Study on sedimentary facies of mixed clastic-carbonate sediments strata system in epicontinental sea——A case of Daniudi Gasfield in northeastern Ordos

It is generally supposed that in the Ordos Basin the sequence of the epicontinental sea is mainly composed of transgressive system tract and high stand system tract, without low stand system tract or only with low stand system tract on the continental margin.

The Benxi-Taiyuan Formation was formed in an epicontinental sea that had subdued floor,so most of the sequence structures in Benxi-Taiyuan Formation are of dual system character.

The upper Carboniferous and lower Permian of Hetian in the south of Tarim Basin are deposited in the epeiric sea.

On the basis of the study of the features of the Palaeozoic restricted epeiric sea in North China,this paper emphasizes the applications of the sequence stratigraphic theory to the study of the coal-bearing formation.

Based on the synthetic study of field outcrops and drilling section data, and using new stratigraphic division program, this paper proposes that the paleogeographic pattern of Ordos area was the compound sedimentary system of epiric sea carbonate platform clastic barrier island shallow water delta.

Study on coal accumulation under marine transgression events in the epicontinental basin of North China;

The development characteristic of the sequence, the distribution pattern of strata, the basin evolution and filling , and the relationship between variations of base level and coal accumulation of epicontinental basin were expounded based on the base level cycles.

The sequence stratigraphic framework in the epicontinental basin and the terrestrial basin is established.

The feature of the sedimentary succession of the epicontinental sea basin in the study area was an- alyzed by means of the stochastic math model,Markov chain.