A Collaborative Proposal: Formation and Preservation of Fluvial and Marine Depositional Events, Waipaoa River Margin, New Zealand Grant uri icon

abstract

  • The underlying goal of this proposal is to better understand if and when fluvial and wave depositional signals are generated on the shelf, and how the former can be transformed into the latter or both can be modified in a dynamic marine setting. The Poverty Bay shelf also offers an exciting opportunity to explore the roles that structural control and oceanographic forcing play in determining the characteristics of short and long-term deposition. This research will be accomplished using a combination of sediment-transport observations, time-series coring with high-resolution sampling, and computer modeling of sediment dynamics. In particular, the following questions and hypotheses will be investigated: 1) Can the location and character of event beds be predicted? Recent research on several margins has documented that river-discharge and storm-waves create depositional event beds, associated with the largest, and sometimes even modest events. Through modeling this proposal will attempt to work backwards and determine where fluvial and/or marine event beds are expected to form and be preserved on the Waipaoa margin, and then test these calculations using field observations. 2) What's the fidelity of the stratigraphic record? The stratigraphic record often is used as a tool for understanding the depositional history of a system, including discrete, significant events. However, process-oriented research is needed to define if and how strata are preserved. 3) How does seabed morphology affect sediment-gravity flow activity and resultant deposition? Sediment-gravity flows have been identified as a mechanism of cross-shelf transport on many river-dominated continental margins. Conditions conducive to gravitationally driven transport include ample sediment supply, energetic waves and / or currents, and steep bathymetry. Modifications to bathymetric slope that result from either morphodynamics or structural controls can therefore create feedbacks and influence cross-shelf sediment transport and deposition.

date/time interval

  • August 2009 - July 2014