Multi-scale Fine-grained Lithosphere Division And Patterns Of Fine-grained Facies In Different Tectonic Setting

The research on fine-grained sedimentary rocks and fine-grained sedimentary facies is a hot topic and a new field in the whole sedimentology.The research about this has far-reaching significance.However,the study on the genesis patterns of grain-grain and different types of fine-grained facies is still not comprehensive enough.Based on this,this paper uses fine-grained sediments from Lingshan Island(Eastern Cretaceous)in eastern Shandong,fine-grained Carboniferous-Permian sediments from the Longgu field in the Luxi area,and fine-grained sediments from the lst and 2nd sections of the Cretaceous Nenjiang Formation in the northeast Songke-2 well as primary examples.Three different types of fine-grained sediments,including deep-sea environment,large-scale terrestrial surface sedimentary environment,semi-deep-deep-lake environment,were studied to analyze three different sediments through observation of field profiles and samples,cores,observation of microflake,etc.The petrological characteristics and sedimentary control factors of the fine-grained rocks in the environment have summarized the fine-grained depositional patterns of the sedimentary environment in the 3 areas and obtained the following understanding:(1)In the unstable structural background,the marine environment fine-grained sediments are mainly formed in deep-water anoxic sedimentary environments and turbidite sedimentary environments.Two kinds of iithofacies can be identified:dark grey stratified layered clay-bearing siltstone facies and yellowish-brown medium and poor Organic stratified siltstone phase,stratum continuity is better,and the extension distance is longer and it is corrugated.(2)In the stable tectonic setting,fine-grained sediments from the land surface sea environment are mainly formed in the microfacies and lagoon environments between the diversional channels.Three types of Iithofacies can be identified:gray-black wavy layered mudstone,siltstone interbedded facies,light gray micro-corrugation The layered muddy siltstone phase and the gray-black organic-rich laminar mudstone facies are mostly streaked,wavy,and slightly flat.(3)Under the unstable-stable transitional structure background,the fine-grained sediments in the deep lake-half-deep lake environment arc mainly formed in hydrostatic and deep-water gravity flow sedimentary environments where there is strong oxygen reduction,and two types of lithofacies can be identified:Brown-rich organic-rich flat stripe Lamellar dolomite and black-grey organic-rich sheetlike clay facies,with fine,flat and continuous strata.(4)By analyzing the three fine-grained sedimentary mechanisms under different tectonic settings,it was found that the types of lithofacies,development sites,and so on were all different,and then three fine-grained deposition models under different tectonic settings were constructed.The results explain fine-grained sediments.Deposition mechanism and energy exploration are of great significance.