The Indiana University Mudflume—Ongoing and Planned Experiments in Mudstone Sedimentology

Juergen Schieber
Indiana University, Bloomington, IN

Modern and ancient mudstones contain a wealth of sedimentary features that relate to depositional conditions and allow interpretations of sedimentary environments. These deductions, however, are largely qualitative because there is insufficient information that links these features to measurable sets of physical variables in modern environments. It is essential to conduct experimental studies of mudstone sedimentation, transport, and erosion, to more accurately interpret the rock record.

A new racetrack flume that has been optimized for research on mudstone sedimentology has been put into operation at IU, and we are currently running a series of experiments that examine for example the influence of substrate variability (clay type, salinity, consolidation, etc.) on threshold of erosion, loading capacity, and accretion rate. In preliminary experiments with a different flume design we already examined the importance of flocculation on mud deposition under current flow and obtained intriguing results. Even at small sediment concentrations (0.4 g/l; freshwater) and flow velocities of 10 cm/s, floccules formed and traveled over the flume bottom. At a sediment load of 0.8g/l, floccule formation strongly increased and led to formation of floccule patches that slowly migrated over the flume bottom. Further sediment addition resulted in continued floccule deposition rather than an increase in water turbidity. The experiment produced a contiguous mud layer that formed through vertical accretion of migrating floccule patches.

These observations point to fundamental processes that occur during the formation of mudstones. Continuation of these studies will provide new insights into the origin of sedimentary features in mudstones.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005