TASKER, D. R., G. M. WEIR, and R. C. DALE, Amoco Production Company, Houston, TX

ABSTRACT: Structural and Stratigraphic Analysis of the Dinaride Thrust Belt: A Frontier Exploration Province in Central-Southern Europe

The Dinarides are a 200-300-km-wide southwest vergent fold and thrust belt extending along the eastern margin of the Adriatic Sea. Structural and stratigraphic relationships are complex and varied across the thrust belt and can be used to define three major tectonic units, termed the internal, central, and external Dinarides. In the internal Dinarides, platform sequences deposited in the Early and Middle Triassic underwent rapid subsidence and drowning in the Late Triassic and Early Jurassic in association with rifting and subsequent formation of oceanic crust. Compressional shortening resulting in obduction of the Mesozoic ophiolites and the closure of Tethyan seaways began as early as the Late Jurassic. Melange and subsequent flysch deposition occurred during the Late Jurassic throu h Cretaceous as the developing thrust belt encroached upon the northeastern margin of the Dinaride carbonate platform.

The Dinaride carbonate platform forms the core of the central and external Dinarides, and is composed primarily of Permian-Triassic clastics and evaporites overlain by Middle Triassic through early Eocene platform carbonates. Localized development of intraplatform basins occurred in the Middle-Late Triassic during an extensional episode, and in the Late Jurassic as previous structures were reactivated during the earliest phase of compression. The entire sequence is overlain by late Eocene and early Oligocene synorogenic flysch. The central and external Dinarides are distinguished by differences in structural style and timing of deformation. In the central Dinarides, Late Jurassic and Early Cretaceous unconformities suggest structural uplift prior to the onset of thrusting, which began in the late Eocene. Deformation involves Paleozoic basement and includes a major decollement within the Permian Triassic clastic and evaporite unit. Thrusting in the external Dinarides occurred in the late Eocene-early Oligocene, and is restricted to Middle Triassic and younger units, with major detachments forming near the base of the Ladinian, and within a Late Jurassic-Early Cretaceous evaporite.

Important oil source and seal lithofacies occur within intraplatform basins and lagoons in the Mesozoic sequences of the central and external Dinarides. Widespread dolomitized units within the Mesozoic carbonate sequence are potential reservoir zones. The presence of surface hydrocarbon seeps, and of existing production on trend to the Dinarides in the thrust belts of Italy and Albania, suggest the potential for hydrocarbon discoveries in this underexplored area.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.