Low crustal velocities and mantle lithospheric variations in southern Tibet from regional Pnl waveforms

被引:29
作者
Rodgers, ATJ [1 ]
Schwartz, SY [1 ]
机构
[1] UNIV CALIF SANTA CRUZ,INST TECTON,SANTA CRUZ,CA 95064
关键词
D O I
10.1029/96GL03774
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
We report low average crustal P-wave velocities (5.9-6.1 km/s, Poisson's ratio 0.23-0.27, thickness 68-76 km) in southern Tibet from modelling regional PnI waveforms recorded by the 1991-1992 Tibetan Plateau Experiment. We also find that the mantle lithosphere beneath the Indus-Tsangpo Suture and the Lhasa Terrane is shield-like (Pn velocity 8.20-8.25 km/s,lid thickness 80-140 km, positive velocity gradient 0.0015-0.0025 s(-1)). Analysis of relative Pn travel time residuals requires a decrease in the mantle velocities beneath the northern Lhasa Terrane. the Banggong-Nujiang Suture and the southern Qiangtang Terrane. Tectonic and petrologic considerations suggest that low bulk crustal velocities could result from a thick (50-60 km) felsic upper crust with vertically limited and laterally pervasive partial melt. These results are consistent with underthrusting of Indian Shield lithosphere beneath the Tibetan Plateau to at least the central Lhasa Terrane.
引用
收藏
页码:9 / 12
页数:4
相关论文
共 17 条
[1]   SEISMIC VELOCITY STRUCTURE AND COMPOSITION OF THE CONTINENTAL-CRUST - A GLOBAL VIEW [J].
CHRISTENSEN, NI ;
MOONEY, WD .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1995, 100 (B6) :9761-9788
[2]   Rupture history and seismotectonics of the 1991 Uttarkashi, Himalaya earthquake [J].
Cotton, F ;
Campillo, M ;
Deschamps, A ;
Rastogi, BK .
TECTONOPHYSICS, 1996, 258 (1-4) :35-51
[3]   THE TECTONIC EVOLUTION OF THE TIBETAN PLATEAU [J].
DEWEY, JF ;
SHACKLETON, RM ;
CHANG, CF ;
SUN, YY .
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, 1988, 327 (1594) :379-413
[4]   COMPUTATION OF SYNTHETIC SEISMOGRAMS WITH REFLECTIVITY METHOD AND COMPARISON WITH OBSERVATIONS [J].
FUCHS, K ;
MULLER, G .
GEOPHYSICAL JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY, 1971, 23 (04) :417-+
[5]   CRUSTAL THICKNESS AND UPPER MANTLE VELOCITIES IN THE TIBETAN PLATEAU REGION FROM THE INVERSION OF REGIONAL PNL WAVE-FORMS - EVIDENCE FOR A THICK UPPER MANTLE LID BENEATH SOUTHERN TIBET [J].
HOLT, WE ;
WALLACE, TC .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1990, 95 (B8) :12499-12525
[6]   PHASE-RELATIONSHIPS OF S-TYPE GRANITE WITH H2O TO 35 KBAR - MUSCOVITE GRANITE FROM HARNEY PEAK, SOUTH-DAKOTA [J].
HUANG, WL ;
WYLLIE, PJ .
JOURNAL OF GEOPHYSICAL RESEARCH, 1981, 86 (NB11) :515-529
[7]   Mapping the descent of Indian and Eurasian plates beneath the Tibetan Plateau from gravity anomalies [J].
Jin, Y ;
McNutt, MK ;
Zhu, YS .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1996, 101 (B5) :11275-11290
[8]  
KIND R, 1996, IN PRESS SCIENCE
[9]  
MCNAMARA D, 1996, IN PRESS J GEOPHYS R
[10]   OBSERVATIONS OF REGIONAL PHASE PROPAGATION ACROSS THE TIBETAN PLATEAU [J].
MCNAMARA, DE ;
OWENS, TJ ;
WALTER, WR .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1995, 100 (B11) :22215-22229