Tectonic control of the subducting Juan Fernández Ridge on the Andean margin near Valparaiso, Chile

Crustal redistribution, crust–mantle recycling and Phanerozoic evolution of the continental crust

“…A significant revision to Clift and Vannucchi's (2004) estimate of the net average global loss rate of 90 km 3 /Ma/km of trench was made after recognition that rates of mass loss along the central Andean margin were in fact much lower than had been inferred from the offshore data alone (Clift and Hartley, 2007). While the evidence for trench retreat is clear in two survey areas offshore the Andean margin (von Huene et al, 1997;Laursen et al, 2002) it was observed onshore that uplift of coastal terraces has been occurring, at least since the Middle Miocene, suggestive of underplating rather than the anticipated tectonic erosion under the terrestrial portion of the forearc (Ortlieb et al, 1996;Marquardt et al, 2004). This observation allowed a new rate of mass loss to be determined for the younger part of the Neogene, even though it was recognized that in the longer term the Andean margin would eventually have to revert to a faster erosion style, because the trench slope cannot steepen indefinitely.…”

Petit-spot lava fields off the central Chile trench induced by plate flexure

“…Assuming the Juan Fernández hotspot track was fixed over the last 10 million years, the D08 lavas, dated at 10.11 ± 0.22 Ma, could have erupted on the flexural arch of the western portion of the contemporary hotspot (Fig. 1) at the present Friday and Domingo seamount sites, approximately 1 million years before the eruption of O'Higgins Guyot at 8.5 ± 0.4 Ma (von Huene et al, 1997). In comparison, the 6.69 ± 0.88 Ma age of the D10 lava indicates eruption far to the east of the contemporary hotspot, where the flexural moat is negated by flexing of the outer-rise plate (Fig.…”

“…The O'Higgins group dominates the eastern end of the Juan Fernández seamount chain and consists of O'Higgins Guyot, O'Higgins Seamount, and O'Higgins Ridge, on the outer-rise of the Chile trench. Ar-Ar total fusion ages of dredge samples from O'Higgins Guyot give an age of 8.5 ± 0.4 Ma (preliminary report in von Huene et al, 1997), whereas magnetic signals suggest that O'Higgins Seamount was formed around 9 Ma (Yáñez et al, 2001). Therefore, the Juan Fernández seamount chain shows a typical hotspot track with an age distribution correlated with the direction of plate motion (Fig.…”

Altos estructurales costa afuera en la región de Valparaíso, Chile central: Réplica a comentarios de C. Rodrigo

“…Su información de batimetría multihaz del AGOR Vidal Gormaz y del RV Sonne, en términos generales, enriquecen la morfología submarina del área, considerando que la primera información respecto del área de estudio relacionada con las geociencias marinas corresponde a Scholl et al (1970) al interpretar un perfil sísmico obtenido en 1967 durante el crucero del USN Charles Davis, siendo la primera vez que se tuvo noticia del grado de deformación del talud inferior (actualmente interpretado como un talud acrecional) y del talud medio (interpretado entonces como una terraza tectónica y hoy conocida como la Cuenca Valparaíso) durante el crucero del RV Sonne de 1995 efectuado como parte del proyecto CONDOR [Chilean Offshore Natural Disaster and Ocean-Environmental Research] (Von Huene et al 1997).…”