Storm-Dominated Shelves

Shelves that face prevailing westerly winds and are open to oceanic waves are most affected by storms Johnson and Baldwin, 1986). The strong near-bottom currents are 

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Carr, D.L. Scott, A.J. (1990) Late Pennsylvanian storm-dominated shelf sand ridges, Sacramento Mountains, New Mexico. J. sediment. Petrol., 60, 592-607. 

Swift, D.J.P., Han, G., and Vincent, C.E. 1986. Eluid processes and sea floor response on a modem storm-dominated shelf, middle Atlantic shelf of North America. Part 1 The storm-cmrent regime. In Shelf Sand and Sandstones, Knight, R.J., and McLean, J.R., eds., Canadian Society of Petroleum Geologists, Memoir 11, Calgary, Alberta, Canada, pp. 99-119. 

The aim of this work is to establish the mechanism for the succession of the brachiopod benthic assemblages based on both their sequences and taphonomic data. The Seillou section (30 km ESW of Brest, W Armoricain Massif) was chosen as it is the most complete exposure of the Faou Formation (Upper Pragian-Lower Emsian) deposited in a storm dominated open shelf environment (GuiUocheau, 1990). The rich and diversified fauna is dominated by brachiopods, crinoids and bryozoans. A study of the section is currently realised in order to understand the relationships between benthic assemblages and palynomorphs and the sea-level variations (Le Menu et ah, 1997). Some preliminary results concerning the brachiopods from the upper part of the section have been recently published (Lecomte et al., 1998). 

The basic classificahon of modem shelf environments is based on tire nature of the hydraulic regime (Johnson and Baldwin, 1986), and may be further subdivided by the distribution of fhe major shelf sedimenf fypes in each of these environments (Swift et al., 1971). The main shelf fypes are fhose dominated by meteorological, tidal, and oceanic currents. Meteorological currents may further be divided into wave-induced currents, mostly confined to inner, nearshore shelves, and storm-induced currents which affect the shelves to considerable depths. Density currents formed by suspended sediments at river mouths and seismically induced waves (tsxmamis) which occur on shelves facing seismically active regions may locally significantly affect specific shelf environments (Coleman, 1969). 

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