DIVISION AND CORRELATION OF MIDDLE AND UPPER SILURIAN IN THE KELAMAILI REGION OF XINJIANG
Wang Baoyu Li Henghai (Institute of Geology and Mineral (No.2 Regional Geological Surveying Resources, BGMR, Xinjiang) Party, BGMR, Xinjiang)
The Kelamaili Region is located in the southern part of the Kelamaili deep fracture of the eastern Junggar region in Xinjiang, analogous to the western part of the Tuvaella biographical province. Based on lithologics and biotic association character, the Silurian strata in the region can be divided into Middle and Upper Series as follows: the Middle Silurian -Baishanbao Formation, the lower part of the Upper Silurian-Hongliugou Fm., the upper part of the Upper Silurian-kushuiquan Fm. Baishanbao Fm.consists of grey, greyish-green siltstone and fine sandstone with calcareous sandstone and a little coglomerate, thickness 181-237m.The faunas from the calcareous sandstone include brachiopods such as Tuvaella rackovskii, T. gigan-tea, Stegerhynchus angaciensis, Tannuspirifer, Spirigerina, Zygospiraella, Resserella obicularia, Leptostrophia elegestica etc. and trilobite (Encrinurus) . The strata can be compared with the same strata in Northeast China, Inner Mongolia and Altai, Tuva, the Far East of USSR, as well as Mongolia. Hongliugou Fm. are composed of dark grey, brownish-grey, purplish-red calcareous fine sandstone, pelitic limestone, bioclastic limestone, having a thickness of 63-333m. The fossil faunas from the limestone are rich and varied, in eluding Tabulate ( Favosites cf. zhifangensis, Mesofavosites shangsiensis, Hillaepora, Pseudoplasmopora) , Rugosa corals (Amsden-oides, Laccophyllum etc.) , Trilobite ( Encrinurs, Phacops) and Cephalopods (Geison-oceras, Michelinoceras) . The strata He conformably in contact with the Baishanbao Fm.. Kushuiquan Fm. is inconformity with the Hongliugou Fm.. The rocks are dark grey, greyish-green, purplish-red midium-thick bedded tuffaceous, fine sandstone, tuffite with a little calcareous sandstone and conglomerate, having a thickness of 381-671m.A few Tabulate (Favosites) , Rugosa corals (Petraia, Hapsiphy-llum, Syringaxon) Trilobite (Encrinurus) Gastropoda and Radiolaria are discovered in the lower part of the Formation. The Upper Silurian in the region can be compared with the same strata in the northern part of Xinjiang, Northeast China, Inner Mongolia, and USSR, Mongolia as well.