Source-to-sink of Late carboniferous Ordos Basin: Constraints on crustal
accretion margins converting to orogenic belts bounding the North
China Block
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Abstract
The Upper Carboniferous Benxi Formation of the Ordos Basin is the lowest strata overlying Middle Ordovician
above the major ca. 150-myr sedimentary gap that characterizes the entire North China Block (NCB). We apply an
integrated analysis of stratigraphy, petrography, and U–Pb dates and Hf isotopes on detrital zircons to investigate
its provenance and relationships to the progressive collisions that formed the Xing’an-Mongolia Orogenic Belt to
the north and the Qinling Orogenic Belt to the south. The results show that, in addition to regional patterns of
siliciclastic influx from these new uplifted sources, the Benxi Formation is composed of two sequences corresponding
to long-term glacial-interglacial cycles during the Moscovian to lower Gzhelian stages which drove
global changes of eustatic sea level and weathering. The spatio-temporal distribution of sediment isopachs and
facies indicate there were two sediment-infilling pulses, during which the southern and the northern Ordos Basin
developed tidal-reworked deltas. The age spectra from detrital zircons, trace element patterns and εHf(t) values
reveal that the siliciclastics forming the southern delta was sourced in the Qinling Orogenic Belt, whereas the
northern delta was derived from the Xing’an-Mongolia Orogenic Belt. The source-to-sink evolution of this Upper
Paleozoic system records the progressive development of orogenic belts and uplifts forming on the southern and
northern margins of the NCB prior to its collisions with the South China and the Siberian plates, respectively.
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