Regional lithospheric deformation beneath the East Qinling-Dabie orogenic belt based on ambient noise tomography

2021 ◽  
Author(s):  
Yu Wei ◽  
Shuangxi Zhang ◽  
Mengkui Li ◽  
Tengfei Wu ◽  
Yujin Hua ◽  
...  
Keyword(s):  
High Velocity ◽  
Lithospheric Mantle ◽  
Lower Crust ◽  
North China ◽  
3D Model ◽  
Orogenic Belt ◽  
Yangtze Block ◽  
North China Block ◽  
The North ◽  
Dabie Orogenic Belt

Summary The Qinling–Dabie orogenic belt, which contain the arc-shaped Dabbashan orocline and is the world's largest belt of HP/UHP metamorphic rocks, formed by a long-term complex amalgamation process between the North China Block and the Yangtze Block. To understand the collision processes and tectonic evolution, we constructed a three-dimensional (3D) S-wave velocity model from the surface to a depth of ∼120 km in the eastern Qinling-Dabie orogenic belt and its adjacent region by inverting 5–70 s phase velocity dispersion data of Rayleigh waves extracted from ambient noise data. Our 3D model reveals low velocities in the middle–lower crust and high velocities in the upper mantle beneath the orogenic belt, suggesting the delamination of the lower crust. Our results support a two-stage exhumation model for the HP/UHP rocks in the study area. First-stage exhumation was caused by the slab breaking away from the subducted Yangtze Block during the Early–Middle Triassic. Partial melting of the lithospheric mantle caused by slab breakoff–related asthenospheric upwelling weakened the lithospheric mantle beneath the orogenic belt, and continued convergence of the two continental blocks led to further thickening of the lower crust. Such processes promoted lower-crust delamination, which triggered the second-stage exhumation of the HP/UHP rocks. In the Dabbashan orocline, two deep-rooted high-velocity domes, that is, Hannan–Micang and Shennong–Huangling domes, acted as a pair of indenters during the formation stage. High-velocity lower crust was observed beneath the Dabbashan orocline. In addition, our 3D model reveals that high-velocity lithospheric mantle extends from the Sichuan Basin to the Dabbashan orocline, with a subhorizontal distribution, providing strong support for the high-velocity lower crust. We also observed the destruction of lithospheric mantle beneath the Yangtze Block; the destruction area is bounded by the North–South Gravity Lineament, suggesting that the destruction mechanism of the Yangtze Block may be similar to the North China Block.

Seismic evidence for the subduction of North China Block to Yangtze Block beneath Tongbai-Dabie Orogenic belt

2020 ◽  
Author(s):  
Hongwei Zheng
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
North China ◽  
Orogenic Belt ◽  
Late Triassic ◽  
Yangtze Block ◽  
North China Block ◽  
Crust And Upper Mantle ◽  
Dabie Orogenic Belt ◽  
Velocity Anomalies

<p>The Tongbai-Dabie Orogenic belt formed in the Middle-to-Late Triassic through a collision between the Yangtze Block (YB) and North China Block (NCB) and is a key component of the Central Orogen of China, which is famous on the most extensive high and ultrahigh pressure (HP/UHP) metamorphic zone in the world and marks the irregular suture between the YB and NCB. It is an ideal place to study the ancient orogenic processes between collided continents. In this study, we used a large number of P-wave arrival times recorded by portable and permanent seismic stations to reveal the structure of the crust and upper mantle beneath the Tongbai-Dabie orogenic belt and its adjacent region. Our images show the south-dipping high-velocity anomalies beneath the Tongbai-Dabie orogenic belt and the east-dipping high-velocity anomalies beneath the Tanlu Fault, which represent the southeastward subducted NCB in Mesozoic. While a huge high-velocity anomaly beneath the Wudang Moutin region extending down to 250 km is possible the ancient lithosphere of the Yangtze Craton remnant since the Paleoproterozoic. The northward subducted YB is only limited in the Eastern Dabie terrane and Yangtze foreland. Break-off retained Paleo-Tethyan oceanic slab are revealed at depths from the upper mantle 250 to 400 km. The structure of the crust and upper mantle suggests that the southeastward subduction of NCB resulted in the collision of NCB with YB.</p>

Crust-mantle velocity structure in Shanxi rift, Central North China Craton

2020 ◽  
Author(s):  
Yan Cai ◽  
Jianping Wu
Keyword(s):  
Upper Mantle ◽  
High Velocity ◽  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Velocity Structure ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
The North ◽  
Shanxi Rift

