A late Holocene record of marine high-energy events along the Atlantic coast of Morocco: new evidences from the Tahaddart estuary

Otmane Khalfaoui (1, 2) , Laurent Dezileau (1) , Jean-Philippe Degeai (3) , Maria Snoussi (2)

1 M2C - Morphodynamique Continentale et Côtière
2 UM5 - Université Mohammed V de Rabat [Agdal]
3 ASM - Archéologie des Sociétés Méditerranéennes

Abstract The Atlantic coast of Morocco has been exposed to marine submersion events from storm surges and tsunamis which have resulted in human and economic losses. The absence of long term records for these hazards makes it difficult to trace their behavior through time, which is the first step to prepare proactive adaptation strategies for events that may happen in the future. In this paper, we present a late Holocene record of marine submersion events along the Atlantic coast of Morocco using a 2.7 m sediment core sampled from the Tahaddart estuary. The sedimentological and geochemical analyses conducted on this geological archive showed a mud-dominated sequence with 14 allochthonous sandy layers (E1-E14) left by marine high-energy events. The deposition age of three layers (E1, E13 and E14) has been determined using conventional dating methods ( 210 Pb ex , 137 Cs and 14 C). The first layer, introduced as E1 seems to fit with the great Lisbon tsunami in 1755 CE (Common Era), an event dated for the first time along the Atlantic coast of Morocco. The other two layers, referred to as E13 and E14, were dated between 3464 and 2837 cal BP (calibrated years Before Present) and chronologically correlated with marine high-energy deposits found on the Spanish Atlantic coast. This correlation confirms the existence of another regional event around 3200 BP.

Domaines: Sciences de la Terre

Otmane Khalfaoui, Laurent Dezileau, Jean-Philippe Degeai, Maria Snoussi. A late Holocene record of marine high-energy events along the Atlantic coast of Morocco: new evidences from the Tahaddart estuary. Geoenvironmental Disasters, 2020, 7 (1), pp.31. ⟨10.1186/s40677-020-00169-5⟩. ⟨hal-03959166⟩