Geochronologic and stratigraphic constraints on canyon incision and Miocene uplift of the Central Andes in Peru

Renewed uplift of the Central Andes Forearc revealed by coastal evolution during the Quaternary

“…The Andean forearc uplift was quantified in Northern Chile to ~ 0.1 mm/yr in the precordillera between 26 and 8 Ma, dropping to ~0.02 mm/yr on average for the last 8 Ma (Farías et al, 2005). More accurate dating indicates uplift and canyon incision between ~10 and ~5 Ma (Hoke et al, 2007;Schildgen et al, 2009;Schildgen et al, 2007), with no more than 250 m postdating the 2.0 to 2.3 Ma-old Ocoña basalt in southern Peru (Schildgen et al, 2009;Thouret et al, 2007). Similarly, near Arica, the 2.55-2.7 Ma Lauca tuff is present at ~60 m amsl in the Lluta river, and between the Lluta river and the Arica airport (Garcia et al, 2004;Wörner et al, 2000), whereas Quaternary marine sediments crop out at a higher elevation, indicating Pliocene subsidence followed by uplift.…”

“…Studies have mainly focused on the Oligo-Miocene uplift (see the review by Ehlers and Poulsen, 2009). There is clear evidence that the Central Andes forearc (Figure 1) was 1,000 m lower than today during mid-Miocene, as demonstrated by the occurrence of mid-miocene marine strata at ~1,000 m amsl (above mean sea level) (Huamán, 1985), and incision timing (e.g., Hoke et al, 2007;Schildgen et al, 2009;Schildgen et al, 2007;Thouret et al, 2007). Most of the uplift must have been achieved at the end of the Pliocene era, as indicated by a basalt flow we encountered at less than 250 m amsl near the bottom of the Ocoña valley, indicating that almost all the incision currently observed had already occurred; it has been dated some kilometres upstream, similarly near the valley bottom at 2.0 to 2.3 Ma (Schildgen et al, 2009; 49 50 51 52 Thouret et al, 2007).…”

“…There is clear evidence that the Central Andes forearc (Figure 1) was 1,000 m lower than today during mid-Miocene, as demonstrated by the occurrence of mid-miocene marine strata at ~1,000 m amsl (above mean sea level) (Huamán, 1985), and incision timing (e.g., Hoke et al, 2007;Schildgen et al, 2009;Schildgen et al, 2007;Thouret et al, 2007). Most of the uplift must have been achieved at the end of the Pliocene era, as indicated by a basalt flow we encountered at less than 250 m amsl near the bottom of the Ocoña valley, indicating that almost all the incision currently observed had already occurred; it has been dated some kilometres upstream, similarly near the valley bottom at 2.0 to 2.3 Ma (Schildgen et al, 2009; 49 50 51 52 Thouret et al, 2007). Despite this, the coast presents many sequences of marine terraces and beach ridges, attesting to Quaternary uplift (e.g., Darwin, 1846;Domeyko, 1848;Gonzalez et al, 2003;Goy et al, 1992;Hartley and Jolley, 1995;Hsu et al, 1989;Machare and Ortlieb, 1992;Marquardt et al, 2004;Ortlieb et al, 1996a;Ortlieb et al, 1996b;Ota et al, 1995;Paskoff, 1977;Quezada et al, 2007;Saillard et al, 2009).…”

International Lateinamerika-Kolloquium 2009

“…Development of valley was enhanced by episodic glaciations and has played a key role in the typical evolutionary scheme of stratocones. In addition, the location wirh respect to one of deep, major canyons on the western flank of the Andean slope (Thouret et al, 2007) was also important in some examples. We distinguished (1) crater-topped active volcano (e.g.…”

Geomorphology of the Ampato volcanic complex (Southern Peru)

“…The most recent layers correspond to the Sencca formation that is formed by two distinct ignimbrites sheets of 4.9-3.6 and 2.3-1.4 Ma (Thouret et al, 2007).…”