A Study Of The Carboniferous Stratigraphy From Kumutag Sand-ridge In Eastern Tianshan, And Its Tectonic Significance

The debate of the strata division and tectonic framework in Kumutag sand-ridge eastern Tianshan has been proceed a long time. Based on the regional geological exploring and mineral surveying (scale at 1:50000), this dissertation will systemic study the geological feature of the Carboniferous Stratigraphy from Kumutag sand-ridge in eastern Tianshan. It has important geological signification in understanding the tectonic framework and evolution of eastern Tianshan.This dissertation will set the sequence stratigraphic framework, integrate the regional tectonic settings, discuss the tectonic framework of the study area and its evolving history combining with stratigraphy, petrography, regional geology, tectonics etc.1. The strata division is redefined, it is partitioned by the Kangguur Tag deep fault, the south of which is belong to qiugemingtashi-huangshan minor strata area, the north of which is belong to Karlik minor strata area; the Carboniferous Stratigraphy can be farther divided into six formations, they are Xiaorequanzi formation, Yamansu formation, Gandun formation-complex, Wutongwozi formation-complex, Dikan'er formation, and Qishan formation.2. Two complex formation were built up, they are Gandun formation-complex and Wutongwozi formation-complex. It has important signification in understanding the feature of the boundary between the Tarim plate and the Junggar plate and its distributing.3. The Dikan'er formation has been discovered in the nearly north of the Kangguur Tag deep fault. The conodonts fossils such as of Streptognathodus suberectus, Idiognathoides sinuate et al of Upper Carboniferous Dalaan Stage had been discovered in limestone. The petrotectonic assemblage of Dikan'er formation is normal-sedimentary rock series of shallow sea facies, and its sedimentary environment is relict sea basic. The north boundary of the Kangguur Tag deep fault zone had been limited by the distributing of the Dikan'er formation, which have an important value in regional stratigraphic division and correlation and the confirmation of tectonic boundary.4. Coral fossils such as Pelalaxis intermedia, Lithostrotionella rarivesicula, Fomichevella kiaeri has been discovered in limestones of the Qishan formation, and the period of which can confirmed in the Dalaan Stage-Xiaodu Stage. This is the new evidence for researching the strata period and tectonic evolution in eastern Tianshan.5. This paper systemic researches the basic feature, tectonic setting, volcanic eruption type of the volcanic rocks of Xiaorequanzi formation and Qishan formation, and their magmatic evolution.6. In study area, there had a island arc in ocean environment in Early Carboniferous, which is named for Xiaorequanzi island arc. After the collision of Xiaorequanzi island arc and Yamansu island arc, the ocean basin between Xiaorequanzi island arc and Yamansu island arc had formed normal-sedimentary rock series of shallow sea facies of Dikan'er formation. The complex geological bodies, the sequence stratigraphy of which is very complex, had been formed between Xiaorequanzi island arc and Yamansu island arc. The Qishan accreting arc island had formed when the Kangguur ocean basin subducted towards south in Upper Carboniferous.7. Based on the strata division, the strata correlation between the study area and regionalarea was discussed in this paper.