关键词: 等深流沉积, 条纹、条带构造, 古水流分析, 筇竹寺组

Abstract: Although Qiongzhusi Formation of Cambrian is one of the most important shale gas exploration targets in South China and
the host rock of Chengjiang Fauna, studies of its sedimentary environments and processes are still inadequate. This study is focused on
the Meishucun Section of Kunyang in central Yunnan Province, where palaeocurrents with directional sedimentary structures are
analyzed and the extensive stripped-and-banded structures in Qiongzhusi Formation are studied based on detailed field observations.
The results show that (1) the palaeocurrent angles between cross-beddings and small flutes are from 43°to 108°, with distribution
mainly between 50° and 79°, and the average angle in the same thin-bedded siltstone is 50°, greater than 45°; (2) most stripped and
banded sedimentary structures have a bidirectional periodic evolution in vertical and some of stripped structures behave a compound of
multiple periods. According to the palaeogeography and the deep-water deposition environment of Qiongzhusi Formation, we suggest
that the deep-water contour currents are responsible for these deposits because of the large angle between the flow direction of
sedimentary currents and the dip azimuth of the ancient regional slope, and also an obvious period of the depositional currents. The
discovery of deep-water contourites in Qiongzhusi Formation has an important significance for understanding the distribution of shale
gas source rocks and reservoir of Qiongzhusi Formation in South China, as well as the survival conditions, death factors and
conservation conditions of the mollusks fossil in Chengjiang fauna.

Key words: contourite , stripped-and-banded structure, palaeocurrent analysis, Qiongzhusi Formation