25th International Meeting on Organic Geochemistry IMOG 2011

P-478
The first findings of 12- and 13-monomethylalkanes in dispersed
organic matter of Upper Proterozoic and Cambrian of Siberian
platform
Aleksey Kontorovich 1 , Vladimir Kashirtsev 1 , Konstantin Nagovitsin 1 , Pyotr Sobolev 2 ,
Valentina Sukhoruchko 2 , Irina Timoshina 1
1 Institute of Petroleum Geology and Geophysics SB RAS, Novosibirsk, Russian Federation, 2 Siberian
Research Institute of Geology, Geophysics, and Mineral Raw Materials, Novosibirsk, Russian Federation
(corresponding author:TimoshinaID@ipgg.nsc.ru)
Mid-chain branched monomethylalkanes, or 12-
and 13-monomethylalkanes (12- and 13-mma), were
first documented in relatively high concentrations (up
to 18%) in the Upper Proterozoic oils in Siberian
Platform (SP) by A.A. Petrov, O.A. Aref‘ev and others
[1-4 and others]. Later, hydrocarbons from this
homologous series were detected in the Precambrian
oils of Oman [5]. It became evident that this group of
biomarker hydrocarbons characterizes the
biochemistry of lipids of the specific Pre-Cambrian
biota (eukaryotes?) in some ecological niches. In the
Upper Proterozoic oils from SP and Oman [5, 6] apart
from the presence of 12- and 13-mma there were
observed steranes abnormally rich in ethylcholestane
(60-70% per the sum of steranes) [7].
12- and 13-mma were first detected by P.J.
Grantham and others [5] in the dispersed organic
matter of Upper Proterozoic source-rocks in Oman.
Later, O.K. Bazhenova and O.A. Aref‘ev identified
those hydrocarbons in some single samples of the
Upper Proterozoic from East European Platform [8];
however, hydrocarbons from this homologous series
have not been established in oils from this region.
Until present, 12- and 13-mma have not been
observed in dispersed organic matter of Upper
Proterozoic sedimentary rocks in SP [3, 9-11 and
others].
In 2010, first findings of these hydrocarbons were
made by the authors in mudstones of the Kumakha
Formation from the Lakhanda Group (Upper
Proterozoic) in the Maya depression in the southeast
of SP (7.3-9.0% per the sum of alkanes), as well as in
mudstone of the Kuonamka Formation (Lower
Cambrian) in the northeast of SP (18%), and in
Middle Cambrian marls and mudstones in
Nizhneimbakskaya-219 well (about 7%), located
within the Bakhta megasalient in the west of SP.
Thus, there have been discovered possible
sources for the specific Pre-Cambrian oils in the
Siberian Platform. For the first time, hydrocarbons
from 12 - and 13-mma homologous series have been
identified in the Cambrian organic-rich marine rocks.
The latter allows extending the stratigraphic range of
organisms known to have contained structures that
had given birth to mid-chain branched
monomethylalkanes, up to and including Cambrian.
This work was supported by RFBR (10-05-00705),
the Earth Sciences Department Program N 15, the SB
RAS Program (Project VII.59.2), the ESD-1
Programme (Project 2.8), the Interdisciplinary
Integration Project of SB RAS N 36.
References
[1] Aref‘ev, O.A., et al. (1980) Izvestiya AN SSSR,
Ser.geol. (in Russian), N 3, 135-140.
[2] Petrov, A.A. (1984) Hydrocarbons of oil (in
Russian), Moscow, Nauka, 263 p.
[3] Kontorovich, A.E., et al. (1999) Russian Geology
and Geophysics 40, N 11, 1647-1665.
[4] Kontorovich, A.E., et al. (2005) Petroleum
Frontiers 20, N 3, 11-26.
[5] Grantham, P.J., et al. (1988) Journal of Petroleum
Geology 11, 61-80.
[6] Grosjean, E., et al. (2009) Organic Geochemistry
40, 87-110.
[7] Kontorovich, А.E. (2004) Russian Geology and
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[8] Bazhenova, O.K., Aref‘ev, O.A. (1998)
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[9] Kashirtsev, V.A. (2003) Organic Geochemistry of
naphthides of the eastern Siberian Platform (in
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[10] Parfenova, T.M., et al. (2004) Russian Geology
and Geophysics 45, N 7, 862-874.
[11] Timoshina, I.D. (2004) Russian Geology and
Geophysics 45, N 7, 852-861.
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