Isla San Pedro Nolasco as a Late Miocene intrusive record at the eastern margin of the Gulf of California: Insights from geological, geochemical and geochronological studies

L. A. Velderrain-Rojas, J. R. Vidal-Solano*, L. M. Alva-Valdivia, R. Vega-Granillo, M. López-Martinez

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Isla San Pedro Nolasco (ISPN) is a structural high bounded by inactive dextral oblique-slip faults in the east-central part of the Gulf of California rift zone and is composed of intrusive rocks not exposed on other Gulf of California islands. Here we present the reconnaissance results from geological mapping, as well as first geochemical and geochronological data for the ISPN intrusive complex. The intrusive rocks compose a sheet-like body of intermediate and felsic composition intruded by an intermediate and acidic dike swarm. All intrusive rocks (host and dikes) range in age from ca. 9 Ma to 10 Ma (40Ar/39Ar) and show a hydrous ferromagnesian mineral association (amphibole and biotite) with a calc-alkalic and transitional affinity. This hydrated mineralogical association has not been recognized in the coeval rocks along the onshore western margin of the North American plate (coastal Sonora). However, such hydrous mineralogical association is found in the coeval rift transitional volcanic rocks from the Baja California Microplate at Santa Rosalía and Bahía de Los Ángeles – Bahía de Las Ánimas. The ISPN continental block, at least 40 km long, has been pulled apart by transtensional faulting of the late Miocene Gulf of California shear zone before the westward migration of the North America-Pacific plate boundary at ca. 3–2 Ma. Eventually, ISPN became isolated as an island during the late Miocene flooding of the Gulf of California seaway.

Original languageEnglish
Article number101351
JournalGeoscience Frontiers
Volume13
Issue number3
DOIs
StatePublished - May 2022

Bibliographical note

Funding Information:
This work was developed as part of Velderrain-Rojas M.S. thesis and Postdoctoral fellowship at Universidad de Sonora. This research was supported by Grant #180784 from CONACyT (Mexico) and Grant USO315007364 from DCEN UNISON to J.R. Vidal-Solano. L.M. Alva-Valdivia appreciates the financial support from PAPIIT-DGAPA-UNAM internal project IN101521. We thank M. Garcia Barrios, D. A. Lucero Acosta and J. A Cruz Obezo for his help in the field. Thanks also to Dr. D. Gimeno and technicians F. Menéndez, M. González, S. Mass, M. Romero and C. Fita from Centros Científicos y Tecnológicos, Universitat de Barcelona, who prepared the samples for geochemical analysis. M. García García y S. Rosas Montoya of CICESE participated in the 40 Ar- 39 Ar analysis. To Domingo de Jesús Zatarain González and Jesús Ventura Trejo from APFF-Islas del Golfo de California-Sonora de la Comisión Nacional de Áreas Naturales Protegidas (CONANP). The authors thank Don Abel Anaya for his great support in the trip to the ISPN and lodging in San Carlos, V. Lopez-Osuna for polishing the English writing of this paper. Finally, S. Bennett is greatly thanked for his constructive comments and suggestions to this work. M. Darin, M. Oskin, an anonymous reviewer, and the editor Stijn Glorie are also thanked for their kind suggestions to improve the MS.

Funding Information:
This work was developed as part of Velderrain-Rojas M.S. thesis and Postdoctoral fellowship at Universidad de Sonora. This research was supported by Grant #180784 from CONACyT (Mexico) and Grant USO315007364 from DCEN UNISON to J.R. Vidal-Solano. L.M. Alva-Valdivia appreciates the financial support from PAPIIT-DGAPA-UNAM internal project IN101521. We thank M. Garcia Barrios, D. A. Lucero Acosta and J. A Cruz Obezo for his help in the field. Thanks also to Dr. D. Gimeno and technicians F. Men?ndez, M. Gonz?lez, S. Mass, M. Romero and C. Fita from Centros Cient?ficos y Tecnol?gicos, Universitat de Barcelona, who prepared the samples for geochemical analysis. M. Garc?a Garc?a y S. Rosas Montoya of CICESE participated in the 40Ar-39Ar analysis. To Domingo de Jes?s Zatarain Gonz?lez and Jes?s Ventura Trejo from APFF-Islas del Golfo de California-Sonora de la Comisi?n Nacional de ?reas Naturales Protegidas (CONANP). The authors thank Don Abel Anaya for his great support in the trip to the ISPN and lodging in San Carlos, V. Lopez-Osuna for polishing the English writing of this paper. Finally, S. Bennett is greatly thanked for his constructive comments and suggestions to this work. M. Darin, M. Oskin, an anonymous reviewer, and the editor Stijn Glorie are also thanked for their kind suggestions to improve the MS.

Publisher Copyright:
© 2022 China University of Geosciences (Beijing)

Keywords

  • Gulf of California
  • Intrusive rocks
  • Isla San Pedro Nolasco
  • PAC-NAM plate boundary

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