依据野外实测剖面资料，在对龙门山甘溪剖面泥盆统土桥子组进行高频旋回类型的识别的基础上，对其三级层序进行了研究。甘溪剖面土桥子组发育碳酸盐台地、碳酸盐缓坡和盆地相3种沉积类型，随着海平面的变化，在沉积演化上交替出现。甘溪土桥子组碳酸盐台地识别出3种类型的高频旋回类型，碳酸盐缓坡有6种类型发育于等斜缓坡，2种类型存在于远端变陡的缓坡中。土桥子组可以划分为2个三级层序，二者沉积特征相似，均由4个体系域组成。二者在高位体系域存在差异，下部层序由碳酸盐等斜缓坡-台地边缘组成，上部层序发育远端变陡的缓坡。%Based on the data of the field measured section , making identification types of high-frequency cycle of on the Upper Devonian Tuqiaozi Formation to research the 3 rd sequence in Ganxi section Longmenshan .There has developed 3 kinds of sedimentary type , carbonate platform , carbonate ramp and basin facies in Tuqiaozi Forma-tion .With the change of sea level , the 3 kinds of sedimentary type alternatively appear in the phases of sedimentary evolution .Three types of high-frequency cycle are recognized in the carbonate platforms in Tuqiaozi Formation .In carbonate ramp six types developed on inclined ramp and two types exist in distal steepening ramp .Tuqiaozi Forma-tion can be divided into 2 third grade sequences which have similar sedimentary characteristics and both composed of 4 systems tracts.There is a difference between the two third grade sequences in highstand system tract .The low-er sequence is composed from carbonate inclined ramp to platform margin and the upper sequence develop distal steepened ramp .
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