Dr. Nong Wu (UW)
Dr. Alan Jones(GSC),
Prof. Chen Leshou (CUG),
Prof. John Booker (UW),
Prof. Wei Wenbo (CUG),
Hu Jiande (CUG)
Tan Handong (CUG)
outside Holiday Inn, Lhasa, just prior to commencement of 1995
MT field program (April 21st 1995)
Prof. Doug Nelson, Syracuse University (INDEPTH Project Leader)
Prof. Larry Brown, Cornell University
Prof. Simon Klemperer, Stanford University
Prof. Jim Ni, New Mexico State University
Activities.....
Phase I: 1995
Using the GSC's 16 LIMS and UW's 5 LIMS-clones (LRMTs built by Phoenix
Geophysics), a long period MT survey was carried out in April to July along
three main transects. For a plot of the sites on the topography of Asia
please press here (Warning: the gif file
is 150 Kb in size).
For a location map of the sites showing the Zangbo suture
and Lhasa, press here.
For a geology map with the MT sites, press
here.
Phase II (part of INDEPTH-III): 1998
In July and August 1998 Long Period magnetotelluric (MT) data were collected
as part of the INDEPTH-III survey in Central Tibet. Long period MT data were
collected at 26 sites on a 400 km profile extending from Nam Tso to Longwei
Tso with the goal of imaging crustal and mantle structure. Broadband MT
data were also collected to image shallow structure by the China University
of Geosciences. In this paper we will present initial results based on the
long period data, since the broadband and long period data have yet to be
merged. Preliminary inversions of the long period MT data show the following
features.
(1) In the south of the profile a strong conductor is observed at a depth of
15 km. This is at a similar depth to the conductor observed beneath the
Yangbaijin graben during INDEPTH-II in 1995. This conductor terminates 50 km
north of the Bangong suture.
(2) Further north, where the shallow conductor is absent, a deeper conductor
is imaged at a depth of 50-60 km. This conductor continues to the northern
end of the profile and is at the same depth as the low velocity zone imaged
by seismic observations. It may represent the asthenosphere beneath a
50-60 km crust.
Leshou, C., J.R. Booker, Jones, A.G., M. Unsworth, N. Wu, 1995
Magnetotelluric study of the India-Asia suture zone
Contributed paper at:
XXI IUGG General Assembly,
Boulder, Colorado, 2-14 July
Chen, L., J.R. Booker, Jones, A.G., M.J. Unsworth, N. Wu, 1995
Magnetotelluric study of the Tsangpo suture zone
Contributed paper at:
Fall AGU,
San Francisco, 11-15 Dec.
Booker, J. R., N. Wu, M. Unsworth, Jones, A.G., C. Leshou, W. Wenbo, and
T. Handong, 1996
Crustal Hot Spots: Electromagnetic Imaging of Magma Chambers in the
Tibetan Crust
Contributed paper at:
13th EM Induction Workshop,
Onuma, Japan, 12-18 July
Jones, A.G., J. R. Booker, N. Wu, C. Leshou, W. Wenbo, and T. Handong, 1996
Electromagnetic Images of Colliding Continents: a Magnetotelluric Survey
of the Tsangpo Suture Zone
Contributed paper at:
13th EM Induction Workshop,
Onuma, Japan, 12-18 July
Jones, A.G., Booker, J.R., Wu, N., Unsworth, M., Chen, L., Wei W. and
Handong, T., 1996
Electromagnetic images of colliding continents: a magnetotelluric survey of
the Zangbo suture zone
Contributed paper at:
7th International Symposium on Deep Seismic Profiling of the Continents,
Asilomar, California, 15-20 September
Jones, A.G., J.R. Booker, M Unsworth, N Wu, L Chen, W Wei and H Tan, 1997
Electromagnetic Image of Colliding Continents: Magnetotelluric Results
from a Survey of the India-Asia Collision Zone at 90 deg East latitude
Contributed paper at:
IAGA Scientific Assembly
Uppsala, Sweden, 3-15 August
Alsdorf, D., Noise Reduction in Seismic Data Using Fourier
Correlation Coefficient Filtering, (in final review
Geophysics, 1996).
Alsdorf, D., L. D. Brown, and K. D. Nelson, Possible Upper
Mantle Reflection Fabric on Seismic Profiles from the
Tethyan Himalaya: Identification and Tectonic Interpretation,
(Journal of Geophysical Research, accepted July 1996).
Brown, L. D., W. Zhao, K. D. Nelson, M. L. Hauck, D. Alsdorf,
A. Ross, M. Cogan, M. Clark, X. Liu, and J. Che, Crustal
Deformation and Magmatism at the Southern Margin of Tibet
from Multichannel Seismic Reflection Profiling during Project
INDEPTH, (submitted to Science, 1996)
Clark, M., The Nyainqentanglha Shear Zone at Depth: Detachment
Faulting in Southern Tibet, Senior Thesis, Cornell
University, 1995.
