Petrographic Characteristics
of Mt. Erebus Lava Flows


Generalized petrographic summary of Mt. Erebus volcanic rocks    
(from Kyle et al., 1992)
                   
Rock Type Texture Ol Cpx Kaer Op Fsp Ap Fspth Groundmass
                   
Basanite fp(10-25) p, x p   p p p g p, I
Ne hawaiite fp(1-20) or p, po r-p, po r, po, x? p p p r-g I, p or gl-h
cp(20-50)               2c, 2o
Ne mugearite cp(20-30) p, po p, po   p p p g I, p, 2o
Ne benmoreite cp(20-50) p, po, x r-p   p p p g I, p or gl
Anorthoclase phonolite cp(30-60) p p   p p p r-g I, p or
                gl-h, c
Benmoreite mp(10-20) p, po, x r-p r-p, po p p-x r   t or gl, c
Phonolite mp(3-10) or r-p, x r-g r-p r-p p-x r g t or h-I, p
p(10-15)     po-co          
Trachyte mp(<5) g-x p   p p     t
                   
Abbreviations:                  
Texture: p-porphyritic; mp-microporphyritic; fp-finely porphyritic; cp-coarsely porphyritic;

percentage of phenocrysts to nearest 5% is given in parenthesis.
Mineralogy: Ol-olivine; Cpx-clinopyroxene; Kaer-kaersutite; Op-opaque oxides; Fsp-feldspar; Ap-apatite; Fspth-feldspathoids;

p-present (>1%); r-rare (<1%); x-xenocrystic; po-partially oxidized; co-completely oxidized; g-groundmass only.
Groundmass: I-intersertal; p-pilotaxitic; gl-glassy; h-hyalophitic; c-cryptocrystalline; t-trachytic;

2c-secondary carbonate; 2o-secondary oxidation.

  

We hope to have more petrographic information on Mt. Erebus volcanic rocks soon, including some digital photos of thin sections.

 

 

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