The crustal structure under Sanjiang and its dynamic implications: Revealed by seismic reflection/refraction profile between Zhefang and Binchuan, Yunnan

Zhang, Zhongjie; Bai, Zhiming; Wang, Chunyong; Teng, Jun; Lü, Qingtian; Li, Jiliang; Yifeng, Liu; Liu, Zhenkuan

doi:10.1360/01yd0567

Cited by 43 publications

(35 citation statements)

References 4 publications

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“…The fast-wave direction of SKS splitting is not in accordance with the maximum shear direction of the surface deformation field. The crustal structure of Yunnan [32][33][34][35][36] reflects that the velocity distribution of lower crust is basically normal (6.6-6.8 km/s) except that there locally exists a low velocity zone in lower crust. Hence, we do not consider the decoupling of lower crust in the deformation analysis.…”

Section: Preliminary Analysis Of the Crustmantle Coupling And Decouplmentioning

confidence: 99%

Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern

et al. 2007

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regional digital networks, and portable broadband seismic networks deployed in Sichuan, Yunnan and Tibet, we obtained the SKS fast-wave direction and the delay time between fast and slow waves of each station by use of the stacking analysis method, and finally acquired the fine image of upper mantle anisotropy in the eastern Tibetan Plateau and its adjacent regions. We analyzed the crust-mantle coupling deformation on the basis of combining the GPS observation results and the upper mantle anisotropy distribution in the study area. The Yunnan region out of the plateau has different features of crust-mantle deformation from the inside plateau. There exists a lateral transitional zone of crust-mantle coupling in the eastern edge of the Tibetan Plateau, which is located in the region between 26° and 27°N in the west of Sichuan and Yunnan. To the south of transitional zone, the fast-wave direction is gradually turned from S60°-70°E in southwestern Yunnan to near EW in southeastern Yunnan. To the north of transitional zone in northwestern Yunnan and the south of western Sichuan, the fast-wave direction is nearly NS. From crust to upper mantle, the geophysical parameters (e.g. the crustal thickness, the Bouguer gravity anomaly, and tectonic stress direction) show the feature of lateral variation in the transitional zone, although the fault trend on the ground surface is inconsistent with the fast-wave direction. This transitional zone is close by the eastern Himalayan syntaxis, and it may play an important role in the plate boundary dynamics.upper mantle anisotropy, SKS wave, fast-wave direction, crust-mantle coupling, lithospheric deformation Since the 1990s, the broadband digital technology has made great progress in the research of the Earth sciences. The seismograms recorded by the broadband seismometers deployed in the world are widely applied to the study of seismology, deep structure and geodynamics. In this paper, we focus on the mantle anisotropy and related geodynamic issues. Generally speaking, the mantle anisotropy is determined by the lattice-preferred orientation of olivine crystals as a result of the mantle deformation. There are various causes resulting in the mantle deformation. Among them, the plate motion is a direct cause. The size and direction of the mantle anisotropy strongly depend on the velocity of the plate motion. In the various subjects of recent studies on geodynamics, the anisotropy in the mantle is one of effective ways to probe the complicated deep structure beneath the continent and its evolution, the crust-mantle coupling deformation, etc. [1,2] .

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Section: Preliminary Analysis Of the Crustmantle Coupling And Decouplmentioning

confidence: 99%

Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern

et al. 2007

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“…However, in comparison with that of the other active domains in Chinese mainland, especially that of Yunnan [17,24,25] and Tibet [26,27] , this undulation is small, and its range approximates that of northeastern China [5] . The P n velocity of 8.06-8.29 km/s was obviously larger than that of the Yunnan and Tibet zones.…”

Section: Geodynamics and Seismotectonic Implicationsmentioning

confidence: 99%

Crustal P-wave velocity structure in Lower Yangtze region: Reinterpretation of Fuliji-Fengxian deep seismic sounding profile

