Paleolake Evolution of Eocene in Fushun Basin

Key words: 
• Fushun Basin

Abstract: In order to interpret continental responses to globally climatic cooling in the EoceneOligocene, we have studied the paleolake features of Fushun Basin, an Eocene faultdepression basin in NE China, through measuring actual strata profiles in the fields and indoor sample testing. The analysis of rock facies, facies indicators and rock thinsections suggests the evolution history of sedimentary facies in Eocene, Fushun Basin. Sedimentary subfacies vary as: lake and marshlandshallow lacustrinehalf deep lacustrinedeep lacustrine half deep lacustrineshallow lacustrine, with the water depth varying as: shallowdeepshallow. On the basis of contents of trace elements (B, Mn, Ti, Co, Cr, Ni, V), element contents ratios (Sr/Ba, V/（V+Ni）, Ni/ Co, ωFe2O3/ωFeO) and ratios of oxides, we point out that there was an abrupt climatic change from early Eocene to late Eocene in Fushun Basin. In the early Eocene, climate was moisture and good for coral forming. While, in the middlelate Eocene, climate changed into drier and made contribution into the interbedding between marlite forming in saline and halfsaline water and clay shale. In general, our study shows that the climate changed from moisture to dry in EoceneOligocene.