Determination of the Paleozoic in buried hills of the Liaohe fault depression and its geological significance

The strata of buried hills in the Liaohe fault depression consist mainly of carbonate rocks and sandstone-shale, which were all assigned to the Meso- and Neoproterozoic. A new view of the existence of the Paleozoic in the Liaohe fault depression was put forward as residual animal fossil fragments were found in some rock sections from the strata. This succession of strata was redefined and the stratal sequence of the Cambrian, Ordovician, Carboniferous and Permian was established on the basis of a study of conodonts, microfloras, animal fossils and rock associations. The results of this study indicate that Paleozoic reservoir rocks exist in the Liaohe fault depression, and that the buried hills of the Liaohe fault depression are not a monocline but a complex faulted block composed of a part of a fold reworked by faults. The conclusion is a new basis on which a new knowledge of the structural features and hydrocarbon reservoir distribution characteristics of the Paleozoic inside the buried hills of the Liaohe fault depression may be gained.