--> ABSTRACT: Bedding Geometry, Grain Composition, Gamma Ray Response and TOC Variation along a Lower Jurassic Carbonate Slope System (Djebel Bou Dahar, High Atlas, Morocco), by J. J. G. Reijmer, D. P. G. Blomeier, and J. A. M. Kenter; #91021 (2010)

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Bedding Geometry, Grain Composition, Gamma Ray Response and TOC Variation along a Lower Jurassic Carbonate Slope System (Djebel Bou Dahar, High Atlas, Morocco) 

REIJMER, JOHN J. G., DIERK P. G. BLOMEIER, and JEROEN A. M. KENTER

High-resolution mapping of the internal architecture of the depositional slope system of the Pliensbachian Djebel Bou Dahar platform showed the presence of distinct low and highstand intervals.

The lowstand intervals exhibit a characteristic tongue shape pinching out towards the basin. The sediments consist of poorly sorted pack- to grainstones. Within these lowstand units the grain size decreases drastically downwards in the lower part of the mid slope.

The highstand intervals dominate the lower slope and display typical on lap patterns onto the lowstand intervals. At the mid-slope, the highstand intervals locally are unconformably overlain by lowstand beds. The micrite percentage changes vertically along the slope. The upper mid-slope consists mainly of packstones, while within the lower slope environment wackestones dominate. Gamma ray response and total organic carbon values show the same separation into highstand and lowstand intervals.

In conclusion, this study displays a high-resolution correlation between original depositional facies and bedding geometry, gamma ray and total organic carbon. Clear differences were found in the preservation of the sea-level signal depending on the setting: (1) an upper slope in which lowstand deposits dominate; (2) a mid-slope with a mixture of low and highstand intervals, and (3) a lower slope in which the highstand deposits prevail. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.