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- Title
Facies associations and evolution of pelagic carbonate platform/basin systems: examples from the Italian Jurassic.
- Authors
Santantonio, Massimo
- Abstract
During the structural and sedimentological evolution of rifted continental margins in carbonate dominated settings, a characteristic stage is commonly reached when pelagic carbonate sedimentation occurs in association with complex fault block systems. An integrated study of thc ammonite biostratigraphy and sedimenlology of Jurassic pelagic rocks in the Umbria-Marche Apennines (central Italy) and in the Sila Mountains (north-east Calabria southern ltaly) has revealed three distinctive facies associations which can be related to specific structural and depositional settings. The condensed pelagic facies association is the constituent of condensed, usually discontinuous sequences with numerous hiatal surfaces. The normal and resedimented pelagic facies association is typical of thicker sequences, comprising, gravity flow and rockfall deposits. The composite pelagic facies association is one in which rockfall deposite are found associated with condensed sequences containing minor or no gravity flow deposits. Palacotopographical highs are dominated by the condensed pelagic facies association and constitute the pelagic carbonate platform (PCP), Structurally, the PCP can be coincident with the top of a horst (or 'central high'} block or the crestal area of a tilted block. In the latter case, the sediment surface of the PCP slopes gently (maximum of 1-3°) this the shallowest area of a pelagic carbonate ramp. PCPs can have erosional, bypass (rare) and depositional margins. Stepped margins also exist as as subparallel rows of erosional and bypass margins Trends from erosional to depositional margins are usually seen as a response to basin filling and burial of submarine tectonic escarpments by pelagic deposits in late synrift or early post-rift times. This is apparent from 'progradation' of PCP facies deposits beyond the structural boundaries of the PCP. Palaeoenvironmental analyasis in pelagic carbonate platform deposits of the Umbria-Marche Apennines suggests that...
- Subjects
APENNINES (Italy); ITALY; FACIES; ROCKS; JURASSIC stratigraphic geology
- Publication
Sedimentology, 1993, Vol 40, Issue 6, p1039
- ISSN
0037-0746
- Publication type
Article
- DOI
10.1111/j.1365-3091.1993.tb01379.x