marine source rocks that contained aquatic algal organic matter and were deposited in an anoxic environment. Biomarkers indicate some significant differences between the seep oil and solid bitumens and their alteration by moderate to severe biodegradation. The Solberga quarry seep oil from the Boda Limestone and Solberga-1 solid bitumen from the Skarlov-Seby-Folkslunda Limestone equivalents do not show signs of mixing and the similarity in their biomarker distributions indicates a genetic relationship. However, solid bitumens recovered from cavities in the underlying Segerstad and Holen limestones were derived predominantly from clay-rich source rocks that contained mixed marine and lacustrine algal organic matter and minor inputs of prokaryotic organic matter, possibly from thin beds of calcareous rocks interbedded within the main clay-rich source rocks. It is inferred that the Siljan Crater seep oil and solid bitumens were generated from the organic rich Upper Ordovician Fjacka Shale, a source rock for economic accumulation of oil in the eastern Baltic region, and/or from Silurian shale units. The presence of various compounds of known biological origin and existence of organic rich Fjacka Shale/Silurian Shale units are consistent with the biogenic origin of Siljan Crater petroleum. Although these seep oil and solid bitumens were generated at peak oil window maturities, the intense heat generated by meteorite impact caused secondary reactions resulting in unusual distributions of maturity sensitive aromatic hydrocarbon isomers and conflicting molecular maturities. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.},
  author       = {Ahmed, Manzur and Lehnert, Oliver and Fuentes, David and Meinhold, Guido},
  issn         = {1873-5290},
  language     = {eng},
  pages        = {13--26},
  publisher    = {Elsevier},
  series       = {Organic Geochemistry},
  title        = {Origin of oil and bitumen in the Late Devonian Siljan impact structure, central Sweden},
  url          = {http://dx.doi.org/10.1016/j.orggeochem.2013.12.010},
  volume       = {68},
  year         = {2014},
}