泥沙颗粒从水介质中沉积到海底后,并不是简单的在加积过程中压实保存,而是经历了物理和生物因素的扰动,然后随着纯沉积的进展,质点从扰动层的底部转为稳定的保留层.因而,海底沉积物在垂向上可分为两带,即上部的混合带和其下部的堆积带,在混合带内,颗粒质点受生物和物理作用而处于运动状态,形成混合层.颗粒在沉积物中活动的时间称为滞留时间T,T=L/A.L为混合层厚度,A为堆积速率,T值大,滞留时间长,混合作用强;T值小,混合作用弱. Sediment particles deposited from the aqueous medium to the sea floor are not simply stored compactly during accretion but undergo physical and biological perturbations, and then, as the pure deposition progresses, the particles move from the bottom of the disturbance layer The seabed sediments can be vertically divided into two belts, that is, the upper mixing belt and the lower accumulation belt. In the mixing belt, the particle particles are in a state of motion biologically and physically, The formation of a mixed layer particles in the sediment activity time is called the residence time T, T = L / AL is the thickness of the mixed layer, A is the stacking rate, T value, retention time, mixing strong; T value is small, mixed Weak.