A deep seismic sounding profile across the Tianshan Mountains

Citation
Dy. Lu et al., A deep seismic sounding profile across the Tianshan Mountains, CHIN SCI B, 45(22), 2000, pp. 2100-2107
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
CHINESE SCIENCE BULLETIN
ISSN journal
1001-6538 → ACNP
Volume
45
Issue
22
Year of publication
2000
Pages
2100 - 2107
Database
ISI
SICI code
1001-6538(200011)45:22<2100:ADSSPA>2.0.ZU;2-O
Abstract
The deep seismic sounding profile across the Tianshan Mountains revealed a two-layer crustal structure in the Tianshan region, namely the lower and up per crusts. Lateral variations of layer velocity and thickness are evidentl y shown. Low-velocity layers spread discontinuously at the bottom of the up per crust. The Moho depth is 47 km in the Kuytun area and 50 km in the Xaya r area. In the Tianshan Mountains, the Moho becomes deeper with the maximum depth of 62 km around the boundary between the southern and northern Tians han Mountains. The average velocity ranges from 6.1 to 6.3 km/s in the crus t and 8.15 km/s at the top of the upper mantle. Two groups of reliable refl ective seismic phases of the Moho (P-m1 and P-m2) are recognized on the sho t record section of the Kuytun area. A staked and offset region, 20-30 km l ong, is displayed within a shot-geophone distance of 190-210 km in P-m1 and P-m2 Calculation shows that the Moho is offset by 10 km in the northern Ti anshan region, 62 km deep in the south while 52 km deep in the north, and p lunges northwards. In comparison with typical collisional orogenic belts, t he structure of the Moho beneath the Tianshan Mountains presents a similar pattern. This can be used to explain the subduction of the Tarim plate towa rds the Tianshan Mountains. This intracontinental subduction is considered the dynamic mechanism of the Cenozoic uplifting of the Tianshan Mountains. The discovery of seismic phases P-m1 and Pm-2 serves as the seismological e vidence for the northward subduction of the Tarim plate.