Supplemental Material: Late Triassic successive amalgamation between the South China and North China blocks: Insights from structural analysis and magnetic fabrics study of the Bikou Terrane and its adjacent area, northwestern Yangtze block, central China

Text: Basic principles of anisotropy of magnetic susceptibility (AMS); Figure S1: Photographs of supplementary shearing indicators of the structural kinematics; Figure S2: Complete magnetic hysteresis data set for specimen selected from 34 sites; Figure S3: Measurements of isothermal remanent magnetization of specimen selected from 34 representative sites of the Bikou Terrane; Figure S4: Thermo-magnetic experiments of specimen selected from 12 representative sites; Figure S5: Mrs/Ms versus Hcr/Hc diagram from the selected specimen of the representative sites to define the size of magnetite; Figure S6: Stereographic projection of the AMS directional fabrics and structural fabrics.

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Supplemental Material: Late Triassic successive amalgamation between the South China and North China blocks: Insights from structural analysis and magnetic fabrics study of the Bikou Terrane and its adjacent area, northwestern Yangtze block, central China

10.1130/gsab.s.17124278.v1 ◽

2021 ◽

Author(s):

Zhenhua Xue ◽

Wei Lin ◽

et al.

Keyword(s):

North China ◽

Stereographic Projection ◽

Magnetic Hysteresis ◽

Central China ◽

Late Triassic ◽

Adjacent Area ◽

Yangtze Block ◽

Data Set ◽

Basic Principles ◽

Magnetic Fabrics

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Late Triassic successive amalgamation between the South China and North China blocks: Insights from structural analysis and magnetic fabrics study of the Bikou Terrane and its adjacent area, northwestern Yangtze block, central China

Geological Society of America Bulletin ◽

10.1130/b36228.1 ◽

2021 ◽

Author(s):

Zhenhua Xue ◽

Wei Lin ◽

Yang Chu ◽

Wei Wei ◽

Zhentian Feng ◽

...

Keyword(s):

Structural Analysis ◽

South China ◽

North China ◽

Late Triassic ◽

Yangtze Block ◽

The South ◽

Structural Geometry ◽

The North ◽

Magnetic Fabrics ◽

Multi Phase

The Bikou Terrane, located at the conjunction of the Longmenshan fold-thrust belt and the west Qinling orogenic belt in centeral China, was involved in the Late Triassic collision between the South China and North China blocks. The Bikou Terrane has preserved crucial information on structural geometry and kinematics of Triassic tectonics, and is therefore of great importance for reconstructing the Paleo-Tethyan evolutionary history. However, multi-phase tectonic events of the Bikou Terrane are unsettled. This work presents detailed structural analysis based on both the field and laboratory works, which reveals three phases of deformation events in Bikou and its adjacent areas, including top-to-the-SW shearing related to SW-ward thrusting (DI) mainly to the north of the Bikou Terrane, top-to-the-NNW shearing related to NNW-ward thrusting (DII) in the Bikou Terrane, and strike-slip faulting (DIII) locally developed in the northern Bikou Terrane. Anisotropy of magnetic susceptibility (AMS) study and related structural analysis not only support the multiphase deformation but also reveal a gradual transition from the DII-related magnetic fabrics to the DIII-related magnetic fabrics in the Bikou Terrane. Integrating published geochronological data, it is constrained that DI occurred at ca. 237−225 Ma, DII occurred at ca. 224−219 Ma, and DIII possibly occurred during the Early Cretaceous. Based on regional tectonics, the DI event corresponds to the collision between the South Qinling block and the Bikou Terrane, and the DII event reflects the intracontinental amalgamation between the Bikou Terrane and the Yangtze block, which indicates a Late Triassic successive amalgamation from the North China block to the South China block. Intracontinental adjustment represented by the strike-slip (DIII event) occurred after the final amalgamation between the North China and South China blocks. By applying AMS on deciphering structural geometry and multi-phase deformation, our study suggests that AMS is a useful tool for structural analysis.

