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Multitaper spectral method to estimate the elastic thickness of South China: Implications for intracontinental deformation 被引量:8
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作者 Yangfan Deng Zhongjie Zhang +1 位作者 weiming fan Marta Pérez-Gussinyé 《Geoscience Frontiers》 SCIE CAS CSCD 2014年第2期193-203,共11页
The effective elastic thickness (Te) represents the thickness of the elastic layer or the flexural rigidity of the lithosphere, the equivalent of which can be calculated from the spectral analysis of gravity and top... The effective elastic thickness (Te) represents the thickness of the elastic layer or the flexural rigidity of the lithosphere, the equivalent of which can be calculated from the spectral analysis of gravity and topographic data. Studies of Te have profound influence on intracontinental deformation, and coupling of the tectonic blocks. In this paper, we use the multitaper spectral estimation method to calculate the coherence between Bouguer gravity and topography data, and to obtain the Te map of South China. Through the process of correction, we discuss the relationships of Te versus heat flow, and Te versus seismicity. The results show that Te distribution of South China is affected by three factors:the original age, which controls the basic feature;the Mesozoic evolution, which affects the Te distribution;and the neotectonic movement, which shaped the final distribution. The crust age has a positive correlation with the first-order Te distribution;thus the Yangtze Craton has a relatively higher Te (about 50 km) whereas the Te in Cathaysia block is only 10e20 km. By analysis and comparison among the tectonic models of South China, the Te distribution can be well explained using the flat-subduction model. As is typical with neotectonics, the region with a higher heat flow is related with a lower Te. The seismicity does not have a clear relationship with Te, but the strong seismicity could cause a low Te. Seismogenic layer (Ts) has a similar trend as Te in the craton, whereas in other areas the relationship is complex. 展开更多
关键词 South China Effective elastic thickness Spectrum estimation Heat flow Seismicity
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The gravity and isostatic Moho in North China Craton and their implications to seismicity 被引量:1
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作者 Yangfan Deng weiming fan +1 位作者 Zhongjie Zhang Kai Liang 《Earthquake Science》 2014年第2期197-207,共11页
The Bouguer gravity is the combination of field sources in different depths. Based on the multi-scale analysis of the Bouguer gravity,we can get the gravity anomaly caused by the Moho undulation. This study presents t... The Bouguer gravity is the combination of field sources in different depths. Based on the multi-scale analysis of the Bouguer gravity,we can get the gravity anomaly caused by the Moho undulation. This study presents the various orders of approximation of gravity anomaly in North China Craton(NCC),the possible source depths with radial logarithmic power spectrum,and the relationship between the deep structure and gravity anomaly. Furthermore,we discuss the isostatic compensation about the Moho depth from gravity and deep seismic sounding profiles(DSS). The results show that:(1) the fourth approximation could have resulted from the Moho undulation,(2) in contrast to the isostatic Moho,the inverted gravity Moho and the DSS Moho show that most of NCC has been isostatically compensated,and(3) the isostatic compensation rate has some close relation to the seismicity. 展开更多
关键词 Multi-scale analysis North China Craton Gravity Moho Compensation rate Seismicity
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K-Ar dating of late Mesozoic volcanism and geochemistry of volcanic gravels in the North Huaiyang Belt, Dabie orogen: Constraints on the stratigraphic framework and exhumation of the northern Dabie orthogneiss complex 被引量:28
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作者 Yuejun Wang weiming fan Feng Guo 《Chinese Science Bulletin》 SCIE EI CAS 2002年第20期1688-1695,共8页
Two eruption episodes are identified through systematic field investigations and K-Ar dating of the late Mesozoic volcanic rocks in the North Huaiyang belt (NHB), Dabie orogenic belt, of which the earlier volcanic sui... Two eruption episodes are identified through systematic field investigations and K-Ar dating of the late Mesozoic volcanic rocks in the North Huaiyang belt (NHB), Dabie orogenic belt, of which the earlier volcanic suite termed Maotanchang Fm. (Fm.) occurring at Jinzhai, Xianhualing and Maotanchang, etc., was erupted from 149 Ma to 138 Ma. The other named Xiaotian Fm. mainly distributed at Xiaotian, Shucheng, etc., was formed between 132 Ma and 116 Ma. During the eruption gap of the two volcanic suites deposited a volcano-sedimentary conglomerate layer, which are composed of the multi-compositional gravels, including the North Dabie orthogneiss complex (NDOC), volcanic gravels, etc. These volcanic gravels in the conglomerate layer show identical geochemical and isotopic compositions (87Sr/86Sr(t) =0.7084-0.7092,εNd(t) =-21.8--24.4) to the Maotanchang Fm. volcanic rocks (87Sr/86Sr = 0.7086-0.7102,εNd = -19.2-24.4), but significantly distinct from those of Xiaotian Fm. (87Sr/86Sr = 0.7076-0.7084, εNd= 展开更多
关键词 multi-gravel CONGLOMERATE layer K-Ar dating geo-chemical comparison late Mesozoic uplifting-erosion North Huai-yang belt.
