This paper presents results of investigations of unusual carbonate formations found in bottom sediments of the South China Sea shelf. These sediments were sampled from a deep fracture found by geophysical methods. According to gas-geochemical data there are high concentrations of methane, hydrogen and carbon dioxide in bottom waters of this area. The carbonate formations were defined as calcium siderite or siderodot by roentgenostructural, microprobe, atomic absorption, and thermal analyses, asawellas infrared spectroscopy. Formation of this mineral results from carbon dioxide and methane flows through bottom sediments.

Supplement to: Sorochinskaya, A V; Mozherovsky, A V; Obzhirov, Anatoly I (2000): Calcium siderite (siderodot) in sediments of the South China Sea. Tikhookeanskaya Geologiya (Pacific Geology), 19(3), 44-48