Crustal Structures beneath West Qinling‐East Kunlun Orogen and its Adjacent Area ‐Result of Wide‐Angle Seismic Reflection and Refraction Experiment

Zhang, Xian‐Kang; Jia, Shanshan; Zhao, Jun‐Hong; Zhang, Chengke; Yang, Jianbo; Wang, Fuyun; Zhang, Jian-shi; Liu, Bao-Fen; Sun, Guo-wei; Pan, Suli

doi:10.1002/cjg2.1221

Cited by 38 publications

(38 citation statements)

References 5 publications

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“…Some profiles extended from the Tarim, Yangtze or North China blocks across the eastern or northern margin of the plateau Qian, 2000, Wang et al, 2003a, b;Li et al, 2001;Vergne et al, 2002, Zhang, personal communication, 2004, Zhang et al, 2008. The 3D survey system has been attempted in the eastern plateau (Zhang et al, symposium report, 2002).…”

Section: Distribution Of Active-sources Seismic Profilesmentioning

confidence: 93%

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The thickness and structural characteristics of the crust across Tibetan plateau from active-sources seismic profiles

Gao

et al. 2009

Earthq Sci

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The Tibetan plateau as one of the youngest orogen on the Earth was considered as the result of continent-continent collision between the Eurasian and Indian plates. The thickness and structure of the crust beneath Tibetan plateau is essential to understand deformation behavior of the plateau. Active-source seismic profiling is most available geophysical method for imaging the structure of the continental crust. The results from more than 25 active-sources seismic profiles carried out in the past twenty years were reviewed in this article. A preliminary cross crustal pattern of the Tibetan Plateau was presented and discussed. The Moho discontinuity buries at the range of 60−80 km on average and have steep ramps located roughly beneath the sutures that are compatible with the successive stacking/accretion of the former Cenozoic blocks northeastward. The deepest Moho (near 80 km) appears closely near IYS and the crustal scale thrust system beneath southern margin of Tibetan plateau suggests strong dependence on collision and non-distributed deformation there. However, the ~20 km order of Moho offsets hardly reappears in the inline section across northern Tibetan plateau. Without a universally accepted, convincing dynamic explanation model accommodated the all of the facts seen in controlled seismic sections, but vertical thickening and northeastern shorten of the crust is quite evident and interpretable to a certain extent as the result of continent-continent collision. Simultaneously, weak geophysical signature of the BNS suggests that convergence has been accommodated perhaps partially through pure-shear thickening accompanied by removal of lower crustal material by lateral escape. Recent years the result of Moho with ~7 km offset and long extend in south-dip angle beneath the east Kunlun orogen and a grand thrust fault at the northern margin of Qilian orogen has attract more attention to action from the northern blocks. The broad lower-velocity area in the upper-middle crust of the Lhasa block was once considered as resulted from partially melted rocks. However the low normal v P /v S ratio and the Moho stepwise rise fail to support significant partial melting in the middle-lower crust of the central-northern Tibetan plateau. Furthermore, the lower-velocity of crust occasionally disappears, and/or local thinned exhibits their non-stationary spatial distribution.

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Section: Distribution Of Active-sources Seismic Profilesmentioning

confidence: 93%

“…3D profile on eastern Kunlun (Zhang et al, symposium report, 2002); 19. Ma'erkang-Gulang (Zhang et al, 2008); 20. Eastern Silin Co-Western Coqen (Zhang et al, symposium report, 2004).…”

Section: Distribution Of Active-sources Seismic Profilesmentioning

confidence: 99%

The thickness and structural characteristics of the crust across Tibetan plateau from active-sources seismic profiles

Gao

et al. 2009

Earthq Sci

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“…The crust section model is obtained by calculation of travel times, synthetic seismograms using Seis83 program package [19,20], and fitting to the observation data of identified seismic phases [6] (Figure 3 (c)). …”

Section: -D Crust Structure and Discussion In Zoigê Basin And Its Sumentioning

confidence: 99%

“…Figure 2 shows the record sections at shot distances of 205, 247 and 290 km. These record sections reflect the crustal structures of Zoigê basin, Aba arcuate fault belt, and A'nyemaqên suture zone located at the southern flank of West Qinling fold zone respectively ( Figure 1) [6]. Pg, Pm, and Pn can be identified on the record sections of Zoigê basin and its surrounding folded belts, which are refracted or overcritical reflected waves from crystalline basement, the Moho, and uppermost mantle respectively.…”

Section: Seismic Phases and Velocity-depth Functions Of The Crustmentioning

confidence: 99%

“…The segment between distances 250 and 430 km of this profile coincides with the nearly vertical reflection profile [5]. The basement and crustal structures, tectonic evolution, and potential oil/gas reserve possibility in Zoigê basin and its surrounding folded regions are discussed in this paper by using the seismic data of southern segment along Barkam-Luqu-Gulang deep seismic sounding profile [6].…”

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Deep seismic sounding data reveal the crustal structures beneath Zoigê basin and its surrounding folded orogenic belts

Jia

Zhang

Zhao

et al. 2009

Sci. China Earth Sci.

