Journal of Petroleum Geology, vol. 23 (3), July 2000, pp. 293-311.
Copyright 2000 by Scientific Press Ltd. All rights reserved.

SILURIAN -- LOWER DEVONIAN BLACK SHALES IN MOROCCO: WHICH ARE THE ORGANICALLY RICHEST HORIZONS?

S. Luning¹*, D. K. Loydell², O. Sutcliffe³, A. Ait Salem⁴, E. Zanella¹, J. Craig¹ and D. A. T. Harper⁵

Lowermost Silurian (Rhuddanian, lower Llandovery) black shales represent the main Palaeozoic petroleum source rock throughout North Africa and Arabia. The unit also occurs in parts of Morocco with recorded TOC values of up to 10.5%. However, in contrast to many other North African and Arabian countries, the Silurian-Lower Devonian shale-dominated succession in Morocco also contains a number of other horizons with elevated organic contents. In order to evaluate the organic richness and better understand the depositional mechanisms of this shale succession in Morocco, samples were collected from petroleum exploration wells, from the spoil heaps of shallow water wells and from outcrops, and were subsequently analysed. Graptolite biostratigraphy provided a high-resolution correlation framework. The data was integrated with that from published and unpublished studies, and the results may help in improved predictions of the source quality of Silurian--Lower Devonian strata in Morocco.