U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism

The coastal Sonora batholith comprises a series of Cretaceous granitoids that intruded a metasedimentary basement of possible Mesozoic age. They are partially covered by Tertiary volcanic flows and pyroclastic rocks. In order to elucidate the crystallization and cooling history of the granitoids, nine rock samples -were collected from Bahía Kino to Punta Tepopa. Eight samples dated by U-Pb zircon geochronology show that the Coastal Sonora batholith was emplaced during the Late Cretaceous, between 90.1 ± 1.1 and 69.4 ± 1.2 Ma. The interval of <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">20 Ma between the different stages of crystallization indicate that magmatism was relatively static within coastal Sonora, although the magmatic arc recorded an eastward migration as a whole during Cretaceous and Paleogene. In addition, three of these samples were also dated by 40Ar/39Ar in biotite and K-feldspar separates. Ages vary from <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">74 to 67 Ma in biotite and from -68 to 42 Ma in K-feldspar. We interpret these ages as the cooling progression of the batholith, associated with exhumation of the region before the Basin and Range extension. Furthermore, these results show a local trend towards younger ages to the north of the batholith, and they are in good agreement with the model of a general eastward migration of the Cretaceous-Tertiary magmatic arc in northwestern Mexico. In general, the available ages suggest that the arc moved slowly across Baja California between 140 and 105 Ma, and continued its eastward migration across the eastern portion of Baja California and Sonora between 105 and <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">60 Ma. According to the isotopic ages, the Coastal Sonora batholith would be the westernmost part of the Laramide magmatic event (<img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">90 - 40 Ma). Thus, on the basis of new and available geochronologic, petrographic, and geochemical data, we propose that the Coastal Sonora batholith and the eastern portion of the Peninsular Ranges batholith belong to a single magmatic arc, which was separated during the continental breakup and rifting of the Gulf of California in the Tertiary.

Saved in:
Bibliographic Details
Main Authors: Ramos-Velázquez,Ernesto, Calmus,Thierry, Valencia,Victor, Iriondo,Alexander, Valencia-Moreno,Martín, Bellon,Hervé
Format: Digital revista
Language:English
Published: Universidad Nacional Autónoma de México, Instituto de Geología 2008
Online Access:http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1026-87742008000200009
Tags: Add Tag
No Tags, Be the first to tag this record!
id oai:scielo:S1026-87742008000200009
record_format ojs
spelling oai:scielo:S1026-877420080002000092009-04-14U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatismRamos-Velázquez,ErnestoCalmus,ThierryValencia,VictorIriondo,AlexanderValencia-Moreno,MartínBellon,Hervé geochronology U-Pb 40Ar/39Ar Cretaceous-Tertiary magmatic arc Laramide Coastal Sonora batholith Mexico The coastal Sonora batholith comprises a series of Cretaceous granitoids that intruded a metasedimentary basement of possible Mesozoic age. They are partially covered by Tertiary volcanic flows and pyroclastic rocks. In order to elucidate the crystallization and cooling history of the granitoids, nine rock samples -were collected from Bahía Kino to Punta Tepopa. Eight samples dated by U-Pb zircon geochronology show that the Coastal Sonora batholith was emplaced during the Late Cretaceous, between 90.1 ± 1.1 and 69.4 ± 1.2 Ma. The interval of <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">20 Ma between the different stages of crystallization indicate that magmatism was relatively static within coastal Sonora, although the magmatic arc recorded an eastward migration as a whole during Cretaceous and Paleogene. In addition, three of these samples were also dated by 40Ar/39Ar in biotite and K-feldspar separates. Ages vary from <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">74 to 67 Ma in biotite and from -68 to 42 Ma in K-feldspar. We interpret these ages as the cooling progression of the batholith, associated with exhumation of the region before the Basin and Range extension. Furthermore, these results show a local trend towards younger ages to the north of the batholith, and they are in good agreement with the model of a general eastward migration of the Cretaceous-Tertiary magmatic arc in northwestern Mexico. In general, the available ages suggest that the arc moved slowly across Baja California between 140 and 105 Ma, and continued its eastward migration across the eastern portion of Baja California and Sonora between 105 and <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">60 Ma. According to the isotopic ages, the Coastal Sonora batholith would be the westernmost part of the Laramide magmatic event (<img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">90 - 40 Ma). Thus, on the basis of new and available geochronologic, petrographic, and geochemical data, we propose that the Coastal Sonora batholith and the eastern portion of the Peninsular Ranges batholith belong to a single magmatic arc, which was separated during the continental breakup and rifting of the Gulf of California in the Tertiary.info:eu-repo/semantics/openAccessUniversidad Nacional Autónoma de México, Instituto de GeologíaRevista mexicana de ciencias geológicas v.25 n.2 20082008-08-01info:eu-repo/semantics/articletext/htmlhttp://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1026-87742008000200009en
