The"Special"TurbiditeMeasure of the Middle Ordovician Series in Zhuozishan Area, Inner Mongolia

Key words: 
• " /
• special" /
• turbidite measure /
• Lashizhong Formation /
• Zhuozishan

Abstract: The Lashizhong Formation of the middle Ordovician in Zhuozishang area, Inner Mongolia is a set of turbidite measures, which is composed of lots of turbidite beds with clear Bouma sequence. However, the eminent differences exist between Lashizhong formation and those formed in the unstable and substable continental shelf margin to the deep-sea basin, such as in their total sequence thickness and internal features. This is the reason thatwe call the turbidite of the Lashizhong Formation as the special'turbidite measure. In this paper, the comparison study is performed according to the two turbidite measures, and, furthermore, elucidate the basin characteristics based on the depositional facies, combination, paleocurrent direction and trace fossil, etc., and reached the conclusion that the Lashizhong turbidite is formed in the stable deep-sea basin, which is located between the stable massifs with simple landscape and gentle slope, and the water depth is 200m under the wave base with ample oxygen.