关键词: 碳酸盐岩 瘤状灰岩 分类 早志留世 川西北地区

Abstract: According to the distribution，components and characteristics of the nodular limPStone of early Silurian in NW Sichuan，the authors have divided it into three patterns A,B,C. The nodular limestone of patterns A and B，the formation of which has much to do with the ac-tion of blue一green algae，deposited on shallow ramp ith reefs and bioherms while the nodu-lar limestone of pattern C deposited of deep ramp，the formation of which has close relation with the effect of pressure一dissolution. The nodular limestone of these three patterns in this area has oil一gas bearing quality to
a certain degree.

Key words: Carbonate rock Nodular limestone Classificatio