The Early Time Of Late Carboniferous And The Study On Fusulinds Fauna In BenXi Area, LiaoNing

Stratigraphic section of niumao ridge in benxi in Liaoning province was named by Benxi stratotype in early time of Late Carboniferous in southern Region of north– northeast China, which established by Zhao Yazeng in 1926. the study area is located in Benxi area, eastern of Liaoning Province. Stratigraphic area belongs to north zoning of northeast China of the North China platform area. And this area is of the features of continuously exposing and good outcrops and clear top and bottom boundaries. The effects of later tectonic movement in this area was slight. Animal and plant fossils were rich here, even the evolutionary sequence about fusulinds fossils was more complete and clear. It is the standard area for stratigraphic division and correlation about the early time of Late Carboniferous in northeast of China.The essay took the Section of Niumao ridge as the study object. And we had identified 71 species in 13 genera (include comparative species) and described the representative species of 33 species in 11 genera through the ways of re-measurement for the profile and collecting systemically for fossils and observation for lines about the corresponding layers of surrounding neighbors. And the essay also had discussed the age of fusulinds-in's layer and divided the layer of organism.The layer of early time of Late Carboniferous in study area was named Benxi group. It's in touch with Majiagou group in middle Ordovician for parallel unconformity and integrated cove-raged by Taiyuan group on it. The thickness of Benxi group in study area is 158.4m and it can be further divided into 2 lithologics according it's lithology. The lower is purple mudstone with Fe-Al and the upper is clastic with limestone. In it 5 thicker limestone layers are rich of fossils like fusulinds , brachiopods, corals, conodonts, bivalves, etc. in various of fossils, the fusulinds is the most significant for the Times except the conodonts. On the other side, 2 layers of limestone were found above the ants limestone layer and Xiaoyu limestone layer when profiles was measured. And folder marl lenses were found in other 3 layers. The limestone above the top of ants is rich of fusulinds fossils and a lot of biological debris (Section 33 layers). Till now there were 6 layers which 1 layer more than the study before. with fusulinds fossils in it.At the research of fusulinds aspect, two stages had been divided according to the characteristics of occurrence, development and prosperity in Taizi river valley. The first stage is the time of erliest fusulinds biological composition in Benxi period in Benxi area with the equivalent of Eostaffella Subsolana belt who had not been found in the profile of Niumao ridge. The second stage of the fusulinds species composition is equivalent to Fusulina-Fusulinella belt. This two kinds of fusulinds fossils were the most common on the top of Benxi group in Niumao ridge. And they represented the peak stage of fusulinds fauna in the early time of Late Carboniferous. And after study 5 subzones were further divided as follows: Fusulina–Fusulinella zone:⑤Fusulina cylindrica-F.quasicylindrica subzones;④Fusulinella provecta subzones;③Pseudostaffella sphaeroidea subzones;②Fusulina konnoi subzones;①Fusulina schellwieni subzonesThe division plan could be juxtaposed on corresponding layers with the most areas domestic and foreign. Millerella,Pseudostaffella were only two distributed in individual layer on the top of Benxi group had been changed. And the true is that they are in all of the fusulinds layers on the top of Benxi group, at least this is the case in Niumao ridge.