Bai

Wang

2006

CHINESE SCI BULL

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The finite-difference inversion method and RayInvr technique had been employed to interpret the wide-angle seismic reflection/refraction data of the Fuliji-Fengxian deep seismic sounding (DSS) profile in Lower Yangtze region, hence the velocity structure was acquired and conclusions were summarized as follows: (1) The velocity model along this profile can be divided into three large layers vertically (upper, middle and lower crusts) and six blocks laterally, and this velocity distribution agrees with the feature of stable platform. (2) The depth of Moho discontinuity is 30-36 km. The thickness of the upper crust is 10.5-13.0 km, where the lateral velocity varies strongly, and the velocity increases to 6.2 km/s −1 at bottom. Besides, the velocity distributions in the bottom layer of middle crust and lower crust have an apparent inhomogeneity. The velocity in upper layer of middle crust, lower layer of middle crust, lower crust and uppermost mantle is 5.9-6.2, 6.3-6.4, 6.6-7.0 and 8.06-8.29 km/s −1 , respectively. (3) On two sides of the Tanlu fault belt (TFB), the mid-crustal velocity structure is quite different, nevertheless no apparent discrimination in velocity distribution and boundary topography exhibits in lower crust, hence it is inferred that the Jiashan segment of TFB had probably cut through whole crust in the Mesozoic, and the fault behaviour in lower crust had disappeared due to the low viscosity produced by the orogenic extension or crustal balance, while the fault features in the rigid middle-upper crust have been preserved up to the present. (4) The moderate earthquakes with Ms > 5.0 nearby Zhenjiang are related to the deep faults extending into the lower crust, and the earthquakes were probably induced by the energy been transferred from mantle lithosphere to upper-mid crust along the deep faults, and aggregated at some preferable tectonic positions.

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“…Large low-velocity belts at the top of the upper mantle were identified by many researchers [64,86,88,89] . The crust is 36-48 km thick along the Ailaoshan-Red River boundary, close to Moho.…”

Section: Figurementioning

confidence: 97%

“…The crust is 36-48 km thick along the Ailaoshan-Red River boundary, close to Moho. So this abnormal low-velocity zone may be related to the thermal dynamic conditions at the crust-mantle boundary, and could be explained by the crust-mantle transitional zone near the Red River faulted belt [64,86,88,89] . It is thought that simple ductile-shear along a fault cannot cause temperatures as high as 700 in the the ℃ mid-lower crust.…”

Section: Figurementioning

confidence: 99%

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Deep-seated structure and metallogenic dynamics of the Ailaoshan polymetallic mineralization concentration area, Yunnan Province, China

Deng

Xiao-dong³

et al. 2009

Sci. China Ser. D-Earth Sci.

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Citation: Ge L S, Deng J, Guo X D, et al. Deep-seated structure and metallogenic dynamics of the Ailaoshan polymetallic mineralization concentration area,The Ailaoshan poly-metallic mineralization concentrated area (MCA) consists of the well known Ailaoshan metallogenic belt and adjacent mineral districts and/or deposits. Located in an area of several complex and intersecting tectonic units, the Ailaoshan poly-metallic MCA is controlled by deep crustal and mantle tectonism. Through interpretation of remote sensing images, we identified a large ring structure system that surrounds the MCA. This ring structure encloses regional deep-crustal faults, ductile shear zones, geothermal anomalies, magmatic rocks, and the major mineral deposits, all of which are the reflections of deep tectonic geodynamics that have been long active in this area. Geophysical data indicate that the crust is comprised of relatively stable two or three layers, with some irregular lower-velocity belts. The Moho in the ring sutures occurs as an area of local uplift. There exists an obvious transitional zone between the crust and mantle boundaries. Asthenopheric mantle shows multi-layer upwelling, which indicates multiple events during different geological epochs. It is believed that these mantle events or pulses were responsible for the formation of the regional shear zones, magmatic rocks, and polymetallic orebodies. Furthermore, an integrated metallogenic dynamics model related to the asthenopheric upwelling pulses in the MCA is established, defining events as old as Late Paleozoic.

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The crustal structure under Sanjiang and its dynamic implications: Revealed by seismic reflection/refraction profile between Zhefang and Binchuan, Yunnan

Cited by 43 publications

References 4 publications

Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern

Seismic anisotropy of upper mantle in eastern Tibetan Plateau and related crust-mantle coupling pattern

Crustal P-wave velocity structure in Lower Yangtze region: Reinterpretation of Fuliji-Fengxian deep seismic sounding profile

Deep-seated structure and metallogenic dynamics of the Ailaoshan polymetallic mineralization concentration area, Yunnan Province, China

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