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Emplacement mechanism of Late Triassic granitic Dushan pluton, North China and its tectonic implications

10.5194/egusphere-egu2020-5668 ◽

2020 ◽

Author(s):

Huabiao Qiu ◽

Wei Lin ◽

Yan Chen ◽

Michel Faure

Keyword(s):

Solid State ◽

North China ◽

Tectonic Setting ◽

Late Triassic ◽

Gravity Modeling ◽

Magnetic Fabrics ◽

Southeastern Margin ◽

Emplacement Mechanism ◽

Southwestern Margin ◽

Magnetic Lineations

<p>To better understand the Late Triassic tectonic setting in the northern North China Craton (NCC), a multidisciplinary investigation, including structural geology, geochronology, anisotropy of magnetic susceptibility (AMS) and gravity modeling, has been carried out in the Dushan pluton. The Dushan pluton consists of monzogranite and biotite-rich facies along the pluton margin without sharp contact between them. The granite varies southwestwards from isotropic texture to arcuate gneissic structures, with locally mylonitic structures. The intensity of solid-state deformation increases southwestwards across the pluton, leaving preserved magmatic fabrics in the northeastern part. The compatible outward dipping magmatic and solid-state magnetic fabrics, together with mesoscopic fabrics, define an elliptic dome-like pattern with a NE-SW oriented long axis, despite the fabrics dip inwards in the southeastern margin of the pluton. Combining gravity modeling, the Dushan pluton presents an overall tabular or tongue-like shape with a northeastern root. The magnetic lineations nearly strike NE-SW, concordant with the stretching lineations observed in the mylonitic zones. We propose the emplacement mode that the Dushan pluton emplaced southwards through the feeder zone in its northeast, beginning probably with a sill. The later successive magma batches may laterally and upwardly inflate, deform and even recrystallize the former cool-down magma. This inflation forms an arcuate, gneissic to mylonitic foliation in the southwestern margin. The Dushan pluton is considered as typically post-tectonic in emplacement, recording a Late Triassic post-tectonic setting of the northern NCC.</p>

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

10.5194/egusphere-egu2020-6341 ◽

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>

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Population genomics and morphological features underlying the adaptive evolution of the eastern honey bee (Apis cerana)

BMC Genomics ◽

10.1186/s12864-019-6246-4 ◽

2019 ◽

Vol 20 (1) ◽

Cited By ~ 2

Author(s):

Li Yancan ◽

Chao Tianle ◽

Fan Yunhan ◽

Lou Delong ◽

Wang Guizhi

Keyword(s):

Adaptive Evolution ◽

North China ◽

Environmental Changes ◽

Population Genomics ◽

Fundamental Problem ◽

Apis Cerana ◽

Morphological Characteristics ◽

Morphological Features ◽

Central China ◽

Data Set

Abstract Background The adaptation of organisms to changing environments is self-evident, with the adaptive evolution of organisms to environmental changes being a fundamental problem in evolutionary biology. Bees can pollinate in various environments and climates and play important roles in maintaining the ecological balance of the earth. Results We performed an analysis of 462 Apis cerana (A. cerana) specimens from 31 populations in 11 regions and obtained 39 representative morphological features. We selected 8 A. cerana samples from each population and performed 2b-RAD simplified genome sequencing. A total of 11,506 high-quality single nucleotide polymorphism (SNP) loci were obtained. For these SNPs, the minor allele frequency (MAF) was > 1%, the average number of unique labels for each sample was 49,055, and the average depth was 72.61x. The ratios of the unique labels of all samples were 64.27–86.33%. Conclusions Using 39 morphological characteristics as the data set, we proposed a method for the rapid classification of A. cerana. Using genomics to assess population structure and genetic diversity, we found that A. cerana has a large genetic difference at the ecotype level. A comparison of A. cerana in North China revealed that some physical obstacles, especially the overurbanization of the plains, have isolated the populations of this species. We identified several migration events in North China and Central China. By comparing the differences in the environmental changes in different regions, we found that A. cerana has strong potential for climate change and provides a theoretical basis for investigating and protecting A. cerana.

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