Late Triassic to middle Jurassic history of the north-central High Atlas, Morocco
The Lower and Middle Jurassic (Liassic and Dogger) rocks in the north-central High Atlas and on the adjacent Oran Meseta, Morocco, were deposited on the subsiding margin of the Triassic/Jurassic High Atlas Trough. This and the Middle Atlas Trough formed as a result of rifting of the Moroccan and Oran Mesetas from the Saharan craton during initial stages of the opening of the modern Atlantic. The Tethys seaway flooded these troughs in the early Liassic, depositing several thousand meters of limestone and marlstone onto the Dogger. Four major Liassic-lower Dogger stratigraphic units were identified, termed Units 1 through 4, oldest to youngest. Unit 1 consists of intertidal and supratidal skeletal pelletal wackestones, algal boundstones, and claystones located on the Oran Meseta and shelf-margin skeletal pelletal oolitic packstones and grainstones along the High Atlas margin. Unit 2 intertongues with and overlies shelf-margin Unit 1 and consists of slope and basin-floor mudstones, wackestones, and turbidite packstones, cyclically interbedded with marlstones. Unit 2 is punctuated by slumps and debris beds near the margin of the basin. At the top of Unit 2 is a condensed zone overlain by basin-floor Unit 3 marlstones, which are cyclically interbedded with mudstones, wackestones, and turbidite packstones. Both Units 2 and 3 thicken basinward, off the ancient shelf margin. Unit 4 lies within Unit 3 and consists of a displaced block (3 /times/ 30 km) of the upper Liassic shelf margin and associated coarse-grained debris, thickest on the marginward side of the block.
- Research Organization:
- Chevron U.S.A. Inc., Houston, TX (USA)
- OSTI ID:
- 5717713
- Report Number(s):
- CONF-8809346-
- Journal Information:
- AAPG Bull.; (United States), Vol. 72:8; Conference: Mediterranean Basins conference and exhibition, Nice, France, 25-28 Sep 1988
- Country of Publication:
- United States
- Language:
- English
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