Major and trace element geochemistry of Permo-Triassic granitoids from NW Sonora, Mexico: Constraints on the origin of the Late Paleozoic-early Mesozoic Cordilleran magmatic arc along SW Laurentia

Alexander Iriondo*, Harim E. Arvizu, Francisco A. Paz-Moreno, Aldo Izaguirre, Andrés F. Velázquez-Santelíz, Fernando Velasco-Tapia, Luis M. Martínez-Torres, Ofelia Pérez-Arvizu, Rufino Lozano-Santa Cruz

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Permo-Triassic granitoids (PTGs) (284–224 Ma) crop out in Sierra Los Tanques (SLT) and surrounding areas in NW Sonora, Mexico. Based on mineralogical and geochemical characteristics, the PTGs are subdivided into three main suites: melanocratic (MS), leucocratic (LS) and pegmatitic-aplitic (PAS) suites. MS has I-type signatures (mostly metaluminous: biotite and hornblende), while LS is weakly peraluminous with biotite, muscovite, and garnet. PAS is composed of garnet-bearing pegmatite-aplite dikes of Permo-Triassic age. MS is slightly older than LS based upon field relations and age dating. PAS cut both granitoid suites and local Paleoproterozoic banded gneisses. PTGs are petrologically and geochemically classified as granodiorites, granites, and quartz monzonites, with medium-to high-K calc-alkaline affinity, and volcanic-arc granite (VAG) signatures. The enrichment in LILE (such as K, Rb, Ba, Sr, and Pb) and LREE over HFSE and HREE, respectively, together with negative Nb, Ta, P, and Ti anomalies, suggest derivation from a crustal source in a continental arc setting. Trace-element ratios of Ba/Ta≫1000, Th/Yb > 1, and Th/Ta>6–20 also support a setting in an active continental margin. All these geochemical features imply that crustal assimilation did play a major role in magma genesis. Crustal contamination is supported by field evidence, including xenoliths, stoped blocks, and roof pendants of Proterozoic basement rocks (Yavapai-type? crust). We propose that the PTGs from NW Sonora formed in a continental arc setting likely derived from the heat-fluxed melting of crustal material induced by mafic (basaltic?) underplating, thus the PTGs record the initiation of subduction and the generation of the early magmas in the nascent Late Paleozoic Cordilleran arc in SW Laurentia.

Original languageEnglish
Article number105359
JournalApplied Geochemistry
Volume143
DOIs
StatePublished - Aug 2022
Externally publishedYes

Bibliographical note

Funding Information:
This research was funded by the Consejo Nacional de Ciencia y Tecnología (CONACyT) grants CB129370 and CB82518, and PAPIIT-UNAM grant IN116709 provided to Iriondo. Arvizu acknowledges to CONACyT for providing a scholarship (grant no. 32533) during his Master's Thesis at Posgrado de Ciencias de la Tierra-UNAM. Lozano acknowledges CONACyT for the support provided for the development of the LANGEM infrastructure at UNAM. We are very thankful to Jon Nourse (Cal Poly Pomona) for providing a few plutonic samples from Sierra Los Tanques and to Jim Budahn (USGS-Denver) for analyzing them for trace elements using INAA. Jesus García Flores, a former undergraduate student at Universidad Estatal de Sonora-Hermosillo, is greatly acknowledged for providing well-dated granitoid samples from Sierra Los Tanques to be analyzed for major and trace element geochemistry. Thin sections for petrographic studies were prepared by Juan Tomás Vázquez Ramírez and Oscar Aguilar Moreno at the Centro de Geociencias-UNAM Juriquilla. Finally, we really appreciate comments and reviews from both Michael Kersten (Executive Editor) and Arturo Barron-Diaz (Guest Editor), and from two anonymous reviewers that helped us improve the manuscript significantly.

Publisher Copyright:
© 2022 Elsevier Ltd

Keywords

  • Calc-alkaline granitic suites
  • Cordilleran continental arc
  • Mexico
  • NW Sonora
  • Permo-Triassic
  • Subduction magmatism

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