Biotites from granitic rocks of the central Sierra Nevada batholith, California

Journal of Petrology
By: , and 



Biotites from plutonic rocks of the central Sierra Nevada and Inyo Mountains, California, have been examined and characterized by powder X-ray diffraction and optical and chemical methods.

Compositions of the biotites define a trend in the compositional triangle Fe+3 Fe+2Mg. When related to the experimentally studied ternary system KFe3+3AlSisO12H-1-KFe3+2 AlSi3O10(OH)2-KMg3AlSi3O10(OH)2 and coupled with the estimated positions of biotite solid solutions for different oxygen buffers, the trend suggests that oxygen fugacities in magmas during biotite crystallization were slightly higher than those defined by the Ni-NiO buffer. The compositional data also suggest that magmas were ‘buffered’ with respect to oxygen by oxides existing within the magmas themselves.

Correlation between the Fe/(Fe+Mg) ratio, an inferred temperature indicator, and other elements is generally poor, which suggests that factors other than temperature at the time of crystallization exerted an important influence on compositions.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Biotites from granitic rocks of the central Sierra Nevada batholith, California
Series title Journal of Petrology
DOI 10.1093/petrology/10.2.250
Volume 10
Issue 2
Year Published 1969
Language English
Publisher Oxford University Press
Description 22 p.
First page 250
Last page 271
Country United States
State California
Other Geospatial Inyo Mountains, Sierra Nevada, Sierra Nevada batholith
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