THE ORIGIN AND DISTRIBUTION OF DOLOSTONE IN FEIXIANGUAN FORMATION IN LOWER TRIASSIC SERIES, NORTHEAST SICHUAN

According to the geochemistry, sedimentology, lithology, the dolostone in Feixianguan Formation in lower Triassic series, northeast Sichuan is studied in terms of geochemistry and lithology, it is pointed out there are two kinds of dolomization in Feixingguan Formation, they are mixed-water and seepage-reflux dolomitization. Oolitic dolostone formed by mixed-water dolomitization distributes along platform edge in the shape of band. Gypsiferous mi-crocrystal dolostone and dolarenite formed by seepage-reflux dolomitization distributes planarly in lagoon. Distribution research of dolomitization is made, and next exploration target is pointed out.