CHARACTERISTICS AND ORIGIN OF CALCAREOUS CONCRETIONS IN THE HUANGHAI AND THE EAST CHINA SEAS

Calcareous concretions are widely distributed over the shallow sea (the Bohai Sea, the Huanghai Sea and the East China Sea) along the coast of China.Both their numerous quantity and vast distribution are all the first on the continental shelf over the world.X-ray diffraction and electron micro-probe analysis show that the authigenic component in the calcareous concretions is calcite.The distributive pattern, mineralogical composition, texture, trace chemical component, and data of carbon-oxygen isotope of the calcareous concretions all prove that the concretions of the area have been formed in a continental environment.