LARGE-SCALE DISH STRUCTURES DEVELOPED IN THICK CONGLOMERATES FOUND IN K1 STRATUM IN NORTHERN ERDOS BASIN, INNER MONGULIA, CHINA

At outcrops, Large-scale dishes are frequently one of the most commonly observed sedimentary structures in otherwise massive sandstone, pebbly sandstone or conglomerates , Zhidan Formation, Lower Cretaceous system in Northern Erdos basin, Inner Mongulia, China. The features of the dish are as follows: (I) Crosscutting, it looks like a dish, concave upwards in the middle and the edge tilting in with about 45-90°dipping angle, partly reversing; (II) 1-2m in thickness and mostly about 3-5m in width, largest up to 40-50cm; (III) Laterally, seperated by sandy mud diapirs (pillar structures or funnel structures, having a sharply defined contact with the sidewalls (IV) Genenrally, the elongate pebbles within the tilting edge tend to be parallel to sidewalls; (V)Often，accompanied by other soft deformation sedimentary structures, such as convolution bedding, sand dike, flame structure and soft deformation fold and so on. The layer containing a typically large-scale dish structures is underlie by reddish brown massive mudstone with flow trace. The large-scale dish structures in Cretaceuos system seems likely to be concerned with violent earthquake.