TY - JOUR
T1 - Estimates of paleo-crustal thickness at Cerro Aconcagua (Southern Central Andes) from detrital proxy-records
T2 - Implications for models of continental arc evolution
AU - Carrapa, Barbara
AU - DeCelles, Peter G.
AU - Ducea, Mihai N.
AU - Jepson, Gilby
AU - Osakwe, Arthur
AU - Balgord, Elizabeth
AU - Stevens Goddard, Andrea L.
AU - Giambiagi, Laura A.
N1 - Funding Information:
We acknowledge financial support from the National Geographic Society (9624-14) and NSF-FRES (EAR2020935). M.N.D. also acknowledges support from the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding project PN-III-P4-ID-PCCF-2016-0014. We are grateful to Dr. Rosemary Hickey-Vargas for handling this manuscript, Dr. Nicholas Perez and an anonymous reviewer for careful reviews that helped us to substantially improve the manuscript.
Funding Information:
We acknowledge financial support from the National Geographic Society ( 9624-14 ) and NSF -FRES ( EAR2020935 ). M.N.D. also acknowledges support from the Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding project PN-III-P4-ID-PCCF-2016-0014 . We are grateful to Dr. Rosemary Hickey-Vargas for handling this manuscript, Dr. Nicholas Perez and an anonymous reviewer for careful reviews that helped us to substantially improve the manuscript.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/5/1
Y1 - 2022/5/1
N2 - The Central Andes represent the archetypical Cordilleran orogenic system, with a well-developed continental volcanic arc and some of the thickest crust on Earth. Yet the relative contributions of shortening and magmatic additions to crustal thickening remain difficult to quantify, which hinders understanding processes of crustal evolution in continental arcs. Cerro Aconcagua, the highest mountain in the Americas and a relict Miocene stratovolcano resting on 55 km-thick crust, is the ideal natural laboratory to address this issue in subduction-related magmatic arcs because it preserves a multi-million year record of magmatism and deformation within the Aconcagua fold-thrust belt. Estimates of paleo-crustal thickness in the Andes can be made using the geochemistry of subduction-related magmatic rocks, or minerals crystallized within them. This study applies a geochemical proxy approach for crustal thickness estimates to detrital syntectonic deposits of the Santa Maria Conglomerate derived from the Aconcagua stratovolcano to reconstruct paleo-crustal thickness of the Andes at this latitude. Detrital zircon trace-element data from ashes intercalated in the conglomerate, combined with previously published paleo-crustal thickness data, indicate crustal thicknesses of ∼35 km ca. 38 Ma and ∼44 km ca. 12 Ma, requiring ∼11 km of crustal thickening after ca. 12 Ma to achieve present-day crustal thickness of ∼55 km. In the absence of significant magmatism since ca. 10 Ma at this location, we show that more than half of the crustal thickening after 12 Ma, corresponding to 2 km of uplift, was achieved by Miocene shortening. Our study also reveals significant differences in crustal thicknesses between the Central Andes and the southern Central Andes which we speculate may be due to southward crustal flow during the last ∼20 My.
AB - The Central Andes represent the archetypical Cordilleran orogenic system, with a well-developed continental volcanic arc and some of the thickest crust on Earth. Yet the relative contributions of shortening and magmatic additions to crustal thickening remain difficult to quantify, which hinders understanding processes of crustal evolution in continental arcs. Cerro Aconcagua, the highest mountain in the Americas and a relict Miocene stratovolcano resting on 55 km-thick crust, is the ideal natural laboratory to address this issue in subduction-related magmatic arcs because it preserves a multi-million year record of magmatism and deformation within the Aconcagua fold-thrust belt. Estimates of paleo-crustal thickness in the Andes can be made using the geochemistry of subduction-related magmatic rocks, or minerals crystallized within them. This study applies a geochemical proxy approach for crustal thickness estimates to detrital syntectonic deposits of the Santa Maria Conglomerate derived from the Aconcagua stratovolcano to reconstruct paleo-crustal thickness of the Andes at this latitude. Detrital zircon trace-element data from ashes intercalated in the conglomerate, combined with previously published paleo-crustal thickness data, indicate crustal thicknesses of ∼35 km ca. 38 Ma and ∼44 km ca. 12 Ma, requiring ∼11 km of crustal thickening after ca. 12 Ma to achieve present-day crustal thickness of ∼55 km. In the absence of significant magmatism since ca. 10 Ma at this location, we show that more than half of the crustal thickening after 12 Ma, corresponding to 2 km of uplift, was achieved by Miocene shortening. Our study also reveals significant differences in crustal thicknesses between the Central Andes and the southern Central Andes which we speculate may be due to southward crustal flow during the last ∼20 My.
KW - Aconcagua
KW - Central Andes
KW - continental arc
KW - crustal flow
KW - crustal thickness
KW - shortening
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U2 - 10.1016/j.epsl.2022.117526
DO - 10.1016/j.epsl.2022.117526
M3 - Article
AN - SCOPUS:85127463004
VL - 585
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
M1 - 117526
ER -