The Red River fault system in the Tonkin Gulf, Vietnam

• Published in: Tectonophysics Vol. 243; no. 3; pp. 209 - 222
• Main Authors: Rangin, C., Klein, M., Roques, D., Le Pichon, X., Le Van Trong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.03.1995
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/0040-1951(94)00207-P

The Red River fault system in the Tonkin Gulf offshore Haiphong was studied using seismic profiles calibrated by deep wells. Well characterised left-lateral strike-slip occurred continuously within a narrow 30-km-wide zone southwest of the Vinh Minh fault between 30 Ma and 5.5 Ma. However, the corresponding amount of offset probably does not exceed a few tens of kilometres. No sign of post-5.5 Ma right-lateral motion can be detected. Prior to 30 Ma, there is a widespread extension in a wider 100-km-wide zone which could be related to a significant amount of left-lateral motion. The motion of the fault splays to the northeast of the Vinh Minh fault prior to 30 Ma was absorbed in the rifting of the Gulf of Beibu. A 15.5-Ma unconformity separates the transtensional regime from a later transpresional regime. This 15.5-Ma date coincides with the cessation of sea-floor spreading in the South China Sea.