Jurassic Proximal and Distal Carbonate Turbidites of Central High Atlas Mountains, Morocco: ABSTRACT

Abstract

The Lower Jurassic sediments of the High Atlas Mountains of Morocco were deposited in a northeast-southwest-oriented trough approximately 100 km wide and 800 km long. The trough margins are characterized by carbonate and marl shelf deposits, whereas the central, axial part is characterized by offshore, deeper water carbonates and marls. The depositional history of some of the deeper water sediments can be determined from a thick, carbonate, turbidite sequence flanking the southern High Atlas shelf. Within this section (800 m thick), it is possible to trace a sequence from proximal turbidites near the base through progressively more distal turbidites in the upper part of the section. Distinctive turbidite units are observed and, when lithology and unit geometry are traced p through the section, distinct changes can be recognized. There is a reduction in bed thickness and grain size, a change in intraclast types, and an increase in bedding regularity; well-developed laminae are more common and beds become well graded. This turbidite sequence represents deposition from successive turbidity currents. The vertical changes from proximal to distal turbidites record either a deepening of the trough, a change in location of the sediment-source area, or a combination of both these factors. End_of_Article - Last_Page 778------------