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Seismological constraints on the crustal structures generated by continental rejuvenation in northeastern China.

Zheng TY, He YM, Yang JH, Zhao L - Sci Rep (2015)

Bottom Line: Here, we present a seismic image across the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB) using a velocity structure imaging technique for receiver functions from a dense array.The imaged structures and geochemical evidence, including changes in the components and ages of continental crusts and significant continental crustal growth during the Mesozoic, provide insight into the rejuvenation processes of the evolving crust in the eastern NCC caused by structural, magmatic and metamorphic processes in an extensional setting.The fossil structural fabric of the convergent boundary in the eastern CAOB indicates that the back-arc action of the Paleo-Pacific Plate subduction did not reach the hinterland of Asia.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.

ABSTRACT
Crustal rejuvenation is a key process that has shaped the characteristics of current continental structures and components in tectonic active continental regions. Geological and geochemical observations have provided insights into crustal rejuvenation, although the crustal structural fabrics have not been well constrained. Here, we present a seismic image across the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB) using a velocity structure imaging technique for receiver functions from a dense array. The crustal evolution of the eastern NCC was delineated during the Mesozoic by a dominant low seismic wave velocity with velocity inversion, a relatively shallow Moho discontinuity, and a Moho offset beneath the Tanlu Fault Zone. The imaged structures and geochemical evidence, including changes in the components and ages of continental crusts and significant continental crustal growth during the Mesozoic, provide insight into the rejuvenation processes of the evolving crust in the eastern NCC caused by structural, magmatic and metamorphic processes in an extensional setting. The fossil structural fabric of the convergent boundary in the eastern CAOB indicates that the back-arc action of the Paleo-Pacific Plate subduction did not reach the hinterland of Asia.

No MeSH data available.


Related in: MedlinePlus

Synthetic CCP images compared with the observational CCP image, and the cross section of the crustal shear-wave velocity structure.(a) Observational CCP image calculated from the observed data; (b) CCP images calculated from the synthetic receiver functions; (c) shear-wave velocity structure of the crust and uppermost mantle compiled from the crustal models beneath each station; and (d) sedimentary structure. In the CCP images, red denotes the positive amplitude of the receiver function as annotated by the color bar, which indicates that velocity increases with depth. Blue denotes negative amplitudes and velocity decreases with depth. Certain station numbers are labeled on the top of the plot. Red arrows mark the surface site of the Tanlu Fault Zone.
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f2: Synthetic CCP images compared with the observational CCP image, and the cross section of the crustal shear-wave velocity structure.(a) Observational CCP image calculated from the observed data; (b) CCP images calculated from the synthetic receiver functions; (c) shear-wave velocity structure of the crust and uppermost mantle compiled from the crustal models beneath each station; and (d) sedimentary structure. In the CCP images, red denotes the positive amplitude of the receiver function as annotated by the color bar, which indicates that velocity increases with depth. Blue denotes negative amplitudes and velocity decreases with depth. Certain station numbers are labeled on the top of the plot. Red arrows mark the surface site of the Tanlu Fault Zone.

Mentions: We developed a velocity structure imaging technique for receiver functions to infer the crustal structures beneath the NCISP-6 from the teleseismic waveform records. Taking advantage of the concentration of energy from the P–S converted phases, direct imaging of the velocity discontinuity structures was achieved by stacking the amplitudes of the receiver functions in the depth domain using common conversion point (CCP) image stacking2122. We simulated the observation CCP image from the data using synthetic CCP images to identify attributes of the velocity discontinuities in the CCP stacking section. The identified velocity discontinuities and corresponding depths were used as the constraint conditions in the global inversion of the receiver function waveforms, and crustal velocity models were obtained beneath each station. Figure 2a shows the CCP depth image beneath the NCISP-6 based on the data. Figure 2b shows the best-fitting CCP image (synthetic CCP image) stacked from synthetic receiver functions. A comparison between the synthetic CCP images and the observations indicates an accurate reconstruction of the crustal models. Traces of the intra-crust velocity discontinuities and the Moho interface for the Ps and PpPs phases are reproduced in the synthetic CCP image. Dual constraints from the CCP images and seismic waveforms can significantly enhance the reliability of receiver function imaging.


