Carbonate ramps: an introduction

Carbonate ramps are carbonate platforms which have a very low gradient depositional slope (commonly less than 0.1°) from a shallow-water shoreline or lagoon to a basin floor (Burchette & Wright 1992). A large proportion of carbonate successions in the geological record were deposited in ramp-like settings. Nevertheless, ramps remain one of the more enigmatic carbonate platform types. In contrast to steeper-sloped rimmed shelves and isolated buildups, where the factors which have controlled their location and development are commonly quite evident, the controls on ramp development have seldom been clearly demonstrated. In order to shed new light on this topic, and related aspects of ramp development, this volume addresses a number of key issues including: terminology (can we classify ramps?), processes (how important are water temperature controls, production-depth profiles); tectonic controls (are ramps by necessity restricted to relatively shallow, flexural basins?); sedimentary processes (e.g. sediment dispersal versus in situ production in maintaining the ramp profile); the origins of ramp reef-mounds; and the reasons for the evolution of ramps into other carbonate platform types (see e.g. Read 1985).