Abstract: High-Resolution Sequence Stratigraphy and Sedimentologic Models of the Algerian Ghadames Basin, Trias Argilo-Greseux Inferieur (T.A.G.I.)

SCOTT, ALAN J., GARY W. FORD, and HAMZA TOURQUI

Recent exploration successes in the Triassic of the Algeria portion of the Ghadames Basin has validated the usefulness of high-resolution sequence stratigraphy and detailed sedimentologic models in nonmarine deposits. The Trias Argilo-Greseux Inferieur (T.A.G.I.) strata form regional chronostratigraphic cycles having a basal fluvial sandstone unit overlain by a regional shale interval including interchannel mudstones, sabkha, lacustrine and eolian facies. Increased aridity of younger cycles aids in the recognition of specific intervals and the development of a stratigraphic framework.

Based on a sequence stratigraphic analysis, the Hercynian Unconformity is the lowstand surface of erosion and the sequence boundary of the Lower T.A.G.I. third-order sequence. All strata of this sequence are components of a transgressive system tract that represents a progressive filling of a pre-T.A.G.I. incised valley system. A second younger sequence includes all Middle and Upper T.A.G.I. intervals. The younger cycles are considered to be a transgressive system tract of a fourth-order sequence associated with a rejuvenation of T.A.G.I. fluvial systems.

Detailed sedimentologic models of the various fields document lateral and vertical variations of the T.A.G.I. intervals.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria