From platform to basin to swell: orbital control on sedimentary sequences in the Oxfordian, Spain

Abstract

AbstractClimatic, oceanographic and ecological changes that control the formation and deposition of sediment in shallow and deep depositional environments commonly occur with periodicities of a few 10 000 years. Consequently, in order to interpret sedimentary sequences in the geological past, high time resolution is required. This is best obtained by cyclostratigraphy. Three sections have been studied in the Oxfordian of north‐eastern Spain: one represents a shallow, siliciclastic‐carbonate platform with repetitive subaerial exposures, one an intraplatform basin with sponge bioherms, and one a swell where iron ooids and glauconite formed. The platform section displays a well‐defined stacking pattern of depositional sequences; the deeper‐water sections are well dated by ammonites. The correlation between the three sections is a best‐fit solution integrating biostratigraphy, sequence stratigraphy and cyclostratigraphy. It is concluded that the small‐scale depositional sequences formed in tune with the 100‐ka orbital eccentricity cycle. An additional factor was differential subsidence that ruled basin morphology.