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Structural
Inversion of the North Uplift of Tarim
Basin, Northwestern China
YAN, JUNJUN
There is much controversy about the formation mechanisms of negative
inversion and its importance to petroleum exploration, because this kind of
structure is hardly observed. In the north uplift of Tarim basin, however, the
negative inversion structures are not only a common structural ingredient, but
also formed the most important oil-bearing traps. The negative inversion of the
uplift is characterized by the extensional reactivation of major preexisting
thrusts, as well as the formation of associated small scale extensional faults
subparallel to the trace of the major thrusts. The inverted structural belt
stretches intermittently for over 200 Km. The extensional deformation is mainly
observed in the Mesozoic and Cenozoic strata and disappears completely at the
upper boundary of the Paleozoic.
The north uplift was a marginal rise of the Tarim cratonic basin in
paleozoic,and in pace with the development of Kuche foreland depression in front
of South Tianshan Mountains, had become a forebulge of the Kuche foreland
depression since Mesozoic. The evolution of negative inversion of the uplift can
be considered in three periods. That is, the strongly contractional and
thrusting deformation of paleozoic;the continued contractional deformation of
Mesozoic and the negative inversion of the Cenozoic. The negative inversion
occured mainly in the Neogene because the difference of subsidence between the
Kuche foreland depression and its forebulge reached to maximum in this time,
which resulted in local extensional stresses in the north uplift.
The great potential of hydrocarbon accumulation in the north uplift has been
confirmed by the exploration activities in the basin. The most discoveries in
the uplift are related to the negative inversion
.