Joint inversion of seismic traveltimes and gravity data on the Micang foreland fold belt and its hydrocarbon potential

Yang, Y. and Li, Y., 2014. Joint inversion of seismic traveltimes and gravity data on the Micang foreland fold belt and its hydrocarbon potential. Journal of Seismic Exploration, 23: 41-63. The Micang foreland fold belt is a transitional zone between the Qinling orogen and Sichuan Basin. Affected by multi-stage tectonic processes and complicated driving forces, the Micang foreland fold belt can not be successfully traced in the seismic sections, due to its complex geological structures. We present a detailed 2D density and velocity transects for the upper crust across the Micang foreland belt using a joint seismic reflection and gravity inversion technique. We use a weighted least square scheme to simultaneously invert the density and velocity. This technique parameterizes the crust as a set of layers that are based on published geologic and seismic models. Each layer has a uniform density and velocity that are constrained where possible by borehole measurements, seismic velocities, and petrologic data. Then the joint inversion of travel time and gravity data is performed to find out a common model having an optimum fit of both travel time and gravity data. Since the global misfit is the addition of the contribution of the two methods, we add a weighting factor in the objective function to better coordinate these two different kinds of data. After being tested with a multi-layered model, the joint inversion scheme is adopted for the Micang foreland belt to construct a more complete upper crustal image. We finally discuss the presence of the overthrusted structure in terms of interaction between the Qinling orogen and Sichuan Basin.
- Aki, K., Christofferson, A. and Husebye, E., 1977. Determination of the three-dimensional seismic
- structure. J. Geophys. Res., 82: 277-296.
- Birch, F., 1961. The velocity of compressional waves in rocks to 10 kilobars. J. Geophys. Res.,
- 66: 2199-2224.
- Buckus., G.E. and Gilbert., J.F., 1967. Numerical application of a formalism for geophysical
- inverse problems. Geophys. J., 13: 247-276.
- Cheng, S.Y., Zhang, G.W. and Li, L, 2003. Lithospheric electrical structure of the Qinling orogen
- and its geodynamic implication. Chin. J. Geophys., 46: 556-567.
- Clark, M. and Royden, L., 2000. Topographic ooze: Building the eastern margin of Tibet by lower
- crustal flow. Geology, 28: 703-706.
- Deng, B., Liu, $.G., Li, Z.W., Liu, $., Wang, G.Z. and Li, G.Z., 2008. A comparative study of
- the late Mesozoic uplifting in the eastern margin of Qinghai-Tibet Plateau and Sichuan Basin,
- China. J. Chengdu Univ. Technol. (Science Technol. Ed.), 35: 477-486.
- Dong, Y.P., Zhang, G.W., Neubauer, F., Liu, X.M., Genserb, J. and Hauzenberger, C., 2011.
- Evolution of the Qinling orogen, China: Review and synthesis. J. Asian Earth Sci., 41:
- 213-237.
- Enkelmann, E., Ratschbacher, L., Jonckheere, R., Nestler, R., Fleischer, M., Gloaguen, R.,
- Hacker, B.R., Zhang, Y.Q. and Ma, Y.S., 2006. Cenozoic exhumation and deformation of
- northeastern Tibet and the Qinling: Is Tibetan lower crustal flow diverging around the
- Sichuan Basin? Geol. Soc. Am. Bull., 118: 651-671.
- Gao. S, Zhang, B.R., Li, Z.J., Wang, D.P., Ouyang, J.P. and Xie, Q.L., 1996. Geochemical
- evidence for the Proterozoic tectonic evolution of the Qinling orogenic and its adjacent
- margins of the North China and Yangtze Cratons. Precambr. Res., 80: 23-48.
- Harris, N., 2007. Channel flow and the Himalayan-Tibetan orogen: a critical review. J. Geol. Soc.
- London, 164: 511-523.
- Jess, K., Nigel, H., Tom, A., Randy, P., Bruce, C., Sarah, S. and Zhang, H.F., 2007. First field
- evidence of southward ductile flow of Asian crust beneath southern Tibet. Geology, 35:
- 721-730.
- Julia, J., Ammon, C., Herrmann, R. and Correig, A., 2000. Joint inversion of receiver function and
- surface wave dispersion observations. Geophys. J. Internat., 143: 99-112.
- Lees, J. and VanDecar, J., 1991. Seismic tomography constrained by Bouguer gravity anomalies:
- Applications in Western Washington. Pure Appl. Geophys., 135: 31-52.
- Lee, J. and Whitehouse, M., 2007. Onset of middle crustal ductile flow in southern Tibet: evidence
- from U/Pb zircon ages. Geology, 35: 45-48.
- Li, X., 1992. The joint inversion of seismic and gravity data- different ways of implementation. Nat.
- Gas Geosci., 5: 37-42.
- Li, Z.W., 2006. The Formation and Evolution of the Daba Thrust Belts and its Foreland Basins in
- the Mesozoic-Cenozoic Period. Ph.D. Thesis, Chengdu University of Technology, Chengdu.
