A total of 237 surface soil pollen samples were collected from less disturbed zonal communities, and a new surface pollen data set has been established in northern China. Pollen—climate parameter transfer functions using weighted-averaging regression and calibration partial least squares (WA-PLS) model as a tool to reconstruct past climate changes from pollen data, were tested with this new surface pollen data set. The results of cross-validation showed that the method worked very well with precipitation ( R = 0.94, R2jack = 0.89, RMSEPjack = 69 mm, the safe dynamic range of the reconstruction was 40 mm~800 mm) and worked well with temperature ( Tann: R = 0.84, R 2jack = 0.71, RMSEPjack = 2.0°C, the safe dynamic range of the reconstruction was −4°C~13°C; MTwa: R = 0.79, R2jack = 0.63, RMSEPjack = 2.5°C, and the safe dynamic range of the reconstruction was 8°C~26°C), indicating that the surface pollen data set and WA-PLS reconstruction technique in this paper have strong potential for palaeoclimatic reconstruction.
Using seismic data from Chinese and ISC stations between 1980~2004, we inverted Pn wave velocity structure and anisotropy of the northeastern South China Sea and adjacent region. The velocity variations at uppermost mantle reflect the features of regional geology and tectonics. Southeastern China has fast velocities, correspondent to the lithospheric mantle in tectonically stable regions. Slow velocities appear near the Binhai fault zone along the coast of southeastern China, which indicates a possible penetration of the fault zone into the uppermost mantle. Similar to southeastern China, fast velocities throughout the northern South China Sea and Taiwan Strait reveal a property of the lithospheric mantle in continental margin, while fast velocities in the Xisha Trough reflect a southward extension of continental shelf and a mantle upwarp produced by Cenozoic rifting. There is no evidence of large‐scale mantle heat flows in the northern South China Sea. However, a very slow velocity anomaly is observed in the eastern sub‐basin of the South China Sea, where is an extinct mantle upwelling center with high heat flows, indicating a thinning or removal of lithospheric mantle. Along the eastern Taiwan, Luzon and northern Philippine, slow velocities are closely related to seismic and volcanic activity and magmatism in the arc zone, while fast velocities in the eastern South China Sea and western Philippine Sea reflect the character of oceanic lithospheric mantle. Pn velocity anisotropy also reveals the stress state in regional tectonics and the history of deformation of lithospheric mantle. Southeastern China has small anisotropy in response to less deformation there. Anisotropy is observed in the northern South China Sea, with fast directions of anisotropy aligned with shallow structures in crust, which reflect the evidence of the Mesozoic‐Cenozoic rifting and shear deformation in lithospheric mantle. Strong anisotropy is also found along the Ryukyu‐Taiwan‐Luzon arc zone, with fast directions parallel to trenches, which indicates that strong deformation of lithospheric mantle in the leading edge of the Philippine Sea plate and Eurasian continent. The change of the fast directions of anisotropy near the eastern Taiwan is probably caused by a conversion of collision mechanisms between the Eurasian continent and the Philippine Sea plate, and the tear of the lithosphere.
In this paper, we prove that the quasihyperbolic metrics are quasiinvariant under a quasisymmetric mapping between two suitable metric spaces. Meanwhile, we also show that quasi-invariance of the quasihyperbolic metrics implies that the corresponding map is quasiconformal. At the end of this paper, as an application of these theorems, we prove that the composition of two quasisymmetric mappings in metric spaces is a quasiconformal mapping.
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