Evaluating the formative and shape‐controlled dispersive mechanisms of mud balls in a low‐energy coastal setting: New insights

Abstract

The study of the mud balls is one of the most common tools to unravel the flow dynamics, energy conditions, and palaeogeographies for both modern and ancient settings. The present study involves detailed analysis of the concentration, size, shape, and alignment of the long axes of the mud balls in a modern coastal setting of Chandipur, east coast of India. The study was performed throughout two consecutive years, during eight different seasonal intervals. Extensive and thorough investigation on mud balls reveals some significant insight about the multifarious mechanisms of clast formation within this low‐energy micro‐ to meso‐tidal coastal setting. The study also reveals shape‐controlled dispersion of transported mud balls under the action of wave‐generated currents. The eventual orientations of their geometric longest axes are not controlled by their mode of transportation, but by their shape and gravitational stability, fundamentally governed by the mass distribution along that axis. This shape‐controlled dispersive model contradicts a long‐standing convention that long axis orientations of the mud balls with respect to the shore line are often random and governed only by their mode of transportation and locally developed complex flow components along the coast line. In contrast, a difference in seasonal concentration of mud balls appears to be a qualitative measure of the variations in energy conditions of this intertidal setting and consequently degree of coastal erosion.

Implications for the resilience of modern coastal systems derived from mesoscale barrier dynamics at Fire Island, New York

“…The top 23 cm of the recovered section reveals a sequence of faintly laminated medium to coarse sand, which we equate with the ridge structure. Directly below this interval is a 24 cm thick unit of coarse sand, with millimeterto centimeter-scale mud balls immediately below the upper contact (see Mukhopadhyay et al, 2022). We interpret this unit as reworked washover and marsh sediments flanking the subaerially exposed portion of the lobe.…”