25th International Meeting on Organic Geochemistry IMOG 2011

P-323
Paleoenvironment significance of geochemical characteristics of
the carboniferous source rocks in eastern part of the Junggar
Basin
Wen Qi, Jianguo Pan, Peng Wang, Kunjun Tan
Research Institute of Petroleum Exploration and Development -Northwest,Petrochina China, Lanzhou,
China (corresponding author:morababy83@126.com)
Carboniferous source rocks of Junggar Basin include
dark shale, coal, tuff and sedimentary tuff.And the
tuffs, tuffites are products of volcanic events in the
area. This study learns the characteristics of organic
geochemistry and trace element by analysing
samples of logging core and outcrop rock. Then,
combined with fossils trait of the Carboniferous strata
to probe the relationship between the environment
and source rocks geochemistry characteristics in the
depositional Basin.
The organic matter of the research area is mainly type
Ⅲ and Ⅱ2. In general , the majority macera of the
upper and lower Carboniferous source rocks is
vitrinite (Upper Carboniferous is 33.2%;Lower
Carboniferous is 65.6%), followed by inertinite,which
shows that the matter influx is dominated terrestrial
higher plants. However , there are differences in
different secondary structural units. By the relative
content of macerals and steranes, the sendimentay
environment of Baijiahai salient and Beisantai salient
are fresh water lacustrine environment or river delta
sediments; Wucaiwan sag and Dajing present
characteristics of transitional facies. And also,
evidence from the Isoprenoid hydrocarbons reflects
that the depositional environment transits from
Oxidizing reduction environment to oxidation
cinditions ,indicating that Carboniferous strata of east
of the Junggar Basin is transitional facies.
For trace elements, the following four element ratios:
Sr/Ba , B/Ga , V/(V+Ni) andCa/(Ca+Fe),can
effectively reflect the Carboniferous
Paleoenvironment . Baijiahai saline and Baijiahai
salient are semi-reuction fresh water facies.
Wucaiwan Sag and Dajing area are reduced
tranzitional facies. Dinan salient are freshwater and
brackish water lacustrine facies deposits. Huoshen1
well are strong reducing offshore sediments.
Fossils evidence indicates that in the late Late
Carboniferous, eastern part of the Junggar Basin
have been in littoralregion condition.In some local
areas. gypsum has appeared lacustrine environment
during the quiet time of Carboniferous. The
emergence of bioclastic limestone indicates the sea
retreating.
In summary, we can see that in the Late
Carboniferous, it is mainly shallow sea transitional
facies in north and south of research area.The west is
wide lake sediments t.Middle part is the river and
shallow lake deposits.Which determine Distribution of
Carboniferous source rocks.
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