ABSTRACT: Sequence Stratigraphy and Systems Tracts of a Carbonate Platform-Basin Model: the Albian of Lunada and Soba, Northern Spain

Joaquin Garcia-Mondejar, Pedro Angel Fernandez-Mendiola

The carbonate platform-basin model between Lunada and Soba (Burgos and Cantabria, northern Spain) has been analyzed using the sequence stratigraphy and systems tracts approach. Rudistid limestones alternating with sandstones and conglomerates characterize the platform. Reef mounds abound in the platform margin, and marls, lutites, turbiditic sandstones, and limestone megabreccias are present in the adjacent intraplatform basin.

Sequence boundaries have been defined after evidence of platform exposure and correlation of the unconformities along a platform-basin transect 15 km long and 350 to 1600 m thick. Six type-1 sequences have been distinguished. These sequences range in time from the late early Albian to the Late Albian. Four sequences have turbiditic sandstones in their respective LSTs. All but one of the sequences enclose limestone megabreccias (clasts up to 200 m across) in the same tract. TSTs are generally thin and preferentially consist of marls, and limestones. HSTs represent the bulk of the succession and are made up of limestones, marls and sandstones. Catch-up rather than keep-up deposition is deduced from the stationary platform margin. The upbuilding character of the reefal margin, together w th the large increase in thickness from platform interior to basin and the presence of angular unconformities, suggest that local tectonics controlled the sedimentary model and that tectonic pulses can account for the origin of the sequences. Nevertheless, comparison with the Vail's curve suggests that some of the sequences can also be attributed to eustasy.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990