Seismological constraints on the crustal structures generated by continental rejuvenation in northeastern China.

Zheng TY, He YM, Yang JH, Zhao L - Sci Rep (2015)

Synthetic CCP images compared with the observational CCP image, and the cross section of the crustal shear-wave velocity structure.(a) Observational CCP image calculated from the observed data; (b) CCP images calculated from the synthetic receiver functions; (c) shear-wave velocity structure of the crust and uppermost mantle compiled from the crustal models beneath each station; and (d) sedimentary structure. In the CCP images, red denotes the positive amplitude of the receiver function as annotated by the color bar, which indicates that velocity increases with depth. Blue denotes negative amplitudes and velocity decreases with depth. Certain station numbers are labeled on the top of the plot. Red arrows mark the surface site of the Tanlu Fault Zone.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595743&req=5

f2: Synthetic CCP images compared with the observational CCP image, and the cross section of the crustal shear-wave velocity structure.(a) Observational CCP image calculated from the observed data; (b) CCP images calculated from the synthetic receiver functions; (c) shear-wave velocity structure of the crust and uppermost mantle compiled from the crustal models beneath each station; and (d) sedimentary structure. In the CCP images, red denotes the positive amplitude of the receiver function as annotated by the color bar, which indicates that velocity increases with depth. Blue denotes negative amplitudes and velocity decreases with depth. Certain station numbers are labeled on the top of the plot. Red arrows mark the surface site of the Tanlu Fault Zone.
Mentions: We developed a velocity structure imaging technique for receiver functions to infer the crustal structures beneath the NCISP-6 from the teleseismic waveform records. Taking advantage of the concentration of energy from the P–S converted phases, direct imaging of the velocity discontinuity structures was achieved by stacking the amplitudes of the receiver functions in the depth domain using common conversion point (CCP) image stacking2122. We simulated the observation CCP image from the data using synthetic CCP images to identify attributes of the velocity discontinuities in the CCP stacking section. The identified velocity discontinuities and corresponding depths were used as the constraint conditions in the global inversion of the receiver function waveforms, and crustal velocity models were obtained beneath each station. Figure 2a shows the CCP depth image beneath the NCISP-6 based on the data. Figure 2b shows the best-fitting CCP image (synthetic CCP image) stacked from synthetic receiver functions. A comparison between the synthetic CCP images and the observations indicates an accurate reconstruction of the crustal models. Traces of the intra-crust velocity discontinuities and the Moho interface for the Ps and PpPs phases are reproduced in the synthetic CCP image. Dual constraints from the CCP images and seismic waveforms can significantly enhance the reliability of receiver function imaging.

Bottom Line: Here, we present a seismic image across the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB) using a velocity structure imaging technique for receiver functions from a dense array.The imaged structures and geochemical evidence, including changes in the components and ages of continental crusts and significant continental crustal growth during the Mesozoic, provide insight into the rejuvenation processes of the evolving crust in the eastern NCC caused by structural, magmatic and metamorphic processes in an extensional setting.The fossil structural fabric of the convergent boundary in the eastern CAOB indicates that the back-arc action of the Paleo-Pacific Plate subduction did not reach the hinterland of Asia.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China.

ABSTRACT
Crustal rejuvenation is a key process that has shaped the characteristics of current continental structures and components in tectonic active continental regions. Geological and geochemical observations have provided insights into crustal rejuvenation, although the crustal structural fabrics have not been well constrained. Here, we present a seismic image across the North China Craton (NCC) and Central Asian Orogenic Belt (CAOB) using a velocity structure imaging technique for receiver functions from a dense array. The crustal evolution of the eastern NCC was delineated during the Mesozoic by a dominant low seismic wave velocity with velocity inversion, a relatively shallow Moho discontinuity, and a Moho offset beneath the Tanlu Fault Zone. The imaged structures and geochemical evidence, including changes in the components and ages of continental crusts and significant continental crustal growth during the Mesozoic, provide insight into the rejuvenation processes of the evolving crust in the eastern NCC caused by structural, magmatic and metamorphic processes in an extensional setting. The fossil structural fabric of the convergent boundary in the eastern CAOB indicates that the back-arc action of the Paleo-Pacific Plate subduction did not reach the hinterland of Asia.

No MeSH data available.


Related in: MedlinePlus