珠江口盆地浅水区和深水区重力流沉积特征对比

Contrast of gravity flows between shallow water and deep water in Pearl River Mouth Basin

通过岩心观察,从层理构造、生物活动、特殊构造和鲍马序列4个方面分析了浅水区和深水区重力流内部不同的构造特征,并从重力流类型、沉积动力机制和相模式3个方面进行了外部特征的对比,分析了2种重力流沉积的形成机制。结果表明:浅水区重力流各种层理发育,生物活动频繁,可见潮汐层理,重力流类型丰富,河流、波浪和潮汐影响显著;而深水区重力流层理单一,生物活动贫乏,鲍马序列明显,重力流类型简单,各种作用微弱,有完整的扇和槽模式。通过对2种重力流成因机制分析,认为深水区重力流形成的主要影响因素是坡度,而浅水区重力流形成的主要影响因素是沉积物的供给。

Based on core observation, the structural features of the gravity flows in shallow water and deep water are analyzed in the aspects of bedding, biological activity, special structure and Bouma sequence. The external features are contrasted in the aspects of gravity flow type, sedimentary dynamics mechanism and facies model, and the formation mechanisms of the two types of gravity flows are beddings, frequent biological activities and tide waveness and tide processes are apparent; While analyzed. The result shows that in the shallow water, there are many beddings, the gravity flow type is full and the influences of fluvial, in the deep water, there are simple bedding, scarce biological activity and obvious Bouma sequence, the gravity flow type is simple, and entire fan model and trough model are formed. Based on the formation mechanism analysis of these two types of gravity flows ,it is believed that the main influencing factor for the gravity flows in deep water is slope gradient, and the influencing factor for the gravity flows in shallow water is sediment supply.