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Songpan-Garze massif is located at the turning position of tectonics from the nearly west-east direction to the nearly north-south direction in the northeastern margin of Tibetan Plateau, with Zoigê basin in the centre of the massif. In this paper, we build a crustal structure model of Zoigê basin and its surrounding folded orogenic belts using the deep seismic sounding data in this region. We also discuss structures and properties of the basement in Zoigê basin, tectonic relations between Zoigê upland basin and its surrounding folded orogenic belts, crustal deformation and thickening in the northeastern margin of Tibetan Plateau, and decoupling and relaxing processes in the crust. The results indicate that a special "Mesozoic basement" is formed of Triassic rocks with high density (2.65-2.75 g/cm 3 ) and high velocity (5.6 km/s) in Zoigê basin. Songpan-Garze tectonic massif was transformed into two types of tectonic units with different crustal structures, i.e., relatively stable Zoigê upland basin and active folded orogenic belts around the basin, in the course of the crustal material of Tibetan Plateau flowing eastward and obstructed by surrounding stable blocks. The thickening of the crust in the northeastern margin of Tibetan Plateau mainly occurred in the mid and lower crust, and the structure characterized by low velocities and multiple reflectors obviously appears in the folded orogenic belts around Zoigê basin. It implies that the mid and lower crust underwent a strong tectonic deformation in the folded orogenic areas. The thickness of the crust is about 50 km in Zoigê basin and the folded orogenic belts at the both southern and northern sides of Zoigê basin. The "Mountain root" cannot be identified. It is inferred that during the later orogenic period the eastwards flowing deep materials moved clockwise along the relatively relaxing southern side around the eastern tectonic knot under the obstructing of surrounding rigid massifs, and it resulted in the strong stretching action of the folded orogenic belts around Zoigê basin.Zoigê basin, folded orogenic belt, deep seismic sounding, basement structure, crustal structure and tectonics Citation:Jia S X, Zhang X K, Zhao J R, et al. Deep seismic sounding data reveal the crustal structures beneath Zoigê basin and its surrounding folded orogenic belts.

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Longriba fault zone in eastern Tibet: An important tectonic boundary marking the westernmost edge of the Yangtze block

Guo

Gao

et al. 2015

Tectonics

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Global Positioning System (GPS) measurements across eastern Tibet reveal a sharp velocity gradient zone located about 150 km west of the Longmen Shan frontal thrust zone, where eastward block motion of Tibet decreases from~12 mm/yr to~3 mm/yr over a distance of less than 10 km. In order to investigate the tectonic cause for this rapid change in GPS velocity, together with systematic review on the available geological and geophysical data in easternmost Tibet, we provide new constraints on the tectonic feature of the Longriba fault zone from Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar data. We propose that the NE striking Longriba fault zone is the key structure responsible for the observed sharp gradient in GPS velocities. In addition, the evidence indicates that the Longriba fault zone, instead of the Longmen Shan fault zone, marks the westernmost edge of the Yangtze crustal block. Given the irregular western margin of the Yangtze block, the Longriba fault zone represents part of the actual tectonic boundary between the Songpan-Ganzi terrane and the Yangtze block. The newly identified western edge of the Yangtze block implies a paleocontinent-ocean boundary at depth. This boundary was a potential weak zone and may have been exploited during the formation of the Longriba fault zone. The results of this paper should advance our understanding of the tectonic relationship between the Songpan-Ganzi terrane and Yangtze block and provide additional constraints for studies of the geodynamic response of eastern Tibet to the ongoing India-Eurasia collision.

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Crustal Structures beneath West Qinling‐East Kunlun Orogen and its Adjacent Area ‐Result of Wide‐Angle Seismic Reflection and Refraction Experiment

Cited by 38 publications

References 5 publications

The thickness and structural characteristics of the crust across Tibetan plateau from active-sources seismic profiles

The thickness and structural characteristics of the crust across Tibetan plateau from active-sources seismic profiles

Deep seismic sounding data reveal the crustal structures beneath Zoigê basin and its surrounding folded orogenic belts

Longriba fault zone in eastern Tibet: An important tectonic boundary marking the westernmost edge of the Yangtze block

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