Progradation geometries of carbonate platforms: examples from the Triassic of the Dolomites, northern Italy
Article first published online: 14 JUN 2006
Volume 31, Issue 1, pages 1–24, February 1984
How to Cite
BOSELLINI, A. (1984), Progradation geometries of carbonate platforms: examples from the Triassic of the Dolomites, northern Italy. Sedimentology, 31: 1–24. doi: 10.1111/j.1365-3091.1984.tb00720.x
- Issue published online: 14 JUN 2006
- Article first published online: 14 JUN 2006
- Manuscript received 28 April 1983; revision received 1 July 1983
Various types of progradation of Triassic carbonate platforms are described from the Dolomites of the Southern Alps. The internal and external geometric relationships are exposed in spectacular natural sections and, moreover, their scale (500–1000 m of thickness) is such that they can be compared with features found in seismic profiles.
The different types of progradation are controlled by a number of factors which, normally, interact with each other. These factors include: rate of basinal sedimentation, rate of subsidence, width of the platform, depth of the surrounding basin and eustatic variations of sea-level.
Progradation is not a continuous process but episodic. Moments of massive debris input, during which the platform advances, alternate with long periods of negligible progradation, during which basinal sediments accrete and onlap the toe of slope. Upper boundary relationships of the prograding platforms include offlap, toplap and erosional truncation. Lower boundary relationships are horizontal, climbing and descending progradations. A variety of phenomena and circumstances have caused the cessation of progradation of the Triassic platforms. They include volcanism, collapse of margins, drowning (rapid relative rise of sea-level), subaerial exposure (relative fall of sea-level) and, probably, a natural decay of the system.
In the Triassic of the Dolomites, two main progradation models can be put forward: in the Ladinian model, progradation took place simultaneously with aggradation (relative rise of sea-level), whereas the characteristic feature of the Carnian model is toplap (relative stillstand of sea-level).