25th International Meeting on Organic Geochemistry IMOG 2011

P-079
Geochemistry of ―just generated‖ oils from Uzon volcano
caldera(Kamchatka) in comparison with oldest pre-Cambrian
oils
Enver Ablya, Irina Slivko
Moscow State University, Moscow, Russian Federation (corresponding author:eablya@yandex.ru)
Uzon volcanic caldera is the largest geothermal
field located in the eastern part of Kamchatka,
Russia. Some hot springs and lakes are notable,
because some are highly acidic and are location
of the occurrence of specific algae and
extremophile. But it is also amazing place of the
generation and occurrence of ―youngest‖ oils. This
oils appear as stains on solutions surface and
quickly evanesce, some oils saturates sediments
around geothermal fields. We studied different oil
samples collected periodically at the same place –
near highly acidic and hot lake. Oils have different
phase from diesel type to very waxy . Oils have
different HC distribution - some as marine type with
prevalence of normal alkanes and Pr/Ph ratio
around 1, and some with prevalence of iso-alkanes
with unusual Pr/Ph ratios less then 0.5-0.3.
Surprisingly that some oils have unusual HC‘s as-
12-and13-methylalkanes. The distribution of
terpanes are characterised by different
concentrations of tri- and tetracyclic - some oils with
low but some – with sharp high value of the C19/C23
ratios; all oils with predominance of the C30hopane
over the C29-norhopane. In some oils
prevalence of C 32 and C 35 homo-hopanes
Saturate and aromatic fractions of Uzon oils are
characterized by polar �13C values from –27‰ to
–34‰. Based on biomarker parameters (steranes,
Ts/Tm, 4-MDBT/1 MDBT, the thermal maturity of
Uzon oils is assessed as low or non-mature ( Fig.
1-2, GC-MS -m/z 217). Oils have relatively low
concentrations of C26 tri and C27 monoaromatic HC
and abundant dibenzotiophen. Distribution of
steranes are also unusual with a significant
predominance of C29 , less C28 and very low C27
steranes (Fig 1-2) . Very interesting that Uzon oils
not content trace elements excluding a hundred
ppm content of As among studied tens usual oils.
We discovered that some Proterozoic (PR) sourced
oils in East Siberia have geochemical fingerprints
similar to those found in some Uzon oils. These PR
oils are characterised by a dominance of C29
steranes ( fig.3), and the occurrence of 12- and 13methylalkanes.
PR oils are characterized by �13C
values around – 33 ‰. . It must be note that some
oldest pre-Cambrian oils from East Siberia and
Paleozoic oils from West Siberia also shows
considerable content of As.
So it believes that this Uzon oils ―just‖
generated by high plant fossils, algae with ―help‖ of
bacteria in boiling toxic geothermal solutions.
Extremophiles are believed to have been some of
the earliest lifeforms on earth, since such early
organisms would have to be adapted to harsh
conditions, for example, Picrophilus torridus, an
extreme archaean acidophile, thrives at pH of
essentially zero, equivalent to a 1.2 molar
concentration of sulfuric acid. Some of ―oldest‖ oils
generated in same conditions ?
Fig.1
Fig.2
Fig.3
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