Compaction-induced subsidence in the margin of a carbonate platform

Abstract The Late Carnian Raibl Formation of the Sella Group (Dolomites, N Italy) forms a sedimentary wedge which thins progressively toward the core of a stratigraphically underlying Middle Carnian carbonate platform (Cassian Dolomite). The platform is composed largely of megabreccia clinoforms displaying progradation above the coeval basinal sequence (San Cassiano Formation). These basinal sediments thin from a maximum in a basinward direction to a pinchout towards the central core of the Sella buildup. The progradational foreslopes thin in an antithetic fashion, from a maximum immediately adjacent to the central core of the Sella to a minimum in a basinward direction. The wedge geometry and onlap of the Raibl Formation atop the Sella platform margin is interpreted as the result of compaction-induced differential subsidence and tilting of the platform top. Basinward increase in subsidence of the platform top resulted from a basinward increase in compaction of basinal San Cassiano sediments. Decompaction calculations and stratigraphic/geometric restoration of Carnian strata support this conclusion.