二连盆地阿南地区早白垩世风暴沉积

LOWER CRETACEOUS STORM DEPOSITS IN A'NAN REGION, ERLIAN BASIN

张天菅 赵徵林 刘孟慧

Zhang Tianying Zhao Chenglin Liu Menghui

阿南地区早白垩世腾格尔组一段下亚段湖相碎屑岩中存在风暴沉积,层序自下至上依次为:(1)突变的底界与冲刷充填构造;(2)滞留沉积段;(3)大波状层理段;(4)丘状交错层理段,(5)波纹段;(6)生物活动段。本区风暴岩属搅混成因,其主要特征是;(1)不具单向底模;(2)底部粗碎屑段表现出振荡和多向水流形成的组构特征,无明显的粒序;(3)缺乏平行层理,发育丘状交错层理和波状层理。根据其层序差异和分布位置,划分出近岸型(粗型)和远岸型(细型)两类。

Storm deposits were discovered in the lower submember of the first member of the Lower Cretaceous Tenggar Formation. The sedimentary sequences in ascending order are:1. Sharp basal boundary with scour-and-fill structure; 2. Basal lag section; 3. Large current-bedding section; 4. Hummocky cross-stratification section; 5. Ripple bedding section; 6. Bioturbate section. Based on these features, the tempestites were originated by stir-mix and the main properties are:1. Having no unidirectional basal casts; 2. The fabric characteristics formed by oscillation and multidirectional currents in basal clastic rock section; 3. Lacking parallel stratification and developing hummocky cross-sttatification and current bedding. According to the sequence differentiae and the distfibution localities, the storm deposits can be divided into nearshore (coarse) type and offshore (fine) type.

10.11743/ogg19910411