<p>North China Craton is the oldest craton in the world. It contains the eastern, central and western part. Shanxi rift and Taihang mountain contribute the central part. With strong tectonic deformation and intense seismic activity, its crust-mantle deformation and deep structure have always been highly concerned. In recent years, China Earthquake Administration has deployed a dense temporary seismic array in North China. With the permanent and temporary stations, we obtained the crust-mantle S-wave velocity structure in the central North China Craton by using the joint inversion of receiver function and surface wave dispersion. The results show that the crustal thickness is thick in the north of the Shanxi rift (42km) and thin in the south (35km). Datong basin, located in the north of the rift, exhibits large-scale low-velocity anomalies in the middle-lower crust and upper mantle; the Taiyuan basin and Linfen basin, located in the central part, have high velocities in the lower crust and upper mantle; the Yuncheng basin, in the southern part, has low velocities in the lower crust and upper mantle velocities, but has a high-velocity layer below 80 km. We speculate that an upwelling channel beneath the west of the Datong basin caused the low velocity anomalies there. In the central part of the Shanxi rift, magmatic bottom intrusion occurred before the tension rifting, so that the heated lithosphere has enough time to cool down to form high velocity. Its current lithosphere with high temperature may indicate the future deformation and damage. There may be a hot lithospheric uplift in the south of the Shanxi rift, heating the crust and the lithospheric mantle. The high-velocity layer in its upper mantle suggests that the bottom of the lithosphere after the intrusion of the magma began to cool down.</p>

Regional Geology Background and Minerogenetic Series in Ongniud Banner of Inner Mongolia

2013 ◽  
Vol 734-737 ◽  
pp. 408-417
Author(s):  
Deng Liu ◽  
Dai Yong Cao
Keyword(s):  
Single Particle ◽  
North China ◽  
Research Area ◽  
Orogenic Belt ◽  
Stratigraphic Correlation ◽  
North China Block ◽  
Northern Margin ◽  
The North ◽  
Geological Unit ◽  
Chlorite Schist

Ongniud Banner is located in the northern margin of the North China platform, possessing binary attribute of the greenville period orogenic belt and North China block. The authors reclassify geological unit through the rock stratigraphic correlation and isotope chronology. Achaean strata is mainly composed of quartz schist, chlorite schist, amphibole schist, and the rocks have been highly metamorphosed into the green schist facies, and its single particle zircon U-Pb age is 2645 ±86Ma, so it is assigned to North China block. Proterozoic strata is mainly composed of metamorphic complex including chlorite schist, marble, basalt, amphibolite, plagiogranite and olivine pyroxenolite, and its single particle zircon U-Pb age is 1620±160Ma, so it is assigned to Greenville period orogenic belt. According to 1:50000 stream sediment geochemical elementary assemblage characteristics, the authors discuss the metallogenic endowment and minerogenetic series of geological unit in research area.

scholarly journals Provenance and tectonic implications of the Yanshi bauxite area in Western Henan, China

2021 ◽  
Vol 261 ◽  
pp. 03058
Author(s):  
Fengyu Sun ◽  
Gaoshe Cao ◽  
Qikai Zhou
Keyword(s):  
North China ◽  
Orogenic Belt ◽  
Detrital Zircons ◽  
Early Paleozoic ◽  
North China Block ◽  
Qinling Orogenic Belt ◽  
The North ◽  
Icp Ms ◽  
Study Support ◽  
North Qinling

The bauxite layer in Western Henan supplies a large number of bauxite ores and is useful for studying tectonic movement. In this paper, the bauxite samples were selected to carry out LA-ICP-MS detrital zircons U-Pb dating and Hf isotope testing. The results indicated that the detrital zircons with the Early Paleozoic ages were mainly derived from the North Qinling Orogenic Belt. The detrital zircons of the Precambrian age may be derived mainly from the basement of the North China Block and the North Qinling Orogenic Belt. The results of this study support the opinion that the North Qinling Orogenic Belt has been uplifted at ~310 Ma, and the surface of the southern craton has an overall north-dipping topography at this time.

