Depositional Dynamics of Fortuna and Tellien Basin
Boukhalfa, Kamel *1
(1) Geology, Faculty of sciences of Tunis, El manar, Tunisia.
Litho-biostratigraphical correlation and detailed sedimentological analysis has been used as a tool to discriminate and illustrate the role of tectonics and eustasy in the configuration of the Fortuna and tellian basin of northern Tunisia, using 17 field sections of shallow to nonmarine oligo-miocene deposits distributed along NW-SE trending from Nefza-Kasseb to Tunisian Atlas domains.
The various and heterogeneous nomenclatures previously proposed for the Oligo-Miocene shallow to nonmarine deposits outcropping in northern Tunisia were examined and revised. In this paper we propose a new lithostratigraphic chart based on litho-biostratigraphical data obtained by planktonic and larger benthic foraminifera and main fossiliferous layers and similar lithofaciès correlation. This chart summarizes and restores the major sedimentary and stratigraphic events recorded in the shallow to nonmarine oligo-miocene sediments. It homogenizes and sees better the spatiotemporal distribution of the Oligo-Miocene sedimentary bodies.
A sedimentological and sequence stratigraphy study of oligo-miocene shallow to nonmarine successions has been carried out in the main outcrops of northern Tunisia, based on the analysis of facies and facies associations and identification of major transgressive-regressive trends. These deposits are composed of twenty facies grouped into eleven facies associations. These facies associations are interpreted as representing a range of facies deposited in a fluvio-deltaic to shallow marine siliciclastic environments in a foreland basin of northern Tunisia.
Four second order Transgressive-Regressive (T-R) facies trends bounded by two major discontinuities and two maximum flooding surfaces are identified. The major and significant time gap unconformity is recorded in the upper Chattian around the Oligocene-Aquitanian boundary during a transgressive trend.
The main phases of the Oligo-Miocene paleogeographic reconstitution are deduced in relation with the main controlling factor which was the result of contractional deformation migrated to the south and east from deformation occurred in the Northern Apennine region and the Western edge of the North African Margin.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain