20世纪中叶以来,海洋中尺度涡的发现与中大洋动力学实验(MOED)改变了此前对海洋深处海水相对平静的传统认识.由于发生中尺度涡的区域海水较深,难于观察,因此有关中尺度涡的讨论目前仅限于海洋物理及海洋生物学领域.根据燕山地区下奥陶统下部竹叶状灰岩地层单元向上变粗的沉积序列、序列内发育的变形层理、倒“V”字形裂口、岩层向下方折弯乃至断裂成藕节状等明显的重力变形和环形波痕等沉积构造,以及竹叶状砾石表面及胶结物中富含原生海绿石等特征,结合沉积动力学分析与水盆实验模拟,提出燕山地区广泛发育的竹叶状灰岩是由古海洋的中尺度涡所形成的深水碳酸盐岩沉积,并建立了竹叶状灰岩中尺度涡沉积模式.

Since the discovery of mesoscale eddy deposition in the 1970s, the traditional view of ocean currents on the continental shelf and adjacent areas has changed. At water depths over 200 m, it is difficult to observe directly the processes of denudation, transportation, and deposition generated by mesoscale eddies. Till present, the discussions about the mesoscale eddy are only in the domains of oceanphysics and marine biology. It is known that an edgewise structure, characterized by flat-pebble conglomerate exists within limestone beds, which is called edgewise limestone, that are widely exposed in the lower part of the Lower Ordovician Strata in Yanshan region. It is shown that the edgewise limestone beds are characterized by coarsening-upward sequences, deformed bedding, inverted V-shaped cracks, microcrystalline glauconite-rich surfaces of flat-pebbles with suborbicular arrangement along long axes, glauconite-rich cements, folded and flowing structures, and ring-shaped wavemarks. It is suggested that the edgewise limestone sequence is formed by marine mesoscale eddies soon after deep-water carbonate deposition in an area from the outer shelf to the upper slope during early Ordovician. A mesoscale eddy deposition model of edgewise limestone is proposed.