The Lower Cretaceous is the target stratum of potential regional oilgas exploration in the Modamuji Depression

Hailaer Basin. Organic geochemistry methods were applied to study geochemical characteristics of Lower Cretaceous hydrocarbon source rocks from the Modamuji Depression. The results showed that the organic matter of K

1

n and K

1

d formation is mainly type Ⅱ

2

-Ⅲ with various abundance and maturity. The proposed maturity evolution model based on restoration of burial history showed that the thermal evolution extent for main source rocks is generally low. The source rocks from K

1

d

2

are at the immature to low mature stage

those from K

1

d

1

are at low mature stage and those from K

1

n

2

are at low mature to mature stage. The hydrocarbon source rocks from K

1

n

1

showed a relatively high thermal evolution degree

which has reached the mature oil-generating stage. The comprehensive analyses indicated that K

1

d hydrocarbon source rocks are generally high in organic matters with a low thermal evolution and low hydrocarbongenerating potential. The thermal evolution degree of hydrocarbon source rocks increases with the buried depth. The K

1

n

2

hydrocarbon source rocks have entered the mature oil-generating stage with a moderate organic matter abundance and relatively higher hydrocarbon-generating potential. The hydrocarbon source rocks from K

1

n

1

are low in organic matter with relatively low hydrocarbongenerating potential.