Tempestite in the Quaternary Huguangyan Formation in Weizhou Island, Beihai City, Guangxi

The Quaternary Huguangyan Formation in Weizhou island, Beihai City, Guangxi is mainly composed of clastic rocks with sedimentary structures developed characteristically in storm deposits, including gutter casts, hummocky or sunken cross bedding, and parallel bedding. The tempestite in the Huguangyan Formation consists of 3 types of lithofacies: A. conglomerate, sandy conglomerate and sandstone with little conglomerate with massive and graded bedding and bottom gutter casts; B. sandstone with hummocky or sunken cross bedding and parallel bedding; C. sandstone with cross-bedding. These lithofacies constitute a typical sedimentary sequence of storm deposits (A-B-C), which represent storm current (A), storm wave (B) and normal wave (C) sediment within storm event deposits. In the Late Pleistocene, Weizhou island, Beihai City was located in a lower latitude shallow marine basin. The Huguangyan Formation is mainly composed of sandstone from shallow marine background deposits, with volcanic clastics above the fair-weather wave base. The discovery of tempestite in the Huguangyan Formation reflects this region's location in a low latitude (5°-20°) zone, the tempestite formed in the shallow continental shelf controlled by storm. The discovery of the storm deposits has important significance for the interpretation of the palaeogeography and palaeoclimate of the Northern Bay in the Late Pleistocene.