Teleseismic tomography beneath Hi-CLIMB station array in western Tibetan Plateau

Feng, Ye

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https://hdl.handle.net/2142/44477 Copy

Description

Title

Teleseismic tomography beneath Hi-CLIMB station array in western Tibetan Plateau

Author(s)

Feng, Ye

Issue Date

2013-05-24T22:17:32Z

Director of Research (if dissertation) or Advisor (if thesis)

Song, Xiaodong

Department of Study

Geology

Discipline

Geology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Himalaya-Tibetan Continental Lithosphere During Mountain Building (Hi-CLIMB)
• teleseismic tomography
• Indian-Eurasion Collision

Abstract

This study aims to explore the velocity structure of the lithosphere and upper mantle beneath the Hi-climb station array in mid-western Tibetan Plateau (TP), thus to understand the deformation scheme of the Indian-Eurasian collision. The Hi-Climb seismic array, which includes 75 seismic stations, was collecting data from late 2002 to 2005. It forms a nearly linear shape extending from the Himalayan foreland into the western-central TP. During the three-year deployment period of the array, 24 teleseisms with good signal-to-noise ratio were chosen out of a large amount of events, allowing 1320 relative travel time residuals to be picked with high accuracy in this study. P phases were recorded and contributed to the calculation of relative travel time residuals, which were finally mapped as P wave velocity perturbations with respect to the ak135 global reference model using teleseismic tomography. Checkerboard synthetic test was performed, showing good resolution at depths between 100 km to 300 km in horizontal slices. Good recovery was also shown in North-South slices at longitudes of 85.2° E and 84.2° E, respectively. The resulting horizontal tomographic images exhibit a high-slow-high velocity structure from north end of the array to the south. The two boundaries separating the velocity structures are Bangong-Nujiang suture (BNS) and the Indus-Yarlung suture (IYS). Positive velocity perturbation was found north to the Bangong-Nujiang suture (BNS), suggesting a higher velocity zone in Qiangtang Terrane compared to Lhasa Terrane. The other high velocity zone is present at the south end of the station array, which is south to the Indus-Yarlung suture. Cross-sections on north-south slices also present a fast-slow-fast velocity, which signals a thicker and less dense lithosphere beneath the middle part of the station array, and thinner but denser lithospheres at north and south edges. The result is in good agreement with previous work and it may be a consequence of the subducting Indian plate toward Eurasian plate.

Graduation Semester

2013-05

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http://hdl.handle.net/2142/44477

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Copyright 2013 Ye Feng

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