BEES Geological research in the Sahara: exploring at ancient marine carbonates

Geologist hiding in the shade of Hollard Mound, one of the Kess Kess Mounds

By Boris Dorschel

Supported by an European Science Foundation Travel Grant and the Research Foundation Flanders, I participated in the Cocarde Workshop and Field Seminar ‘Recent and Ancient Carbonate Mounds in Morocco’ from the 24th to the 30th of October 2011. 31 scientists from 10 countries participated in a field-based study visiting carbonate outcrops of Ordovician bryozoan mounds to Silurian seep mounds, the famous Devonian Kes Kes mounds, Carboniferous Waulsortian-type mounds and Jurassic mounds.

Kess Kess Mounds exposed by erosion. Walking on these mounds was like walking on 400 million years old seabed

In the School of BEES, my research focuses on cold-water coral carbonate mounds offshore Ireland. These recent mounds are the result of complex bio-geological interactions where repeated growth of cold-water corals has generated mounds in 500 to 1000m water depth that elevate up to 300m above the surrounding seabed. The formation of mound is, however, not limited to the latest earth history with many fossil mounds been known throughout the Phanerozoic. Some of the worlds most spectacular outcrops of Palaeozoic mounds can be found in Morocco.

Arguably, the most famous mounds are the Devonian Kes Kes Mounds in the Hamar Laghdad area ca. 18 km southeast of Erfoud in the Tafilalt region of the Moroccan Anti Atlas comprising approximately 50 small mound structures elevating up to 55m above the adjacent terrain. These mounds have been exhumed by erosion. With all the younger infill removed, walking on and in between the mounds feels like promenading on the 400 million years old seabed. In this respect, the Kes Kes Mounds are unique on Earth in that it seems that erosion has not overprinted the mound’s original morphology. Shapes and geometries, and also the internal structures of mounds, are spectacularly exposed. These insights can help to better understand recent mounds where such information is covered by several hundreds of meters of water.

Camels were only mildly impressed by our presence

One of the Waulsortian-type mounds close to the Moroccan Algerian border

Less famous but nevertheless equally spectacular are the Carboniferous Waulsortian-type mounds close to the Moroccan-Algerian border. These mounds are located with in the military-restricted area and we were privileged in the way that our Moroccan colleagues managed to arrange a visit to site and provided military protection. The mounds themselves comprise more then 50 small, less than 30m high structures that occur along a line on a palaeo-slope. Like the Kes Kes mounds, these Carboniferous are also exceptionally exposed. But what is even more striking is the mound’s close resemblance to the Belgica mounds recently active in the Porcupine Seabight approximately 120 nautical miles southwest offshore Ireland. More detailed comparison studies of these Carboniferous mounds with recent mounds would be an exciting geological project potentially cross-fertilising palaeo and recent mound research.

Sunset in the Ait Bahaddou Ydir

In addition to being a real geological treat, this field excursion was also an exiting cultural experience with spectacular scenic components. For me personally, one of the most impressive experiences was the journey home from the Kess Kess mound in a sand storm and the view from the hotel the next morning. And I also learned that there is always time for a tea.

Stop for tea and cookies

 

Dr. Boris Dorschel

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