Abstract:

In the Middle Caledonian period, extensive lateral compression and vertical uplift occurred in Keping area, Tarim basin. Ordovician Yijianfang Formation and the top of Yingshan Formation were exposed for three times, resulting in wide karst and different types of paleocaves, which were uplifted to the surface in Himalayan movement and became outcrops now, with a variety of shapes and sizes. Based on the outcrops observation, types of the paleocaves were categorized by their shapes and textures, and the features and main controlling factors of each type were studied as well. Research shows that paleocaves could be classified into four types. The tubular and branching types of caves are slender pipes, with circular or ellipse shape in cross section and many branches possibly, which  were caused by underground rivers; Controlled by faults, fractures, and corrosion along layers, single isolated type could be funnel-shaped, inverted funnel-shaped, plate profile or combined shape; Karst caverns type caves scattered around the ancient water table and were connected by fault, fractures or small resolved channels, layering vertically. Karst caves with broad halls and many small scale branches are formed by corrosion along layers.

Key words: paleocaves, fracture, corrosion along layer, water table, Kepingtage tectonic belt