Features of the Distribution of Abnormal Gasgeochemical Fields in the Red River Rift (Gulf of Tonkin, South China Sea)

Abstract

This paper reports the results of the third Russian–Vietnamese expedition (V.I. Il'ichev Pacific Oceanological Institute, Far East Branch, Russian Academy of Sciences and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology) in the Gulf of Tonkin, South China Sea (April 2016). The studies revealed new specific features of the distribution and origin of gasgeochemical fields in sediments within the rift zone of the Red River along a 150-km profile. Four zones with high-amplitude anomalies of hydrocarbon gases, helium, hydrogen, carbon dioxide, and carbon monoxide were revealed. The distribution of the anomalies reflects the tectonic structure of the area and points to the presence of several lithospheric sources of gases including gases of deep origin. The studies were carried out within the scope of the Joint Vietnamese–Russian Laboratory for Marine Geoscience (V.I. Il'ichev Pacific Oceanological Institute, Far East Branch, Russian Academy of Sciences and the Institute of Marine Geology and Geophysics, Vietnam Academy of Science and Technology).