Provenance of Carboniferous strata (the Meishan Group) on the northern margin of the Dabie orogenic belt and implications of oblique convergence between the North and South China blocks

2021 ◽  
Vol 91 (9) ◽  
pp. 1010-1023
Author(s):  
Cheng Cheng ◽  
Shuangying Li ◽  
Xiangyang Xie ◽  
Yanlin Lu ◽  
Arthur B. Busbey ◽  
...  
Keyword(s):  
South China ◽  
Orogenic Belt ◽  
South China Block ◽  
The South ◽  
North China Block ◽  
Northern Margin ◽  
The North ◽  
Dabie Orogenic Belt ◽  
Oblique Convergence ◽  
North And South

ABSTRACT The newly defined Carboniferous Meishan Group, along the northern margin of the Dabie orogenic belt, provides unique opportunities to document the poorly understood Paleozoic tectonic evolution of the Dabie orogenic belt and the Paleozoic convergence between the North and South China blocks. We apply sandstone petrology, geochemistry, and U-Pb detrital-zircon geochronology to constrain the provenance of the Carboniferous Meishan Group and to document its potential tectonic significance. We conclude that the Meishan Group received most sediment directly from early Paleozoic continental island arc rocks that are currently missing in the Dabie orogenic belt, with minor contributions from middle Neoproterozoic magmatic rocks of the South China Block and recycling of Archean to Proterozoic basement rocks of both the North and South China blocks. Compilation and comparison of detrital zircons and geochemistry data of the Silurian–Devonian and Carboniferous units suggests that all of them share similar source areas, but that individual contributions from each source were different. These results support the hypothesis that the Dabie orogenic belt developed a similar Paleozoic accretionary system, and shares a similar tectonic history, with the Qinling orogenic belt. These provenance patterns can be explained by a model of oblique convergence between the North and South China blocks during the Paleozoic. The South China Block was obliquely subducted beneath the North China Block with its opening to the east, forming an eastward-widening sedimentary basin. As a result, the eastern part of the basin received more sediment from the northern passive margin of the South China Block, while the western part of the basin received more material from the southern active margin of the North China Block.

scholarly journals Petrogenesis of the Early Cretaceous Hongshan Complex in the Southern Taihang Mountains: Constraints from Element Geochemistry, Zircon U-Pb Geochronology and Hf Isotopes

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1111
Author(s):  
Xiaolei Chu ◽  
Jinggui Sun ◽  
Fanting Sun ◽  
Yanxiong Mei ◽  
Yang Liu ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
North China Craton ◽  
Lithospheric Mantle ◽  
Lower Crust ◽  
North China ◽  
Coarse Grained ◽  
Geochemical Data ◽  
Fine Grained ◽  
The North ◽  
T Values

The Hongshan complex, located in the southern part of the Taihang Mountains in the central part of the North China Craton, consists of syenite stocks (including fine-grained biotite aegirine syenite, medium-grained aegirine gabbro syenite, coarse-grained aegirine gabbro syenite, syenite pegmatite, and biotite syenite porphyry), with monzo-diorite and monzo-gabbro dikes. This paper presents zircon U-Pb ages and Hf isotope data and whole-rock geochemical data from the Hongshan complex. LA–ICP-MS zircon U–Pb age from the fine-grained biotite aegirine syenite, monzo-diorite, and monzo-gabbro are 129.3 ± 2.0Ma, 124.8 ± 1.3Ma, and 124.1 ± 0.9Ma, respectively, indicating their emplacement in the Early Cretaceous when the North China Craton was extensively reactivated. The monzo-diorite and monzo-gabbro have low SiO2 contents (48.94–57.75 wt%), total alkali contents (5.2–9.4 wt%), and εHf (t) values of −22.3 to −18.4 and are enriched in MgO (4.0–8.2 wt%), Al2O3 (14.3–15.8 wt%), light rare earth elements (LREEs) and large ion lithophile elements (LILEs). Interpretation of elemental and isotopic data suggests that the magma of monzo-diorite and monzo-gabbro were derived from partial melting of the enriched lithospheric mantle metasomatized by slab-derived hydrous fluids. Syenites with high alkali (K2O + Na2O = 9.4–13.0 wt%) and Sr contents (356–1737 ppm) and low Yb contents (0.94–2.65 ppm) are enriched in Al (Al2O3 = 16.4–19.1 wt%), but depleted in MgO (0.09–2.56 w%), Cr (Avg = 7.16 ppm), Co (Avg = 6.85 ppm) and Ni (Avg = 9.79 ppm), showing the geochemical features of adakitic rocks associated with thickened lower crust. Combining zircon 176Hf/177Hf ratios of 0.282176 to 0.282359, εHf(t) values of −18.3 to −11.8 and εNd (t) values of −11.1 to −8.2, we conclude that the syenite magma was derived from the mixing of the thickened lower crust and the enriched lithospheric mantle magma. These magma processes were controlled by Paleo-Pacific plate subduction and resulted in the destruction and thinning of the central North China Craton.

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