Quaternary coastal uplift along the Talara Arc (Ecuador, Northern Peru) from new marine terrace data

Kevin Pedoja , L. Ortlieb , J.-F. Dumont (1) , M. Lamothe , Bassam Ghaleb , M. Auclair , B. Labrousse (1)

1 GEOAZUR 6526 - Géoazur

Marine terrace sequences have been investigated along the Talara Arc, a 1000-km-long stretch of the coast of Ecuador and northern Peru, characterized by subduction with a concave plan-view. Seven areas were investigated, evidencing flights of up to seven marine terraces with elevations reaching up to 360 m above mean sea level (amsl). Dating of the terraces was made using the Infra Red Stimulated Luminescence (IRSL) technique on sands as old as MIS 9 (∼330 ka). 14 C and U-series dates were obtained from fossil shells for geochronological cross control. Mean uplift rates along the Talara Arc range from about 0.10 up to 0.50 mm/ yr. The strongest uplift is observed in the Manta Peninsula of Ecuador in front of the subduction of the Carnegie Ridge. The uplift rate tends to slow down towards the northern and southern ends of the Talara Arc and then the transition toward the stable or subsiding coasts of central Peru and northern Ecuador and Colombia is sharp. The uplift appears to be homogeneous and related to 1) the map view curvature of the Arc, 2) the concave subduction pattern and 3) the Carnegie Ridge subduction.

Mots clés: marine terrace; coastal uplift; concave subduction; ridge subduction; tablazo

Domaines: Sciences de la Terre

Kevin Pedoja, L. Ortlieb, J.-F. Dumont, M. Lamothe, Bassam Ghaleb, et al.. Quaternary coastal uplift along the Talara Arc (Ecuador, Northern Peru) from new marine terrace data. Marine Geology, 2006, 228 (1-4), pp.73-91. ⟨10.1016/j.margeo.2006.01.004⟩. ⟨hal-00407620⟩