Ti-in-zircon thermometry and crystallization modeling support hot grenville granite hypothesis

D. P. Moecher, S. M. McDowell, S. D. Samson, C. F. Miller

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Quantitative modeling of crystallization histories using the program rhyolite-MELTS indicates that zircon crystallization in 1.0 to 1.2 Ga Grenville granitoids with Zr concentrations of 300-1200 ppm begins at 930-1000 °C, and always after onset of crystallization of most other phases (pyroxenes, feldspars, quartz, apatite, ilmenite). Zircon saturation temperatures, calculated from whole-rock compositions and Zr concentrations for modeled samples, range from 835 to 997 °C. Zircon in the two samples with the highest Zr (1201 and 829 ppm) analyzed by sensitive high-resolution ion microprobe (SHRIMP) yielded Ti contents of 10-77 ppm, corresponding to Ti-in-zircon temperatures as high as 1035 °C and 915 °C, respectively. These are among the highest Ti-in-zircon temperatures recorded in magmatic rocks. The modeling and SHRIMP data support the hypothesis that high-Zr Grenville granites are hot granites, and support tectonic models that invoke high-temperature (>900 °C) crustal conditions for generation of Grenville magmas.

Original languageEnglish (US)
Pages (from-to)267-270
Number of pages4
JournalGeology
Volume42
Issue number3
DOIs
StatePublished - 2014

ASJC Scopus subject areas

  • Geology

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