Petrogenesis analysis of lacustrine analcite dolostone of the Member 4 of Paleogene Shahejie Formation in Liaohe Depression, Bohai Bay Basin

The analcime dolostone and its rock association were found in Dujiatai reservior of the Member 4 of Paleogene Shahejie Formation in Leijia area of western sag of Liaohe Depression, Bohai Bay Basin. These rocks have complex mineral assemblages and sedimentary structures, and were regarded as argillaceous dolostone and dolomitic mudstone association previously. Through integrated study of petrography, X-ray diffraction whole rock analysis, scanning electron microscope analysis and electron probe analysis, abundant sedimentary analeites in study area are discovered firstly, and are mixed with lamellar argillaceous dolomites, forming analcimite locally. Carbon and oxygen isotope analyses show that their delta super(13)C value are positive while their delta super(18)O value are negative, similar with those of the hydrothermal dolostones reported by domestic and foreign papers. The rare earth element patterns of the analcite dolostones are similar with the alkali basalts in the same layer and the lower Fangshenpao