Relative contents of ferrodolomite in source rocks identified by Mössbauer effect can be used to deduce the maturity of source rocks.22 samples collected from 3 drill holes in Jurong County

Jiangsu Province

the Middle-Lower Triassic

Permian and Lower Silurian in age

are studied with this technique.The results suggest that Middle Triassic sediments are immatured or lowmatured source rocks

the ferrodolomite of them could hardly be found or found in the bottom

whereas Lower Triassic sediments are matured

the ratio of the iron contents of ferrodolomite to total iron increases with the increases of burial depth of the formation

and the ratio of mudstone samples is lower than that of limestone samples.As for the Lower Siluriam

Lower Permiam and the coal-series of the lower part of Upper Permian

the dolomite contents are naught possibly in relation to that they are supermatured.