institution SCIELO
collection OJS
country México
countrycode MX
component Revista
access En linea
databasecode rev-scielo-mx
tag revista
region America del Norte
libraryname SciELO
language English
format Digital
author Ramos-Velázquez,Ernesto
Calmus,Thierry
Valencia,Victor
Iriondo,Alexander
Valencia-Moreno,Martín
Bellon,Hervé
spellingShingle Ramos-Velázquez,Ernesto
Calmus,Thierry
Valencia,Victor
Iriondo,Alexander
Valencia-Moreno,Martín
Bellon,Hervé
U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
author_facet Ramos-Velázquez,Ernesto
Calmus,Thierry
Valencia,Victor
Iriondo,Alexander
Valencia-Moreno,Martín
Bellon,Hervé
author_sort Ramos-Velázquez,Ernesto
title U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
title_short U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
title_full U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
title_fullStr U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
title_full_unstemmed U-Pb and 40Ar/39Ar geochronology of the coastal Sonora batholith: New insights on Laramide continental arc magmatism
title_sort u-pb and 40ar/39ar geochronology of the coastal sonora batholith: new insights on laramide continental arc magmatism
description The coastal Sonora batholith comprises a series of Cretaceous granitoids that intruded a metasedimentary basement of possible Mesozoic age. They are partially covered by Tertiary volcanic flows and pyroclastic rocks. In order to elucidate the crystallization and cooling history of the granitoids, nine rock samples -were collected from Bahía Kino to Punta Tepopa. Eight samples dated by U-Pb zircon geochronology show that the Coastal Sonora batholith was emplaced during the Late Cretaceous, between 90.1 ± 1.1 and 69.4 ± 1.2 Ma. The interval of <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">20 Ma between the different stages of crystallization indicate that magmatism was relatively static within coastal Sonora, although the magmatic arc recorded an eastward migration as a whole during Cretaceous and Paleogene. In addition, three of these samples were also dated by 40Ar/39Ar in biotite and K-feldspar separates. Ages vary from <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">74 to 67 Ma in biotite and from -68 to 42 Ma in K-feldspar. We interpret these ages as the cooling progression of the batholith, associated with exhumation of the region before the Basin and Range extension. Furthermore, these results show a local trend towards younger ages to the north of the batholith, and they are in good agreement with the model of a general eastward migration of the Cretaceous-Tertiary magmatic arc in northwestern Mexico. In general, the available ages suggest that the arc moved slowly across Baja California between 140 and 105 Ma, and continued its eastward migration across the eastern portion of Baja California and Sonora between 105 and <img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">60 Ma. According to the isotopic ages, the Coastal Sonora batholith would be the westernmost part of the Laramide magmatic event (<img border=0 src="../../../../../img/revistas/rmcg/v25n2/a9s1.jpg">90 - 40 Ma). Thus, on the basis of new and available geochronologic, petrographic, and geochemical data, we propose that the Coastal Sonora batholith and the eastern portion of the Peninsular Ranges batholith belong to a single magmatic arc, which was separated during the continental breakup and rifting of the Gulf of California in the Tertiary.
publisher Universidad Nacional Autónoma de México, Instituto de Geología
publishDate 2008
url http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S1026-87742008000200009
work_keys_str_mv AT ramosvelazquezernesto upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
AT calmusthierry upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
AT valenciavictor upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
AT iriondoalexander upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
AT valenciamorenomartin upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
AT bellonherve upband40ar39argeochronologyofthecoastalsonorabatholithnewinsightsonlaramidecontinentalarcmagmatism
_version_ 1756224881122344960