Geodynamic controls in the southernmost Northern Andes magmatic arc: Trace elements and Hf-O isotopic systematics in forearc detrital zircon

U-Pb dating of single detrital zircon grains by laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS) paired with Hf and O isotopic trace-element analyses provide first-order indicators the Late Cretaceous−Cenozoic evolution southern Ecuadorian magmatic arc. Detrital ages define significant clusters that are tentatively interpreted as intense arc magmatism at ca. 72 Ma, 60 43 Ma. A major accretionary event in Cretaceous (75−65 Ma) is marked a broad range values (εHf[t] > 20 δ18O 8‰) suggest melting both lower upper crust (most likely continental affinity) well enriched mantle components. Highly fractionated signatures patterns Eu/Eu* combined mantle-like juvenile εHf characterize zircons from to 45 suggesting Cretaceous−middle Eocene originated an reflects persistence overthickened previously attributed main period. Subsequently, negative shifts εHf(t) composition 30 Ma decreases U/Yb Eu/Eu*. These could be magma emplacement thinner existence extensional extending current forearc toward areas near craton; however, other scenarios cannot excluded. This was characterized melt sources residence times pointing known crustal events (Sunsás) Amazonian craton. From 10 record slightly evolved depleted signature substantial increase fractionation. Our results published records found modern rivers that, for least last m.y., southernmost Northern Andes has been segmented, magmas north more related recycling ancient and/or subducted sediments south—aspects settings which constructed oceanic crust.