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| Titel |
Basin-mountain structures and hydrocarbon exploration potential of west Junggar orogen in China |
| VerfasserIn |
Xiaozhi Wu, Dengfa He, Xuefeng Qi |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250124096
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| Publikation (Nr.) |
 EGU/EGU2016-3471.pdf |
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| Zusammenfassung |
| Situated in northern Xinjiang, China, in NE-SW trend, West Junggar Orogen is adjacent to
Altai fold belt on the north with the Ertix Fault as the boundary, North Tianshan fold
belt on the south with the Ebinur Lake Strike-slip Fault as the boundary, and the
Junggar Basin on the southeast with Zaire-Genghis Khan-Hala’alat fold belt as the
boundary. Covering an area of about 10×104 km2 in China, there are medium
and small intermontane basins, Burqin-Fuhai, Tacheng, Hefeng and Hoxtolgay,
distributing inside the orogen. Tectonically West Junggar Orogen lies in the middle
section of the Palaeo-Asian tectonic domain where the Siberia, Kazakhstan and
Tarim Plates converge, and is the only orogen trending NE-SW in the Palaeo-Asian
tectonic domain. Since the Paleozoic, the orogen experienced pre-Permian plate
tectonic evolution and post-Permian intra-plate basin evolution. Complex tectonic
evolution and multi-stage structural superimposition not only give rise to long term
controversial over the basin basement property but also complex basin-mountain coupling
relations, structures and basin superimposition modes. According to analysis of
several kinds of geological and geophysical data, the orogen was dominated by
compressive folding and thrust napping from the Siberia plate in the north since the Late
Paleozoic. Compressive stress weakened from north to south, corresponding to subdued
vertical movement and enhanced horizontal movement of crustal surface from north
to south, and finally faded in the overthrust-nappe belt at the northwest margin
of the Junggar Basin. The variation in compressive stress is consistent with the
surface relief of the orogen, which is high in the north and low in the south. There are
two kinds of basin-mountain coupling relationships, i.e. high angle thrusting and
overthrusting and napping, and two kinds of basin superimposition modes, i.e. inherited and
progressive, and migrating and convulsionary modes. West Junggar orogen has rich
oil and gas shows, and oil and gas fields have also been discovered in the Zaysan
Basin in adjacent Kazakhstan and in adjacent Junggar, Tuha and Santanghu Basins.
Drilling data, geochemical analysis of outcrop data, and the disection of ancient
Bulongguoer oil reservoir at the south margin of the Hefeng Basin show there developed
two sets of good transitional source rocks, the lower Hujierste Formation in the
Middle Devonian (D2h1) and the Hebukehe Formation in the Upper Devonian
and Lower Carboniferous (D3-C1h) in this area, which, 10 to 300 m thick, mainly
distribute in the shoal water zone along Tacheng-Ertai Late Paleozoic island arc belt.
Reservoirs were mainly formed in the Jurassic and then adjusted in two periods, one
from the end of the Jurassic to middle Cretaceous and the other in early Paleogene.
Those early oil reservoirs might be destroyed in areas such as Bulongguoer with
poor preservation conditions, but in an area with good geologic and preserving
conditions, oil and gas might accumulate again to form new reservoirs. Therefore, a
potential Middle Devonian-Lower Carboniferous petroleum system may exist in
Tacheng-Ertai island arc belt, which may become a new domain for exploration, north
faulted fold belt in the Heshituoluogai basin, and Hongyan fault bench zone in north
Ulungur Depression in the Junggar Basin are promising areas for hydrocarbon
exploration. |
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