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The data base so far available has permitted the delineation of the following facies as potential source rocks:
Palaeozoic
The Ordovician, Silurian and Devonian organic facies are predominantly sapropelic (type II kerogen) although, in places, these facies are becoming lipidic (type I kerogen). These Palaeozoic organic facies are widespread over the whole Moroccan territory and constitute the continuation of those encountered in Algeria and North Africa in general. The Carboniferous organic facies, however, is predominantly humic (type III kerogen). The Silurian source rocks with TOC value of up to 12 % (Tadla Basin) are the most important. The Ordovician and Devonian sequences exhibit interesting source rock intervals with TOC values in the order of 4 % in the same basin. Visean and Namurian sequences contain shaly intervals with humic organic facies (type III kerogen) having TOC values around 1.5 % in the High Plateaux. Similar facies are also encountered in the Tadla Basin. The Westphalian and the Stephano-Autunian organic facies with frequent coaly and lignitic intervals yielded TOC values in excess of 30 % in the High Plateaux and Argana valley. Some oils sampled from reservoirs or well shows in the Prerif (Tselfate field), Doukkala, Tadla, and Essaouira basins are interpreted to be generated from Palaeozoïc source rocks.
Triassic
The synrift sequence, infilling Triassic graben and half graben along the Atlantic coastal basins, may yield excellent lacustrine (type I kerogen) source rock. These intervals have been tested in the Doukkala Basin. TOC values are in the order of 2.5 %.
Jurassic
Recent geochemical survey shows that the Rif, the Middle and the High Atlas basins contain rich Lower Jurassic (Liassic) source rock. The organic facies is predominantly amorphous type II kerogen with TOC values up to 10 % and within the oil window in most places. This facies is producing oil in the Prerif Ridges and is the source for many seeps distributed throughout the Prerif and the Middle Atlas areas.
The petroliferous character of this Jurassic organic facies may have a widespread distribution. The oil at Sidi Rhalem field in the Essaouira Basin is produced from Oxfordian shale (TOC up to 4 %). The oils produced in the Cap Juby structure in the Tarfaya Basin were probably sourced from Jurassic marly facies. In the Tarfaya-Layoune-Dakhla Basin, Lower and Middle Jurassic organic facies have TOC values ranging from 1.47 to 2.49 %.
Cretaceous
Marine organic facies (Aptian-Albian and Cenomano-Turonian) are, by far, the richest in organic matter with TOC up to 20 %. These facies are widespread over most of Moroccan sedimentary basins. Under adequate burial, the Cretaceous marine organic facies may constitute an excellent effective source rock. Recent synthesis shows that this could be the case in the Rif, Tadla and, basinward, in the offshore Atlantic basins.
Neogene
the Neogene (Oligocene and Miocene) marls and shales have TOC values of up to 7 % in the Atlantic basins and up to 2 % in the Mediterranean offshore area. This source rock produces biogenic gas but can yield oil where sufficiently buried. This is seen particularly in the Rharb Basin where we have either biogenic gas or oil production, depending on the depth of burial of this source rock.
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