SELECTED ELASTIC-MODULI AND THEIR TEMPERATURE DERIVATIVES FOR OLIVINEAND GARNET WITH DIFFERENT MG (MG+FE) CONTENTS - RESULTS FROM GHZ ULTRASONIC INTERFEROMETRY/
Gl. Chen et al., SELECTED ELASTIC-MODULI AND THEIR TEMPERATURE DERIVATIVES FOR OLIVINEAND GARNET WITH DIFFERENT MG (MG+FE) CONTENTS - RESULTS FROM GHZ ULTRASONIC INTERFEROMETRY/, Geophysical research letters, 23(1), 1996, pp. 5-8
Selected P-wave acoustic travel times through single crystal samples o
f olivine and garnet with different Mg/(Mg+Fe) ratios were measured at
elevated temperatures (from 293 K to 363 K) using a newly developed G
Hz ultrasonic interferometer. These high precision data allow us to ex
amine aspects of the elasticity-composition systematics of olivine (fo
rsterite-fayalite) and garnet (pyrope-almandine) solid solution series
. For every 10% decrease in the Mg/(Mg+Fe) content, the P-velocity of
olivine along the b-axis decreases about 3% and partial derivative lnC
(22)/partial derivative T decreases about 7%; for garnet partial deriv
ative lnright perpendicularC(44) + (C-11 + C-12)/2left perpendicular/p
artial derivative T decreases about 6%. If such velocity-composition s
ystematics are typical and hold at the P-T regime of the mantle, only
a 3-4% variation in the Mg/(Mg+Fe) content of olivine is required to e
xplain the lateral seismic velocity variation in the upper portion of
the mantle within one tectonic region (dlnVp similar to 1%), and 7-8%
variation in the Mg/(Mg+Fe) content to explain the 2% lateral seismic
velocity variation of the upper mantle globally.