The Late Paleogene to Neogene volcanic arc in the Southern Central Andes (28°-37°S)

VANESA LITVAK; STELLA POMA; ROSEMARY JONES; LUCIA FERNANDEZ; SOFIA IANNELLI; MAURO SPAGNUOLO; LINDA KIRSTEIN; ANDRES FOLGUERA; VICTOR RAMOS

The evolution of the Chilean-Argentinean Andes

Springer

Año: 2018; p. 1 - 34

Evolution of arc magmatism along the Southern Central Andes (*28°?8 37° S) is strongly controlled by changes in the geometry of the downgoing slab9 (e.g., slab dip angle). This is particularly evident in the present-day10 Chilean-Pampean flat-slab and the late Miocene Payenia shallow subduction seg-11 ments. Typical Andean-type volcanism was established from the late Oligocene to12 late Miocene in the high Andes (29°30″?30°30″S), with arc-related calc-alkaline13 volcanism having geochemical signatures that reflect changes in the residual min-14 eral assemblages related to increased crustal thickness (>50 km). The increase in15 crustal thickness resulted from increased compression along the Southern Central16 Andean margin due to the subduction of the Juan Fernández Ridge, and consequent17 shallowing of the downgoing slab during Mid to Late Miocene. Associated with the18 decrease in the slab dip angle, the volcanic front migrated to the east. Further south,19 magmas developed across the present-day Payenia back-arc region (35°?37° S)20 show an increase in slab-derived components in the middle Miocene to early21 Pliocene times, which also suggests a progressive shallowing of the subducting slab22 at these latitudes. However, trace element ratios indicate a low-to-intermediate