International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Time series analysis (orbital cycles) of the uppermost Cenomanian–Lower Turonian sequence on the southern Tethyan margin using foraminifera

Pages: 111 - 120


Abstract: Time series analysis has been performed for the first time on the Cenomanian-Turonian sequence in Central Tunisia in order to shed light on its Milankovitch-like cyclicity. This analysis was applied to two foraminiferal genera: the biserial Heterohelix, an oxygen-minimum zone (OMZ) dweller, and the triserial Guembelitria, a eutrophic surface dweller. Average sedimentary rates and the duration of the oceanic anoxic event (OAE2) in each studied section were estimated. The fluctuations in abundance of these two opportunistic species can be related mainly to both precessional (ca. 20 kyr) and eccentricity (100 and 400 kyr) cyclicity suggesting that changes in surface water fertility were linked to climate changes in the Milankovitch frequency band.

Keywords: Cenomanian-Turonian boundary, time series analysis, cyclostratigraphy, Milankovitch cyclicity, Heterohelix spp., Guembelitria spp.

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