松辽白垩纪陆相盆地嫩江组泥质铁白云岩结核主要呈顺层状产于灰绿色粉砂质泥岩、页岩与介形虫层的互层层序中。其同位素组成δ１３Ｃ（ＰＤＢ）＝１．１０５±２．４，δ１８Ｏ（ＰＤＢ）＝－５．１７４±３．５，８７Ｓｒ／８６Ｓｒ＝０．７０７８±０．０００５。结核多不切割层理，结核内部具水平纹理。该类结核形成于湖平面快速波动过程中的浅水期，属沉积结核和早期成岩结核，椭圆状外形是碳酸盐同生胶结过程中始终受到上覆泥质沉积物持续压实作用的结果。白云岩为海水－淡水混合成因 The Nodular iron dolomite nodules of the Nenjiang Formation in the Songliao Cretaceous continental basin mainly occur in the order of interbedded layers of greyish silt shale, shale and ostracode. The isotopic composition δ13C (PDB) = 1.105 ± 2.4, δ18O (PDB) = -5.174 ± 3.5,87Sr / 86Sr = 0.7078 ± 0.0005. Tuberculosis and more non-cutting layering, tubercles internal horizontal texture. This type of nodules formed in the shallow water phase during the rapid fluctuation of the lake level. It belongs to sedimentary tuberculosis and early diagenetic nodules. The elliptical shape is the result of continuous compaction of overlying muddy sediments during the carbonate cementation. Dolomite is a seawater - freshwater mixed cause