Evolution of granitoids in the Catalina metamorphic core complex, southeastern Arizona: U-Pb, Nd, and Hf isotopic constraints

Katherine F. Fornash, P. Jonathan Patchett, George E. Gehrels, Jon E. Spencer

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

The Santa Catalina Mountains, SE Arizona, was one of the first metamorphic core complexes to be described. Despite its status as a type example, relatively little is known about precise ages and origins of the intrusive rocks that make up most of the crystalline core. U-Pb and Hf isotopic data by laser ablation-inductively coupled plasma-mass spectrometry from zircons and Nd isotopic results from whole rocks were obtained for 12 granitoids ranging from 1,440 to 26 Ma. Results confirm that the 1.44-Ga Oracle Granite extends through the Catalina Range as variably mylonitic granite and banded gneiss. Laramide intrusions (67-73 Ma) display initial εNd values -5 to -8 and εHf from -7.5 to -9. Magmatic ages for the prominent white granite sills of the Wilderness suite are 46-57 Ma, in agreement with Terrien (2012), and these granites have initial εNd values -8 to -10 and εHf from -7 to -14. Lastly, the undeformed Catalina Granite has an age of 26 Ma, with an initial εNd and εHf of -6 and -8, respectively. Our Nd results agree with limited results from Farmer and DePaolo (89:10141-10160, 1984). Although the Catalina Granite seems to have a significant juvenile component based on Nd and Hf, most of the Laramide and Wilderness intrusions contain Nd and Hf compositions lying close to the evolution of 1.44-Ga Oracle Granites, a fact that is confirmed by the U-Pb data, which show both 1.7- and 1.4-Ga zircon cores in these samples, with 1.4 Ga as the dominant core age. In order to become the dominant source of most of the 72-45-Ma magmas, the Oracle pluton must not only extend across the whole Catalina region, but also have abundant deep-seated equivalents to provide magma sources.

Original languageEnglish (US)
Pages (from-to)1295-1310
Number of pages16
JournalContributions to Mineralogy and Petrology
Volume165
Issue number6
DOIs
StatePublished - Jun 1 2013

Keywords

  • Granite origins
  • Hafnium isotopes
  • Neodymium isotopes
  • Santa Catalina metamorphic core complex
  • U-Pb ages

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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