title: Quantifying crustal thickness over time in magmatic arcs.
abstract: We present global and regional correlations between whole-rock values of Sr/Y and La/Yb and crustal thickness for intermediate rocks from modern subduction-related magmatic arcs formed around the Pacific. These correlations bolster earlier ideas that various geochemical parameters can be used to track changes of crustal thickness through time in ancient subduction systems. Inferred crustal thicknesses using our proposed empirical fits are consistent with independent geologic constraints for the Cenozoic evolution of the central Andes, as well as various Mesozoic magmatic arc segments currently exposed in the Coast Mountains, British Columbia, and the Sierra Nevada and Mojave-Transverse Range regions of California. We propose that these geochemical parameters can be used, when averaged over the typical lifetimes and spatial footprints of composite volcanoes and their intrusive equivalents to infer crustal thickness changes over time in ancient orogens.
authors.affiliation: University of Arizona, Department of Geosciences, AZ 85721, USA.
authors.forename: Lucia
authors.initials: L
authors.lastname: Profeta
authors.affiliation: University of Arizona, Department of Geosciences, AZ 85721, USA.|University of Bucharest, Faculty of Geology and Geophysics, Bucharest, 010041, Romania.
authors.forename: Mihai N
authors.initials: MN
authors.lastname: Ducea
authors.affiliation: University of Arizona, Department of Geosciences, AZ 85721, USA.
authors.forename: James B
authors.initials: JB
authors.lastname: Chapman
authors.affiliation: University of Southern California, Department of Earth Sciences, Los Angeles, CA 90089, USA.
authors.forename: Scott R
authors.initials: SR
authors.lastname: Paterson
authors.affiliation: University of Arizona, Department of Geosciences, AZ 85721, USA.
authors.forename: Susana Marisol Henriquez
authors.initials: SM
authors.lastname: Gonzales
authors.affiliation: University of Southern California, Department of Earth Sciences, Los Angeles, CA 90089, USA.
authors.forename: Moritz
authors.initials: M
authors.lastname: Kirsch
authors.affiliation: University of Bucharest, Faculty of Geology and Geophysics, Bucharest, 010041, Romania.
authors.forename: Lucian
authors.initials: L
authors.lastname: Petrescu
authors.affiliation: University of Arizona, Department of Geosciences, AZ 85721, USA.
authors.forename: Peter G
authors.initials: PG
authors.lastname: DeCelles