- Lines, L., Schultz, A. and Treitel, S., 1988. Cooperative inversion of geophysical data. Geophysics,
- 53: 8-20.
- Liu, S.F., Zhang, G.W. and Dai, S.W., 2001. Evolution of Qinling Mianlue Belt: Evidence from
- Sedimentology and Tectonics of the Northern Yangtze, China. Gondw. Res., 14: 690-691.
- Liu, S., 2007. Structural Characteristics of the Thrust Fold of Foreland. Ph.D. Thesis, Institute of
- Geology, China Earthquake Administration, Beijing.
- Liu, S.G., 1993. The formation and evolution of the Longmenshan thrust belt and the foreland
- basins in the western Sichuan. Publishing House, Chengdu Univ. of Technology, Chengdu.
- Liu, S.G., Li, Z.W. and Cao, J.X., 2009. The four-dimensional structure of the Longmenshan
- composite orogen. Chin. J. Geol., 44: 1151-1180 (In Chinese with English abstract).
- Liu, S.G., Li, Z.W., Liu, S., Luo, Y.H., Xu, G.Q., Dai, G.H., Gong, C.M. and Yong, Z.Q.,
- The formation and evolution of the Daba thrust belts and its foreland basins.
- Geological Publishing House, Beijing.
- INVERSION OF TRAVELTIMES AND GRAVITY DATA 61
- Lin Y.F., Zeng, X.P. and Guo, Q.H., 1985. Analysis of secular variations of non-dipole
- geomagnetic-field in east-Asia. Acta Geophys. Sinica, 28: 482-496.
- Maceira, M. and Ammon, C., 2009. Joint inversion of surface wave velocity and gravity
- observations and its application to central Asian basins shear velocity structure. J. Geophys.
- Res., 114: B02314.
- McClay, K.R. (Ed.), 1992. Trust Tectonics. Chapman and Hall, London.
- Meng, Q.R. and Zhang, G.W., 1999. Timing of collision of the North and South China blocks:
- Controversy and reconciliation. Geology, 27: 123-126.
- Meng, Q.R. and Zhang, G.W., 2000. Geologic framework and tectonic evolution of the Qinling
- orogen, Central China. Tectonophys., 323: 183-196.
- Menke, W., 1989. Geophysical Data Analysis: Discrete Inverse Theory. Academic Press Inc., San
- Diego.
- Parsons, T., Blakely, R. and Brocher, T., 2001. A simple algorithm for sequentially incorporating
- gravity observations in seismic traveltime tomography. Internat. Geol. Rev., 43: 1073-1086.
- Coward, M.P., Deramond, J., Hossack, J. and Platt, J.P. (Eds.), 1986. Internat. Conf. Thrusting
- and Deformation. J. Struct. Geol., 8: 215-483.
- Rasmussen, R. and Pedersen, L.B., 1979. End corrections in potential field modeling. Geophys.
- Prosp., 27: 749-760.
- Sun, D., 2011. The structural character and Meso-Cenozoic evolution of Micang Mountain
- Structural Zone, Northern Sichuan Basin , China. Ph.D. Thesis, Chengdu Univ. of
- Technology, Chengdu.
- Sun, Y., Lu, X.X., Han, S. and Zhang, G.W., 1996. Composition and formation of Paleozoic
- Erlangping ophiolitic slab, North Qinling: evidence from geology and geochemistry. Sci.
- Sinica, 39: 50-59.
- Tikhotsky, S. and Achauer, U., 2008. Inversion of controlled-source seismic tomography and gravity
- data with the self-adaptative wavelet parametrization of velocities and interfaces. Geophys.
- J. Internat., 172, 619-630.
- Vernant, P., Masson, F., Bayer, R. and Paul, A., 2002. Sequential inversion of local earthquake
- traveltimes and gravity anomaly - The example of the Western Alps, Geophys. J. Int. 150:
- 79-90.
- Zhang, D., Xie, B.L., Yang, Y., Fu, X.R. and Qin, Q.Q., 2009. A ray tracing method based on
- improved linear traveltime interpolation. Chin. J. Geophys., 52: 200-205 (in Chinese with
- English abstracts).
- Zhang, G.W., Cheng, S.Y., Guo, A.L., Dong, Y.P, Lai, S.Z. and Yao, A.P., 2004. Mianlue
- paleo-suture on the southern margin of the Central Orogenic System in Qinling-Dabie with
- a discussion of the assembly of the main part of the continent of China. Geol. Bull. China,
- 23: 846-853 (in Chinese with English abstract).
- Zhang, K.J., 1997. North and South China collision along the eastern and southern North China
- margin. Tectonophys., 270: 145-156.
- Zhao, X.X. and Coe, R.S., 1987. Paleomagnetic constraints on the collision and rotation of North
- and South China. Nature, 327: 141-144.
- Zhou, G.F., Luo, X.K. and Guan, Z.N., 1992. Research on relationship between characteristics of
- geophysical field and crustal architecture and deep structure in the Qinling-Daba Mts. China
- Univ. of Geosciences Press Co. Ltd., Wuhan.
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