2023-12-11 17:59:13
The DESIRéE mission organized in Afar country in Gobaad from March 8 to 24, 2023 allowed the sampling of 16 m of sedimentary sequence in Djibouti’s Lake Abhé (also called Lake Abbé) as well as a 30 km grid of high quality seismic .
This region corresponds to the lower valley of the Awash River which has its source near Addis Ababa (2500 m altitude) and ends in Lake Abhé, endorheic (~330 m altitude) at the end of a journey of 1200 km.
This mission was financed by theANR NILAFAR The NILe and AFAR regions: hydrologic changes and impact on human adaptation in the last 20,000 years (PI Marie Revel GEOAZUR laboratory) and organized by Jessie Cauliez (TRACES Laboratory).
The mission brought together a team of 8 people: Marie Revel, Jessie Caulie, Fabien Arnaud, Eric Chaumillon, Bernard Fanget, Emmanuel Malet, from the CNRS and the Universities of Nice Côte d’Azur UniCA (UMR Géoazur), Savoie Mont Blanc (UMR Edytem ), La Rochelle (UMR LIENs), and Toulouse II Jean Jaurès (UMR TRACES) as well as Mohamed Sahal and Mohamed Djama from ORREC (Regional Research Observatory for the Environment and Climate in East Africa).
For 10 days, in the heart of the waters of Lake Abhé-Gobaad, the mission had the dual objective:
– to extract a sedimentary sequence 16 m long (dubbed) from the Edytem UWITEK platform which covers the last 20,000 years of flood history of the Awash River in Afar.
– to carry out geophysical studies. They recorded 30 km of seismic from the Seistek system showing, at an unprecedented resolution, the phases of sedimentation of the lake for around 20,000 years. The first results show that sedimentation took place in around ten successive phases. These changes suggest a strong potential for recording the frequencies and intensity of Awash floods and Gobaad flash floods. We also highlight fault zones and erosional unconformities.
In the longer term, these data will make it possible to specify the timing and amplitude of arid episodes around 4.2 ka and 8.2 ka. The results thus acquired will be put into perspective with recent work on the expression of events 4.2 and 8.2 on the African continent, north of Madagascar, in the Mediterranean and in the Atlantic and Indian Oceans (link with the el Nino and IOD process) in order to improve the understanding of the mechanisms controlling the African monsoon through climate modeling.
Publication submitted to Climate of the past:
50-years seasonal variability of East African droughts and floods recorded in Central Afar lakes sediments (Ethiopia) and their connections with ENSO
Mologni C, Revel M., Chaumillon E., Malet E., Coulombier T., Sabatier P., Brigode P., Hervé G., Develle A.-L., Schenini L., Messous M., Davtian G., Carré, A., Bosch D., Volto N., Ménard C., Khalidi L., Arnaud F.
Contacts :
Contact UMR Géoazur (UniCA, CNRS, Obseratoire de la Côte d’Azur, IRD)
Marie Revel
revel@geoazur.unice.fr
Contact UMR TRACES (CNRS, Toulouse II Jean-Jaurès University, Ministry of Culture)
Jessie Cauliez:
jessie.cauliez@cnrs.fr
1702318175
#coring #geophysical #studies #mission #Lake #Abhé
