DYNAMIC STRATIGRAPHY WORKGROUP

Sediment supply: the main driver of shelf-margin growth

 

People:

Cristian Carvajal, Ron Steel, Andrew Petter

 

Research question(s):

Despite the obvious importance of sediment supply to shelf-margin architecture and to the potential of margins to contain and bypass deep-water sands, the role of supply in shelf-margin growth has received limited attention. Can shelf-margin accretion rates be used as proxies for relative sediment supply? What is the potential of these proxies for prediction of deepwater sands?

 

Summary of work:

Review of a number of ancient shelf-margin successions from both Greenhouse and Icehouse climate settings reveals that shelf margins prograde at rates of several to 10’s of km/Myr and aggrade at rates of several to 100’s of m/Myr. Based on structural style and water depth, two broad types of shelf margins were identified. Moderately deepwater margins produce clinoforms <1000 m high and prograde rapidly with relatively undeformed slopes, while very deepwater margins produce highly deformed clinoforms >1000 m high with more aggradational architectures. Accretion rates are shown to correlate with occurrence of deepwater sands for the Cenozoic Gulf of Mexico margin. The differences between rapidly and slowly prograding margins indicate that sediment supply (and not sea level) is likely to be the key limiting factor on the growth of shelf margins and that sediment supply, as interpreted through progradation rates, can therefore be used as a first-order prediction of relative amounts of sand bypassed to deep-water areas.

 

Publications and presentations: 

Publications:

Carvajal, C., Steel, R., and Petter, A., 2009, Sediment supply: the main driver of shelf-margin growth: Earth-Science Reviews, doi: 10.1016/j.earscirev.2009.06.008.

 

Conference/meeting presentations:

Carvajal, C., Steel, R., and Petter, A., 2009, Influence of sediment supply in shelf margin accretion and sand bypass to deepwater: AAPG/SEPM Annual Meeting, Denver, Colorado.