沙滩子牛轭湖沉积特征

曲颈裁弯形成的沙滩子牛轭湖,属开放型沉积体系,经历了四岸崩塌凸岸堆积及裁弯形成两个阶段。出水口和入水口是主要沉积部位,沉积速率2～3m/a,顶湾则沉积相当缓慢;粒度曲线第Ⅰ类代表早期、第Ⅱ类代表早中期、第Ⅲ类代表中晚期沉积物的粒度特征;以发育中、小型水平、平行、波状等层理和泥裂为主。

SEDIMENTARY CHARACTERISTICS OF BAYOU IN SHATANZI

Shatanzi bayou,formed of "Ω"-shape river cove, is an open sedimentary system.The bayou underwent concave bank collapse,covex bank cumulation and cut-cove bar forming stages.Water inlet and outlet are the main positionsof deposition.The deposit rate is 2-3m per year,but that of the apex of the cove is considerably slow.As for grain size curves,type-Ⅰ represents the grain size of the early stage sediments;type-Ⅱ represents the grain size of the early to middle stage sediments and type-Ⅲ shows that of middle to late sediments.Small or medium size of horizontal,parallel and wave bedding and mud cracks developed in the bayou.