Propagation of continental break-up in the southwestern South China Sea
P. Huchon, T. N. H. Nguyen, N. Chamot-Rooke, 2001. "Propagation of continental break-up in the southwestern South China Sea", Non-Volcanic Rifting of Continental Margins: A Comparison of Evidence from Land and Sea, R. C. L. Wilson, R. B. Whitmarsh, B. Taylor, N. Froitzheim
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We present new bathymetric, seismic and gravity data on the southwestern tip of the South China Sea oceanic basin, where propagation of continental break-up occurred before c. 15 Ma. The oceanic domain has a V-shape typical of oceanic propagating rifts. The tectonic fabric of its margins shows that the main stretching direction was slightly oblique to that of the rift axis. A 2D gravity anomaly inversion, corrected for the thermal effect, is used to estimate the crustal structure. At the continent-ocean boundary, the continental crust is stretched by a factor of about four, rapidly decreasing to about two over a few tens of kilometres, a distance corresponding to just over 1 Ma of break-up propagation. Thus, strain localization occurs at the tip of the propagating oceanic crust just before break-up. The along-axis variation in continental crustal stretching is in good agreement with the kinematics of the oceanic crust derived from magnetic anomalies. This analysis suggests that break-up propagates toward the pole of relative rotation and is primarily controlled by the amount of stretching of the continental crust before oceanization.