2013/08/07 by Suzanne Mahlburg Kay, Constantino Mpodozis, M. Gardeweg · 1 citation
Earth and Planetary Sciences · Computer Science · #Geological and Geochemical Analysis #earthquake and tectonic studies #Geochemistry and Geologic Mapping #Forearc #Subduction #Andesites #Geology #Thickening #Tectonics #Delamination (geology) #Seismology #Erosion #Geomorphology #Andesite #Volcano #Volcanic rock
paper · doi:10.1144/sp385.11
openalex publication_date 2013/08/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Abstract The Central Andean margin, where the name andesite originated, is the type locality for arc andesites erupted through thick continental crust. The <25 Ma mid to high K 2 O andesites erupted from 25.5°S to 28.2°S exhibit a large variation in trace element and isotopic ratios, reflecting formation over an evolving slab, a crust thickening to 65–75 km and a frontal arc that migrated c. 45 km eastward at 8–3 Ma. Andesites at 28–26.8°S have the most variable and extreme heavy rare earth element (REE), high field strength element (HFSE) and Ba/La ratios and wt% Na 2 O, with the highest values in those erupted as the frontal arc migrated and the slab shallowed to the south. The required garnet-bearing, feldspar-free residue is generated in both the thick crust and the mantle wedge, into which crust was injected in a peak of forearc subduction erosion as the arc migrated. Andesites at 25.5–26.8°S, east of the Puna plateau under which the slab shallowed at 18–7 Ma and then steepened as lithospheric delamination occurred, generally lack extreme REE and HFSE ratios. Their upper crust-like features reflect eruption in a mixed stress regime and incorporation of westward-flowing radiogenic crust from a region of extensive deep crustal melting to the east.