期刊
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
卷 184, 期 3-4, 页码 186-193出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.pepi.2010.11.007
关键词
Receiver function; Ordos Block; Yinshan Mountains; Hetao Graben; Crust and upper mantle; Mantle transition zone; Lower-crustal ductile flows
资金
- Chinese National Natural Science Foundation [40674048, 40974025, 40721003]
A temporary seismological network of broadband three-component stations has been deployed N-S to investigate the crust and upper mantle structure across the Ordos Block and the Yinshan Mountains. P wave receiver functions reveal the Moho depth to be about 41 km beneath the central Ordos Block and down to 45 km beneath the northern Ordos Block, a slight uplifting to 42-43 km beneath the Hetao Graben, increasing to 47-48 km beneath the Yinshan Mountains and then decreasing to 44 km beneath the northern Yinshan Mountains along the profile. In the Ordos Block, the crustal Vp/Vs ratio (about 1.80) south to the Hetao Graben differs from that (about 1.75) beneath the center Ordos Block. The crustal Vp/Vs ratio is significantly lower (about 1.65-1.70) beneath the Yinshan Mountains. The P wave receiver function migration imaging suggests relatively flat discontinuities at 410 and 660 km, indicating the lack of a strong thermal anomaly beneath this profile at these depths, and a low S wave velocity anomaly in the upper mantle beneath the Hetao Graben. We suggest that the low S wave velocity anomaly may be attributable to heat and that the thermal softening advances the evolution of the Hetao Graben, while the lower-crustal ductile flows transfer from the Hetao Graben to the northern Ordos Block, resulting in crustal thickening. (C) 2010 Elsevier B.V. All rights reserved.
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