Paper Number: 602
The Silurian- Carboniferous in the north and south of Karamaili tectonic zone (Xinjiang): Tectono- Sedimentation
ZHAO, L., NIU, B.G., REN, J.S. and XU, Q.Q.
Institute of Geology, Chinese Academy of Geological Sciences, Baiwanzhuang road 26, Xicheng District, Beijing, 100037, P. R. China. E-mail: jleiz@163.com
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The ophiolite- bearing Karamaili tectonic zone is located on the northeastern margin of Junggar Basin, Xinjiang Uygur Autonomous Region, China. This study focuses on the Paleozoic tectonic settings in the Karamaili tectonic zone revealed by comparison of the Silurian-Carboniferous tectono-sedimentation in its north and south sides. In the north of the Karamaili tectonic zone, the angular unconformities are widely developed between Upper Silurian, Lower Devonian and underlying Middle-Upper Ordovician strata and Caledonian granitoids. The Middle, Upper Silurian- Devonian- Lower Carboniferous sediment deposition system in the north of Karamaili tectonic zone is similar with that in the south, including conformably contact, flat occurrence and undeveloped folds, faults and metamorphism. Anticlines or synclines are mainly short axis, which is apparently different from the strong deformations shown in the Karamaili ophiolitic mélange. Besides, pyroclastics dominated rock associations, widely occurred inclined beddings and cross-beddings and abundant kinds of animals and plants fossils indicate littoral- shallow marine environment. Therefore, during Late Paleozoic, no ocean existed in the Karamaili tectonic zone and the oceanic basin represented by the Karamaili ophiolitic mélange was closed before Middle Silurian.