THE DEPOSITIONAL ENVIRONMENT OF SALT ROCKS IN DONGPU DEPRESSION

Dongpu Depression is asecond graded structure unit in Pohai Gulf Basin with thick formation of salt-sediments interbedded with dark mudstones developed during Paleogene. In this paper, the rhyme, cycle, structure and ecological properties of contained fossils in the depression are discussed and the author suggests that the salt rocks were generated in a depositional environment of still-stand deepwater and probably experienced sea water immersions in a short period expect for the salt rocks derived from surface flows. The various haloclines formed in saline lakes caused multiple dissolutions and crystal sedimentations of halogen rocks foming the saline deposits. Based on macroscopic viewpoint, the saline deposit is controlled by the highland bailt up with the marginal deep faults and is a typical example of "high mountain-deep basin" saline model.