--> ABSTRACT: Sequence Stratigraphic Interpretation of an Upper Cretaceous-Lower Tertiary Carbonate Base-Of-Slope Succession: Gran Sasso d'Italia (Italy), by J.-H. Van Konunenburg, M. Mutti, and D. Bernoulli; #91021 (2010)

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Sequence Stratigraphic Interpretation of an Upper Cretaceous-Lower Tertiary Carbonate Base-Of-Slope Succession: Gran Sasso d'Italia (Italy)

VAN KONUNENBURG, JAN-HENK, MARIA MUTTI and DANIEL BERNOULLI

Carbonate slopes are key areas for correlating shelf and basinal sediments. They provide important clues to the problem of correlation of sequential units on platforms with unconformity- and conformity-bounded units on the slope and in the deep basins. This study aims to define major (2nd order) sequences in a base-of-slope succession and to trace 2nd order sequence boundaries defined on a carbonate platform into deeper water, even though no physical connection between platform-margin and base-of-slope is preserved.

The Upper Cretaceous to Lower Tertiary pelagic and redeposited carbonate sediments, exposed in the Gran Sasso d'Italia, were deposited on the base-of-slope separating the Lazio/Abruzzi (southwest) and Maiella carbonate platforms (south) from the Marche basin (north). The three major facies types include: (1) breccias and mega- breccias, containing a large variety of platform- and slope-derived lithoclasts as well as skeletal fragments; (2) turbidite beds, with mainly skeletal fragments and minor amounts of smaller lithoclasts; and (3) pelagic foraminiferal lime mud- and wackestones. Although reworking of slope deposits occurs, the bulk of the redeposited material is derived from the adjacent platforms and, therefore, provides additional evidence for platform evolution.

Sedimentologic and (bio)stratigraphic criteria allowed to define several orders of sequence boundaries. Second order sequence boundaries are defined at major unconformities and rapid (within 10 m) vertical changes in facies associations, which subdivide the Gran Sasso base-of-slope succession into seven second order depositional sequences.

Our data indicate that long-term (second order) changes in the depositional system, observed for the different sequences in the Gran Sasso area, were largely controlled by changes in the sedimentary regime on the adjacent platform. However unconformities of lower order within the second order base-of-slope sequences seem to be related to local submarine erosion, rather than platform development.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.