Cogan, M. J., INDEPTH Seismic Refraction Analysis of the Yadong-
Gulu Rift: Evidence for a Fluid Middle Crust Beneath
Southern Tibet, China, M.S. Thesis, Syracuse University, 1995.
Edwards, M. A., and T. M. Harrison, When did the Roof Collapse?
Late Miocene N-S Extension in the High Himalaya Revealed
by Th-Pb Monazite Dating of the Khula Kangri Granite,
(submitted to Nature, 1996).
Edwards, M. A., C. Wu, W. S. F. Kidd, J. Li, Y. Yue, and K. D. Nelson,
Two New Mylonites from Yadong-Gulu Rift System: Implications
for East-West Extension in Southern Tibet, (to be submitted
to Tectonics, 1996).
Edwards, M. A., W. S. F. Kidd, L. Jixiang, Y. Yongjun, and M. Clark,
Multi-stage Development of the Southern Tibet Detachment
System Near Khula Kangri. New Data from Gonto La,
Tectonophysics, paper no. TECTO 4863, July 1996.
Hauck, M. L., K. D. Nelson, L. D. Brown, and A. Ross, Crustal Structure
of the Central Himalaya: INDEPTH Reflection Profiles in Southern
Tibet, (to be submitted to Tectonics, 1996).
Hauck, M. L., L. D. Brown, K. D. Nelson, J. T. Kuo, A. Calvert,
W. Zhao, J. Che, and J. Guo, INDEPTH-I Case Study: The First
Deep Seismic-reflection Profile in Tibet and the Himalayas,
(submitted to Geophysics, 1996).
Kuo, J. T., T. Morgan, K. D. Nelson, L. D. Brown, W. J. Zhao,
M. L. Hauck, Y. C. Teng, and Y. F. Sun, Finite-element Modeling
of Primary Geological Structures along the INDEPTH Profiles
in Southern Tibet in Tentner, A.M., Ed., Proceedings of the 1996
Simulation Multiconference -- High Performance Computing '96:
Society for Computer Simulation, 84-94.
Makovsky, Y.., S. L. Klemperer, L. Ratschbacher, J. Mechie, H. Steentoft,
R. Meissner, M. Li, W. Zhao, F. Meng, and J. Guo, INDEPTH Wide-angle
Profiling in Southern Tibet: Mid-crustal Reflector Truncating
the India-Asia Suture and Magma beneath the Tibetan Rift System,
(submitted to Science, 1996).
Makovsky, Y., S. L. Klemperer, L. Huang, D. Lu, and the Project
INDEPTH Team (W. Zhao, X. Liu, J. Guo, M. Li, K. D. Nelson,
C. Wu, L. D. Brown, M. L. Hauck, J. T. Kuo), Structural Elements
of the Southern Tethyan Himalaya Crust from Wide-angle
Seismic Data, Tectonics, accepted,1996.
Ni, J., E. Sandvol, W. Zhao, R. Kind, J. Nabelek, M. Brunner,
K. Wu, L. Zhao, J. Wu, A. Fabritius, C. Reese, and T. Hearn,
INDEPTH-II Passive-source Experiment: Implications for
Underthrusting of the Indian Continental Lithosphere beneath
Southernmost Tibet, (submitted to Science, 1996).
Reese, C. C.and J. Ni, Attenuation of Coda Waves in Southern Tibet,
(submitted to Geophysical Research Letters, 1996).
Ross, A., L. D. Brown, D. Alsdorf, K. D. Nelson, and W. Zhao,
CMP Profiling Evidence for Magma beneath Southern Tibet,
(to be submitted to Journal of Geophysical Research, 1996).
Sandvol, E., J. Ni, R. Kind, J. Nabelek, and W. Zhao, Shear-wave
Splitting along the India-Asia Collisional Zone (Azimuthal
Seismic Anisotropy beneath Eastern India-Asia Collision Zone),
(to be submitted to Bulletin of the Seismological
Society of America, 1996).
Wu, C., K. D. Nelson, Y. Yue, J. Li, W. S. F. Kidd, and M. A. Edwards,
Yadong Cross-structure and South Tibet Detachment, Southern
Yadong-Gulu Rift, Tibet, (to be submitted to Tectonics,
1996).
Wu, J., J. Ni, R. Hermann, and R. Kind, Mid-crustal Low Velocity
Zone in Southern Tibetan Plateau: Evidence from Rayleigh
Phase Velocities, (submitted to Geophysical Research
Letters, 1996).
Zhao, L., J. Ni, E. Sandvol, and R. Kind, Shear-wave Velocity
Structure along the INDEPTH-II Profile, (to be submitted
to Journal of Geophysical Research, 1996).
Zhao, W., K. D. Nelson, and the Project INDEPTH Team (J. Che, J. Guo,
D. Lu, C. Wu, X. Liu, L. D. Brown, M. L. Hauck, J. T. Kuo,
S. L. Klemperer, Y. Makovsky), Deep Seismic-reflection Evidence
for Continental Underthrusting beneath Southern Tibet, Nature,
vol. 366, 557-559, 1993.
