New Challenges for High-Resolution Palynostratigraphy in the Neoproterozoic and Early Palaeozoic (Cambrian Through Silurian) of North Africa

Vecoli Marco¹, Bindra Thusu², Florentin Paris³, and Syed Rasul^4
1Earth Sciences, CNRS - University of Lille1, Villeneuve d`Ascq, France
²Earth Sciences, University College London, London, United Kingdom
³Geosciences, CNRS - University of Rennes, Rennes, France
⁴Independent Consultant, London, United Kingdom

Palynomorphs (acritarchs, chitinozoans, miospores) constitute the most suitable tools for the detailed biostratigraphic dating and correlation of Palaeozoic successions in the subsurface of North Africa. Recent progresses in Neoproterozoic palynostratigraphy have revealed considerable potential for the dating and correlation of the deeper parts of the North African stratigraphic sequences, which are increasingly targeted in oil exploration.

In this talk, we present the most recent developments in Neoproterozoic through Early Palaeozoic palynostratigraphy, based on a new synthesis of published and unpublished investigations of a large number of boreholes across North Africa. Key case-studies are illustrated, demonstrating the potential of palynomorphs for the biostratigraphic "fingerprinting" of stratigraphic horizons of particular interest, for long-distance correlation, palaeoenvironmental reconstruction, and tracking of lateral facies variations.
Many of previously undated stratal sequences which were informally named "Infracambrian" or "Cambro-Ordovician" can now be dated by organic-walled microfossils, at a good level of resolution. Clear evidence for a Late Riphean age (Tonian-Cryogenian) exists for the "Infracambrian" stromatolitic limestones in the subsurface of Toudeni basin as well as for "Cambro-Ordovician" subsurface sequences of the Cyrenaica Platform (E. Sirte Basin, Libya). Other Algerian and Libyan "Infracambrian" sequences are now precisely dated to Middle - Late Cambrian. In the Ordovician, a detailed database of occurrence of 250 acritarch species has been developed and independently age-constrained by the co-occurrence of chitinozoans. Detailed palynological analysis allows to map the spatial-temporal distribution of organic-rich horizons (e.g., early Silurian "Hot Shales) and sandstone reservoirs (e.g., glacial-related Late Ordovician sandstones).

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery