Mudstones are the most abundant, yet least understood sedimentary rock type. Throughout Earth history, these fine-grained sediments have preserved a record of ancient surface conditions and climates, as well as of organic activity in the form of biomarkers and fossils. In spite of their significance, however, our understanding of the depositional processes of mudstones is still rudimentary. In a newly built flume the PI's have conducted a series of initial experiments and can demonstrate that, contrary to conventional wisdom, mud deposition from swift currents (10-30 cm/sec) should be a common phenomenon in a wide range of sedimentary environments. Flocculation of clays leads to bedload transport of clay floccules, formation of low relief migrating ripples, and to buildup of mud layers. The aligned magnetic fabrics of ancient mudstones suggest that this process was active for many mudstones in the rock record as well. Proposed modifications to the existing flume facility will allow the PI's to more efficiently pursue the measurement of physical parameters that control mud deposition, and record the small scale sedimentary features that result from different combinations of parameters (e.g. salinity, clay type, flow velocity). These data will provide the baseline for understanding the physical conditions of mud deposition, and will be the first step in an effort to integrate physical, chemical, and biological parameters of mud deposition.
