scholarly journals Numerical Constraints on Folding and Thrusting in Jiudong Basin: Implication for the Northeastward Growth of Qinghai–Tibetan Plateau

2022 ◽  
Vol 9 ◽  
Author(s):  
Qizhi Chen ◽  
Caibo Hu ◽  
Felipe Orellana-Rovirosa ◽  
Longshou Zhou ◽  
Huai Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Deformation ◽  
Equivalent Plastic Strain ◽  
Model Parameters ◽  
Thrust Faults ◽  
Northern Margin ◽  
The North ◽  
Thrust Belts ◽  
Fold And Thrust Belts ◽  
North Qilian

Under regional tectonic shortening in the northern margin of Qinghai–Tibetan Plateau, the fold-and-thrust belts composed of four thrust faults (North Qilian-Shan, North Yumu-Shan, South Heli-Shan, and North Jintanan-Shan) formed from southwest to northeast discontinuously sequentially in the Jiudong Basin area during Late Cenozoic. Meanwhile, the North Qilian-Shan, Yumu-Shan, and Heli-Shan ranges were formed successively, as the Earth's local surface was unequally uplifted. In this study, based on geological and geophysical observations, a simple two-dimensional elastic-plastic numerical finite element method model for a southwest-northeast section in Jiudong Basin is successfully established to simulate the spatiotemporal evolution of the local fold-and-thrust belts. Results show that the computed equivalent plastic strain concentration zones and the four observed thrust faults are consistently correlated in spatial position orientation and time sequence. The simulated upper-surface deformation is congruent with the observed topographic peaks and uplift sequences of the North Qilian-Shan, Yumu-Shan, and Heli-Shan ranges. This study provides a geodynamic basis for understanding the growth mechanism of the northern margin of Qinghai–Tibetan Plateau under tectonic horizontal shortening. Also, we provide a thorough sensitivity analysis for the model parameters of this particular geologic setting. Our sensitivity simulations, considering systematic case variations about the regional geometrical-material parameters, suggest the manifestation of three different possible evolution patterns of fold-and-thrust belts for a wedge above a decollement layer, with wedge plastic deformation migrating from 1) thick to thin end (well-known), 2) thin to thick end, and 3) both ends to middle. Finally, our results suggest that in this region, further growth of mountain ranges is expected to continue in the future.

Age and origin of accreted ocean plate stratigraphy in the North Qilian belt, NE Tibet Plateau: Evidences from microfossils and geochemistry of cherts and siltstones

2021 ◽  
pp. jgs2020-231
Author(s):  
Zhen Yan ◽  
Wenjiao Xiao ◽  
Jonathan C. Aitchison ◽  
Chao Yuan ◽  
Chuanzhou Liu ◽  
...  
Keyword(s):  
Tibet Plateau ◽  
Geochemical Analysis ◽  
Accretionary Complex ◽  
Content Type ◽  
Middle Ordovician ◽  
The North ◽  
Ophiolitic Mélange ◽  
Thrust Belts ◽  
Fold And Thrust Belts ◽  
North Qilian

The accretionary complex (AC) in the North Qilian belt comprises coherent and chaotic units consisting of bedded cherts, pelagic mudstone, shale, turbidites, basalt, limestone, blueschist, eclogite lenses, and ophiolitic mélange. Cherts from the Donggoukou and Biandukou outcrops in the north of blueschist belt contain abundant Middle Ordovician radiolarians together with rare conodonts. Well-preserved radiolarians also occur in cherts associated with high-pressure/low-temperature rocks in the Baijingsi AC outcrop. Conodonts of Floian-Dapingian age and Middle Ordovician radiolarians also occur in the Shihuigou AC. Geochemical analysis of 23 cherts reveals variable SiO2 contents (74.56-97.16 wt%) and high mean Al/(Al + Fe + Mn) ratios ranging from 0.35 to 0.85, indicating a non-hydrothermal origin. Ce/Ce* and LaN/YbN ratios of 0.70-1.22 and 0.67-1.59 are high and variable, similar to those of associated muddy siltstone (0.59-0.96 and 1.14-1.55, respectively), suggesting near trench deposition with associated terrigenous input. Together with the metamorphic ages of blueschists and eclogites, the North Qilian belt AC formed by accretion of ocean plate stratigraphic successions in response to subduction of the Proto-Tethyan Ocean prior to 450 Ma.Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts

Integrated analyses constraining the provenance of sandstones, mudstones, and conglomerates, a case study: the Laojunshan conglomerate, Qilian orogen, northwest China

2007 ◽  
Vol 44 (7) ◽  
pp. 961-986 ◽  
Author(s):  
Zhen Yan ◽  
Wenjiao Xiao ◽  
Zongqi Wang ◽  
Jilian Li
Keyword(s):  
Tibetan Plateau ◽  
Middle Devonian ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Geochemical Data ◽  
The North ◽  
Northern Tibetan Plateau ◽  
Wide Range ◽  
Qilian Orogen ◽  
North Qilian

The Qilian orogenic belt in the northern Tibetan plateau connects the Altaids to the north with the Tethyan orogenic system to the south and occupies a key tectonic position in the evolution and assembly of Asia. The belt contains a wide range of subduction–accretion-related petrotectonic units. The Early–Middle Devonian Laojunshan conglomerate, deposited unconformably upon Cambrian–Silurian strata along the northern margin of the North Qilian terrane, contains a record of the late Paleozoic tectonism of the Qilian orogen. Its provenance and tectonic setting are critical in understanding not only the tectonic evolution of Tibetan plateau, but Paleozoic global reconstructions as well. The composition of clastic conglomerates and heavy mineral assemblages of sandstones suggests that coeval mafic, felsic, metamorphic, and sedimentary rocks were the main sources. The geochemistry of volcanic clasts and paleocurrent and paleogeographic data suggest derivation from subduction–accretion complexes in the North Qilian terrane. The geochemistry of siltstones and mudstones indicates that the Laojunshan conglomerate was derived from an arc and accumulated in an active continental margin. Geochemical data of granitoid clasts suggest that they were derived from Ordovician–Silurian subduction-related magmatic rocks. Mafic and ultramafic clasts, chromite, and magnetite decrease upwards in the stratigraphy whereas metamorphic, sedimentary and granitoid clasts, and garnet increase. These data imply that mafic rocks were the predominant source during initial deposition. Regional studies suggest that the North China plate subducted southwards and produced subduction-related arc magmatism along the southern margin of the North Qilian terrane during the Early–Middle Devonian. Therefore, we interpret the Laojunshan conglomerate as a fore-arc basin fill.

scholarly journals Erosion, fault initiation and topographic growth of the North Qilian Shan (northern Tibetan Plateau)

Geosphere ◽  
2010 ◽  
Vol 6 (6) ◽  
pp. 937-941 ◽  
Author(s):  
Dewen Zheng ◽  
Marin K. Clark ◽  
Peizhen Zhang ◽  
Wenjun Zheng ◽  
Kenneth A. Farley
Keyword(s):  
Tibetan Plateau ◽  
The North ◽  
Northern Tibetan Plateau ◽  
North Qilian
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