Sedimentology and sediment distribution of upper Triassic fluvio-aeolian reservoirs on a regional scale (Central Algeria, SW Morocco, NE Canada) : an integrated approach unravelling the influence of climate versus tectonics on reservoir architecture

• Main Author: Kayser, Nadine Mader
• Other Authors: Redfern, Jonathan
• Published: University of Manchester 2005
• Subjects: 553.28
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635557

The Upper Triassic of North Africa contains a number of extensive sandstone units, which are important hydrocarbon reservoirs in Algeria, Libya, Morocco and Tunisia. The stratigraphic subdivision of the Triassic reservoirs (TAGI- Triassic Argilo-Gréseux Inférieur) in the main Algerian fields is currently adequate for initial field development. However, doubts exist with regard to chronostratigraphic equivalence of reservoir zones and the identification of key bounding surfaces from field to field. A major problem is the definition of sequence boundaries in continental settings that are detached from direct effects of sea-level changes lacking biostratigraphic control. An accurate method of dating and correlating these sediments is therefore required in order to provide a refined stratigraphic and sedimentological model. Attempting to address these correlation problems, the influence of climate on sedimentation and cyclicity was introduced as an alternative method in order to link continental sequence. The influence of climate has increasingly been recognised as a control on runoff and sediment input into siliciclastic basins (e.g. Perlmutter & Matthews, 1989; 1990; Olsen, 1990; Clemmensen et al., 1994). Furthermore, the Upper Triassic documents an era when vast amounts of land were elevated and subjected to the direct effect of extreme climatic regimes driving sedimentation on the mega-continent. This study of Carnian-Norian continental fluvio-aeolian successions therefore tests the hypothesis whether sediment deposition in low palaeolatitudes of around 10 to 25° N on Pangaea was driven by mega-monsoonal oscillations (sensu Kutzbach & Gallimore, 1989). The study is based on the comparison of time- and facies-equivalent siliciclastic deposits within geographically separate basins integrating outcrop and subsurface data from the Agadir-Essaouira Basins (SW Morocco), the Fundy Basin (E Canada) and subsurface data from the Berkine Basin (Central Algeria). Comparable outcrop and subsurface studies have been undertaken with the ultimate aim of (1) providing analogues for the prolific TAGI (Triassic Argilo-Gréseux Inférieur) of the main Algerian fields; (2) correlating major climatic periods on a regional scale; in order to introduce a semi-chronostratigraphic component; and to (3) consequently assess the temporal and spatial distribution of these prolific fluvio-aeolian reservoir sandstones on a regional scale.