Fig. 4

Outcrop and thin section features of the upper part of Interval II and the Interval III of Xiaoerblak Formation (Cambrian Series 2) of the Sugaitblak section, Tarim Basin, Xinjiang, China. a and b Stratiform thrombolites at the top of the Interval II. Some dark mesoclots (marked in gray color) are fused with each other and interconnected with width less than 2 cm, composed of fine and microcrystalline dolomites or clay-sized minerals, and the inter-clot brighter spaces (marked in pale orange color) are cemented by medium or coarse dolomites. c Thin-bedded argillaceous dolomicritic dolostones in the Interval III. d Close-up of the black square in the lower part of c. Most laminae are continuously straight with few in microrelief. The dark fine dolomite laminae and the light coarse dolomite laminae are parallel to each other and the thickness of them is less than 0.3 cm