The characteristics of pyrolysis(P-FID)

thermogravimetric analysis (TGA)

infrared spectrums(IR)

elements composition and carbon isotope ratios of kerogen in the Palaeozoic rocks of the Shaanxi-Gansu-Ningxia Basin have been investigated

and the types of kerogen in vari-ous sequences have been described in this paper.The main types of ke-rogen favourable to oil-gas formation in this basin are sapropel(O

2

)and mixed humus and sapropel(C

2

b

C

3

t)

because of their high con-tents of C degradation hydrocarbons

It is suggested that

with the grade of metamorphism getting higher

the H/C(atomic ratio) and O/C(atomic ratio)of kerogen tend to de-crease

the H/C(atomic ratio)of asphaltene and the fractionation ofδC

13

to increase.