Jurassic

During the Permo-Trias, formation of the supercontinent Pangea and a gradual warming of global temperatures led to exceptionally arid conditions. Carbonate sedimentation became extensive across the Arabian Plate, and within Permian Basin of North America and the Zechstein Basin of northern Europe. Periodic dessication of basins led to precipitation of thick intervals of evaporites – gypsum, halite and potassium chloride. These conditions continued into the Jurassic, and on the Arabian Plate shallow water carbonate sedimentation took place on the margins of large intrashelf basins. The intrashelf basins accumulated organic-rich sediment but dessicated periodically to precipitate thick intervals of salt. This combination of porous carbonate, organic rich mudstone and salt created ideal conditions for the generation, storage and sealing of hydrocarbons, including deep gas reservoirs which are now under appraisal and development (e.g. Hollis et al., 2017, Marine and Petroleum GeologyPublications).

During the Triassic and Jurassic, continental break-up began along the present day Atlantic margins. In Morocco, carbonate platforms were developed on the footwalls of normal fault blocks and salt domes, formed by the remobilisation of Triassic salt. Volcanism associated with continental break-up increased PCO2 in the atmosphere, initiating global warming. Acidification of the ocean resulted in periodic Ocean Anoxic Events, which led to the periodic demise of carbonate platforms within basins, where stratified water columns and anoxic bottom waters led to the formation of some of the World’s most prolific source rocks. Projects in Morocco, as part of the North Africa Research Group, have established the depositional conditions for carbonate platform growth and dolomitization on the Atlantic margins.

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