Lithofacies Division And Paleo-lake Change Of The One And Two Member Of Nenjiang Formation In Songliao Basin

Greenhouse climate issues have become a hot topic in global research.The Cretaceous represents an extreme greenhouse climate in the geological history.As the impact of human activities intensifies,atmospheric CO2 levels continue to increase and may break through the critical concentration in the near future,thus approaching or reaching the Cretaceous concentration level.So the study and understanding of the Cretaceous climate in urgent need to understand and find the time of the climate change in the law and control factors.Fine-grained sedimentary rocks contain a lot of paleoclimate information,often corresponding to a special depositional environment.The sedimentary facies of the mudstone facies of the Late Cretaceous in the second member of the Songliao Basin can be used to invert the sedimentary environment at that time,which provides an important basis for further revealing the paleoenvironmental changes.This paper mainly relies on the core of the mining of Songke Second Well,its fixed,cutting,polishing,paste the depth of the scale.The rock is then described by the rock facies.The lithofacies description is mainly carried out from five aspects: its color,structure,structure,composition and biology.And get the following understanding:1.By dividing the petrographic facies of the two-stage fine-grained sedimentary rocks,we obtained nine lithofacies of the fine-grained sedimentary rocks.Among them,nine kinds of fine-grained sedimentary facies and facies facies facies of the five fine-grained sedimentary rocks.There is a lot of rock in the tender section,mainly related to its lake water turbulence.Seasonal climate change has led to the ever-changing salinity of the lake,resulting in a lithofacies with a calcium-rich layer and a rich clay layer.The second part of the lake water body is basically in a stable state after the transgression,and the distance from the material source is moderate,resulting in siliceous clay as the main component of the mudstone.2.Through the comparison of the chemical phase,it was found that the pale salinity of the lower section of the tender section was compared with that of the rock we divided.This may be reflected from the side of the entire tender section of the lower part of the main control by the salinity.Through the comparative analysis,it is found that the redox phase of the second segment is fitted with the rock we divide.Which may reflect from the side of the whole two sections of the rock facies and lake water oxidation reduction has a very good relationship.3.In the second paragraph of the tender there was a transgression incident,and a total of three transgressions occurred,twice at the bottom of the tender section,once at the bottom of the second paragraph.Due to the rapid increase of lake water caused by two transgressions,a set of mudstone facies with fine mudstone is deposited.And organic matter in the reduction of the environment is easy to save,the content relative to other segments in a high state.