A Study On Devonian-Carboniferous Stratigraphic Division And Stratotype Section Comparison In Western Junggar

This dissertation is object on the devonian-carboniferous stratotype section in Western Junggar.Divide and compare those sections from the aspect of rock composition,biological composition,contact relationship and sedimentary environment.Mainly achieved the following understanding:Newly divided the Baogutu formation community.The Baogutu formation community belongs to the northeastern Mayile formation community and is now separated.Its boundary with the northern Mayile formation community roughly bounded by the northern side of the Halaalate Mountain-Hatu Fault-Miaoergou-Tangbale boundary.The two communities are separated by regional structures,and the sedimentary strata are significantly different.The newly-independent Baogutu formation stratum lacks Devonian sediments.The reference section of the Zhulumute Formation was revised.The study confirmed that there is a phenomenon of stratigraphic inversion on the Brongoergou section.The overall Late Devonian to Early Carboniferous stratigraphy was the Hongguleleng Formation marine formation in the nuclear region,and the Zhulumute Formation continental formation on both sides.The inverted steering slanted structure.In this study,we chose the northerly wing with relatively complete outcrop as the layered section of the Zhulumute Group and the Honggule leng Formation.The times and horizons of the Sawuershan Formation have been redefined.It was discovered that the original Middle Devonian Sawuershan Formation in Heishantou area was not integrated on the Heishantou Formation and that LA-ICP-MS zircon U-Pb ages were obtained in the lower quartz-porphyrite porphyry of the Sawuershan Formation.(328.7 ± 5.4)Ma,confirmed as Early Carboniferous.Combining with fossils obtained by predecessors,it was determined that the age of the Sawuershan Formation was Early Carboniferous rather than Middle Devonian.The horizon of the Sawuershan Formation has been re-determined and placed above the Heishantou Formation and below the Nalinkara Formation.By comparing the rock composition,fossil composition,contact relationship,and sedimentary environment of the stratotype sections,the layered profiles of the same layers of the Devonian and Carboniferous in the various layers of West Junggar are generally different and difficult to compare.There is basically no foreign object with the same name.It supports the independent named strata.The evolution process of Devonian-Carboniferous sedimentary environment in West Junggar was discussed.In Devonian and Carboniferous,there were many transgression-regression events in the West Junggar area.The difference in the tectonic settings created a rich and varied depositional environment evolution process in each district.In the Sawuershan formation community,the sedimentary environment from the Late Devonian to the Late Carboniferous evolved from deep-sea and semi-deep marine facies → hallow marine facies → marine-continent interaction → continental facies → shallow sea shelf facies;Saerbuertishan stratigraphic community,from The early Devonian to Late Devonian sedimentary environment evolved from shallow marine facies → fluvial facies → terrestrial facies → shallow marine facies;the Mayile formation community,from the Early Devonian to Late Devonian sedimentary environments evolved from shore shallow sea phase → Shallow marine-terrestrial → shore shallow sea phase→Land-sea interaction;the Baogutu formation community,the Early Carboniferous to Late Carboniferous sedimentary environment evolved from deep-sea and semi-deep ocean → shallow marine → coastal → continental.