Marine Sedimentary Processes

Spring 2006

Instructors:

Andrea Ogston (543-0768; ogston@ocean.washington.edu; 107A MSB)

Chuck Nittrouer (543-5099; nittroue@ocean.washington.edu; 111B MSB)

Introduction to Marine Sedimentary Processes

Initially, we will introduce basic terms and background, and progress to initial development of the concepts of sediment transport and accumulation.

Mechanics of sediment transport (how particles get there)

(Lecture notes for this part of course)

The first part of the course will focus on the mechanics of sediment transport – the physical processes by which sediment particles are moved in the marine environment. We will start with the removal of sediment from plumes, and progress to resuspension processes where we will study the "Law of the Wall" and methods of evaluating bed shear stress. Threshold of sediment motion will be covered, and then transport as suspended load in the marine environment. The contributions of waves and wave-current interactions, particle aggregation, and density effects will be discussed within the context of experimental studies. Instrumentation and field methods for study of sediment dynamics will also be discussed.

Discussion topics:

Particle distributions, settling velocity, and particle aggregation

"Law of the Wall" boundary layer velocity profiles

Boundary shear stress & the quadratic stress law

Initiation of sediment motion

Suspended-sediment load

Density effects

Sedimentary environments (where particles accumulate)

The latter part of the course will be an examination of sedimentation in diverse marine environments ranging from the shoreline to the abyssal plains. The concept of sediment accumulation will be addressed, in terms of how deposition, erosion and bioturbation conspire to control the strata formed at particular sites. The impacts of these processes cause local and progressive changes of sedimentary characteristics in the seabed, which will be examined along fluvial dispersal systems from shallow to deep settings. We'll start with beaches and barrier coastlines, where surface gravity waves have a dominant impact. Next the evolution of river mouths from estuaries to deltas will be examined. Continental shelves are areas affected most dramatically by sea-level fluctuation, and thus experience a broad range of terrestrial and marine processes. The steep gradients of continental slopes make gravitational flows common there, especially during low stands of sea level. These flows spread sediment onto the continental rise and into the deep sea, forming abyssal plains. The fundamental mechanisms of fluvial dispersal systems will be contrasted with low-latitude carbonate and high-latitude glacial-marine systems.

Discussion topics:

Radioisotope techniques for measuring sedimentation

Interactions of sediment mixing, accumulation, and strata formation

Sedimentary environments

   Beaches and barrier islands

   Estuaries and deltas

   Continental shelf

   Continental slope, rise, and abyssal plain

   Carbonate and glacial-marine margins

Organization of the course:

Homework problem sets will be required in the course. During the discussion on sedimentary environments, each student will give a short oral presentation, relating concepts presented in this course to their research interests.

Two exams will be given: one following "mechanics of sediment transport" and the other following "sedimentary environments".

Grading breakdown:

Homework 30%

Exam (mid-quarter – mechanics of sediment transport) 30%

Davis, R. A., Coastal Sedimentary Environments
Pethick, J., An Introduction to Coastal Geomorphology
Reading, H.G., Sedimentary Environments and Facies
Komar, P., Beach Processes and Sedimentation, Second Edition
Wright, L. D., Morphodynamics of Inner Continental Shelves
Nielsen, P., Coastal Bottom Boundary Layers and Sediment Transport
U.S. Army Corp of Engineers, Shore Protection Manual
Dean, R. G. and Dalrymple, R.A., Water Wave Mechanics for Engineers and Scientists.