Hummocky cross-stratification and its formation : Approaches from flume experiments and field observation

隆起交叉层化是一种主要的沉积构造，在世界许多地区不同地质时代的古代浅海沉积中都能观察到。HCS被解释为由波浪或组合的振荡和单向流动形成的风暴沉积。该构造仍然是关于其形成方式和古水动力解释的持续争论的焦点。本研究试图通过实验室水槽实验和野外观测两种方法来阐明HCS的沉积过程和形成过程。取得了新的成果，并发表了《Hummocky交叉层结及其形成》的报告。1)HCS是在两种条件下形成的，振荡单向流动。2)在自然条件下，HCS的波长从几厘米到几十米。3)HCS由大范围的粗粉砂到颗粒组成。4)在上部流态的平底沙丘条件下，形成了典型的驼峰状和燕尾状的HCS结构。5)在较宽的波浪场、平床和反沙丘区域可以形成振荡的HCS。

Hummocky cross-stratification(HCS)is a primary sedimentary structure and is observed in ancient shallow marine deposits of various geologic ages in many world localities. HCS is interpreted as a storm deposits formed by waves or combined oscillatory and unidirectional flows. The structure continues to be focus of ongoing debate regarding its mode of formation and paleohydrodynamic interpretation. In this research we try to clarify the depositional processes and formation of HCS based on two approaches, laboratory flume experiments and field observations.Following new achievements can be obtained and published the report of "Hummocky cross-stratification and its formation".1)HCS is formed under the two conditions, oscillatory and unidirectional flows.2)HCS has a wave-length from several cm to several tens m in natural condition.3)HCS is composed of a wide range in grain-size of coarse silt to granule.4)Typical HCS structure with hummocky and swaley forms was constructed under the condition of plane-bed antidune in upper flow-regime.5)Oscillatory HCS may be formed in a wide range of ripple, plane-bed and antidune fields.6)Discrete oscillatory HCS storm bed was formed during combined flows and following waning oscillatory flow conditions.