Lithofacies palaeogeography of the Middle-Late Ordovician Kelimoli and Wulalike Ages in western Ordos area
Ma Zhanrong1,2, Bai Haifeng1,2, Liu Baoxian1,2, Wang Hongwei1,2, Chen Tiaosheng1,2
1 National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields,Xi′an 710018,Shaanxi 2 Research Institute of Exploration & Development of Changqing Oilfield Company,PetroChina,Xi′an 710018,Shaanxi
Abstract：During the Middle Ordovician Kelimoli Age,a rimmed carbonate platform occurred in western Ordos area,with open marine platform,platform-margin shoal,slope,toe-of-slope,deep shelf and deep trough facies orderly distributed from east to west.Massive calcareous breccias packages in thin or thick lenticular shapes derived by debris-flow from east shallow water facies,accumulated along slope to toe-of-slope,and surrounded by in-site deep water micrite and mudstone.Strong tectonic movement happened during the Wulalike Age,faulting in the western margin and uplifting in the whole eastern Ordos Basin.Sediments restricted by border syn-sedimentary faults.As sea level rising,sedimentary setting changed to relative restricted deep slope-basin.Rocks of the Wulalike Formation are mainly composed of abundant graptolite bearing mudstone and shale,intercalated with several calcareous breccias which transported by debris flow from the early collapsed Kelimoli Formation limestone in the east uplift land.
Ma Zhanrong,Bai Haifeng,Liu Baoxian et al. Lithofacies palaeogeography of the Middle-Late Ordovician Kelimoli and Wulalike Ages in western Ordos area[J]. JOPC, 2013, 15(6): 751-764.