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Plume-ridge interaction induced migration of the Hawaiian-Emperor seamounts 被引量:5
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作者 Weidong Sun Charles H.Langmuir +7 位作者 Neil MRibe Lipeng Zhang Saijun Sun He Li Congying Li weiming fan Paul J.Tackley Patrick Sanan 《Science Bulletin》 SCIE EI CSCD 2021年第16期1691-1697,M0004,共8页
The history of the Hawaiian hotspot is of enduring interest in studies of plate motion and mantle flow,and has been investigated by many researchers using the detailed history of the Hawaiian-Emperor Seamount chain.On... The history of the Hawaiian hotspot is of enduring interest in studies of plate motion and mantle flow,and has been investigated by many researchers using the detailed history of the Hawaiian-Emperor Seamount chain.One of the unexplained aspects of this history is the apparent offset of several Emperor seamounts from the Hawaii plume track.Here we show that the volcanic migration rates of the Emperor seamounts based on existing data are inconsistent with the drifting rate of the Pacific plate,and indicate northward and then southward “absolute movements”of the seamounts.Numerical modeling suggests that attraction and capture of the upper part of the plume by a moving spreading ridge led to variation in the location of the plume’s magmatic output at the surface.Flow of the plume material towards the ridge led to apparent southward movement of Meiji.Then,the upper part of the plume was carried northward until 65 Ma ago.After the ridge and the plume became sufficiently separated,magmatic output moved back to be centered over the plume stem.These changes are apparent in variations in the volume of seamounts along the plume track.Chemical and isotopic compositions of basalt from the Emperor Seamount chain changed from depleted(strong mid-ocean ridge affinity)in Meiji and Detroit to enriched(ocean island type),supporting declining influence from the ridge.Although its surface expression was modified by mantle flow and by plume-ridge interactions,the stem of the Hawaiian plume may have been essentially stationary during the Emperor period. 展开更多
关键词 Pacific plate Emperor-Hawaii chain Plume-ridge interaction GEOCHEMISTRY Numerical modeling
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Effects of Crustal Eclogitization on Plate Subduction/Collision Dynamics: Implications for India-Asia Collision 被引量:2
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作者 Pengpeng Huangfu Yuejun Wang +2 位作者 Zhonghai Li weiming fan Yan Zhang 《Journal of Earth Science》 SCIE CAS CSCD 2016年第5期727-739,共13页
2D thermo-mechanical models are constructed to investigate the effects of oceanic and continental crustal eclogitization on plate dynamics at three successive stages of oceanic subduction, slab breakoff, and continent... 2D thermo-mechanical models are constructed to investigate the effects of oceanic and continental crustal eclogitization on plate dynamics at three successive stages of oceanic subduction, slab breakoff, and continental subduction. Crustal eclogitization directly increases the average slab density and accordingly the slab pull force, which makes the slab subduct deeply and steeply. Numerical results demonstrate that the duration time from initial continental collision to slab breakoff largely depends on the slab pull force. Specifically, eclogitization of subducted crust can greatly decrease the duration time, but increase the breakoff depth. The detachment of oceanic slab from the pro-continental lithosphere is accompanied with obvious exhumation of the subducted continental crust and a sharp uplift of the collision zone in response to the disappearance of downward drag force and the induced asthenospheric upwelling, especially under the condition of no or incomplete crustal eclogitization. During continental subduction, the slab dip angle is strongly correlated with eclogitization of subducted continental lower crust, which regulates the slab buoyancy nature. Our model results can provide several important implications for the Himalayan-Tibetan collision zone. For example, it is possible that the lateral variations in the degree of eclogitization of the subducted Indian crust might to some extent contribute to the lateral variations of subduction angle along the Himalayan orogenic belt. Moreover, the accumulation of highly radiogenic sediments and upper continental crustal materials at the active margin in combination with the strong shear heating due to continuous continental subduction together cause rising of isotherms in the accretionary wedge, which facilitate the development of crustal partial melting and metamorphism. 展开更多
关键词 numerical modeling crustal eclogitization oceanic subduction slab breakoff continen-tal subduction Himalayan-Tibetan collision zone.
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