INternational DEep Profiling of Tibet and the Himalaya IV

INDEPTH IV

In the summer of 2007 as part of the INDEPTH IV project, a controlled-source seismic experiment was conducted along a 270 km long profile across the Kunlun mountains in northern Tibet. Wide-angle reflection / refraction measurements were carried out along the whole profile while near-vertical incidence reflection measurements were carried out along the central 100 km of the profile. A total of 100 small shots (~80 kg) and 5 large shots (1000-2000 kg) was recorded by 48 three-component instruments (34 Earth Data Logger PR6-24 (EDL) recorders with either a Güralp 3ESP or a Mark 1 Hz seismometer provided by the Geophysical Instrument Pool Potsdam (GIPP) and 14 Güralp DCM or SAM recorders with a 40T seismometer provided by SEIS-UK), about 975 one-component instruments (Reftek RT 125 recorder (Texan) with a 4.5 Hz vertical geophone supplied by IRIS/PASSCAL) and one 1000-channel Sercel instrument provided by the Chinese Academy of Geological Sciences. The aims of the project are to determine the crustal and uppermost mantle structure across the northern boundary of the high plateau, detect the sharpness of any steps in major crustal boundaries (e.g. Moho) across the northern margin of the high plateau and detect how deep major faults penetrate in order to examine the viability of the crustal flow hypothesis.

Principal Investigators  

• Dr. J. Mechie (contact person)
• Prof. Dr. R. Kind (GFZ Potsdam)
• Prof. Dr. L. Ratschbacher (Uni. Freiberg)
• Prof. Dr. R. Meissner (Uni. Kiel)

Cooperation  

• Chinese Academy of Geological Sciences, Ministry of Land and Resources, Beijing, China
• Stanford University, Cornell University

Experiment time frame  

• controlled-source (refraction / wide-angle reflection & near-vertical incidence reflection) experiment - June 2007

Methods & equipment  

• refraction / wide-angle reflection & near-vertical incidence reflection - 34 EDLs with either a Güralp 3ESP or a Mark 1 Hz seismometer from GIPP, 14 Güralp DCM or SAM data loggers with 40T seismometers from SEIS-UK, 975 Texans from IRIS-PASSCAL, 1000-channel Sercel from Chinese Academy of Geological Sciences

Publications  

• Zhao, W., Brown, L., Wu, Z., Klemperer, S.L., Shi, D., Mechie, J., Su, H., Tilmann, F., Karplus, M.S. and Makovsky, Y., 2008. Seismology across the northeastern edge of the Tibetan plateau. EOS Trans. Am. Geophys. Union, 89: 487.
• Mechie, J., Kind, R. and Saul, J., 2011. The seismological structure of the Tibetan plateau crust and mantle down to 700 km depth. In: R. Gloaguen and L. Ratschbacher (Editors), Growth and Collapse of the Tibetan Plateau. Geological Society, London, Special Publications, 353: 109-125, doi:10.1144/SP353.7.
• Karplus, M.S., Zhao, W., Klemperer, S.L., Wu, Z., Mechie, J., Shi, D., Brown, L.D. and Chen, C., 2011. Injection of Tibetean crust beneath the south Qaidam Basin: Evidence from INDEPTH IV wide-angle seismic data. J. Geophys. Res., 116, B07301, doi: 10.1029/2010JB007911.
• Feng, M., An, M., Zhao, W., Xue, G., Mechie, J. and Zhao, Y., 2011. Lithospheric structures of northeast Tibetan Plateau and their geodynamic implications. J. Geodyn., 52: 432-442, doi:10.1016/j.jog.2011.07.002.
• Zhao, W., Kumar, P., Mechie, J., Kind, R., Meissner, R., Wu, Z., Shi, D., Su, H., Xue, G., Karplus, M. & Tilmann, F., 2011. Tibetan plate overriding the Asian plate in central and northern Tibet. Nat. Geosci., 4: 870-873, doi:10.1038/ngeo1309.
• Mechie, J., Zhao, W., Karplus, M.S., Wu, Z., Meissner, R., Shi, D., Klemperer, S.L., Su, H., Kind, R., Xue, G., & Brown, L.D., 2012. Crustal shear (S) velocity and Poisson's ratio structure along the INDEPTH IV profile in northeast Tibet as derived from wide-angle seismic data. Geophys. J. Int., 191: 369-384, doi:10.1111/j.1365-246X.2012.05616.x.

For more information contact J. Mechie