Modern observations of floccule ripples: Petitcodiac River estuary, New Brunswick, Canada

摘要

Mud floccule ripples, small mud rip-up clasts, erosional scars and tool marks are reported for the first time from the macrotidal Petitcodiac River estuary, New Brunswick, Canada. The ripples occur on the intertidal flats and are ebb-oriented. Observations have been conducted during the spring low tide at high-river and low-river discharge. Floccule ripples forming during the high-river flow are characterized by increased silt fraction, low relief and sinuous to lunate form. The ripples forming during the low flow are clay-dominated, have very low relief and are characterized by narrow straight ridges and patchy distribution. The preserved mud floccule ripples manifest in interbedded silt-rich and clay-rich deposits with parallel, wavy, lenticular and current-ripple lamination. Presented floccule ripples are current-generated, non-episodic in nature and are sedimentologically characterized. The ripple origin is constrained by morphometric and grain-size analyses, and observed hydraulic processes. It is confirmed that mud floccule ripples originate under a similar range of hydraulic parameters as documented in previous flume studies. This study confirms application of work conducted in recent decades on mud-dominated marginal-marine environments and helps with understanding of properties and distribution of fine-grained sediments in tidally influenced settings.