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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract:
Structural
Development of the Kuche Fold and Thrust Belt,
Northern Tarim Basin, China
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By
1Amoco Production Co.
2Tarim Petroleum Exploration and Development Bureau
The Kuche Depression is a Mesozoic
foreland basin located along the northern
margin of the Tarim Basin, China. It is characterized
by long, subparallel, south-directed
thrust faults and folds that formed in
response to uplift of the Tian Shan Mountains
to the north. The structural
timing of
the thrust system as seen on seismic data
indicates that there were two main episodes
of thrusting: late Jurassic and mid to late
Tertiary. This thrusting coincides with the
Indonesian and early Himalayan orogenies
and helps document the tectonic history of
the northern Tarim region.
The earliest evidence for thrusting seen on
seismic in the Kuche Depression is during
the Indonesian orogeny, when the Lhasa
plate collided with the Tarim plate. Regional convergence along the proto-Tian
Shan Mountains formed a series of stacked
thrust sheets that appear to ramp over a
Paleozoic-aged host block in the Kuche
foreland basin. The floor thrust of this duplex
occurs in the basal Triassic lacustrine
shale sequence, which may also be one of
the principal source rocks in the Kuche
Depression. The Paleogene and lower Neogene
sections
are nearly uniform in thickness
across the Depression, indicating that
a period of tectonic quiescence followed the
first thrusting event.
The second major episode of thrusting occurred
during the early Himalayan orogeny,
when India collided with southern Asia.
This collision reactivated uplift in the Tian
Shan Mountains and caused renewed thrusting
in the Kuche Depression. A series of
out-of-sequence thrusts is seen on seismic,
resulting in the southward transport of isolated
piggyback basins, further growth of
the duplexes, and refolding of previous
structures. The dramatic thinning of Miocene
and younger units across the crests
of the shallow folds helps time the second
thrust episode. Balanced cross
-section
modeling suggests thrust-related shortening
on the order of 35 to 50% and helps
unravel the complex
structural
style in the
Kuche Depression. Understanding the
structural
development of this foreland
basin assists in reconstructing regional tectonic
events and better brackets the interaction
between the various plates in northwestern
China.
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